



COURT OF APPEAL FOR ONTARIO

CITATION: Hacopian-Armen Estate v. Mahmoud,
    2021 ONCA 545

DATE: 20210729

DOCKET: C68655

Strathy C.J.O., Feldman and
    Sossin JJ.A.

BETWEEN

Armen
    Hacopian-Armen as Litigation Administrator for the Estate of Armineh
    Hacopian-Armen, deceased, Armen Hacopian-Armen as Estate Trustee for the Estate
    of Vrijouhi Casper, deceased and Armen Hacopian-Armen,
personally

Plaintiffs (Respondents)

and

Dr. Haidar Mahmoud
, Dr. Hassan Deif, Dr. Neil Isaac,

and North York General Hospital

Defendant (
Appellant
)

Kosta Kalogiros and Brittany Cerqua,
    for the appellant

Christopher I.R. Morrison and Paul J.
    Cahill, for the respondents

Heard: May 20, 2021 by video conference

On appeal from the judgment of Justice Carole
    J. Brown of the Superior Court of Justice, dated August 19, 2020, with reasons
    reported at 2020 ONSC 4946.

Strathy C.J.O.:

A.

BACKGROUND

[1]

This appeal raises issues of factual and legal
    causation in the context of a medical negligence action.

[2]

Armineh died on August 24, 2011, as a result of Stage IV uterine leiomyosarcoma ("uLMS"), which had metastasized to her lungs. The respondents, members of her family, brought this action against the appellant, her gynecologist. They alleged that the appellant was negligent when he examined Ms. Hacopian-Armen on May 25, 2009, in failing to conduct an endometrial biopsy, a simple in-office procedure for the detection of uterine pathologies and abnormalities. The respondents claimed that this would probably have detected her cancer at an early stage, when treatment would likely have been effective.

[3]

The trial judge found that: the appellant
    breached the applicable standard of care; Ms. Hacopian-Armen and family members
    had suffered damages as a result; the damage was foreseeable; and the
    appellants negligence was causative of the damages.

[4]

On appeal, the appellant does not challenge the
    trial judges finding that he breached the standard of care by failing to
    perform an endometrial biopsy. He alleges, however, that the trial judge erred
    in concluding that his breach of duty caused Ms. Hacopian-Armens death.

B.

FACTS

[5]

To appreciate the issues in this appeal, it is
    necessary to understand the nature and progress of Ms. Hacopian-Armens condition
    and the course of treatment she received.

[6]

Ms. Hacopian-Armen was diagnosed with fibroids
    in 1999. Fibroids, also called leiomyoma, are benign, non-cancerous growths
    that develop in smooth muscle tissues. Uterine fibroids develop in the
    myometrium, the smooth muscle of the uterus. Fibroids are common, but the
    majority are asymptomatic  they are frequently very small and cause no problems.
    They can, however, grow to a significant size, and their size and location can
    cause pain, heavy bleeding and other symptoms. Fibroids can be treated in
    several ways, including a procedure known as uterine artery embolization, in
    which the blood supply to the fibroid is restricted, causing it to shrink and
    the symptoms to subside.

[7]

Counsel called uLMS the evil twin of fibroids.
    It is a rare form of cancer that, like fibroids, also originates in the
    myometrium. It has features similar to fibroids and cannot be distinguished
    from fibroids on imaging. For that reason, it frequently goes undetected. It is
    a very aggressive form of cancer and there is often a poor prognosis when it is
    discovered.

[8]

The uterus has a hollow inner cavity. The
    interior lining of the uterus is called the endometrium. It, in turn, is
    surrounded by the muscular wall of the myometrium.

[9]

An endometrial biopsy was described by the
    experts as a simple procedure that can be done in a gynecologists office and
    takes only a minute or two. A narrow, straw-like instrument, called a cannula
    or pipelle is inserted through the cervix into the uterine cavity. There, it
    can be manipulated to suction out a small sample of tissue. The tissue sample can
    then be tested to detect the presence of uterine malignancies or abnormalities,
    including uterine and endometrial cancers. Depending on certain conditions,
    discussed by the experts at trial, it may also detect uLMS.

[10]

In 2004, some five years after the diagnosis of
    her fibroids, Ms. Hacopian-Armen began to experience heavy bleeding, with
    clots, during her menstrual periods. This bleeding lasted approximately two
    weeks each month. In 2009, her family physician referred her to the appellant for
    treatment.

[11]

At her first appointment with the appellant on May
    25, 2009, she presented with what the respondents experts described as several
    risk factors for diseases of the uterus and intrauterine pathology: she was
    over 40 years old (in fact, she was 47); she was experiencing abnormal uterine
    bleeding (AUB); and she was nulliparous  she had never given birth to a
    child. The appellant took a vaginal swab but did not perform an endometrial
    biopsy. He referred her to another physician to discuss the possibility of
    treating her fibroids with uterine artery embolization.

[12]

A few months after her first appointment with
    the appellant, Ms. Hacopian-Armen began to experience several health problems.
    In August 2010, she visited the emergency room four times because she felt
    weak, had heart palpitations, or was short of breath. These visits to the ER
    led to a variety of tests, which revealed that she had deep vein thrombosis (DVT)
    and pulmonary nodules.

[13]

In February 2011, two new lung nodules were
    discovered during a CT scan. In March 2011, Ms. Hacopian-Armen met with a
    specialist in respiratory and internal medicine at North York General Hospital.
    The specialist noted that her recurrent DVT and the new lesions on her lungs
    indicated that she possibly had cancer. The specialist sent a consultation
    request to the appellant indicating that she needed a Pap test as soon as
    possible.

[14]

On April 7, 2011, the appellant performed an
    endometrial biopsy, which indicated that Ms. Hacopian-Armen had a high-grade
    cancerous tumour in her uterus, likely uLMS. At this point, her cancer had
    metastasized to Stage IV.

[15]

In May 2011, Ms. Hacopian-Armen had a
    hysterectomy and began chemotherapy. Despite these treatments, the disease
    progressed. Ultimately, she died on August 24, 2011.

C.

THE TRIAL JUDGES REASONS

(1)

Overview

[16]

There were three issues before the trial judge:
    the standard of care, factual causation, and legal causation. The trial judge
    concluded at para. 156 that: (i) the appellant breached the standard of care
    that he owed to Ms. Hacopian-Armen by failing to perform an endometrial biopsy;
    (ii) a biopsy performed at the first appointment on May 25, 2009 would have
    detected the uLMS and thus significantly improved her prognosis; and (iii) the
    harm that occurred was foreseeable and related to the appellants failure to
    perform the biopsy.

[17]

I will explain the trial judges analysis and
    conclusions on each of these three issues, but first I will explain the role of
    expert evidence at the trial.

(2)

Expert Witnesses

[18]

The trial judges acceptance of the evidence of
    the respondents experts, in preference to that of the appellants experts,
    figured large in her findings of fact: at para. 90. The respondents experts
    provided opinions on the standard of care, causation, and the identification of
    metastatic disease. While the appellant contested the respondents submissions
    on the standard of care, he led no evidence on this issue. His experts only
    provided opinions on causation. I will identify the principal experts.

(a)

Respondents Experts

[19]

Dr. Allan Covens was a specialist in
    gynecological oncology  that is, the diagnosis and treatment of cancers of the
    female reproductive system. He held the position of Chair of the Division of
    Gynecologic Oncology in the Department of Obstetrics and Gynecology at the
    University of Toronto. He was also the head of the Division of Gynecologic
    Oncology at the Odette Cancer Centre at Sunnybrook Hospital in Toronto. He runs
    a weekly gynecology-oncology clinic, which investigates AUB, among other things.
    He was qualified to give evidence on the issues of standard of care and
    causation.

[20]

Dr. Andrew Browning was an obstetrician and
    gynecologist with some 27 years experience. He had served for two years as
    Chief of Obstetrics and Gynecology at the Royal Victoria Hospital Regional
    Health Centre in Barrie, Ontario. He had extensive experience treating fibroids
    and AUB. He was qualified to give evidence on the issues of standard of care
    and causation.

(b)

Appellants Experts

[21]

Dr. George Vilos was an obstetrician and
    gynecologist with a primary appointment as a gynecologist in the Department of
    Obstetrics and Gynecology at the London Health Sciences Centre. He was also a
    professor in the Department of Obstetrics and Gynecology at the Schulich School
    of Medicine at the University of Western Ontario. He gave evidence in relation
    to causation and the likelihood of detecting uLMS with an endometrial biopsy.

[22]

Dr. Nicholas Leyland was a specialist in
    gynecological oncology, focusing on general gynecology. His evidence was
    confined to the likelihood of detecting uLMS with an endometrial biopsy.

[23]

Dr. Jason Dodge had been a gynecological
    oncologist until August 2015 and, at the time of trial, had been practicing
    gynecology in general practice. He was qualified to give evidence on causation.

(c)

The Trial Judges Assessment of the Expert Evidence

[24]

The trial judge specifically commented on the
    credibility of the experts, all of whom were well qualified in their fields.
    She found the evidence of the respondents experts, Dr. Browning and Dr. Covens,
    to be forthright, impartial and consistent and found their testimony to be
    credible.

[25]

In contrast, while the trial judge found the
    appellants experts to be knowledgeable, she found their evidence in
    cross-examination contradicted their evidence-in-chief, they were less than
    forthright in cross-examination and were argumentative.

[26]

At para. 90 of her reasons, she explained that
    she preferred the evidence of the respondents experts:

Based on the evidence, the medical records,
    the agreed statements of fact, the reports and testimony of the experts, where
    there is a discrepancy between the testimony of the plaintiffs experts and the
    testimony of the defendants experts, I prefer the evidence of the plaintiffs
    experts, unless I state otherwise.


[27]

As I will explain, in an appeal that is largely
    fact-based, the trial judges assessment of the frequently conflicting evidence
    of experts is entitled to deference in the absence of palpable and overriding
    error.

[28]

Against this background, I turn to the trial
    judges findings in relation to the issues before her.

(3)

Part I: The Standard of Care

[29]

The trial judge first considered whether the
    appellant breached the applicable standard of care by failing to perform an
    endometrial biopsy. At para. 104 of her reasons, she set out the standard of
    care as that of a reasonable and prudent physician of the same experience and
    standing, having regard to all the circumstances of the case.

[30]

The trial judge found that the appellant had
    breached the standard of care by failing to consider and perform an endometrial
    biopsy as recommended by the Guidelines of the Society of Obstetricians and
    Gynecologists of Canada for the Management of AUB (the Guidelines). The
    Guidelines recommended an endometrial biopsy for patients over 40 who
    experienced AUB, in order to rule out abnormal pathologies. Ms. Hacopian-Armen presented
    with both risk factors.

[31]

The appellant argued that he did not contravene
    the Guidelines because Ms. Hacopian-Armen did not have AUB. Without this risk
    factor, he contended, a biopsy was not required. The appellant submitted that she
    did not have AUB because her menstrual period occurred regularly, every two
    weeks, and the heavy bleeding was attributable to her fibroids. The trial judge
    rejected this submission. Ms. Hacopian-Armens heavy bleeding began five years
    after she was diagnosed with fibroids. The trial judge accepted the respondents
    experts opinion that two weeks of heavy bleeding per month was highly abnormal:
    at para. 115.

(4)

Part II: Factual Causation

[32]

The trial judges causation analysis turned on
    three questions, set out at para. 96 of her reasons:

1.

Did Ms. Hacopian-Armen have uLMS at the time of
    her first appointment with the appellant on May 25, 2009?

2.

If so, would an endometrial biopsy performed on
    May 25, 2009 have detected abnormal pathology or uLMS?

3.

If so, would her prognosis likely have been
    substantially improved as a result?

[33]

Both of the respondents experts opined that Ms.
    Hacopian-Armen likely had Stage I uLMS on May 25, 2009: at para. 149.

[34]

Dr. Browning testified that her AUB in May 2009
    was likely caused by the presence of cancerous cells in her uterus. Both Dr.
    Browning and Dr. Covens testified that uLMS was likely present on May 25, 2009
    because the cancer had reached Stage IV by April 2011. The trial judge accepted
    this evidence: at para. 149.

[35]

The trial judge also accepted the respondents
    experts opinions that an endometrial biopsy performed on May 25, 2009 would
    have likely detected abnormal pathology or uLMS: at para. 146. The medical
    literature explained that the sensitivity for the detection of uLMS is
    increased in patients who are menopausal. Dr. Browning and Dr. Covens testified
    that, in their opinion, women who are nulliparous have a much greater likelihood
    of early menopause and Ms. Hacopian-Armen was probably close to menopause. The
    trial judge accepted this evidence and found that Ms. Hacopian-Armen was
    hormonally closer to post-menopause than pre-menopause given her age and the
    fact that she was nulliparous: at para. 146.

[36]

The appellant relied on scientific studies to
    argue that it was unlikely that an endometrial biopsy could have detected the uLMS
    because imaging from 2009 showed that the uLMS had not yet broken through the
    endometrium into the uterine cavity. The trial judge rejected this argument, accepting
    the evidence of the respondents experts that it was likely that uLMS was in or
    near the endometrium, causing AUB, which would further increase the likelihood
    of detection.

[37]

Finally, the trial judge found that Ms.
    Hacopian-Armens prognosis would have been substantially improved if the uLMS had
    been found and treated in 2009: at para. 150. The trial judges conclusion was,
    again, largely based on the evidence of the respondents experts. Dr. Browning
    noted that early intervention would have likely included a hysterectomy, which
    would have removed the cancer that had not yet metastasized to the rest of the
    body. Dr. Covens testified that treatment for the Stage I uLMS in 2009 would have
    effectively been a cure.

[38]

Having found that she likely had uLMS at her
    first appointment with the appellant, that an endometrial biopsy would have
    likely detected abnormal uterine pathology or uLMS, and that her prognosis
    would have been substantially improved, the trial judge concluded that the
    respondents had proved factual causation on a balance of probabilities. In
    other words, but for the appellants failure to perform the biopsy in May 2009,
    Ms. Hacopian-Armen would probably not have died of Stage IV uLMS.

(5)

Part III: Legal Causation

[39]

On the third and last issue of legal causation,
    the trial judge considered whether Ms. Hacopian-Armens death was foreseeable
    and sufficiently connected to the appellants failure to perform an endometrial
    biopsy. She found that the risk of uLMS was real, and that it was not something
    that a reasonable, skilled, specialist would have brushed aside as
    far-fetched: at para. 155. She also concluded that it was foreseeable that the
    presence of uLMS, if not treated, would likely result in serious injury or
    death.

(6)

Part IV: Disposition and Damages

[40]

As a result of her findings, the trial judge
    held, at para. 157, that the appellant was liable for his negligence. The
    respondents were awarded $300,000 in damages.

D.

issues on appeal

[41]

The appellant does not challenge the trial
    judges finding that he breached the standard of care by failing to perform an
    endometrial biopsy. He does, however, allege several errors in the trial
    judges analysis and conclusions on legal and factual causation.

(1)

Legal Causation

[42]

The appellant acknowledges that the trial judge
    correctly identified the principles of legal causation set out at para. 155 of
    her reasons. He submits, however, that her analysis was inconsistent with these
    principles and that she erred by engaging in a retrospective approach to
    causation. He asserts that the trial judge erred by asking whether it was
    foreseeable that the presence of uLMS, if untreated, would lead to serious
    injury or harm. According to the appellant, the correct question was whether
    uLMS, specifically, was foreseeable in May 2009.

[43]

To answer this question, the appellant submits
    that the trial judge should have asked whether it would occur to a reasonable
    gynecologist that: (i) Ms. Hacopian-Armen had uLMS in May 2009; (ii) an
    endometrial biopsy would have diagnosed uLMS; and (iii) not performing an
    endometrial biopsy in May 2009 could lead to a delayed diagnosis of uLMS.

[44]

The appellant also submits that the trial
    judges erroneous approach to legal causation would create a dangerous
    precedent, resulting in an increase of retrospective claims and would overburden
    the medical system by encouraging physicians to order unnecessary tests to
    avoid the risk of missing an unforeseeable disease.

(2)

Factual Causation

[45]

The appellant submits that the trial judge
    committed two reviewable errors in her analysis and conclusion on factual
    causation. First, he alleges that the trial judge erred when she found that
    uLMS was likely present in May 2009. According to the appellant, that error has
    three components: (i) admitting Dr. Covenss testimony, despite the fact that his
    expert report did not comply with Rule 53.03 of the
Rules of Civil Procedure
;
    (ii) misapprehending Dr. Covenss and Dr. Brownings testimony on this issue
    and concluding that uLMS was likely present, despite the fact that there was no
    evidence to support that conclusion; and (iii) in stating, at para. 152, that
    the defendants submit that there is
no proof
that
    uLMS was present on May 25, 2009 (emphasis added), when this did not reflect
    the appellants position. The appellants expert, Dr. Vilos, testified that the
    evidence showed that it was
unlikely
that uLMS was
    present in 2009, not that there was no proof. This misapprehension, the
    appellant says, went to the core of the defence theory on the absence of uLMS.

[46]

Second, the appellant alleges that the trial
    judge erred in finding that an endometrial biopsy would have likely detected
    uLMS in 2009. He submits that a single paragraph of the trial judges reasons
    contains five palpable and overriding errors. I will identify and discuss these
    in the analysis section below.

[47]

Ultimately, the appellant argues that the trial
    judges reasons were overwhelmed by these factual and analytical errors. The
    appellant asks that the trial decision be set aside, and the claim dismissed or
    that a new trial be ordered.

E.

ANALYSIS

[48]

While the
issues on this
    appeal relate to the trial judges conclusion on factual and legal causation,
    it is helpful to situate those issues in the context of the negligence
    analysis.

[49]

A plaintiff asserting a claim in negligence must
    establish four things: (a) that the defendant owed the plaintiff a duty of
    care; (b) that the defendants conduct breached the applicable standard of
    care; (c) that the plaintiff sustained damage; and (d) that the defendant
    caused the damage in fact (factual causation) and in law (legal causation):
Mustapha v. Culligan of Canada Ltd.
,
    2008 SCC 27, [2008] 2 S.C.R. 114, at para. 3.

[50]

There was no dispute at the trial about the existence
    of a duty of care, since Ms. Hacopian-Armen had been referred to the appellant
    for treatment of her fibroids. Nor was it disputed that she and her family
    members had suffered compensable damages, which were recoverable if negligence
    were established. The applicable standard of care and whether it had been
    breached, was very much in issue, as was causation.

[51]

The standard of care and its breach took up a
    considerable amount of time at trial. Although the appellant did not adduce
    expert evidence on these issues, he challenged the evidence of the respondents
    experts, Dr. Covens and Dr. Browning. They testified that having regard to Ms.
    Hacopian-Armens AUB  heavy bleeding, with blood clots, for over 14 days each
    month  her age (47), and the fact that she was nulliparous, all of which
    increased the risk of some form of uterine pathology, an endometrial biopsy should
    have been performed to rule out uterine pathologies or other abnormalities that
    could have been causing her AUB.

[52]

The appellants evidence was that he assumed that her bleeding
    was attributable to her fibroids, did not consider that there could be other
    potential causes of her bleeding and, on those assumptions, did not conduct an
    endometrial biopsy.

[53]

The trial judge accepted the evidence of the
    respondents expert witnesses and found that the standard of care required an
    endometrial biopsy in such circumstances. She also found that the appellant had
    breached that standard.

[54]

Although the evidence concerning Ms. Hacopian-Armens age,
    nulliparous state and abnormal bleeding was relevant to standard of care, it
    was also relevant to legal and factual causation because, in the opinion of Dr.
    Browning and Dr. Covens, it meant that she was probably close to menopause,
    making it more likely that an endometrial biopsy would detect her cancer.

(1)

First
ground
of appeal:
    Did the trial judge err in finding legal causation?

[55]

The appellant does not dispute that the trial judge
    identified the appropriate test for legal causation. Referring to
Mustapha
,

the trial judge
    set out at para. 126 that the plaintiff must establish that the injuries
    suffered were foreseeable or not too remote:

[I]t must be
    determined whether the harm is too unrelated to the wrongful conduct to hold
    the defendant fairly liable. The injury must have been a real risk which could
    occur to the mind of a reasonable man in the position of the defendant  and
    which he would not brush aside as far-fetched.


[56]

The trial judges findings on legal causation were
    summarized at para. 155 of her reasons:

In this case, I am satisfied that having
    failed to conduct an endometrial biopsy on the plaintiff at the first consultation
    which would have detected whether there was LMS present, it was foreseeable
    that the presence of LMS, if not treated, would likely result in serious injury
    or death to the plaintiff, which indeed, it did. I do not find the risk to be
    something that a reasonable, skilled, specialist would have brushed aside as
    far-fetched. Accordingly, I am satisfied that legal causation has also been
    established.

[57]

The appellant submits the trial judge asked herself
    the wrong question and assessed causation with the benefit of hindsight,
    improperly blending her factual findings with her legal analysis. He submits
    that the question should have been whether it was foreseeable to a reasonable
    gynecologist that (a) Ms. Hacopian-Armen had uLMS in May 2009; (b) an endometrial
    biopsy would have diagnosed the uLMS; and (c) not performing an endometrial
    biopsy could lead to a delayed diagnosis of uLMS. Relying on the observations
    of Nash J. in
Tilley v. Man Roland Canada
, 1999 ABQB 364, affd
    2002 ABCA 309, at para. 183, the appellant submits that [o]ne cannot now, in
    hindsight, review the circumstances and conclude, based on the fact of the
    accident, that it was reasonably foreseeable or ought to have been foreseeable.
    The appellant submits that uLMS is a rare form of uterine cancer, it was not
    foreseeable and the harm to Ms. Hacopian-Armen was too remote to fairly hold
    him liable.

[58]

I accept the appellants submission that the trial
    judge inappropriately blended into her foreseeability analysis her finding of
    fact that an endometrial biopsy performed in May 2009 would have detected the
    presence of uLMS. The foreseeability analysis ought to have focused on the
    information reasonably available to the appellant in May 2009, when he failed
    to conduct an endometrial biopsy. However, on the correct analysis, it did not
    matter that the appellant was not aware that Ms. Hacopian-Armen had uLMS  what
    mattered was that the combination of her AUB, her age, and her nulliparous
    state, not only required an endometrial biopsy, but also made it reasonably
    foreseeable that the failure to conduct one would preclude detection of a
    uterine pathology that would cause her serious harm if left untreated.

[59]

The appellants proposed foreseeability analysis is
    flawed because in focusing on the presence of
uLMS
, he inappropriately narrows the scope of
    the risk that he ought to have foreseen. The appellant was not required to
    foresee the presence of uLMS or the precise concatenation of events:
R. v. Coté et al.
, [1976] 1 S.C.R. 595, at p. 604. It is
    sufficient that the harm suffered must be of a kind, type or class that was
    reasonably foreseeable as a result of the defendants negligence:
Frazer v. Haukioja
, 2010 ONCA 249, 101
    O.R. (3d) 528, at para. 51.
In failing to conduct a test that would have detected
    the presence of cancers of the same class or character as uLMS, including
    uLMS, it was foreseeable that uLMS or other malignancies would go undetected,
    with consequent injury to Ms. Hacopian-Armen:
Ter Neuzen v. Korn
, [1995] 3 S.C.R. 674, at para. 60.

[60]

Based on the evidence accepted by the trial judge as
    to the circumstances that Ms. Hacopian-Armen presented with in May 2009, it was
    foreseeable to a reasonable gynecologist of the same experience and standing
    that the failure to perform an endometrial biopsy could preclude the detection
    of a uterine pathology or abnormality, which could lead to serious injury or
    death.

[61]

I reject the appellants submission that the trial
    judges approach to foreseeability would require physicians to order
    unnecessary tests. The evidence accepted by the trial judge was that in the
    circumstances that presented themselves to the appellant on May 25, 2009, an
    endometrial biopsy was a
necessary
test and one
    that should have been performed by a competent gynecologist.

[62]

I would therefore reject the first ground of appeal.

(2)

Second ground of
    appeal: Did the trial judge err in finding factual causation?

[63]

The appellant submits that the trial judge erred in
    finding factual causation  that is, on a balance of probabilities, but for
    the defendants negligence, the injury would not have occurred:
Clements v. Clements
, 2012 SCC 32,
    [2012] 2 S.C.R. 181, at para. 8.

[64]

There are two branches to the appellants submission.
    The first branch, discussed in sub-section (a), below, asserts that the trial
    judge erred in finding that uLMS was likely present in May 2009. This branch
    has three parts, identified below. The second branch, discussed in sub-section
    (b), is that the trial judge erred in finding that an endometrial biopsy would
    have detected uLMS, had it been present.

[65]

To a considerable extent, these submissions challenge
    the trial judges findings of fact or assert that the trial judge
    misapprehended certain evidence. For that reason, I begin with the applicable
    standard of review.

[66]

A trial judges findings of fact are entitled to
    deference, particularly where those findings are based on findings of
    credibility in relation to conflicting evidence. As the Supreme Court observed
    in
Housen v. Nikolaison
, 2002 SCC 33,
    [2002] 2 S.C.R. 235, at para. 36:

To summarize, a finding of negligence by a
    trial judge involves applying a legal standard to a set of facts, and thus is a
    question of mixed fact and law. Matters of mixed fact and law lie along a spectrum.
    Where, for instance, an error with respect to a finding of negligence can be
    attributed to the application of an incorrect standard, a failure to consider a
    required element of a legal test, or similar error in principle, such an error
    can be characterized as an error of law, subject to a standard of correctness. Appellate
    courts must be cautious, however, in finding that a trial judge erred in law in
    his or her determination of negligence, as it is often difficult to extricate
    the legal questions from the factual. It is for this reason that these matters
    are referred to as questions of mixed law and fact. Where the legal principle
    is not readily extricable, then the matter is one of mixed law and fact and
    is subject to a more stringent standard. The general rule is that, where the
    issue on appeal involves the trial judges interpretation of the evidence as a
    whole, it should not be overturned absent palpable and overriding error.
    [Citations omitted.]

[67]

That principle applies where, as here, the trial judge
    makes factual findings based on the assessment of the credibility of experts
    called by one party and rejection of the evidence of the other partys experts:
Lapointe v. Hôpital Le Gardeur
, [1992] 1 S.C.R.
    351, at paras. 16-23;
Waxman v. Waxman
, 2004 CanLII
    39040 (Ont. C.A.), at paras. 300-1, leave to appeal refused, [2004] S.C.C.A.
    No. 291. The trial judge explicitly found the evidence of the respondents
    expert witnesses, notably Dr. Browning and Dr. Covens, to be more reliable than
    the appellants witnesses and she gave reasons for her conclusions. Where there
    was conflict between the experts evidence, she preferred the respondents
    witnesses.

[68]

As this court emphasized in
Waxman
, at
    paras. 291-92, referring to the majority reasons in
Housen
, there is
    one, and only one, standard of review applicable to all factual conclusions
    made by the trial judge and the palpable and overriding standard demands
    strong appellate deference to findings of fact made at trial. Thus, as in
Waxman
,
    a palpable error may not be overriding if the impugned finding is supported
    by other evidence: at para. 297.

[69]

In
Waxman
, at paras. 296-97, this court
    observed:

The palpable and overriding standard
    addresses both the nature of the factual error and its impact on the result. A palpable
    error is one that is obvious, plain to see or clear. Examples of palpable
    factual errors include findings made in the complete absence of evidence,
    findings made in conflict with accepted evidence, findings based on a
    misapprehension of evidence and findings of fact drawn from primary facts that
    are the result of speculation rather than inference.

An overriding error is an error that is
    sufficiently significant to vitiate the challenged finding of fact.
Where the challenged finding of fact is based on a
    constellation of findings, the conclusion that one of those findings is founded
    on a palpable error does not automatically mean that the error is overriding.
    The appellant must demonstrate that the error goes to the root of the
    challenged finding of fact such that the fact cannot safely stand in the face
    of that error
. [Emphasis added; citations omitted.]

[70]

In
Carmichael v. GlaxoSmithKline Inc.
,
    2020 ONCA 447, 151 O.R. (3d) 609, at paras. 124-25, leave to appeal refused,
    [2020] S.C.C.A. No. 409, this court explained when a trial judges
    misapprehension of the evidence warrants appellate intervention:

In my view, therefore, the motion judge's
    finding that he had "no trouble" concluding that several of the
Huang/Hengeveld
indicators of capacity
    were not met reflects a misapprehension of the evidence. A misapprehension of
    the evidence "may refer to a failure to consider evidence relevant to a
    material issue, a mistake as to the substance of the evidence, or a failure to
    give proper effect to the evidence". Here, the motion judge made a mistake
    about the substance of the evidence and failed to give proper effect to the
    evidence, by finding that the evidence showed that several of the
Huang/Hengeveld
indicators of capacity
    were absent, when that was not so.

A misapprehension of
    evidence justifies appellate intervention where it is palpable and overriding,
    that is, where the misapprehension is obvious and goes to the very core of the
    outcome of the case
. That is so here, because
    the motion judge's misapprehension is obvious and was essential to his
    conclusion that Mr. Carmichael was incapable of suing GSK until December 2,
    2009, because of his psychological condition.

[Emphasis
    added; citations omitted.]

[71]

In
Benhaim v. St. Germain
, 2016 SCC 48,
    [2016] 2 S.C.R. 352, itself a medical malpractice case, the majority of the
    Supreme Court emphasized that a trial judges findings of fact are entitled to
    deference when they are based on her assessment of all the evidence, including
    medical literature and the conflicting evidence of experts: at paras. 37, 72, 75
    and 84. It cautioned, at para. 84, that [a]ppellate courts must be cognizant
    of the risk of tunnel vision in reviewing medical evidence at trial for
    palpable and overriding error.

[72]

Wagner J. (as he then was) concluded, at para.
    86:

It could be said that it would have been open
    to the trial judge to find in favour of the plaintiff, particularly if
    individual components of the evidence had been examined in isolation. However,
    the trial judge carefully weighed the evidence as a whole, including both the
    statistical evidence and the evidence specific to Mr. Émond. Against that
    backdrop, she considered and evaluated three expert opinions, all of which
    necessarily involved some speculation. Her causation analysis was based on all
    of this evidence. She made no palpable and overriding error in finding that the
    plaintiff had failed to establish causation on a balance of probabilities, and
    deference to her conclusion is in order.

[73]

In my respectful view, the Supreme Courts
    caution against the risk of tunnel vision should be kept in mind when we are
    invited to review a fact-laden decision under the rubric of misapprehension of
    the evidence. The focus on individual misapprehensions or even individual
    errors in the assessment of evidence may tend to exaggerate the significance of
    the disputed finding of fact and divert attention from the trial judges
    assessment of the entirety of the evidence. Bearing this in mind, I turn to the
    appellants submissions concerning the alleged errors in the trial judges
    analysis of factual causation.

(a)

First branch: Did the trial judge err in finding
    uLMS was likely present in May 2009?

[74]

Dr. Browning and Dr. Covens testified that uLMS was
    likely present on May 25, 2009 when the appellant first examined Ms.
    Hacopian-Armen. Dr. Browning opined that the uLMS was likely in or near the
    endometrium and was likely the cause of her AUB. He testified that because such
    tumours do not grow overnight, and the fact that it was present and in Stage
    IV when it was discovered in April 2011, made it reasonable to conclude that it
    was present and in an early stage (Stage I) in May 2009. Dr. Covenss opinion
    was similar.

[75]

The trial judge accepted this evidence, and concluded
    [b]ased on all of the evidence before this court, I accept the evidence of the
    plaintiffs experts that the LMS, which was found to have metastasized to Stage
    IV by April 7, 2011, would have been at Stage I in and around May 25, 2009.

[76]

The appellants argument that the trial judge erred in
    finding that uLMS was likely present in May 2009 rests on three foundations,
    which I will address in turn, setting out my conclusion in the applicable
    heading.

(i)

The trial judge did not err in admitting
    the evidence of Dr. Covens on this issue and, having admitted his evidence, did
    not misapprehend it

[77]

At trial, the appellant sought to limit Dr. Covenss
    evidence regarding factual causation on the ground that he had failed to
    provide the foundational basis for his opinion in his expert report, filed
    pursuant to r. 53.03 of the
Rules of Civil
    Procedure
, R.R.O. 1990, Reg. 194.

[78]

Rule 53.03 requires a party intending to call an
    expert witness at trial to serve the experts report at least 90 days before
    the pre-trial conference. The purpose of r. 53.03 is to avoid surprise at
    trial, to enable counsel to prepare to challenge the opinion and to allow for
    efficiency in preparation and trial.

[79]

The experts report is required to contain certain
    information set out in r. 53.03(2.1), including the experts opinion concerning
    each issue to which the report relates and the experts reasons for their opinion.
    It must include the factual assumptions on which the opinion is based, any
    research conducted by the expert and any documents relied on by the expert in
    forming the opinion. It is well-settled that the report must not simply set out
    the experts conclusions, but must also set out reasons for their opinion:
Marchand (Litigation guardian of) v. Public General Hospital Society
    of Chatham
, 2000 CanLII 16946, at para. 38, leave
    to appeal refused [2001] S.C.C.A. No. 66;
Hoang v. Vicentini
, 2012
    ONSC 1358, affd 2016 ONCA 723, at para. 10.

[80]

The relevant portion of Dr. Covenss report was as
    follows:

Ms. Hacopian-Armen was noted to have lung
    metastases on CT scan in February 2011. It is impossible to be 100% certain
    when this malignancy developed, but I do note that she developed a
de novo
DVT [deep vein thrombosis] in
    her left calf on August 16, 2010 and a recurrence of it in February 2011, both
    of which are very suspicious for an underlying malignancy (malignancy disposes
    patients to DVTs). With no precipitating events (Danazol is not associated
    with DVT and she took Ovral for only 2 days in August 2010), for her DVT and
    the fact she was diagnosed with metastatic disease six months later, I am
    fairly certain that she had her malignancy in August 2010.
Furthermore, I think it likely that it was
    present prior to that, including at her first visit with Dr. Mahmoud in May
    2009.
[Emphasis added.]

[81]

The appellant argued that the report was deficient,
    because, although Dr. Covens explained why he believed the tumour was present
    in August 2010, he failed to explain the basis for his opinion that uLMS was
    present in May 2009. He argued that the first three sentences of the above
    extract provided the foundational basis for Dr. Covenss opinion that the
    malignancy was present in
2010
, but had nothing
    to do with the separate issue of whether it had been present in May 2009.

[82]

The respondent, however, contended that the basis of that
    opinion was set out in the report: reasoning backward from the fact that Ms.
    Hacopian-Armen died in August 2011 from a metastatic cancer discovered in 2011,
    and that she had symptoms of malignancy in August 2010, it was likely that she
    had the disease in May 2009.

[83]

The trial judge accepted the respondents
    interpretation of the report. The malignancy was probably present in May 2009 
    because of the presence of DVT in August 2010 and the fact that the cancer had
    metastasized by February 2011. She found that if there was a different
    interpretation, as advanced by the appellant, it would be for Dr. Covens to
    explain on examination.

[84]

When Dr. Covens testified, he was clear that in his
    opinion it would take a considerable time for the cancer to reach the point of
    metastasizing. Extrapolating back from its condition in 2011, it was likely
    present in May 2009. He observed that there has been little study of the growth
    pattern of such tumours, because they are typically discovered after the uterus
    has been surgically removed due to malignancy or abnormality.

[85]

I see no error in the trial judges decision to permit
    Dr. Covens to testify on this issue. Her interpretation of the report was
    reasonable and consistent with the opinion given in Dr. Covenss testimony. It
    was obvious that the timing of the origin of the malignancy was a central issue
    at trial and the appellant adduced expert evidence on that very question. As a
    result, the appellant could not have been taken by surprise by Dr. Covenss
    evidence. The appellant demonstrated no prejudice as a result of
    misunderstanding Dr. Covenss report.

[86]

Nor do I accept the appellants submission that the
    trial judge misapprehended Dr. Covenss evidence when she stated that it was
    his opinion that it was highly likely that Ms. Hacopian-Armen had Stage I
    uLMS in May 2009. That was in fact Dr. Covenss opinion, based on the facts set
    out in his report and his experience with uterine cancers.

(ii)

The trial judge did not
    misapprehend Dr. Brownings evidence

[87]

In his factum, the appellant asserted that the trial
    judge misapprehended the evidence of Dr. Browning when she said that, [Dr.
    Browning] stated that [uLMS] does not occur overnight and that in May 2009, it
    was likely at Stage I, given the progression by April 2011 and that Ms.
    Hacopian-Armen was likely suffering from a malignancy on May 25, 2009 which
    caused the abnormal bleeding.

[88]

There was no misapprehension. Dr. Brownings testimony
    was that there was a very good chance that her abnormal bleeding in 2009 was
    due to the uLMS and that it was more likely than not that an endometrial
    biopsy performed on May 25, 2009 would have detected uLMS.

[89]

The appellant did not pursue this issue in oral
    argument. I would reject this ground of appeal.

(iii)

The trial judge did not misapprehend the evidence of
    the defence expert, Dr. Vilos

[90]

The appellant submits that the trial judge
    misapprehended Dr. Viloss evidence when she stated at para 152: The
    defendants submit that there is no proof that [uLMS] was present on May 25,
    2009 when an endometrial biopsy should have been performed. They, therefore,
    argue that there is no evidence which would establish a link of causation
    necessary for this case. The appellant says that this misstated his case. He
    did not contend there was an absence of evidence. Instead, he contended that
    there was affirmative evidence of Dr. Vilos, based on Ms. Hacopian-Armens clinical
    history  the absence of rapidly growing tumours and what he described as
    bleeding that tracked her menstrual cycle  which established that uLMS was not
    present in May 2009. This misapprehension of Dr. Viloss evidence, he contends,
    was a reversible error.

[91]

I do not agree that the trial judge misapprehended Dr.
    Viloss evidence. She adverted, correctly, to his testimony that an endometrial
    biopsy performed on May 25, 2009 would not have been positive because there is
    no evidence that a leiomyosarcoma, in my opinion, was there at this time. She
    also referred to his opinion that Ms. Hacopian-Armen had regular bleeding at
    the time. In my view, the trial judges rejection of Dr. Viloss evidence was
    not the result of a misapprehension of his evidence. It was simply the result
    of her acceptance of the evidence of the respondents experts in preference to
    that of Dr. Vilos.

[92]

Finally, although it is not raised as a discrete
    ground of appeal, the appellant is critical of the trial judges reference to
    the principle expressed in
Goodwin v.
    Olupona
, 2013 ONCA 259, 305 O.A.C. 245.

At paras. 152-54,
    the trial judge observed:

The defendants submit that there is no proof
    that LMS was present on May 25, 2009 when an endometrial biopsy should have
    been performed. They, therefore, argue that there is no evidence which would
    establish a link of causation necessary for this case.

The reason that there is no evidence is
    attributable to the fact that Dr. Mahmoud did not perform an endometrial biopsy
    which would have provided the necessary evidence.

As stated above, where there is a gap in the
    evidence as regards establishment of causation which is caused by the
    defendant's own negligence, this cannot be used to shield the defendant from
    any responsibility. The inability to prove the causal link between the
    defendant's negligence and the plaintiff's damages, if a direct result of the
    defendant's failure to act appropriately, cannot be used to shield the
    defendant:
Goodwin (Litigation Guardian of) v. Olupona, supra, Ghiassi v.
    Singh, supra, Adams v. Taylor, supra
.

[93]

I am not satisfied that the principle expressed in
Goodwin
, at paras. 72-74 and in
Ghiassi v. Sing
, 2018 ONCA 764, at para. 29

has any application to a case such as this, where both parties adduced
    evidence on the issue of causation. I accept the respondents submission,
    however, that the reference to this principle was unnecessary as the trial
    judge independently accepted the evidence of the respondents expert witnesses
    that Ms. Hacopian-Armens cancer was probably at Stage I in May 2009.

[94]

For these reasons, I would not give effect to this
    ground of appeal.

(b)

Second branch: Did the trial judge err in
    finding that an endometrial biopsy would likely have detected uLMS, had it been
    present?

[95]

Before addressing this branch of the appellants
    submissions, I observe that the appellant does
not
challenge the trial judges findings that (a) Dr. Mahmoud breached the standard
    of care in failing to perform a routine biopsy that was capable of identifying
    uterine malignancies, including uLMS; (b) the biopsy should have been performed
    because Ms. Hacopian-Armen was at risk for uterine malignancies because of her
    age, her AUB and her nulliparous state; and (c) had she been diagnosed with
    uLMS on May 25, 2009, her outcome would have been substantially improved.

[96]

In coming to these conclusions, the trial judge
    accepted the evidence of Dr. Covens and Dr. Browning, and rejected the evidence
    of the appellants experts.

[97]

As I have rejected the first ground of appeal,
    in which the appellant asserted that the trial judge erred in concluding that
    the uLMS was present in May 2009, the remaining issue is the appellants
    assertion that the trial judge erred in concluding that the endometrial biopsy
    would probably have detected the uLMS. The appellant alleges that the trial
    judge misapprehended the evidence, including aspects of the evidence of the
    appellants experts. These submissions focus on one paragraph of the trial
    judges reasons, para. 144, which I set out in full for reference:

It is the evidence of the defendant's experts
    that the likelihood of having found LMS at the first consult in May 2009 is
    purely speculative and unknowable. The defence argued that there was no
    evidence of any LMS having broken through the myometrial/endometrial lining
    into the uterine cavity based on all of the imaging. They contended throughout
    that LMS could not be detected unless it were in the uterine cavity. The
    plaintiff's experts refute this position. I note as well that the endometrial
    biopsy finally undertaken on April 7, 2011 did detect the sarcoma, although the
    LMS had not yet entered the uterine cavity. The defendant further maintained
    that the plaintiff was clearly pre-menopausal such that sensitivity of
    detection would be under 50%. While there were no fibroids seen in the uterine
    cavity on imaging, this does not exclude the likelihood that LMS, was in or
    near the endometrium, causing or contributing to the abnormal bleeding while it
    was still undetectable by diagnostic imaging. The evidence at trial indicated
    that the diagnostic imaging would not detect a LMS and that 95% of LMS
    malignancies originate
de novo
and are not part of an existing
    fibroid. It is of note that the endometrial biopsy conducted in April 2011 did
    diagnose the presence of a LMS at a time when the plaintiff was still,
    according to the defendants, pre-menopausal as opposed to peri-menopausal,
    and at a time when the LMS was not in the uterine cavity. Further, there was no
    evidence of uterine invasion of the LMS on any kind of diagnostic imaging at
    that time. This is contrary to the defence theory of the case which suggests
    that in the circumstances described, the biopsy should have been negative. I
    should add that I do not find this fact determinative of whether there was LMS
    present on May 25, 2009. In that regard, I have based my findings on other
    evidence, without using a retrospective analysis.

[98]

With that background, I turn to the alleged
    errors, again summarizing my conclusions in the applicable heading.

(i)

The trial judge did not misapprehend the
    appellants experts evidence on the likelihood of detection of uLMS

[99]

The appellant submits that the trial judge
    misapprehended the appellants experts position, when she stated that they testified
    that the likelihood of having found LMS in May 2009 was purely speculative and
    unknowable. The appellant submits that this was a misapprehension because the appellant
    led affirmative evidence that even if uLMS was present in May 2009, it was
    unlikely that an endometrial biopsy would have diagnosed it, given the poor
    sensitivity of the test and the fact that the uLMS was not likely in a location
    that was amenable to sampling.

[100]

I begin by
    observing that the appellants expert, Dr. Vilos, testified that there was no
    evidence that uLMS was present at the time and no evidence that the uLMS had
    moved into the uterine cavity where, in his opinion, the cancer had to be
    located in order to be detected by an endometrial biopsy. As the trial judge
    correctly noted, it was Dr. Viloss evidence that the uLMS would have had to
    have broken through the myometrium/endometrium and into the uterine cavity to
    be detected.

[101]

The trial judge
    did not overlook or misapprehend the appellants evidence. The appellant is
    correct to point out that Dr. Viloss position on the likelihood of finding uLMS
    in 2009 was not that it was purely speculative and unknowable, but rather
    that it was
unlikely
to have been
    detected. However, the trial judge correctly referred to Dr. Viloss evidence a
    number of times, at paras. 48 and 52. The trial judges characterization of his
    evidence, at para. 144, was not central to her conclusion. Again, she simply
    accepted the evidence of the respondents experts, who disagreed with Dr. Viloss
    evidence. They testified that Ms. Hacopian-Armen was closer to being menopausal
    than pre-menopausal and that this status increased the sensitivity of the
    endometrial biopsy and made detection of uLMS more likely than not. Further,
    the trial judge found, at para. 70, that the studies relied on by the appellant
    on the correlation between the location of the LMS and its detectability by a
    biopsy were unreliable and inconclusive.

(ii)

The trial judge did not misapprehend the
    appellants experts evidence on the location of uLMS

[102]

The appellant
    submits that the trial judge misapprehended the evidence of the defence
    experts, when she stated, at paras. 48, 53, and 58, that Dr. Vilos and Dr.
    Leyland had testified that the uLMS had to be in the uterine cavity to be
    detected by an endometrial biopsy. The appellant asserts that his experts
    evidence throughout trial was that the cancer had to be in a location such as
    the uterine cavity or just underneath the endometrium, so as to be amenable to
    sampling by endometrial biopsy which, as the name suggests, is a sampling of
    the endometrium.

[103]

I would not
    accept this submission. On numerous occasions, the appellants experts testified
    that the uLMS had to be in the uterine cavity to be detected. In his
    examination-in-chief, Dr. Vilos was asked the following questions and gave the
    following answers:

Q. And so I understand that's your view on
    whether or not the cancer was present. I want you to assume for the time being
    that the cancer was there in May 2009, and when I mean the cancer, I mean the
    uterine leiomyosarcoma. Assuming the uterine leiomyosarcoma was present in May
    2009, Dr. Vilos, would an endometrial biopsy have diagnosed it in any event?

A. No.

Q. And why not?

A. For the biopsy to pick up a leiomyosarcoma,
    the leiomyosarcoma  remember, its genesis is in the wall of the uterus.
For it to be picked up, it would have to move inside the
    uterine cavity, and we have no evidence here that the  the ultrasound, that it
    had moved into the uterine cavity
. And the other evidence comes from the
    literature, multiple papers where they say that the sensitivity of endometrial
    biopsy, it's very low in the presence of leiomyosarcoma, picking up a leiomyosarcoma.
    [Emphasis added].

[104]

And again, later
    in his evidence:

Q. And what, if anything, is the significance
    of this to your opinion?

A. It's pretty much what I said.
For the leiomyosarcoma to be picked up by
    endometrial biopsy, it has to be sticken [sic] inside the uterine cavity.

Q. And based on the imaging we looked at all
    the way to December 2009, were there any masses reported to be invading the
    endometrium or uterine cavity?

A. Not according to any of the ultrasounds.
    [Emphasis added].

[105]

Similarly, Dr. Leyland testified in
    cross-examination:

Q.
But if I understood your evidence, you said that the tumour has to
    be in the endometrial cavity in order for the biopsy to be successful. Is that
    right?

A.
Yes.

Q. And if it's not in the, if it's not in the
    uterine cavity the, the biopsy will not work.

A. Yes. [Emphasis added].

[106]

In contrast to this evidence, the respondents
    expert, Dr. Covens, testified that the uLMS did
not
have to be in the uterine cavity
    to be detected by an endometrial biopsy. He stated, however, in his evidence-in-chief
    that obviously the closer [the tumour] is to the uterine cavity, the higher
    the likelihood one is going to pick it up on a biopsy.

[107]

Dr. Covens also explained his disagreement with
    Dr. Vilos in his examination-in-chief:

A. [H]ow does an endometrial biopsy identify a
    leiomyosarcoma? Clearly, if there's invasion into the endometrial tissue that's
    one possibility.

Q. Mm-hmm.

A. Second of all, if you've got a deep biopsy
    that, biopsies not only in the endometrium but that tissue underlying the
    endometrium, the myometrium, that can pick it up, as well. And thirdly, if
    you've got a leiomyosarcoma that is what we call a submucosal where it starts
    impinging, outgrowing towards the uterine cavity, which fibroids can do, as
    well, that can denude the endometrial lining and you can just biopsy that mass.
    So, so that's all the endometrial biopsy would indicate from a patient with a
    leiomyosarcoma.

[108]

I am not satisfied that the trial judge
    misapprehended the evidence of the appellants experts on this issue. There was
    a clear conflict in the expert evidence as to whether an endometrial biopsy
    could detect a cancer that was not in either the uterine cavity or the
    endometrium. The trial judge was entitled to prefer the evidence of the
    respondents experts on this issue.

[109]

As noted earlier, there was another aspect of
    the evidence, hotly contested by the appellant at trial, as to whether Ms.
    Hacopian-Armen was likely close to menopause, making it more likely that an
    endometrial biopsy would detect her uLMS. The trial judge found:

While the defendants relied heavily on certain
    studies which indicated,
inter alia
, that in pre-menopausal women, an
    endometrial biopsy has a lower percentage likelihood of detection of LMS, Dr.
    Browning testified that women who are nulliparous have a 13 times more likely
    chance of having early menopause; that women 40 to 49 years of age have a greater
    differentiation in their production of hormones in comparison with 20-29, and
    30-39 age ranges and stated that there was evidence to suggest that the
    plaintiff was beginning to have changes which would make her hormonally closer
    to menopause than pre-menopause, or what he indicated as
    "peri-menopausal". It was a laboratory report during that time which
    indicated her to be "peri-menopausal" or "peri". Her FSH
    levels were rising, which was also a sign that her body was hormonally moving
    toward menopause. Therefore, even based on the studies relied on by the
    defendant, there was a greater likelihood that LMS would have been detected in
    the plaintiff.

[110]

In sum, I am not satisfied that the trial judge
    misapprehended the evidence on this issue or made either a palpable or
    overriding error in her assessment of the evidence. She simply preferred the
    respondents experts evidence that Ms. Hacopian-Armens menopausal or peri-menopausal
    status was a better indicator of whether an endometrial biopsy would have
    detected uLMS in 2009 than the location of the LMS. I would not give effect to
    this ground of appeal.

(iii)

The trial judge did not misapprehend the nature
    and significance of the diagnostic imaging evidence

[111]

The appellant submits that the trial judge misapprehended
    the evidence concerning the capabilities of diagnostic imaging. He asserts there
    was no evidence to support the trial judges conclusion
that
uLMS could have been in or near the endometrium while it was still
    undetectable by diagnostic imaging. Further, he submits the imaging from 2009
    did not show any masses in or near the uterine cavity, which reduced the
    likelihood of detection by endometrial biopsy.

[112]

I begin by setting out the relevant portion of
    the reasons for judgment, reproduced in full earlier:

The defence argued that there was no evidence
    of any LMS having broken through the myometrial/endometrial lining into the
    uterine cavity based on all of the imaging.  While there were no fibroids seen
    in the uterine cavity on imaging, this does not exclude the likelihood that
    LMS, was in or near the endometrium, causing or contributing to the abnormal
    bleeding while it was still undetectable by diagnostic imaging. The evidence at
    trial indicated that the diagnostic imaging would not detect a LMS and that 95%
    of LMS malignancies originate
de novo
and are not part of an existing
    fibroid.

[113]

The appellant submits that [o]n the correct
    evidence, there is no scenario in which uLMS would be in the uterine cavity or
    submucosal (i.e. near the endometrium) but not appear on imaging. His position
    at trial was that because uLMS did not show up on Ms. Hacopian-Armens ultrasounds
    taken prior to and after May 2009, it was not present in the uterus and
    obviously could not have been detected by an endometrial biopsy.

[114]

The problem with this submission is that it does
    not accord with the evidence of Dr. Covens, which the trial judge accepted.

[115]

To begin with, it was common ground that it was
    impossible to distinguish between fibroids and uLMS by imaging. Dr. Browning testified
    that they could only be distinguished at the microscopic level. Dr. Covens opined
    that she in all likelihood  did have her sarcoma in 2009, albeit small. He
    testified that the cancer originates at the cellular level and grows from
    there. However, Dr. Covens noted that even though it might grow to a mass, a
    tumour, a bump that can be visualized, we dont have any really good
    detection methods of separating fibroids from leiomyosarcoma. On
    cross-examination, he agreed with the observation that in order to be visible
    on imaging, the cancer has to grow to a size in which it can be observed on
    radiology. He also stated that at an early stage, the tumour may have been
    undetectable from an ultrasound point of view where it might have been
    detectable by pathology [i.e., a biopsy].

[116]

Dr. Covens also noted that Ms. Hacopian-Armen had
    declined to have a pelvic transvaginal ultrasound, which he described as the
    gold standard test to interpret endometrial, myometrial pathology. When it
    was put to Dr. Covens that up to December 2009 there was no imaging report of
    any submucosal or intracavity fibroid, he responded, [y]es, but she didnt
    have a transvaginal ultrasound so that might have been somewhat difficult to
    identify.

[117]

I conclude that the trial judge did not
    misapprehend the evidence on this issue. She simply accepted Dr. Covenss
    evidence that the tumour was not visible on imaging because it was very small
    or because it was only detectable by a pelvic transvaginal ultrasound and that
    did not take place until April 2011, when her cancer was well advanced.

(iv)

The trial judge did not err in asserting that
    the uLMS had not yet entered the uterine cavity in April 2011 and the trial
    judge did not improperly rely on the April 2011 endometrial biopsy that
    detected the uLMS

[118]

The appellants last two submissions on this
    issue can be addressed together. First, the appellant submits that the trial
    judge misapprehended the implications of the endometrial biopsy that diagnosed Ms.
    Hacopian-Armens uLMS in April 2011. He submits the trial judge misapprehended
    the evidence when she stated that the tumour had not invaded the uterine cavity
    in April 2011 when the endometrial biopsy was performed, and subsequently used
    her erroneous assessment of the evidence to reject the defence submission that
    uLMS has to be in a location amenable to an endometrial biopsy for a diagnosis
    to be made. The appellant submits that the 2011 biopsy supported the defence
    theory that location of the tumour is critical to diagnostic sensitivity, and
    that the absence of masses in or near the uterine cavity in 2009 made it
    unlikely that an endometrial biopsy would have detected the cancer.

[119]

The appellants second submission is that the
    trial judge erred in relying on the 2011 endometrial biopsy altogether because Ms.
    Hacopian-Armen demonstrated a dramatically different clinical picture in 2011 as
    opposed to 2009, and the results of the 2011 biopsy were of no value in
    assessing her condition in 2009.

[120]

The appellants submissions on this issue omit
    reference to the full scope of the trial judges reasoning, in which she made
    it clear that the detection of uLMS by endometrial biopsy in 2011 was not
    central to her findings about Ms. Hacopian-Armens condition in 2009. At para.
    144, she said:

It is of note that the endometrial biopsy
    conducted in April 2011 did diagnose the presence of a LMS at a time when the
    plaintiff was still, according to the defendants, pre-menopausal as opposed
    to peri-menopausal, and at a time when the LMS was not in the uterine cavity.
    Further, there was no evidence of uterine invasion of the LMS on any kind of
    diagnostic imaging at that time. This is contrary to the defence theory of the
    case which suggests that in the circumstances described, the biopsy should have
    been negative.
I should add that I do not find this fact
    determinative of whether there was LMS present on May 25, 2009. In that regard,
    I have based my findings on other evidence, without using a retrospective
    analysis.
[Emphasis added.]

[121]

Further, the question of whether the uLMS had
    invaded the uterine cavity by 2011 was contested at trial. It was open to the
    trial judge to note that the defences theory was potentially undermined if the
    uLMS was detected by an endometrial biopsy in spite of being outside the
    uterine cavity. Ultimately, it did not matter, because the trial judge based
    her findings on the respondents experts theory that Ms. Hacopian-Armens menopausal
    status, among other things, would have made detection of the uLMS by
    endometrial biopsy more likely than not.

[122]

I am not persuaded that the trial judge erred in
    her assessment of the evidence in relation to the 2011 biopsy.

[123]

I would therefore reject this ground of appeal.

F.

DISPOSITION

[124]

For these reasons, I would dismiss the appeal.

[125]

The parties advised that they expected to agree
    on costs. If they have been unable to do so, they may make written submissions.
    The respondents shall serve and file their submissions within ten days of the
    release of these reasons and the appellant shall have ten days within which to
    serve and file responding submissions. The submissions shall not exceed three
    pages, excluding costs outlines.

Released: July 29, 2021   G.R.S.

George
    R. Strathy C.J.O.

I
    agree. K. Feldman J.A.

I
    agree. Sossin J.A.


