over the centuries obstetrics was a purely interventional medical discipline , either a craft or an art , aimed at helping the pregnant to deliver a baby .
this vocation was firstly held by midwives , then by physicians , initially in private houses , then in hospitals . in the past , obstetricians were forced to perform heroic procedures to save the pregnant and her fetus . unfortunately , not always successfully as shown by high mortality rates of both .
the pregnancies were not supervised by a physician and the pregnant women were left with no attention until labor pains occurred .
not so long ago , the pregnancies have started to be controlled , the heart rate monitored and the fetal wellbeing evaluated .
ultrasonography ( us ) , and resultant ability to visualize directly the womb and the fetus , were implemented to obstetrical practice in 1980 's .
more and more commonly used , ultrasonography has become a basic tool for gynecologists and obstetricians . due to the introduction of ultrasonography ,
progress in anesthesiology and surgical techniques , the strain of obstetrics was moved from the delivery suites to the pathology of pregnancy and sonographic department .
nowadays , ultrasonography plays a key role at every stage of woman life  it is used in pediatric gynecology , therapy of infertility and pregnancy screening , as well as post - partum and in post - menopausal patients .
while 15 years ago , the size of the ovarian tumor was commonly compared to fruits , e.g. an orange or tangerine , or to the size of man 's or woman 's fist .
presently , in the 21 century , it seems ridiculous due to the availability of a tool that enables one an accurate evaluation of the size and topography of every lesion within reproductive organs .
now we can not imagine the qualification for surgery or even minor gynecological procedure without a prior ultrasonography .
moreover , we can diagnose ectopic pregnancies , abnormal fetal growth or fetal demise . at present , it is extremely unusual for the pregnant to be admitted with bleeding due to ruptured ectopic pregnancy , which was quite common in the past .
ultrasonography enables us to predict many pathologies , such as preeclampsia , fetal hypotrophy , chromosomal aberrations and pre - term labor .
we can also detect cervical insufficiency , fetal macrosomia , placenta and vasa previa , and placenta increta .
it is quite peculiar , is n't it ? in most delivery units around the world , patients are examined solely by palpation .
digital examination is , and will certainly remain for long , a gold standard , as obstetricians are invariably trained in digital internal and external examinations .
digital examination is challenging and one should perform hundreds of exams for the patient 's safety .
leopold 's maneuvers , common way to determine the position of fetal head and pelvis , is quite straightforward , contrary to the assessment of fontanels and distance between the leading part and interspinal line .
it is subjective and depends mainly on the examiner 's experience and examination conditions ( e.g. , cervical dilation ) .
vaginal examination becomes inaccurate in the case of caput succedaneum and molding or asynclitism ( non - axial presentation of fetal head ) .
several studies showed that digital vaginal examination is highly inaccurate , both in the evaluation of fetal occiput position and fetal head station .
importantly , erroneous results are obtained not only by residents by also by attending physicians . in one of previous studies ,
496 women in the 1 and 2 stage of labor were subjected to digital examination and ultrasonography .
the result of digital examination regarding fetal occiput positon was inconclusive in 34% of the cases , and in 52% of the patients the results were highly inappropriate as fetal occiput position differed by more than 45 as compared to objective ultrasonographic assessment . in another study
including a total of 214 women in labor , the results of digital and ultrasonographic examination differed by at least 45 in nearly half ( 46% ) of the cases .
the accuracy of digital examination documented in another study of 148 pregnant women was even worse . while discrepancies between the results of digital and ultrasonographic examination during the 1 stage of labor corresponded to only 31% ( ! ) , they reached up to 65% during the 2 stage . in another study
, 32 residents and 25 attending physicians were subjected to test with a birth simulator .
the participants were asked to assess fetal head in terms of its engagement ( engaged in the pelvis or not ) , station ( high , mid , low and outlet ) and distance from the interspinal line ( in cm ) . depending on fetal head position , residents and attending physicians made  numerical  errors regarding the distance from interspinal line in 5088% and 3680% of the cases , respectively .
mean error rate for head station assessment ( high , mid , low and outlet ) was 30% ( 95% , ci : 2535% ) for residents and 34% ( 95% , ci : 2741% ) for attending physicians .
the majority of errors pertained to wrong evaluation of fetal head at mid station instead of high station .
the error rate in evaluating fontanels was shown to correlate inversely with cervical dilation , amounting to 80% for small dilation and > 60% for 8 - 10 cm dilation .
other studies showed that the risk of failure during digital examination at full cervical dilatation approximates 2530% .
what are the practical benefits of intrapartum sonography ? for many of us , the most obvious ones include estimation of fetal weight and fetal doppler velocimetry .
although theoretically achievable , these tests are difficult to perform in clinical practice during delivery due to several reasons .
the examination should be performed early , prior to or at the very beginning of labor .
even most basic measurements are challenging during regular uterine contractions , let alone fetal doppler velocimetry when fetal head is engaged in the small pelvis . fetal well - being
is generally evaluated by means of cardiotocography , and doppler ultrasound is not routinely used during labor except from clinical trials .
the term  intrapartum ultrasound  ( itu ) refers exclusively to examination verifying correctness of the delivery mechanism .
initial reports on the application of intrapartum sonography were published in 1990 's , when it was used to assess fetal head station . during recent years , this method has started to be in the center of interest .
ultrasonographic evaluation of fetal head position and engagement is far more accurate than digital examination .
intrapartum sonography is quite straightforward , has flatter learning curve than digital examination and , importantly , provides objective and reproducible results .
the use of ultrasonography for pregnancy monitoring was reflected by a decrease in the number of digital examinations , and thus lower rate of ascending infections , especially in women with ruptured membranes .
furthermore , ultrasonography provides objective documentation of labor , which seems to be of vital importance in the present era of suing .
in contrast to common ultrasonography performed in pregnancy , intrapartum sonography does not require an advanced equipment or special training .
using ultrasonography , an obstetrician can assess fetal position , situation , presentation and head station .
using intrapartum sonography , one can estimate the likelihood of natural delivery in primipara , objectively monitor the stage of labor , decide on the mode of delivery in the case of prolonged labor , and assess the conditions for operative vaginal delivery .
moreover , intrapartum ultrasound can be used for immediate verification of clinical diagnosis , just as in the case of ultrasonography performed in a doctor 's office .
a total of 100 digital vaginal examinations and 99 intrapartum sonographies were performed at > 7 cm dilation .
the group of examiners included midwifery students with no experience in digital examination and ultrasonography .
the error rate for the first 50 digital examinations performed by students approximated 50% and then decreased gradually , reaching plateau at 82 examinations .
error rate was lower and the errors were less significant than in the case of digital examination .
overall error rate for sonography was 8% , and did not exceed 45 except from one case .
ultrasonography was shown to be highly reproducible , with intra - observer and inter - observer variability for the angle of progression smaller than 3.
the examination is performed with the patient in a supine position and with emptied bladder . during the first stage of examination , fetus orientation ,
if fetal head is still visible above the symphysis , localization of fontanels can be assessed on the basis of the occiput position ( fig .
also an angle between the fetal spine and occiput can be determined ; an extended head detection can be helpful in diagnosing face presentation .
posterior occipital position , fetal eyeballs can be seen above the symphysis during the second stage , fetal head engagement is assessed .
a transducer should be protected with a sterile cover and covered with gel , and a probe should be placed interlabially , parallel to labia majora .
importantly , a transducer should be rotated clockwise from transverse to longitudinal position in such way that the right side of the probe is placed inferiorly , in the perineal region , with the left side of the probe , i.e. the one on which the thumb is kept , inferior to the clitoris .
the pubis should be visible on the left side ( i.e. on top of the screen ) . in this
setting , one can visualize fetal head below the symphysis , with vagina and uterine cervix localized in front of the fetal head ( fig .
although some may consider this description unnecessary , yet serious mistakes in fetal head engagement can be made if the probe is rotated inappropriately . using freeze frame ,
several measurements can be taken , including several clinically vital parameters : angle of progression ( aop ) , head direction ( hd ) and head  symphysis distance ( hsd ) .
caput succedaneum , molding and asynclitism can be easily observed on a single image ( cross - section ) ( fig .
second stage of labor in order to measure the distance between fetal head and perineum , a transducer should be placed transversely on labia majora , in the vicinity of posterior frenulum . to obtain more reproducible measurements
, the strain should be put on the probe until resistance of pelvic bones is perceived .
labia , vagina , uterine cervix and fetal head , but not symphysis , should be visible on the screen . using freeze frame
cervical dilatation ( cd ) can be assessed by placing the probe transversely to the labia , and subpubic arch angle ( subpubic arch ) can be measured if the probe is moved below the symphysis .
4 ) is formed by the line parallel to the long axis of the symphysis and the line tangential to the fetal head .
it constitutes an objective , reproducible , noninvasive and easy to determine measure of fetal head engagement .
angle of progression can be used for accurate evaluation of fetal head station , as well as to predict the mode of delivery and time of parturition .
an analysis of computer - generated 3d images of the skeletal pelvis and the true images obtained during intrapartum sonography showed that interspinal line is situated 3 cm distally to the ultrasonographically - determined line being perpendicular to the inferior edge of symphysis ( subpubic line ) . measuring a distance between the leading point and subpubic line
, one can determine the distance between the leading point and interspinal line . if the fetal head is engaged in high station ( leading point on the level of interspinal line , station 0 ) , the angle of progression approximates 116 ( fig . 5 ) .
subpubic line ( in blue ) runs perpendicular to inferior edge of the symphysis ( level -3 ) .
red line : a line running at the level of the ischial spines ( level 0 ) not surprisingly , the greater the angle of progression , the more likely spontaneous delivery . in primipara ,
fetal head should descent to pelvic cavity several weeks before labor , and the angle of progression at the time of labor should exceed 95. the angle of progression > 110 during the first stage and > 120 during the second stage is a predictor of spontaneous delivery . in one study ,
spontaneous delivery occurred in all patients in whom the angle of progression exceeded 120 during the second stage .
it is not surprising , as such value means that fetal head has already descended to pelvic cavity .
the angle of progression < 138 at qualification for operative vaginal delivery can be used to predict ( and avoid ) a difficult forceps birth ( sensitivity 85.7% , specificity 100% ) .
6 ) is defined as the direction of the perpendicular to the widest fetal head diameter line to the subpubic line .
this parameter is postulated to be a quick and easy predictor of successful vaginal delivery in cases in which the second stage is prolonged .
uncomplicated vacuum delivery is likely if the  head up  sign occurs , and low if the 
orientation of fetal head (  head - up  sign ) head  symphysis distance ( fig .
7 ) is the distance between the inferior edge of the symphysis and the closest point of fetal head on the perpendicular to the symphysis .
hsd > 2 cm at early active phase of the second stage suggests that this stage will last longer than 60 min , 1.5 h on average .
8) is the shortest distance between the perineal skin and fetal head ( skull ) .
contrary to digital examination , which is frequently hindered due to presence of caput succedaneum , this parameter can be easily measured by means of ultrasonography ( fig .
spontaneous delivery occurred in more than 90% of primiparas with prolonged labor , head - perineum distance below 4 cm and the angle of progression > 110. sonographic evaluation of head - perineum distance was also shown to be an accurate predictor of vaginal delivery after induction , with predictive value similar to that for ultrasonographic assessment of the cervix assessment and bishop 's score .
9 ) is formed by the midline of fetal head and the anteroposterior dimension of the pelvis .
midline angle < 45 corresponds to internal rotation and 3 cm engagement of fetal head in relation to the interspinal line .
one study showed that the difference between cervical dilation evaluated by digital examination and sonography is smaller than 1 cm ( 0.8 cm ) .
the assessment is quite simple if the transducer is placed transversely and inferiorly to the symphysis .
the likelihood of spontaneous delivery was shown to decrease if the subpubic arch was smaller than 120110. transperitoneal transverse scan .
as widely known , it often results in delivery obstruction , low vaginal delivery rate ( 25% in primiparas and 50% in multiparas ) and higher ( 2- to 4-fold ) rate of instrumental deliveries .
moreover , it is markedly more often associated with severe perineal tear ; the risk for grade 3 perineal tear during occiput posterior delivery is up to 3-fold higher than for anterior occipital position .
furthermore , occiput posterior delivery is associated with more significant loss of blood ( usually > 500 ml ) and significantly higher neonatal complication rate ( e.g. the risk of encephalopathy is 4 times higher ) .
unfortunately , as mentioned above , posterior occipital position is often misdiagnosed during digital examination . in turn , it can be easily detected ultrasonographically : when the transducer is placed above the symphysis , fetal orbits and eyeballs can be seen instead of the occiput and cerebellum . as every third fetus resumes posterior occipital position at the onset of labor , but most of them will change it thereafter , location of fetal occiput determined ultrasonographically at early stages should not be considered a predictor of delivery mode .
only 78% of fetuses remain in posterior occipital position during the second stage . how these cases can be identified ? in order to estimate the likelihood of spontaneous posterior rotation of fetal occiput , also the position of fetal spine should be determined .
the likelihood of the spontaneous rotation is 80 - 90% if the occiput is located posteriorly and the spine laterally or anteriorly .
however , if both the occiput and spine are located posteriorly , the probability of rotation is markedly lower ( ca .
12 ) is the length of line being perpendicular to subpubic line , extending to distal part of fetal head .
it generally represents a real track that fetal head takes in birth canal ; however , until the hypomochlion leans on the inferior pubic symphysis edge and the occiput is expulsed , the angle of descend increases less noticeably that in anterior occipital position , while the head - symphysis distance raises .
in some delivery units , in which intrapartum sonography is a routine practice , sonopartograms , i.e. ultrasonographic parameters of labor progress ( e.g. caput succedaneum , molding , cervical dilation and head - perineum distance ) are recorded , rather than the results of common digital examination .
sonopartogram reflects patient 's status before admission to the delivery room ; aside from the abovementioned parameters , it also includes information on amniotic fluid volume ( depth of the largest pouch ) and umbilical artery flow .
we should accept this fact and try to keep up , approach the new , implement new technologies .
, perform digital examination with closed eyes and compare tumors to fruits , dilation to the number of fingers , thus wasting an opportunity that ultrasonography is trying to give our specialty .
we should remember that the one who does not move forward , makes a step back .
complicated vaginal procedures , such as manually assisted delivery , rotation or fetotomy , are no longer performed in obstructed labor .
if the labor prolongs or fetus is under threat , obstetrician decides whether it still should be delivered vaginally , or rather by cesarean .
the status of a neonate delivered instrumentally ( vacuum , forceps ) to a large extent depends on correct assessment of obstetrical setting prior to the procedure .
patients who were inappropriately qualified for vaginal instrumental delivery ( too high position of fetal head in the pelvis , erroneous evaluation of fontanels ) , are at increased risk of complications after multiple vacuum traction or failed forceps procedure .
another example from everyday practice : at present , pelvic dimensions are determined with the use of pelvimeter in most delivery units . many of us do take this measurement without strong belief that it matters in establishing the delivery mode in cases other than narrow pelvis . as widely known , clinical confirmation of fetal head engagement , being a kind of  internal pelvimeter  , is the only criterion confirming that bony birth canal is wide enough for a fetus .
this measurement provides us with an information on fetal head station , reflecting the likelihood of spontaneous delivery , and indirectly also birth canal size .
sonography really facilitates our practice , thus we hope that even experienced obstetricians , who do not use this method on a regular basis , will start to do so , as an adjunct to digital examination .
not only sonographic monitoring of labor seems to improve the safety and patient comfort , but also decreases the cesarean section rate .
too many various measurements are proposed in literature and it is unclear which of them should be taken in everyday practice .
probably , one or two parameters of greatest clinical significance will be identified in near future . for the time being , we can , and should conduct our own studies aiming at developing intrapartum sonography standards . despite this illusive chaos , an attempt to  place a transducer  ourselves
is worth making  only then it will occur that the image is really readable and the abovementioned measurements are intuitive and reflect what we examine digitally . when ignoring these measurements , an advantage of dynamic examination in ultrasonography can be applied , while placing a probe on the perineum
 ultrasonography has been extensively used in obstetrics and gynecology since 1980 's . 
 it found application in pediatric gynecology , procreation period , post - menopause , pregnancy monitoring and after delivery . 
 although the first reports on the use of ultrasonography in assessing delivery mechanism were published in 1990 's , yet to date labor progress is evaluated by means of physical examination in most delivery units . 
 intrapartum sonography is not routinely performed despite the fact that numerous studies documented high error rates of conventional obstetrical examination . 
 even an experienced physician makes a mistake in every third case of the fetal head descent and fontanelle position assessment . 
 nowadays , obstetrician 's role is not to strain for vaginal delivery at all costs , but to provide the patient in labor and her newborn with maximal safety . to achieve this objective 
 , an obstetrician should distinguish between women who will deliver spontaneously and whose who require cesarean section . 
 proper decision should be made on the basis of objective and valid evaluation of obstetric setting , which can not be achieved solely with physical examination . 
 intrapartum sonography was shown to be far more accurate than digital examination . 
 moreover , it is not technically demanding , provides high reproducibility and neither increases the rate of ascending infection or causes discomfort to the patient . 
 current research suggests that if used routinely , intrapartum sonography can increase the safety of labor and reduce cesarean section rate . 
Introduction
The use of intrapartum sonography
Intrapartum sonography technique
Occiput posterior delivery
The sonopartogram
Conclusion
Conflict of interest