- The umbilicus and signs and symptoms of associated pathology The umbilicus represents the l ocation of four fetal structures \200\224the umbili- cal vein, two umbilical arteries, and the urachus which is a tube extending from the superior aspect of the bladder towards the u mbilicus (it repre- sents the obliterated vesicourethral canal). The urachus may remain open at various points, leading to the following abnormalities. - Completely patent urachus: urine through the umbilicus; usually doesn \200\231t present unt il adulthood (strong contractions of bladder of a child closes the mouth of the \201 stul a). Vesicourachal diverticulum: bladder; usually symptomless. can become infected, forming an abscess Umbilical cyst or sinus: or may chronically discharge infected material from the umbilicus. A cyst can present as an immobile, midline swelling between the umbilicus and b ladder, deep to the rectus sheath. It may have a small communication with the bladder and, therefore, its size can \202 uctuate as it can becomes swollen with urine. communicates with the bladder and leaks a diverticulum in the dome of the Other causes of umbilical masses Metastatic deposit (from abdominal cancer, metastatic spre ad occurring via lymphatics in the edge of the falciform ligament, running alongside the ob literated umbilical vein); \200\230deposit \200\231 of endometriosis (becomes painful and discharges blood at the same time as menstruation). CHAPTER 2 Signi \201 cance & preliminary investigation 30 Digital rectal examination (DRE) The immediate anterior relationship of the rectum in the m ale is the pros- tate. The DRE is the mainstay of examination of the prostate. Explain the need for the examination. Ensure the examination is done in privacy. In the UK, DRE is usually done in the left lateral position \200\224with the patient lying on their l eft side, and with the hips and knees \202 exed to 90 or more. Examine the anal region for \201 stulae and \201 ssures. Apply plenty of lubricating gel to the gloved \201 n ger. Lift the tight buttock upwards with your other hand to expose the anus and gently and slowly insert your index \201 nger into the anal canal, then into the rectum. Palpate anteriorly with the pulp of your \201 nger and feel the surface of the prostate. Note its consistency (normal or \201 rm), its surface (smooth or irregular), and estimate its size. (It can be helpful to relate its size to com- mon objects (e.g. fruit or nuts!) A normal prostate is the size of a walnut, a moderately enlarged prostate that of a tangeri ne, and a big prostate the size of an apple or orange.) The normal bilobed prostate has a g roove (the median sulcus) between the two lobes and in prostate cancer, this groove may be obscured. Many men \201 nd DRE uncomfortable or even painful and the inexpe- rienced doctor may equ ate this normal discomfort with prostatic ten- derness. Prostatic tenderness is best elicit ed by gentle pressure on the prostate with the examining \201 nger. If the prostate is re ally involved by some acute, in \202 ammatory condition such as acute, infective prostatit is or a prostatic abscess, it will be very tender. DRE should be avoided in the profoundly neutropenic patient (risk of septicaemia) and in pa tients with an anal \201 ssure where DRE would be very painful. Other features to elicit in the DRE The integrity of the sacral nerves that innervate the b ladder and of the sacral spinal cord can be established by eliciting the bulbocavernosus re \202 ex (the BCR) during a DRE. The sensory side of the re \202 ex is elicited by squeez ing the glans of the penis or the clitoris (or in catheterized patients, by gently pulling the balloon of the catheter onto the bladder neck). The motor side of the re \202 ex is te sted by feeling for contraction of the anus during this sensory stimulus. Contraction of th e anus represents a positive BCR and indicates that the afferent and efferent nerves of the sacral spinal cord (S2 \200\2234) and the sacral cord are intact. This page intentionally left blank CHAPTER 2 Signi \201 cance & preliminary investigation 32 Lumps in the groin Differential diagnosis Inguinal hernia, femoral hernia, enlarged lymph n odes, saphena varix, hydrocele of the cord (or of the canal of N ck in women), vaginal hyd rocele, undescended testis, lipoma of the cord, femoral aneurysm, psoas abscess. Determining the diagnosis Hernia A hernia (usually) has a cough impulse (i.e. it expands on coughing) and (usually) reduces with direct pressure or on lying down unless, uncom- monly , it is incarcerated (i.e. the contents of the hernia are \201 xed in the hernia sac by t heir size and by adhesions). Movement of the lump is not the same as expansion. Many groin lumps have a transmitted impulse on coughing (i.e. they move), but do not expand on coughin g. Since inguinal and femoral hernias arise from within the abdomen and descend into the gr oin, it is not possible to \200\230get above \200\231 them. For lumps that arise from with in the scrotum, the superior edge can be palpated (i.e. it is possible to \200\230get abov e \200\231 them). Once a hernia has protruded through the abdominal wall, it can expand in any direction in t he subcutaneous tissues and therefore, the position of the unreduced hernia cannot be used to establish whether it is inguinal or femoral. The point of reduction of the hernia establ ishes whether it is an inguinal or femoral hernia. Inguinal: the hernia reduces through the abdominal wall at a point above and medial to the pubic tubercle. An indirect inguinal hernia often descends into the scrotum; a direct ingui nal hernia rarely does. Femoral: the hernia reduces through the abdominal wall at a point below and lateral to the pubic tubercle. Enlarged inguinal lymph nodes A \201 rm, non-compressible, nodular lump in the groin. Loo k for pathology in the skin of the scrotum and penis, the perianal area and anus, and the s kin and super \201 cial tissues of the thigh and leg. Saphena varix A dilatation of the proximal end of the saphenous vein. Can be confused with an inguinal or femoral hernia because it has an expansile cough impulse (i.e. expands on co ughing) and disappears on lying down. It is easily compressible and has a \202 uid thrill when the distal saphenous vein is percussed. Hydrocele of the cord (or of the canal of N ck in women) A hydrocele is an abnormal quanti ty of peritoneal \202 uid between the parietal and visceral layers of the tunica vaginali s, the double layer of peri- toneum surrounding the testis, and which was the processus vag inalis in the fetus. Normally, the processus vaginalis becomes obliterated along its entire length, apart from where it surrounds the testis where a potential LUMPS IN THE GROIN 33 space remains between the parietal and visceral layers. If the central part of the processu s vaginalis remains patent, \202 uid secreted by the \200\230trapped \200\231 peritoneum accumulates and forms a hydrocele of the cord (the equiva- lent in females is known as the canal of N ck). A hydrocele of the cord may, therefore, be present in the groin. Undescended testis May be on the correct anatomical path, but may have failed to reach the scrotum (incompletely descended testis) or may have descended away from the normal anatomic al path (ectopic testis). The \200\230lump \200\231 is smooth, oval, tender to palpation, non-compressible, and there is no testis in the scrotum. Lipoma of the cord A non-compressible lump in the groin, with no cough impulse. Femoral aneurysm Usually in the common femoral artery (rather than super \201 cial or prof unda femoris branches) and, therefore, located just below the inguinal ligament. Easily con fused with a femoral hernia. Like all aneurysms, they are expan- sile (but unlike hernias, they do not expand on coughing). Psoas abscess The scenario is one of a patient who is unwell with a fever and with a soft, \202 uctuant, compressible mass in the femoral triangle. CHAPTER 2 Signi \201 cance & preliminary investigation 34 Lumps in the scrotum Differential diagnosis Inguinal hernia, hydrocele, epididymal cyst, te sticular tumor, varicocele, sebaceous cyst, tuberculous epididymo-orchitis, gumma of the te stis, carcinoma of scrotal skin. Determining the diagnosis Inguinal hernia An indirect inguinal hernia often extends into th e scrotum. It usually has a cough impulse (i.e. it expands on coughing) and usually reduces with direct pressure or on lying down. It is not possible to get above the lump. Hydrocele A hydrocele is an abnormal quantity of peritoneal \202 uid between the pari- et al and visceral layers of the tunica vaginalis, the double layer of peri- toneum surroundin g the testis and which was the processus vaginalis in the fetus. Normally, the processus va ginalis becomes obliterated along its entire length, apart from where it surrounds the test is where a potential space remains between the parietal and visceral layers. Usually painless, unless the underlying testicular disease is painful. A hydrocele has a sm ooth surface and it is dif \201 cult or impossible to feel the testis which is surrounded by the tense, \202 uid collection (unless, rarely, the hydrocele is very lax). The superi or margin can be palpated (i.e. you can get above the lump). It is possible to transillumin ate a hydrocele (i.e. the light from a torch applied on one side can be seen on the other s ide of the hydrocele). May be primary (idiopathic) or secondary. Primary hydroceles develop slowly (over the cours e of years usually) and there is no precipitating event such as epididymo-orchitis or traum a, and the underlying testis appears normal on ultrasound (no testicular tumor). Secondary hydro- celes (infection, tumor, trauma) represent an effusion between the lay- ers of the t unica vaginalis (the visceral and parietal layers), analogous to a pleural or peritoneal ef fusion. In \201 lariasis (infection with the \201 larial worm,Wuchereria bancrofti), ob struction of the lymphatics of the sper- matic cord give rise to the hydrocele. Epididymal cyst (Also known as a spermatocele if there are spermatozoa in the contained \202 uid.) Derived from the collecting tubules of the epididymis and contains clear \202 uid. They develop slowly (overy), lie within the scrotum (you can get above them), and usua lly lie above and behind the testis. They are often multiple (multiloculated). Orchitis In the absence of involvement of the epididymitis, due to a viral infection, e.g. mumps. Often occurs with enlargement of the salivary glands. LUMPS IN THE SCROTUM 35 Tuberculous epididymo-orchitis Infection of the epididymis (principally) by TB, which has s pread from the blood or urinary tract. The absence of pain and tenderness is noticeable. Th e epididymis is hard and has an irregular surface. The spermatic cord is thickened and the vas deferens also feels hard and irregular (a \200\230string of beads \200\231). Testicular tumor (seminoma, teratoma) A solid mass, arising from within the scrotum that, i f very large, may extend up into the spermatic cord. They may present with symptoms which m imic an acute epididymorchitis (i.e. pain and tenderness in the testis and fever). Not infr equently, the patient reports a history of minor trauma to the testis in the days or weeks preceding the onset of symp- toms. They may have undergone an orchidopexy as a child ( \201 xation of the testis in the scrotum for an undescended testis). The lump is usually \201 rm or hard, and may have a smooth or irregular surface. Examine for abdominal and supraclavicular lymph nodes. Gumma of the testis Rare; syphilis of the testis resulting in a round, hard, insensitive ma ss involving the testis (a so-called \200\230billiard ball \200\231); dif \201 cult to di stinguish from a tumor. Varicocele Dilatation of the pampiniform plexus \200\224the collection of veins surrounding the testis and extending up into the spermatic cord (essentially varicose veins of the tes tis and spermatic cord). Small, symptomless varicoceles occur in approximately 20% of norma l men and are more common on the left side. They may cause a dragging sensation or ache in the scrotum. Said to feel like a \200\230bag of worms \200\231. The varicocele disappears when the patient lies down. Sebaceous cyst Common in scrotal skin. They are \201 xed to the skin and have a smooth su rface. Carcinoma of scrotal skin Appears as an ulcer on the scrotal skin, often with a purulent or bloody discharge. This page intentionally left blank 37 Chapter 3 Urological investigations Assessing kidney function 38 Urine examination 40 Urine cytology 42 Prostatic-speci \201 c antigen (PSA) 43 Radiological imaging of the urinary tract 44 Uses of plain abdominal radi ography (the \200\230KUB \200\231 X-ray \200\224kidneys, ureters, bladder) 46 Intravenous urography (IVU) 48 Other urological contrast studies 52 Computed tomography (CT ) and magnetic resonance imaging (MRI) 54 Radioisotope imaging 60 Uro \202 owmetry 62 Post-void residual urine volume measurement 66 Cystometry, pressure \202 ow studies, and videocystometry 68 CHAPTER 3 Urological investigations 38 Assessing kidney function When we talk about measuring kidney function, what we mean is mea s- urement of glomerular \201 ltration rate (GFR). This is regarded as the best measure o f kidney function and we grade the degree of renal impairment and renal failure according t o the GFR. Normal GFR in young men is approximately 130mL/min per 1.73m2 of body surface ar ea. In young women, it is 120mL/min per 1.73m2 of body surface area. Mean GFR declines with age (Table 3.1). The ideal \201 ltration marker is excreted by \201 ltration alone. Exogenous markers th at can be used to measure include inulin, iothalamate, ethyl- ene diamine tetra-acetic acid (EDTA), diethylene triamine penta-acetic acid, and iohexol. Measurement of GFR using exoge nously administered markers is complex and expensive and is dif \201 cult to do in routine clinical practice. Urinary clearance of endogenous markers, such as creatinine, can be used to estimate GFR. C reatinine is a 113D-amino acid derivative that is freely \201 ltered at the glomerulus. A timed urine collection and measure- ment of serum creatinine concentration allows calculat ion of GFR accord- ing to the formula: Clearance (GFR) = U \227 V/P where U is the concentration of urine in urine, P the concentration in plasma, and V the ur ine \202 ow. As an alternative, estimation of GFR can be made from simple measure- ment of serum creatin ine since the main mechanism of creatinine excre- tion is by glomerular \201 ltration and GFR has a reciprocal relationship with serum creatinine. Thus, as GFR falls (indicating wo rsening renal function), creatinine rises. However, creatinine is not the ideal \201 ltra tion marker since it is also excreted by proximal tubular secretion as well as by glomerula r \201 ltration and therefore, creatinine clearance exceeds GFR, i.e. creatinine clearanc e tends to overestimate GFR. Estimated GFR (eGFR) Since the endogenous production of creatinine is determined by muscle mass, serum levels of creatinine will not only vary according to renal func- tion (glomerul ar \201 ltration), but also according to age, body size, ethnic group, and sex. Taking ac count of these factors can overcome some of the limitations of measurement of serum creatin ine alone. Two equations have been widely used for calculating eGFR \200\224the Cockcroft \200\223Gaul t formula and the Modi \201 cation of Diet in Renal Disease (MDRD) equation. Both were dev eloped from populations of patients with chronic kidney disease. They are less accurate est imates of renal func- tion in populations without chronic kidney disease. The Cockcroft \200\223Gault formula (overestimates GFR because of tubular secre- tion of cr eatinine and the value is not adjusted for body surface area). CCr in mL/min = [(140 \200 \223 age) \227 weight]/(0.84 \227 SCr) if male CCr in mL/min = [(140 \200\223 age) \227 weight]/(0.85 \227 SCr) if female where SCr = serum creatinine (mM/L) and CCr = creatinine clearance. ASSESSING KIDNEY FUNCTION 39 The MDRD equation (modi \201 ed in 2005; adjusts for body surface area). GFR (mL/min/1.73m 2) = 30 849 \227 (SCr) \200\2231.154 \227 (age) \200\2230.203 ( \227 0.742 if female; \227 1.212 if black) The MDRD is reasonably accurate as an estimate of GFR, the mean differ- ence between eGFR a nd measured GFR ranging from \200\2235 to 1mL/min/1.73m2. The eGFR provides substantial improvements over serum creatinine measurements alone in the clinical assessment of renal function in terms of the detection, evaluation, and management of chronic kidney disease (Table 3.1). Table 3.1 Chronic kidney disease (CKD) classi \201 cation eGFR (mL/min/1.73m2) Stage 1 (kidney damage with normal or >90 increased GFR) 2 (mild decrease in GFR) 60 \200\22389 3 (moderate decrease in GFR) 30 \200\22359 4 (severe decrease in GFR) 15 \200\22329 5 (kidney failure) <15 CHAPTER 3 Urological investigations 40 Urine examination Dipstick testing Analysis for pH, blood, protein, glucose, and white cell s can be done with dipstick testing. pH Urinary pH varies between 4.5 and 8, averaging between 5.5 and 6.5. Blood Normal urine contains <3 RBCs per high-powered \201 eld (HPF) (1000 erythrocytes/mL of urine; upper limit of 5000 \200\2238000 erythrocytes/mL). Positive dipstick for blood i ndicates the presence of hemoglobin in the urine. Hemoglobin has a peroxidase-like activity and causes oxidation of a chromogen indicator which changes color when oxidized. Sensitivi ty of urine dipsticks for identifying haematuria (>3 RBCs/HPF is >90%); speci \201 - city is lower (i.e. a higher false positive rate with the dipstick due to con- tamination with m enstrual blood, dehydration (concentrates what RBCs are normally present in urine)). Haematuria due to a urological cause does not elevate urinary protein. Haematuria of nephro logical origin often occurs in association with casts and there is almost always signi \201 cant proteinuria. Protein Normal, healthy adults excrete about 80 \200\223150mg of protein per day in their u rine (normal protein concentration <20mg/dL). Proteinuria suggests the presence of renal di sease (glomerular, tubulo-interstitial, renal vascular) or multiple myeloma, but it can occ ur following strenuous exercise. Dipstick test is based on a tetrabromophenol blue dye colo r change (green color develops in the presence of protein of >20mg/dL). White blood cells Leukocyte esterase activity detects the presence of white blood cells in the urine. Leukocyte esterase is produced by neutrophils and causes a color change in a chr omogen salt on the dipstick. Not all patients with bacteriuria have signi \201 cant pyuria . False negatives: concentrated urine, gly- cosuria, presence of urobilinogen, consumption of large amounts of ascor- bic acid. False positives: contamination. Nitrite testing Nitrites in the urine suggest the possibility of bacteriuria. They are not normally found in the urine. Many species of Gram negative bacteria can convert nitrates to nitrites and these are detected in urine by a reaction with the reagents on the dipstick, which form a red azo dye. The speci \201 city of the nitrite dipstick for detecting bacter iuria is >90% (false positive nitrite testing is contamination). Sensitivity is 35 \200\223 85% (i.e. lots of false negatives); less accurate in urine containing fewer than 105 organi sms/mL. Cloudy urine that is positive for white blood cells and nitrite-positive is very likely to be infected. URINE EXAMINATION 41 Urine microscopy Red blood cell morphology Determined by phase contrast microscopy. RBCs de rived from the glomerulus are dysmorphic (they have been distorted by their passage through the glomerulus). RBCs derived from tubular bleeding (tubulo- interstitial disease) and tho se from lower down the urinary tract (i.e. uro- logical bleeding from the renal pelvis, ure ters, or bladder) have a normal shape. Glomerular bleeding is suggested by the presence of dysmorphic RBCs, RBC casts, and proteinuria. Casts A protein coagulum (principally, Tamm \200\223Horsfall mucoprotein derived from tubul ar epithelial cells) formed in the renal tubule and \200\230cast \200\231 in the shape of the tubule (i.e. long and thin). The protein matrix traps tubu- lar luminal contents. If th e cast contains only mucoproteins, it is called a hyaline cast. Seen after exercise, heat e xposure, and in pyelonephritis or chronic renal disease. RBC casts contain trapped erythroc ytes and are diagnostic of glomerular bleeding, most often due to glomerulonephri- tis. Whi te blood cell casts are seen in acute glomerulonephritis, acute pyelonephritis, and acute t ubulointerstitial nephritis. Crystals Speci \201 c crystal types may be seen in urine and help diagnose underly- ing pr oblems (e.g. cystine crystals establish the diagnosis of cystinuria). Calcium oxalate, uric acid, and cystine are precipitated in acidic urine. Crystals precipitated in alkaline urin e include calcium phosphate and triple phosphate (struvite). CHAPTER 3 Urological investigations 42 Urine cytology \200 exfoliated cells lying in urine that has Urine collection for cytology: been in the bladder for several hours (e.g. early morning specimens) or in a urine specimen that has been allo wed to stand for several hours are degenerate. Such urine specimens are not suitable for cy tological interpretation. Cytological examination can be performed on bladder washings (usi ng normal saline) obtained from the bladder at cystoscopy (or following catheterization) or from the ureter (via a ureteric catheter or ureteroscope). The urine is centrifuged and th e specimen obtained is \201 xed in alcohol and stained by the Papanicolaou technique. Nor mal urothelial cells are shed into the urine and under the microscope, their nuclei appear regular and monomorphic (diffuse, \201 ne chromatin pattern, single nucleolus). Causes of a positive cytology report (i.e. abnormal urothelial cells seen \200\224high nuclear:cytop lasmic ratio, hyperchromatic nuclei, prominent nucleoli): \200 Urothelial malignancy (TCC , SCC, adenocarcinoma). \200 Previous radiotherapy (especially if within the last 12 mont hs). \200 Previous cytotoxic drug treatment (especially if within the last 12 months, e.g. cyclophosphamide, busulfan, ciclosporin). Urinary tract stones. Renal adenocarcinoma (clear cell cancer of the kidney) usually does n ot exfoliate abnormal cells, although occasionally clusters of clear cells may be seen, sug gesting the diagnosis. High-grade urothelial cancer and carcinoma in situ exfoliate cells w hich look very abnormal and usually the cytologist is able to indicate that there is a high likelihood of a malignancy. Low-grade bladder TCC exfoliates cells which look very much li ke normal urothelial cells. The dif \201 culty arises where the cells look abnormal, but n ot that abnormal \200\224here, the likelihood that the cause of the abnormal cytology is a benign process is greater. Sensitivity and speci \201 city of positive urine cytology for detecting TCC of the bladder depends on the de \201 nition of \200\230positive \200\231 \200\224if only obviously malignant or highly suspicious samples are considered positive, t hen the speci \201 city will be high. Urine cytology may be negative in as many as 20% of high-grade cancers. If \200\230atypical cells \200\231 are included in the de \201 nition of \200\230abnormal \200\231, the speci \201 city of urine cytology for diagnosing uroth elial cancer will be relatively poor (relatively high number of false positives) because ma ny cases will have a benign cause (stones, in \202 ammation). PROSTATIC-SPECIFIC ANTIGEN (PSA) 43 Prostatic-speci \201 c antigen (PSA) (see also b pp. 318 \200\223321) PSA is a 34kD glycop rotein enzyme produced by the columnar acinar and ductal prostatic epithelial cells. It is a member of the human kallikrein family and its function is to liquefy the ejaculate, enabl ing fertilization. PSA is present in both benign and malignant cells, although the expressi on of PSA tends to be reduced in malignant cells and may be absent in poorly differentiated tumors. Large amounts are secreted into the semen and small quantities are found in the ur ine and blood. The function of serum PSA is unclear, although it is known to liber- ate the insulin-like g rowth factor type 1 from one of its binding proteins. Seventy- \201 ve percent of circulat ing PSA is bound to plasma proteins (com- plexed PSA) and metabolized in the liver, while 2 5% is free and excreted in the urine. Complexed PSA is stable, bound to alpha-1 antichymotr ypsin and alpha-2 macroglobulin. Free PSA is unstable, recently found to con- sist of two i soforms:pro-PSA is a peripheral zone precursor, apparently elevated in the presence of pros tate cancer, and BPSA is the transition zone precursor and associated with BPH. The half-li fe of serum PSA is 2.2 days. The normal range for the serum PSA assay in men is <4.0ng/mL, though this varies with age. Table 3.2 shows a published age-speci \201 c nor- mal range ( 95th centile). In the absence of prostate cancer, serum PSA concentrations also vary physiologically, according to race and prostate volume. Indications for checking serum PSA \200 Patient request, following counseling (see \200 LUTS. \200 Abnormal DRE. \200 Progressive bone pain, especially back pain. \200 Unex plained anemia, anorexia, or weight loss. \200 Spontaneous thromboembolism or unilateral leg swelling. \200 Monitoring of prostate cancer patients. b p. 322). Table 3.2 The age-adjusted normal range for PSA Age range Normal PSA range (ng/mL) All ages <4.0 40 \200\22349 <2.5 50 \200\22359 <3.5 60 \200\22369 <4.5 >70 <6.5 CHAPTER 3 Urological investigations 44 Radiological imaging of the urinary tract Ultrasound A non-invasive method of urinary tract imaging. While it provides good images of the kidneys and bladder, anatomical detail of th e ureter is poor and the mid-ureter cannot be imaged at all by ultrasound because of overly ing bowel gas. Uses of ultrasound Renal \200 \200 Assessment of haematuria. Determination of nature of renal masses \200\224can differentiate simple cysts (smooth, well-demarcated wall, re \202 ecting no echoes; benign) from solid masses (almost always malignant; cystic masses with solid components or multiple septae or calci \201 cation may be malignant), from those casting an \200\230acoustic shadow \200 \231 (stones; Fig. 3.1). Can determine the presence/absence of hydronephrosis (dilatation o f the collecting system) in patients with abnormal renal function (Fig. 3.2). Allows ultras ound-guided nephrostomy insertion in patients with hydro-nephrosis and renal impairment or with infected, obstructed kidneys. Bladder \200 \200 Measurement of post-void residual urine volume. Allows ultrasound-guided placement of a sup rapubic catheter. Prostate: TRUS \200 Measurement of prostate size (where gross prostatic enlargement is suspected on the basis o f a DRE and surgery in the form of open prostatectomy is contemplated). To assist prostate biopsy (allows biopsy of hypo- or hyper-echoic lesions). Investigation of azoospermia (can establish the presence of ejaculatory duct obstruction). \200 Urethra Can image the urethra and establish the depth and extent of spongio \201 bro- sis in urethral stricture disease. Testes \200 Assessment of the patient complaining of a \200\230lump in the testicle (or scrotum) \200 \231 \200\224can differentiate benign lesions (hydrocele, epididymal cyst) from malignant t esticular tumors (solid, echo poor, or with abnormal echo pattern). When combined with powe r Doppler, can establish the presence/ absence of testicular blood \202 ow in suspected t orsion. Assessment of testicular trauma (rupture is indicated by abnormal echo pattern due to blood within the body of the testis; surrounding haematoma may be seen \200\224blood wit hin the scrotal soft tissues that has escaped through a tear in the tunica albuginea and th e visceral and RADIOLOGICAL IMAGING OF THE URINARY TRACT 45 parietal layers of the tunica vaginalis; haematocele \200\224blood contained by an intact p arietal layer of the tunica vaginalis). Investigation of infertility \200\224varicoceles an d testicular atrophy may be identi \201 ed. Fig. 3.1 An acoustic shadow cast by a stone within the kidney. Fig. 3.2 Hydronephrosis. Urine in dilated calyces appears black (hypoechoic). CHAPTER 3 Urological investigations 46 Uses of plain abdominal radiography (the \200\230KUB \200\231 X-ray \200\224kidneys, urete rs, bladder) - For detection of stones and determination of their size and (to an extent) t heir location within the kidneys, ureters, and bladder (Fig. 3.3). - Renal calculi: a calci \201 cation overlying the kidneys is intrarenal if it maintains its relationship to the kidney on inspiratory and expiratory \201 lms (i.e. if it moves with the kidney). If in doubt as to whether an opacity overlying the outline of th e kidney is intrarenal or not, get an ultrasound (look for the characteristic \200\230acou stic shadow \200\231 within the kidney), IVU, or CT urogram (CTU). Ureteric calculi: sensitivity for detection of renal calculi is in the order of 50 \200\223 70% (i.e. the false negative rate is between 30 and 50%; it misses ureteric stones when the se are present in 30 \200\22350% of cases). CTU or IVU, which relate the position of the op acity to the anatomical location of the ureters, are required to make a de \201 nitive dia gnosis of a ureteric stone. However, once the presence of a ureteric stone has been con \201 rmed by another imaging study (CTU or IVU) and as long as it is radio-opaque enough an d large enough to be seen, plain radiography is a good way of following the patient to esta blish whether the stone is progressing distally, down the ureter. It is not useful for \200\230following \200\231 ureteric stones that are radiolucent (e.g. uric acid), small (ge nerally a stone must be 3 \200\2234mm to be visible on plain X-ray), or when the stones pas s through the ureter as it lies over the sacrum. Ability of KUB X-ray to \200\230see \200 \231 stones is also dependent on amount of overlying bowel gas. Plain tomography (a plain X-ray taken of a \201 xed coronal plane through the kidneys) can be useful, but is rarely done nowadays with the availability of ultrasound and CT. Opacities that may be confused with stones (renal, ureteric) on plain radiography: calci \201 ed lymph nodes, pelvic phleboliths (round, lucent center, usually below the ischial sp ines). Look for the psoas shadow \200\224obscured where there is retroperitoneal \202 uid (pus or blood; Fig. 3.4). USES OF PLAIN ABDOMINAL RADIOGRAPHY 47 Fig. 3.3 Small staghorn calculus on KUB X-ray. Fig. 3.4 Leaking AAA on plain X-ray; the right psoas shadow cannot be seen due to retroperi toneal hemorrhage. CHAPTER 3 Urological investigations 48 Intravenous urography (IVU) Also known as intravenous pyelography (IVP). Now virtually obso lete in the era of CT-KUB scanning (non-contrast CTU) used for the investiga- tion of acute loin pain and CTU (a contrast CT of the kidneys, ureters, and bladder). The author has not requested an IVU for the best part of 10 years. The reconstructed digital images obtained on CTU are superior to those of IVU. However, for the bene \201 t of those urologists in o ther parts of the world where IVU may still be the standard method of upper tract imaging, the author has retained this section. A control \201 lm is obtained before contrast is given. Intravascular contrast is adminis tered followed by a series of X-rays of the kidneys, ureters, and bladder over the followin g 30min or so to image their anatomy and pathology and to give some indication of renal fun ction. - Radio-opacity of contrast agents depends on the presence of a tri- iodinated benzene ring in the molecule. Ionic monomers (sodium and meglumine salts) ionize, thereby producing high osmolality solutions (e.g. iothalamate \200\224Conray , diatrizoate \200 \224Hypaque , Urogra \201 n ). Non-ionic monomers \200\224low osmolality (e.g. iopamidol \200\224Niopam , iohexol \200\224Omnipaque ). At a concentration of 300mg of iodine per mL, ionic monomers have an osmolality \201 ve t imes higher than plasma, compared with non-ionic monomers which have an osmolality twice th at of plasma. Excreted from plasma by glomerular \201 ltration. Films and \200\230phases \200\231 of the IVU Plain \201 lm: looking for calci \201 cati on overlying the region of the kidneys, ureters, and bladder. Nephrogram phase: \201 rst phase of IVU; \201 lm taken immediately follow- ing intraven ous administration of contrast (peak nephrogram density). The nephrogram is produced by \201 ltered contrast within the lumen of the proximal convoluted tubule (it is a proximal t ubular, rather than distal tubular phenomenon). Pyelogram phase: as the contrast passes along the renal tubule (into the distal tubule), it is concentrated (as water is absorbed, but the contrast agent is not). As a consequence, t he contrast medium is concentrated in the pelvicalyceal system and thus this \200\230pyelo gram \200\231 phase (Fig. 3.5) is much denser than the nephrogram phase. The pyelogram phas e can be made more dense by dehydrating the patient prior to contrast administration. Pelvi c compression can be used to distend the pelvicalyceal system and demonstrate their anatomy more precisely. Compression is released and a \201 lm taken (20 \200\22330min; Fig. 3.6) . INTRAVENOUS UROGRAPHY (IVU) 49 Fig. 3.5 Normal IVU at 15min. Fig. 3.6 Normal IVU at 20min. Lower abdominal compression has been released. CHAPTER 3 Urological investigations 50 Side effects of administration of intravenous contrast media - Occur in 1% of patients give n non-ionic and 5% given ionic contrast media. The most serious reactions represent an anaphylactic reaction \200\224 hypotension with \202 ushing of the skin (marked peripheral vasodilatation), oedema (face , neck, body, and limbs), bronchospasm, urticaria. Rarely, cardiac arrest can occur. The de ath rate, as a consequence of these reactions, is 1 in 40 000 to 1 in 70 000 with the ionic media and 1 in 200 000 with non-ionic contrast agents. A contrast reaction is more likely to occur in patients with an iodine allergy, previous co ntrast reaction, asthma, multiple other allergies, and heart disease and is less likely wit h non-ionic contrast media. Steroid premedication (at least 12h before) can reduce the risk of a contrast reaction. Contrast media are also nephrotoxic. Ten percent of patients with a raised creatinine will develop an increase in creatinine after an IVU (more likely in diabetics, with dehydration, and with large contrast doses). The increase in creatinine usually resolves spontaneously. Uses of the IVU - Investigation of haematuria \200\224detection of renal masses, \201 lli ng defects within the collecting system of the kidney and within the ureters (stones, TCCs) . Localization of calci \201 cation overlying the urinary tract (i.e. is it a stone or not?). Investigation of patients with loin pain (e.g. suspected ureteric colic). Increasingly bein g replaced with CTU which has superior sensitivity and speci \201 city. Very good for identi \201 cation of congenital urinary tract abnormalities (e.g. ureteric anatomy in duplex systems; Fig. 3.7), malrotation, horseshoe kidneys. Used for follow-up of post-ureteric surgery to identify strictures. - There is a trend towa rds IVU being replaced by MDCTU (a rapid acquisition CT done following intravenous contrast administration with high spatial resolution) at least in the investigation of haematuria a nd of loin pain. To a large extent, whether one uses an IVU or MDCTU depends on the availab ility of the latter in your radiology department. INTRAVENOUS UROGRAPHY (IVU) 51 Fig. 3.7 Bilateral duplex as seen on a tomogram from an IVU. CHAPTER 3 Urological investigations 52 Other urological contrast studies Videocystourethrography (VCUG) (Fig. 3.8) To identify the presence of vesicoureteric re \202 ux during \201 lling and emptying of the bladder and the presence and site of obstruction in the outlet of the bladder and within the urethra, particularly in patients with neuropathic bladder problems (e.g. spinal cord injury). Cystography Retrograde \201 lling of the bladder via a catheter with contrast. Identi \201 es vesicocolic and vesicovaginal \201 stulae and bladder rupture (extraperitoneal an d intraperitoneal). Urethrography (Fig. 3.9) Retrograde \201 lling of the urethra with contrast, to identify the site and length of urethral strictures (Fig. 3.10) or presence, extent, and site of ure thral injury (in pelvic fracture, for example). Ileal loopogram Retrograde \201 lling of an ileal conduit with contrast, to establish the pres- ence of free re \202 ux into the ureters (a normal \201 nding; absence of free re \202 ux suggests obstruction at the uretero-ileal junction due to ischaemic stenosis or r ecurrent TCC in the ureters at the uretero-ileal junction) and the presence of TCCs in the ureters or renal pelvis (an occasional \201 nding in patients who have had a cystectomy f or bladder TCC with ileal conduit urinary diversion). Retrograde ureterography Retrograde instillation of contrast into the ureters by a ureteric catheter inserted into the ureter via a cystoscope (rigid or \202 exible). Provides exce l- lent de \201 nition of the ureter and renal pelvis for detection of ureteric and renal pelvic TCCs or radiolucent stones in patients with persistent haema- turia where other test s have shown no abnormality. Also used to diagnose presence and site of ureteric injury (ob struction, ureteric leak) in cases of ureteric injury (e.g. post-hysterectomy or Cesarean s ection). OTHER UROLOGICAL CONTRAST STUDIES 53 Fig. 3.8 VCUG showing bilateral ureteric re \202 ux. Fig. 3.9 Normal urethrogram. Fig. 3.10 A urethrogram showing a bulbar urethral stricture. CHAPTER 3 Urological investigations 54 Computed tomography (CT) and magnetic resonance imaging (MRI) CT Widely used for investigat ion of urological symptoms and disease. It can detect very small differences in X-ray absor ption values of tissues, provid- ing a very wide range of densities (and, therefore, differ entiation between tissues) when compared with plain radiography. The computer calculates th e absorption value (attenuation) of each pixel and reconstructs this into an image. The att enuation values are expressed on a scale from \200\2231000 to +1000 Houns \201 eld units (water = 0, air = \200\2231000, bone = +1000). More recently, advances in computing power have enabled the data to be refor- matted so that images can be produced in sagittal and co ronal planes as well as in the more familiar horizontal plane (Figs. 3.11 and 3.12). \200\230Plain \200\231 CT scans (without contrast) can detect calci \201 cation and calcu li within the urinary tract.