Infertility is common, affecting 15-20% of couples, and is defined as the inability to conceive after one year of regular unprotected intercourse 3,4. Subfertility is a synonym 4. It can be due to a variety of both female and male factors, and these are discussed in separate articles:
Inflammatory myofibroblastic tumors (IMT), also known as plasma cell granulomas, are rare neoplasms that have a diverse spectrum of biological behavior.
These tumors were previously referred to as inflammatory pseudotumor.
They can occur at any age and there is cu...
The inguinal canal is a passage in the anterior abdominal wall that transmits structures from the pelvis to the perineum formed by the fetal migration of the gonad from the abdomen into the labioscrotal folds.
The inguinal canal has an oblique course, is 4 cm in length and has tw...
The inguinal lymph nodes (often shortened to the inguinal nodes) are a major group of lymph nodes in the lymphatic system. They are the major drainage pathway of the lower limbs, genitals, dorsal perineum and the inferior most aspect of the anterior abdominal wall. Inguinal lymph nodes larger th...
The internal iliac lymph nodes (often shortened to internal iliac nodes) are the lymph nodes found adjacent to the internal iliac artery and its branches and drain the regions supplied by these vessels. This encompasses a large area from the genitalia anteriorly, the psoas muscle posteriorly and...
The internal pudendal veins are the set of accompanying veins to the internal pudendal artery draining the perineal region to empty into the internal iliac vein.
inferior rectal veins
penile bulb and scrotum vein
clitoris and posterior labial vein
The international prostate symptom score (IPSS) is an 8 question (7 symptom questions + 1 quality of life question) screening tool used in screening, diagnosis, symptom tracking, and aiding management of the symptoms associated with bladder emptying and is useful in those with benign prostatic h...
The International Society of Urological Pathology Vancouver classification of renal neoplasia is a now-outdated classification of renal tumors published in 2013. It formed the basis for the most recent revision of the WHO classification of tumors of the kidney, published in 2016. For reference, ...
Interstitial cystitis (or painful bladder syndrome) refers to an inflammatory condition affecting the bladder. It is usually defined as urinary bladder pain and irritative symptoms of more than six months' duration. It usually represents a diagnosis of exclusion. Traditionally, it has been defin...
Intra-abdominal calcification in a neonate can be caused by a number of pathologies that cause calcification within the peritoneal space or within organs.
The commonest cause is meconium peritonitis which is the result of aseptic peritonitis secondary ...
Intramural fat of the urinary bladder is an occasional benign finding on CT/MRI.
Incidence of this finding on histopathological studies is up to 4%. Published radiological and pathological cohorts both report a male predominance.
Incidental asymptomatic fi...
Intrapelvic cup migration is a serious complication after total hip arthroplasty, in which the prosthetic acetabular cup migrates or drifts into the pelvic inlet.
Fortunately, this complication is very rare. There seems to be a female predisposition 1-3.
Intrarenal reflux (IRR) involves intrarenal extension of vesicoureteral reflux (VUR) into the tubular system of the kidney.
IRR occurs in 3-10% of cases and can lead to renal injury, which may eventually result in renal scarring. The condition can be diagnosed by micturating cystourethrography ...
Intratesticular hematomas typically result from testicular trauma.
isoechoic/hyperechoic region in the traumatised testicle, becoming more hypoechoic as it resolves
lack of color Doppler flow
segmental testicular infarct
Intratesticular varicocele is a rare entity, occurring in ~2% of symptomatic population.
It is defined as dilated intratesticular veins seen in relation to the mediastinum testis and extending peripherally. It is usually seen in the presence of ipsilateral extratesticular varicocele....
An intrathoracic kidney is a very rare form of ectopic kidney. There has been no reported increased incidence of stones or infections as can be seen with other forms of ectopic kidneys. The adrenal glands are usually normal in location.
Thoracic ectopic kidney is rare with male pr...
Intravenous urography (IVU), also referred to as intravenous pyelography (IVP) or excretory urography (EU), is a radiographic study of the renal parenchyma, pelvicalyceal system, ureters and the urinary bladder. This exam has been largely replaced by CT urography.
Some prefer the ...
Intravesical prostatic protrusion (IPP) is a anatomical feature that may be present in some patients with BPH (benign prostatic hyperplasia), being characterized by the enlargement of the prostate towards the floor of the bladder 1,2.
IPP has a correlation with difficulty...
Inverted papillomas of the urinary tract are rare, benign tumors that most commonly occur at the bladder neck or trigone and are characterized by an inverted growth pattern on histology 1.
Iron deficiency anemia is a common cause of anemia and a common precipitant to radiological investigation.
Amongst men and postmenopausal women, the incidence in the developed world is around 2%. Among premenopausal women, the incidence is greater and in most cases, investigation ...
The ischiocavernosus muscles are one of the three main muscles found in the superficial perineal pouch along with the bulbospongiosus and superficial transverse perineal muscles.
origin: ischial tuberosity and ramus
males: corpus cavernosum
Isthmus (plural isthmi) is an anatomical term and refers to a slender structure joining two larger components. Some of these uses of the word isthmus are now rarely used or only seen in older texts and articles:
isthmus (auditory tube)
isthmus (auricle of the ear)
Jackstone calculus is the name assigned to the appearance of a subset of urinary calculi.
Jackstone calculi are almost always composed of calcium oxalate dihydrate. They are nearly always created, and thus, located, in the bladder rather than the upper urinary tract.
They are compos...
Junctional parenchymal defects in renal imaging are a normal variant, which results from the incomplete embryonic fusion of renunculi.
It can be seen as a triangular echogenic cortical defect, frequently seen in upper lobe parenchyma. The defect is the extensi...
Juxtaglomerular cell tumors, also known as reninomas, are uncommon renal tumor of the juxtaglomerular cells. The tumor cells secrete renin and often cause severe hypertension and hypokalemia.
Juxtaglomerular cell tumor affect all age groups, but are most common in adolescents and ...
The Kerr kink is a sign of renal tuberculosis. Scarring in the adjacent tissues due to chronic inflammation leads to a sharp kink at the pelviureteric junction (PUJ).
History and etymology
William "Bill" K Kerr, a Canadian urologist, described his eponymous sign in 1967 3.
Ketamine bladder or ketamine bladder syndrome refers to lower urinary tract symptoms associated with long-term ketamine use.
The presence of lower urinary tract symptoms in long-term ketamine users has been identified to be as high as 90% in some studies 1.
The keyhole sign may refer to:
keyhole sign (intracapsular breast implant rupture)
keyhole sign (posterior urethral valves)
keyhole sign (neural exit foramina)
The keyhole sign is an ultrasonographic sign seen in boys with posterior urethral valves. It refers to the appearance of the proximal urethra (which is dilated) and an associated thick-walled distended bladder which on ultrasound may resemble a keyhole.
The kidneys are paired retroperitoneal organs that lie at the level of the T12 to L3 vertebral bodies.
The kidneys are located on the posterior abdominal wall, with one on either side of the vertebral column, in the perirenal space. The long axis of the kidney is parall...
The kidney sweat sign refers to the presence of thin, hypoechoic, extracapsular fluid collections around kidneys in renal failure patients. This fluid is thought to represent perirenal edema. It can be appreciated on ultrasound, CT and MRI.
This article lists a series of labeled imaging anatomy cases by system and modality.
CT head: non-contrast axial
CT head: non-contrast coronal
CT head: non-contrast sagittal
CT head: angiogram axial
CT head: angiogram coronal
CT head: angiogram sagittal
CT head: venogram axial
The labia majora (singular: labium majus) form the anteroinferior most part of the vulva, they are continuous with the mons pubis anteriorly and the perineum posteriorly. The labia are apposed in the midline forming the, externally-visible, pudendal cleft.
The labia majora have ...
The labia minora (singular: labium minus) are small glabrous cutaneous folds lying between and just superior to the labia majora. At their posterior margin the labia may be conjoined by a thin cutaneous fold of skin, the frenulum of the labia (also known as the fourchette or posterior commissure...
Lactate dehydrogenase (LDH or LD) is a key enzyme in most cells, catalyzing the reversible conversion of pyruvate to L-lactate. Its contemporaneous main clinical uses are limited primarily to the investigation of hemolysis, serous collections and as a tumor marker.
Lacuna magna, also known as the sinus of Guérin, is a congenital blind-ended pouch located dorsal to navicular fossa of penis separated by fold and both share an external common opening to external urethral meatus. This diverticulum is located above and parallel to the urethra.
The term lamellated (or laminated which means the same thing) is a radiopathological term used to describe the layered appearance of many calculi, including those of the renal tract, the salivary glands, and the biliary tree. The internal structure of these calculi has been likened to that of an...
The lateral fossae are concave depressions of peritoneum in the paravesical space that lie between the lateral umbilical folds and the lateral parietal peritoneum. The lateral fossae are the smallest of the anterior paravesical fossae, and typically partially contain the cecum and/or sigmoid col...
The lateral umbilical folds are bilateral raised ridges of parietal peritoneum in the deep aspect of the anterior abdominal wall overlying the inferior epigastric vessels. The paired folds originate medial to the deep inguinal ring and end at the arcuate line on the posterior aspect of the anter...
The lateroconal fascia is the peritoneal thickening which extends anterolaterally from the adjoining merging lateral borders of the anterior and posterior perirenal fasciae.
It increases progressively in length as it ranges distally. It traverses laterally in a transverse plane a...
A handy mnemonic to recall the layers of the scrotum is:
Some Damn Englishman Called It The Testes
D: dartos fascia and muscle
E: external spermatic fascia
C: cremasteric fascia
I: internal spermatic fascia
T: tunica vaginalis
T: tunica albuginea
Lead poisoning or plumbism is a multisystem condition due to the way in which lead interferes with the function of virtually every organ system. Plumbism most severely manifests due to its devastating effects on the CNS, but it also has important deleterious consequences on the skeletal, renal, ...
Leiomyoma of the urinary bladder is a rare benign mesenchymal tumor of the bladder. The most common presenting complaints are urinary voiding symptoms such as obstruction and irritation.
These leiomyomas exhibit imaging characteristics on ultrasound, CT and MRI similar to those of uterine leio...
Leiomyosarcoma of the prostate is a rare mesenchymal smooth muscle malignancy of the prostate gland.
It is a rare tumor with less than 200 cases reported in the literature accounting for approximately 25% of all sarcomas of the prostate gland and less than 0.1% of primary prostate...
The lentiform fork sign has been described on MRI and is seen as bilateral symmetrical hyperintensities in the basal ganglia surrounded by a hyperintense rim delineating the lentiform nucleus.
It has been postulated to result from metabolic acidosis due to any cause 1, e.g. end stage renal dise...
Leptospirosis results from infection by the zoonotic Leptospira spp. The condition can have multiorgan manifestations. Commonly affected organs include:
lung: pulmonary leptospirosis
liver: hepatic leptospirosis
central nervous system: CNS leptospirosis
skeletal muscle: muscular leptospirosi...
Lesch-Nyhan syndrome is a rare X-linked genetic disease caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT).
Affects 1 per 380,000 individuals, which are nearly all male given the X-linked inheritance 1.
Leukemia testicular manifestations, or 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 testi...
Leukoplakia of the urinary tract is a squamous metaplasia of the urothelium (keratinization).
Clinically the condition presents with hematuria in one-third of cases, dysuria, frequency and nocturia, and thus it can mimic cystitis. Passage of the desquamated keratinized e...
The levator ani muscle, also known as the muscular pelvic diaphragm, is the musculotendinous sheet that forms the majority of the pelvic floor, supports the pelvic viscera, and aids in urinary and fecal evacuation as well as maintaining continence.
The levator ani has three main ...
A Leydig cell tumor of the testis is an uncommon testicular neoplasm. Its imaging appearance on ultrasound and MRI is nonspecific, but clinically it is associated with serum hormonal imbalance.
1-3% of all testicular tumors, but the most common sex-cord stromal tumor. Tend to be b...
Lichen planus refers to a dermatological condition that typically affects the skin, nails, oral cavity, genitals or perineum.
Skin lesions are characterized by violaceous scaly pruritic plaque eruption while oral lesions are characterized by erosions and lace-like reticular plaques. It is a chr...
Liddle's syndrome is an autosomal dominant condition which inhibits the normal degradation of the ENaC sodium channel, resulting in findings that mimic Conn's syndrome (hyperaldosteronism); hypernatremia, hypokalemia and elevated serum bicarbonate. Typically patients are asymptomatic other than ...
Lipomatosis is a condition where there is diffuse excessive fat deposition within the body. This can especially affect certain regions.
neck and upper region of trunk
lipomatous hypertrophy of the interatrial septum
lipomatous metaplasia of th...
Lithium induced renal disease is characterized by a progressive decline in renal function, evidenced by increasing serum creatinine and decreased creatinine clearance. The lithium salt causes direct injury to the renal tubules. The duration of lithium therapy increases the risk of progression to...
Lobar nephronia, also known as acute focal nephritis, refers to an intermediate stage between acute pyelonephritis and renal abscess, and is a focal region of interstitial nephritis.
It appears as a wedge of poorly perfused renal parenchyma, without a cortical rim sign.
The condition is discu...
Lobster claw sign refers to a urographic pattern of papillary excavation that may be seen with renal papillary necrosis.
The lobster claw sign occurs when there is excavation around the edge of the papilla and the contrast material that extends into this excavated region looks like the "claws" ...
Localized cystic renal disease (LCRD), also known as localized cystic kidney disease, is an uncommon, non-familial, non-progressive disease characterized by clusters of cysts within the normal renal parenchyma. It can be confused with unilateral autosomal dominant polycystic kidney disease (ADPK...
Loin pain hematuria syndrome is a rare disorder in which patients suffer episodes of severe unilateral or bilateral flank pain with microscopic or gross hematuria in the absence of renal pathology.
Approximately 70% of patients are young females with a peak incidence in the third ...
A loopogram is a fluoroscopic study of an ileal conduit, which is a type of urinary diversion.
This procedure is also known is an ileal conduitogram, ileal loopography or ileostoureterography.
It is a retrograde study in which contrast is injected via the anterior abdo...
The loop-to-loop colon describes an abnormal colonic course associated with the absence of the left kidney from the renal fossa.
The transverse colon extends to the lateral margin of the abdominal wall and the descending colon courses medially to fill the renal fossa, resulting in a "looped" c...
Lower urinary tract symptoms (LUTS) are a constellation of symptoms including 1:
poor stream despite straining
hesitancy, frequency, and incomplete emptying of the bladder
terminal dribbling (at the end of the urinary stream)
Although they are most frequently encountered in men wit...
Lowe syndrome, also known as the oculocerebrorenal syndrome of Lowe, is a multisystem disorder characterized by anomalies primarily affecting the eyes, nervous system, and kidneys.
It is an extremely rare, pan-ethnic disease, with an estimated prevalence in the general population ...
There are relatively few causes of low signal intensity renal parenchyma. Causes include:
paroxysmal nocturnal hemoglobinuria
mechanical: malfunctioning prosthetic cardiac valve
sickle cell disease
hemorrhagic fever with renal syndrome (HFRS)
Lumbar hernias (alternative plural: herniae) are a rare form of posterior abdominal hernia.
Most common in patients aged between 50 and 70 years with a male predominance 1.
Patients with lumbar hernias can present with a variety of symptoms, including a p...
The lying down adrenal sign is a cross-sectional imaging sign of renal agenesis or ectopia in which the ipsilateral adrenal gland appears to be 'lying down' on the psoas muscle posteriorly. Due to the linear as opposed to Y-shaped configuration of the gland in such situations, it is also describ...
Lymphangioleiomyomatosis (LAM) is a rare multi-system disorder that can occur either sporadically or in association with the tuberous sclerosis complex (TSC) and is often considered a forme fruste of TSC.
It almost exclusively affects women of childbearing age 7. The estimated in...
Macronodular adrenal hyperplasia refers to a morphological type of adrenal hyperplasia in which there is adrenal enlargement in the form of large distinct nodules. It can be congenital or acquired.
A specific subtype under this entity is adrenocorticotropin independent macronodular adrenocortic...
A maiden waist deformity is a name given to the appearance when there is medial deviation of both ureters. This typically occurs in retroperitoneal fibrosis. In this condition, there is medial indrawing of the ureters due to deposition of fibrous tissue in the retroperitoneum at the level of the...
Mainzer-Saldino syndrome (also known as conorenal syndrome (CRS)) is a rare condition and is one of the ciliopathies. It is due to mutations in the IFT140 gene, whose protein product is one of the six parts of the intraflagellar transport complex A.
The syndrome's key characteristics are:
Malacoplakia is an uncommon chronic granulomatous inflammatory disease that can affect essentially any part of the body but most frequently involves the bladder wall.
Malacoplakia has a peak incidence in middle age and has a reported female-to-male ratio of 4:1 1. Other risk fact...
Male pseudohermaphroditism (MPH) is a variation of gender development.
Patients with male pseudohermaphroditism have 46 XY karyotype and may manifest as a female phenotype with various degrees of undervirilization secondary to partial androgen insensitivity.
The male reproductive system (or tract) includes:
It can be imaged using almost the entire range of imaging modalities but ultrasound and MRI are most often used (in part because...
The male urethra is a fibromuscular tube that drains urine from the bladder. It has a longer, more complicated, course than the female urethra and is also more prone to pathology.
The male urethra measures, on average, 18-20 cm in length. It commences at the internal urethral ori...
A helpful mnemonic to remember the 4 segments of the male urethra from proximal to distal is:
Pet My Beautiful Pig
Posterior urethra equates to the prostatic and membranous urethras. Anterior urethra equates to the bulbous and peni...
The Management of Incidental Adrenal Masses revised in 2017 by the Adrenal Subcommittee of the Incidental Findings Committee of the American College of Radiology is an algorithm for the management of patients who are:
adults (i.e. 18-year-old or over)
asymptomatic for adrenal pathology
The manta ray sign is a radiographic appearance in bladder exstrophy. It describes wide midline separation of the pubic bones simulating the appearance of a manta ray swimming towards you 1. The sacrum and iliac wings recall the manta ray’s head and body, with the widely spaced pubic rami formin...
A mature metastasizing teratoma is an uncommon complication of mature testicular teratomas, whereby distant metastatic deposits of histologically mature cells are encountered.
McCune-Albright syndrome (MAS) (also known as McCune-Albright-Sternberg syndrome) is a genetic disorder characterized by the association of:
endocrinopathy: precocious puberty
polyostotic fibrous dysplasia: more severe than in sporadic cases
cutaneous pigmentation: coast of Maine 'café au lai...
McDonald and McClellan classified crossed renal ectopia into four types 1:
bilateral crossed renal ectopia without fusion
unilateral crossed renal ectopia
bilaterally crossed renal ectopia: represents 90% of all crossed ectopias and includes crossed fused renal ectopia
crossed unfused rena...
The medial fossae are concave depressions of peritoneum in the paravesical space bounded by the medial umbilical folds and the lateral umbilical folds. The fossae are contained within the inguinal (Hesselbach’s) triangle. The right medial fossa typically partially contains the cecum and/or ileum...
The medial umbilical folds are bilateral raised ridges of parietal peritoneum in the deep aspect of the anterior abdominal wall formed by the underlying medial umbilical ligaments running from the pelvis to the umbilicus. The medial umbilical ligaments are anatomical remnants of the obliterated ...
The median umbilical fold is a raised ridge of parietal peritoneum in the deep aspect of the anterior abdominal wall overlying the median umbilical ligament (urachal remnant). It is seen to lie between the transversalis fascia and peritoneum. It is one of five umbilical folds and should not be c...
Medical devices in the abdomen and pelvis are important to be recognized, just like medical devices of the chest. Often we ignore these devices, considering them to be incidental and non-pathological, however it is essential to be aware of potential complications.
Medullary cystic disease complex belongs to group of pediatric cystic renal diseases charaterised by progressive tubular atrophy with glomerulosclerosis (chronic tubulointerstitial nephritis) and multiple small medullary cysts.
There is no recognized gender predilection
Renal medullary nephrocalcinosis is the commonest form of nephrocalcinosis and refers to the deposition of calcium salts in the medulla of the kidney. Due to the concentrating effects of the loops of Henle, and the biochemical milieu of the medulla, compared to the cortex, it is 20 times more co...
A common mnemonic used to remember the etiology of medullary nephrocalcinosis is:
A: (renal tubular) acidosis
M: medullary sponge kidney
P: papillary necrosis
renal papillary necrosis mnemonic
Medullary sponge kidney is a sporadic condition where the medullary and papillary portions of the collecting ducts are dysplastic and dilated and in most cases develop medullary nephrocalcinosis.
The incidence of medullary sponge kidney is estimated at ≈1:5000.
Megacystis megaureter syndrome describes the radiologic appearance of a large capacity thin-walled bladder and massive primary vesicoureteral reflux.
The pathophysiology of these massively dilated ureters and the large capacity bladder is the constant recycling of large volumes of r...
Melioidosis is an infectious disease caused by the bacterium Burkholderia pseudomallei (previously known as Pseudomonas pseudomallei) and is a multisystem disorder which may affect the lungs, brain, visceral organs, or musculoskeletal system.
Melioidosis is a disease of the monsoo...
Mesoblastic nephroma, also sometimes known as a congenital mesoblastic nephroma (CMN) or fetal renal hamartoma, is, in general, a benign renal tumor that typically occurs in utero or in infancy.
It is the commonest neonatal renal tumor. Diagnosis is usually made in the antenatal p...
Metallic ureteric stents are a type of ureteric stent developed to offer improved symptomatic relief of obstruction when compared to polymeric (polyurethane) stents. They are often used in patients with chronic malignant ureteric obstructions who require placement of long-term ureteral stents to...
Metanephric adenoma (MA) of the kidney is a type of benign renal neoplasm.
While it can present at any age 6, the peak age of occurrence is thought to be around the 5th to 6th decades 2. There may be a 2:1 female preponderance 2.
Metanephric adenoma is as...