Sexual differentiation refers to the embryological development of male and female phenotypes. Unlike sexual genotype which is determined at the time of fertilisation, the male and female phenotypes do not begin to differentiate substantially until the seventh week of gestation.
Sickle cell disease (SCD) is a hereditary (autosomal recessive) condition resulting in the formation of abnormal hemoglobin (a hemoglobinopathy), which manifests as multisystem ischemia and infarction, as well as hemolytic anemia.
There is no recognised gender predilection. The h...
Abdominal manifestations of sickle cell disease (SCD) are wide and can involve many organs.
For a general discussion, please refer to sickle cell disease.
may occur transiently with the sequestration syndrome, where rapid pooling of blood occurs in the spleen, resulting ...
A sigmoid kidney is an uncommon variant of the horseshoe kidney. Whereas the typical horseshoe kidney is fused only at the lower poles, in a sigmoid kidney both the upper and the lower poles are fused 1.
In the past 15 years sildenafil citrate-induced penile Doppler has emerged as a technique for evaluating erectile dysfunction. It has greater patient acceptability than the usual papaverine-induced color Doppler and is safer.
Sildenafil citrate is a popular vasodilator drug used in treatment of...
Small cell carcinomas of the bladder are rare bladder cancers with a poor prognosis. Its appearance overlaps other bladder cancers, in particular, urothelial/transitional cell carcinoma.
A very rare tumor, it has been estimated at <0.0001% of bladder cancers. It is thought to have...
The soft-tissue rim sign is used to distinguish a ureteric calculus from a phlebolith. The former appears as a calcific density with a surrounding rim of soft tissue which represents the edematous ureteric wall. Phleboliths on the other hand usually have imperceptible walls (although up to 8% ma...
Solitary filling defect with a ureter, as seen on conventional IVU or CT IVU has some differentials, including:
within the lumen
within the wall
transitional cell carcinoma (TCC)
When multiple fi...
SpaceOAR is a technique in which a physical space is created between the prostate gland and rectum for electron beam radiotherapy targeted to the prostate gland in cases of prostate cancer.
OAR stands for "organ at risk", and in cases of prostate cancer radiotherapy treatment the rectum is the...
The spaghetti sign may be seen in upper urinary tract bleeding.
It refers to the presence of a linear worm- or spaghetti-like filling defect within a contrast-opacified bladder 1,2. This linear filling defect represents blood clot extruded from the ureter and thereby moulded into a tubular shap...
The spermatic cord is the tubular structure that suspends the testes and epididymis.
The spermatic cord starts at the deep inguinal ring, passes through the inguinal canal and exits at the superficial inguinal ring into the scrotum 3. In the scrotum, the spermatic cord t...
Handy mnemonics to recall the contents of the spermatic cord are:
Papers Don't Contribute To A Good Specialist Level
3 arteries, 3 nerves, 3 other things
Papers Don't Contribute To A Good Specialist Level
P: pampiniform plexus
D: ductus deferens
C: cremasteric artery
Spermatic cord hydrocele (SCH) refers to a loculated fluid collection along the spermatic cord. It is separated from, and located above, the testis and the epididymis.
It results from aberrant closure of the processus vaginalis.
There are two recognised subtypes
encysted hydrocele ...
Spermatic cord leiomyosarcomas are uncommon malignant paratesticular masses.
Accounts for ~10% of spermatic cord sarcomas. The average of a patient at presentation is 58 years old (although has been seen as young as 15 years old).
Patients may have left inguina...
Spermatic cord liposarcomas are the most common malignant tumor of the spermatic cord. Most present as painless, slow-growing masses and can be mistaken for inguinal hernias. They are usually well-differentiated and spread by local extension.
In a large population-based registry,...
Spermatoceles are a common type of extratesticular cyst, and represents cystic dilatation of tubules of the efferent ductules in the head of the epididymis.
Usually a painless, incidental finding but can present as a mass lesion if large 3.
Spermatoceles are u...
Sperm cell granuloma, also termed epididymitis nodosa, is a benign lesion that can occur in the scrotum. They can particularly occur in those with a prior vasectomy (occurs after vasectomy in up to 40% of patients 2).
It is considered a form of chronic epididymitis which occurs secon...
Spigelian-cryptorchidism syndrome is the association of Spigelian hernias and cryptorchidism in children.
It is reported that ~50% (range 28-75%) range of pediatric patients with Spigelian hernias will have ipsilateral cryptorchidism 1,2.
Along with Spigelian hernia and cryptorchi...
Spinning top urethra is non-obstructive posterior urethral dilatation seen on voiding cystourethrography, mainly in females. It was initially considered as an indicator of distal urethral narrowing/stenosis. However, it is now believed to be due to functional discoordinate voiding or bladder ins...
Splenogonadal fusion is a rare anomaly that occurs when there is congenital fusion between a portion of the spleen and a gonad or other mesonephric derivative.
Much more common in male patients (~95%), occurs most commonly on the left (98%) and usually involve the testis (95%). Ha...
The split bolus technique is a CT imaging investigation used in patients with hematuria aiming to put together, in a single image acquisition, both the nephrographic and renal excretory phases and thus reducing the radiation dose of the study. It is a CT protocol adopted for some institutions fo...
A spoke wheel pattern in renal imaging refers to a vascular appearance seen with certain renal tumors, typically seen in oncocytomas but can also be seen in renal cell carcinomas.
This appearance refers to a peripheral rim of vessels from which centripetal vessels converge centrally giving the...
Spontaneous retroperitoneal hemorrhage (SRH) is a distinctive clinical pathology of retroperitoneal bleeding without a preceding history of trauma.
Clinical presentation may be vague and varied:
no inciting history
no evidence of cutaneous bruising
back, lower abdomina...
Spontaneous rupture of the renal pelvis, also known as pyelosinus backflow, is a rare complication that can occasionally occur with obstructive urolithiasis (usually in the distal third of the ureter) or occasionally infection 1. Leakage of urine can result in a urinoma, and there is an increase...
A spotted nephrogram is a descriptive term indicating an appearance of patchy, segmental and subsegmental renal parenchymal enhancement.
The pattern is indicative of focal areas of cortical ischemia or necrosis, as a result of small vessel occlusion. This abnormal perfusion pattern c...
Squamous cell carcinoma of the penis arises most commonly at the distal end of the penile urethra with local invasion of the glans.
In addition to TNM classification, the following staging is used:
stage I: confined to the glans or foreskin
stage II: invasion of penile shaft
Squamous cell carcinoma of the urinary bladder is rare and accounts for only ~3-8% 1,2 of all bladder cancers (90% are transitional/urothelial cell carcinomas) but nevertheless, SCC is the most common type of nontransitional cell carcinoma involving the bladder 2. SCC of the bladder is observed ...
Staghorn calculi, also sometimes called coral calculi, are renal calculi that obtain their characteristic shape by forming a cast of the renal pelvis and calyces, thus resembling the horns of a stag.
For a general discussion of renal calculi please refer to nephrolithiasis.
Steinstrasse [stīn′shtra-se] is the German word for "stone street", describing a possible complication of extracorporeal shock wave lithotripsy (ESWL) for urinary tract calculi, wherein a column of stone fragments forms that blocks the ureter.
Steinstrasse usually develops 1 day to 3...
The stipple sign refers to the pointillistic end-on appearance on intravenous pyelography or retrograde pyelography of contrast material tracking into the interstices of a papillary lesion. Because the majority of transitional cell carcinomas (TCC) have a papillary configuration, the presence of...
Striated nephrogram is a descriptive term indicating an appearance of alternating linear bands of high and low attenuation in a radial pattern extending through the corticomedullary layers of the kidney on iodine-based intravenous contrast enhanced imaging.
It is important to know that a simila...
The string of beads sign is the description typically given to the appearance of the renal artery in fibromuscular dysplasia (FMD) but may also be used to describe the appearance of splanchnic arteries in segmental arterial mediolysis (SAM). It refers to the appearance arising from the stenoses ...
A subcapsular perirenal hematoma is a form of perirenal hematoma where blood accumulates beneath the renal capsular margin.
It can arise from a number of causes
trauma, important in assessing renal trauma grading
post procedural, e.g. extracorporeal shock-wave lithotripsy (ESWL) 5-...
The sunburst sign refers to the appearance of arterial blush seen at selective arterial DSA angiography of a renal angiomyolipoma.
Angiomyolipoma is a hypervascular renal mass that shows dense early arterial vascular network of tortuous irregular vessels with micro- or macro-aneurysms.
The superficial perineal pouch is an anatomic space below the perineal membrane in the urogenital triangle of the perineum.
The superficial perineal pouch is inferior (superficial) to the perineal membrane in the urogenital triangle, anterior to the transverse line between the is...
The superior adrenal (suprarenal) arteries area a group of one of the three adrenal arteries that supply the adrenal gland. There are usually numerous small arteries arising from the inferior phrenic artery.
The superior suprarenal arteries arise from the inferior phrenic...
Supernumerary kidneys are a rare congenital anomaly of the urogenital system, where there are one or two accessory kidneys.
Less than 100 cases are documented.
Patients may be asymptomatic. If present symptoms range from fever, pain to abdominal mass. Thes...
Suprapubic cartilaginous cysts (SPCC) are rare cystic lesions arising from the symphysis pubis thought to be degenerative in origin. They have also been called retropubic or subpubic cysts.
In the small number of cases in the literature, all bar one patient, have been female. The ...
The supravesical fossae are concave depressions of peritoneum in the paravesical space bounded by the median umbilical fold and the medial umbilical folds. It partially overlies the inguinal (Hesselbach’s) triangle. The supravesical fossae are usually occupied by small bowel loops and the urinar...
Surgical hemostatic material is used to control bleeding intraoperatively and is hence frequently voluntarily left in the operative bed, not to be confused with a gossypiboma which is caused by foreign material left behind in error. It can mimic an abscess on imaging studies. Various types are a...
Syphilis is the result of infection with the gram negative spirochete Treponema pallidum, subspecies pallidum. It results in a heterogeneous spectrum of disease with many systems that can potentially be involved, which are discussed separately.
Despite the discovery of penicillin...
Systemic lupus erythematosus (SLE) is a complex autoimmune disease with multisystem involvement. Although abnormalities in almost every aspect of the immune system have been found, the key defect is thought to result from a loss of self-tolerance to auto-antigens.
There is a stron...
Tamm-Horsfall proteins, also known as uromodulin, may be a cause of echogenic renal pyramids in a neonate.
Tamm-Horsfall proteins are physiologically excreted by the renal tubular epithelium. They are most often encountered on neonatal renal ultrasound, where the concentrated proteins in the re...
Tc-99m DMSA (dimercaptosuccinic acid) is a technetium radiopharmaceutical used in renal imaging to evaluate renal structure and morphology, particularly in pediatric imaging for detection of scarring and pyelonephritis. DMSA is an ideal agent for the assessment of renal cortex as it binds to the...
Tc-99m DTPA (diethylene-triamine-pentaacetate) is one of the technetium radiopharmaceuticals used in renal imaging and primarily used to measure the glomerular filtration rate (GFR).
photon energy: 140 KeV
physical half-life: 6 hours
biological half-life: 2.5 hours
Tc-99m MAG3 (mercaptoacetyltriglycine) is one of the technetium radiopharmaceuticals used in renal imaging.
photon energy: 140 KeV
physical half life: 6 hours
biological half life: 4 hours
normal distribution: kidneys (100%)
uptake by tubular secretion (9...
Tc-99m pertechnetate is one of the technetium radiopharmaceuticals used in imaging of thyroid, colon, bladder and stomach.
photon energy: 140 keV
biological half-life: 6 hours
normal distribution: stomach, thyroid, salivary glands, (testicles)
Technetium agents based on the technetium-99m (Tc-99m) radioisotope are frequently used agents in medical imaging. The radioactive technetium radiotracer can be chelated to a number of different compounds to create specific radiopharmaceuticals and optimise the functional imaging of various stru...
Teratomas are germ cell tumors that arise from ectopic pluripotent stem cells that fail to migrate from yolk sac endoderm to the urogenital ridge during embryogenesis. By definition, they contain elements from all three embryological layers: endoderm, mesoderm and ectoderm although frequently, e...
Testicular abscess is usually a complication of severe epididymo-orchitis and needs to be distinguished from other testicular pathology that may present with similar clinical or imaging features.
The majority of patients develop a testicular abscess as a result of untreated or se...
Testicular adrenal rests are a rare cause of a testicular mass.
Testicular adrenal rests can be known by a variety of terms 2:
testicular adrenal rest tumor (TART)
testicular adrenal rest tissue
testicular tumor of the adrenogenital syndrome
testicular adrenal-like tissue
Testicular and scrotal ultrasound is the primary modality for imaging most of the male reproductive system. It is relatively quick, relatively inexpensive, can be correlated quickly with the patient's signs and symptoms, and, most importantly, does not employ ionising radiation.
MRI is occasion...
Testicular and epididymal appendages are remnants of embryonic ducts and are quite common, with one or more being present in ~70% of patients 1.
Four such appendages have been described:
testicular appendix (hydatid of Morgagni)
it is a Müllerian duct remnant (paramesonephric d...
A testicular appendix (alternatively called appendix of testis or appendix testis) represents a developmental remnant of the paramesonephric duct (Müllerian duct) which is situated in the upper pole of the testis inside a groove between the testicle and the head of epididymis 1.
The testicular arteries (also known as the spermatic arteries) are the long, small-diameter gonadal arteries in the male that supply the testis alongside the cremasteric artery and the artery to the ductus deferens.
As paired structures they arise symmetrically, slightly...
Testicular cancers are the most common neoplasm in men between the ages of 20 and 34 years.
Testicular cancer is uncommon, accounting for less than 1% of all internal organ malignancies 2.
The demographics of affected individuals depends on the age of the histology of the tumor. ...
The staging for testicular tumors is performed according to the TNM system with staging groupings. It can be remembered in its abbreviated form as:
stage I: confined to testis, epididymis, spermatic cord, scrotum
stage II: lymph nodes involved but no distant metastases and serum tumor markers...
Testicular choriocarcinoma is a type of non-seminomatous germ cell tumor.
Incidence peaks at around 20-30 years of age.
Can be variable with some patients initially presenting with metastates.
It is most commonly detected as a component of a mi...
Simple testicular cysts are usually nonpalpable and thus are detected incidentally.
Testicular cysts require no treatment when discovered.
anechoic with posterior acoustic enhancement
no flow on color Doppler
Testicular descent occurs after the fourth month of fetal life. The testes are derived from the gonadal ridge medial to the mesonephric ridge of the intermediate cell mass. An elongated diverticulum of the peritoneal cavity, the processus vaginalis precedes the testis through the inguinal canal ...
Testicular dislocation is a rare condition in which a testicle is dislocated from its normal position within the scrotum to another location, most commonly the superficial inguinal pouch.
The condition mainly occurs in younger men with a mean age of 25 years 2.
Testicular embryonal cell carcinoma is a type of non-seminomatous germ cell tumor.
Incidence peaks at around 25-30 years.
It may occur as part of a mixed germ cell tumor (more common and may be present as a component in around 80% of mixed germ cell tumors) or very ra...
Testicular epidermoid cysts, also known as keratocysts, are rare benign tumors of germ cell origin that occur in the testis.
Testicular epidermoid cysts account for around 1-2% of all testicular masses and typically present in mid-adulthood (2nd to 4th decades) 1,2. They are the ...
Testicular fracture refers to a break in the parenchyma of the testicle as a result of blunt trauma.
A fracture line can be seen as a hypoechoic and avascular area within the testis but is only seen in 17% of cases 1. A tunica albuginea rupture may also be pr...
Testicular germ cell tumors account for 90% of primary tumors of the testes. They are the most common nonhaematologic malignancy in men 15-49 years old.
They are divided into:
testicular seminoma: 40% of germ cell tumors 1
non-seminomatous germ cell tumor: 60% of germ cell tumors
Testicular leukemia can be seen in patients during and after acute leukemia. The blood-testis barrier limits chemotherapy from reaching the testicle, and therefore the testicle can act as a harbor for leukemic cells.
Typically presents with painless testicular enlargement...
Testicular lipomatosis is a rare condition characterized by homogeneously hyperechoic non-shadowing lesions within the testes on ultrasound without flow on color Doppler. It is seen as a component of PTEN (phosphatase and tensin homolog (gene)) hamartoma tumor syndrome which includes:
Testicular lymphoma is an uncommon testicular malignancy. Lymphoma can involve the testes in three ways:
primary site of extranodal disease (primary testicular lymphoma)
secondary involvement of systemic disease
primary manifestation of subclinical systemic disease
This article is concerned ...
Testicular microlithiasis (TM) is a relatively common condition that represents the deposition of multiple tiny calcifications throughout both testes.
The most common criterion for diagnosis is that of five microcalcifications in one testicle, although definitions have varied in the past. In t...
Testicular mixed germ cell tumors are, as the name suggests, testicular tumors composed of two or more types of germ cell tumor. They are considered to be part of non-seminomatous germ cell tumors, as it is that component which dictates prognosis and treatment.
Overall they account for over 10...
Testicular sarcoidosis is a rare manifestation of sarcoidosis. In cases of urogenital sarcoidosis, more commonly the epididymis is affected.
Testicular sarcoidosis is more common in African-American patients, as are other forms of sarcoidosis 1. Up to 5% of patients with chronic s...
Testicular seminomas are the most common testicular tumors and account for ~45% of all primary testicular tumors. This article concerns itself only with testicular seminomas, however, seminomas can arise outside of the testicle most often within the anterior mediastinum, e.g. anterior mediastina...
Testicular teratoma, unlike ovarian teratoma, is often aggressive in its biological behavior, and often exists as part of testicular mixed germ cell tumors.
Pure testicular teratomas account for only 4-9% of all testicular tumors. A similar number are seen in the context of test...
Testicular torsion occurs when a testicle torts on the spermatic cord resulting in the cutting off of blood supply. The most common symptom is acute testicular pain and the most common underlying cause, a bell-clapper deformity. The diagnosis is often made clinically but if it is in doubt, an ul...
Testicular trauma is the third most-common cause of acute scrotal pain and may result in various degree of damage to the testes.
Testicular rupture and testicular ischemia/infarct are two severe complications which need to be ruled out. Other injuries that can occur include 1:
Testicular vasculitis can occur as either part of a systemic vasculitis or an isolated vasculitis involving only the testes with both having roughly equal prevalence.
The mean age of onset is approximately 40 years.
Symptoms can include a testicular mass w...
Testicular yolk sac tumors (also known as endodermal sinus tumor of the testis) is the most common childhood testicular tumor (80%), with most cases occurring before the age of two years 1. In adults, pure yolk sac tumor is extremely rare, however mixed germ cell tumor are commonly seen.
The testes, also known as the testicles, are the male gonads and are contained within the scrotum. The testes are responsible for the production of sperm and testosterone.
At birth, testes measure approximately 1.5 cm (length) x 1 cm (width), reaching ~4 mL volume at puberty 1.
Thimble bladder is a descriptive term for extreme fibrosis and contracture of the bladder walls, resulting in a tiny bladder. The term is usually used to describe changes from advanced genitourinary tuberculosis.
The threads and streaks sign refers to an angiographic appearance of a vascularized tumor thrombus extending into the ipsilateral renal vein or the inferior vena cava from a renal cell carcinoma. This gives an appearance of linear, thread-like or string-like appearance of the involved vessel.
Throckmorton sign, also known as John Thomas sign, refers to when the penis points in the direction of unilateral disease, typically of the pelvis or hip.
Throckmorton sign is a slang term used humorously by medical students and residents.
According to the first serious study of the sign publ...
Torsion of the appendix testis is the most common cause of an acute painful hemiscrotum in a child. The appendix testis is located at the upper pole of the testis (between the testis and the head of the epididymis).
The normal appendix testis is 1 to 4 mm in length, and it is oval or pedunculat...
Transitional cell carcinoma (TCC) is the most common primary neoplasm of the urinary bladder, and bladder TCC is the most common tumor of the entire urinary system.
This article concerns itself with transitional cell carcinomas of the bladder specifically. Related articles include:
Transitional cell carcinomas of the urothelium are graded histologically as follows:
transitional cell papilloma
benign tumor, not a carcinoma but sometimes included in classification systems
carcinoma in situ
do not penetrate the basement membrane
cells resemble those of grade II or III t...
Transitional cell carcinoma of the bladder staging uses the TNM system which has replaced the previously widely used Jewett-Scott-Marshall tumor staging system. It is very similar to the staging of TCC of the renal pelvis and staging of TCC of the ureter.
Ta: non-invasive papill...
Transitional cell carcinoma of the renal pelvis staging uses the TNM system and is very similar to staging of TCC of the bladder and to staging of TCC of the ureter.
Ta: noninvasive papillary tumor
Tis: in situ (noninvasive flat)
T1: through lamina propria into sub-epithelial ...
Transitional cell carcinoma of the ureter staging uses the TNM system and is very similar to staging of TCC of the bladder and to staging of TCC of the renal pelvis.
Ta: noninvasive papillary tumor
Tis: in situ (noninvasive flat)
T1: through lamina propria into sub-epithelial...
Transitional cell carcinoma of the renal pelvis is uncommon compared to renal cell carcinoma and can be challenging to identify on routine imaging when small.
This article concerns itself with TCCs of the renal pelvis specifically. For a general discussion of this tumor, please see transitiona...
Staging of transitional cell carcinomas of the urinary tract vary according to the location of the tumor, and are staged using the TNM staging system.
transitional cell carcinoma of the renal pelvis
transitional cell carcinoma of the ureter
transitional cell carcinoma of the bladder
Transitional cell carcinoma of the ureter are uncommon compared to similar tumors elsewhere along the urinary tract but are nonetheless the most common primary tumor of the ureter.
This article concerns itself with transitional cell carcinomas of the ureter specifically. For a general discussio...
Transitional cell carcinoma (TCC), also called urothelial cell carcinoma (UCC), is the most common primary malignancy of the urinary tract and may be found along its entire length, from the renal pelvis to the bladder.
As imaging findings and treatment vary according to where along the urinary...
Transjugular renal biopsy can be performed to obtain an adequate tissue sample for histopathologic diagnosis on renal dysfunctions. It is usually performed in high-risk patients in whom percutaneous renal biopsy is not feasible or is contraindicated. This is also useful in morbidly obese patient...
Transplant renal arterial pseudostenosis is uncommon. It is a lesion in the iliac artery proximal to the implantation of the transplant renal artery.
Uncommon, although as the population of renal transplant recipients has become older and more diabetic, the incidence of this disea...