Fibromuscular dysplasia (FMD) is a heterogeneous group of vascular lesions characterized by an idiopathic, non-inflammatory, and non-atherosclerotic angiopathy of small and medium-sized arteries.
The prevalence is unknown 7. It is most common in young women with a female to male r...
Fibrous pseudotumor of the scrotum is a relatively rare, non-neoplastic extratesticular non-epididymal lesion.
It affects any age. Although rare, it is considered the third most common extra testicular mass after a scrotal lipoma and an epididymal adenomatoid tumor.
The filarial dance sign refers to a twirling motion of microfilariae (e.g. W. bancrofti) in dilated lymphatic channels. It is identified as a characteristic sign of scrotal filariasis.
The dilated channels are identified with the absence of color flow on color Doppler study and the microfilari...
Filariasis refers to infection with nematodes (roundworms) of the family Filarioidea. There are three species of these thread-like filarial worms:
Wuchereria bancrofti: responsible for 90% of cases
Brugia malayi: causes most of the remainder of cases
Brugia timori: an uncommon cause
It can a...
A filling defect is a general term used to refer to any abnormality on an imaging study which disrupts the normal opacification (filling) of a cavity or lumen. The opacification maybe physiological, for example, bile in the gallbladder or blood in a dural venous sinus, or maybe due to the instal...
The Finnish type congenital nephrotic syndrome is a sub type of congenital nephrotic syndrome. A large placenta and proteinuria from birth are considered hallmarks of the disease 2. The proteinuria is often of intra-uterine onset. Although it is named the Finnish type, it can occur outside Finla...
Fishhook ureters, also known as J-shaped ureters or hockey stick ureters describe the appearance of the distal ureter in patients with significant benign prostatic hypertrophy. It has also been used to describe the appearance of a retrocaval ureter in type 1 or low loop variety. As the right ur...
A fistula (plural: fistulae) is an abnormal connection between two epithelial surfaces such as between hollow organs, skin or vessels. Conventionally, the name of a specific fistula type is a combination of the two organs
For discussions of specific fistulae please refer to individual articles....
Fluorine-18-labeled sodium fluoride (also known as 18F-NaF or sodium fluoride) is a PET radiotracer used primarily for skeletal imaging.
Fluorine-18-labeled sodium fluoride is an ionic compound comprised of a single sodium atom bound to a positron-emitting isotope of fluorine.
The Foley catheter is a urinary catheter with a balloon at its distal tip, which is inflated post-insertion to ensure that the catheter remains in the bladder. Originally inflation of the balloon required the instillation of fluid or air via a separate port, next to the external end of the cathe...
The term fornix (plural: fornices) is used for anatomical structures in multiple organ systems that all share an arch-like morphology:
History and etymology
Fornix is Latin for...
The fossa navicularis refers to a normal mild dilatation of the urethra. It occurs at the most distal/downstream portion of the urethra.
It is more evident in males, where it occurs in the penile/pendulous urethra, near the urethral meatus. There is also a fossa navicularis in women: the more f...
The fountain sign is a sonographic sign described in acute idiopathic scrotal edema (AISE).
It refers to the appearance of the pattern of vascularity seen during transverse color Doppler sonography of the scrotum with both testes together 1. In this transverse view, in patients with AISE, marke...
Fournier gangrene is necrotizing fasciitis of the perineum. It is a true urological emergency due to the high mortality rate but fortunately, the condition is rare. It is primarily a clinical diagnosis, and definitive treatment must not be delayed to perform imaging, which usually has an ancilla...
Fraley syndrome is the eponymous term for a dilated calyx (hydrocalyx) due to compression of a calyceal infundibulum from an adjacent artery or vein.
It is rare, but it occurs more often involving the upper pole calyx. It is common in young women.
The free/total PSA ratio (%fPSA) is an additional new parameter used in assessing prostate specific antigen (PSA) levels. It is the simple mathematical ratio of the free PSA in the serum over the total PSA in the serum and is expressed as a dimensionless quantity 4.
Some authors 1,2 recommend t...
Frenulum (plural: frenula) is an anatomical term and refers to a small fold of soft tissue that checks the movement of an anatomical part.
frenulum (ileocecal valve)
frenulum (labia minora)
History and etymology
Frenulum derives from ...
Frozen pelvis refers to a condition in which pelvic organs are distorted and tethered to each other as a consequence of adhesive processes.
It is commonly seen in endometriosis. Other causes include tumors, infections including pelvic inflammatory disease, post-surgical adhesions and post-treat...
Fungal balls of the urinary tract, also known as fungal bezoars or mycetomas of the urinary tract, are a rare manifestation of funguria, usually candiduria.
While candiduria may be seen in approximately 20% of hospitalized patients 1, development of fungal balls is considered very...
Ganglioneuromas are fully differentiated neuronal tumors that do not contain immature elements and potentially occur anywhere along with the peripheral autonomic ganglion sites.
On imaging, usually, they present as well-defined solid masses and can be quite large at presentation. Generally, th...
There are numerous causes of gas in the urinary bladder. In the hospital setting by far the most common is the recent placement of an indwelling urinary catheter. Other causes include 1:
indwelling urinary catheter is by far the most common cause
Genitourinary tuberculosis is the second most common site of infection in humans by Mycobacterium tuberculosis, second only to pulmonary tuberculosis.
It can most easily be divided anatomically into:
renal tuberculosis (renal parenchyma, calyces and renal pelvis)
bladder and ureteric tubercu...
Germ cell tumors are classified into two broad groups: seminoma and non-seminomatous germ cell tumors (NSGCT). The later is then divided further according to histology:
non-seminomatous germ cell tumors (NSGCT)
embryonal cell carcinoma
yolk sac tumor
Germ cell tumors are found widely throughout the body and encompass a wide range of individual tumors.
This article does not deal with any specific body locations. For detailed discussion please refer the articles listed at the end of this page.
Germ cell tumors arise from ectopic ...
A mnemonic for the differential diagnosis for germ cell tumors is:
E: embryonal cell carcinoma
E: endodermal sinus tumor (yolk sac tumor)
Germinoma is a term that if unqualified, usually refers to a tumor of the brain but can also refer to similar tumors of other regions particularly the ovary and testis.
dysgerminoma of the ovary
seminoma of the testis
CNS germinoma: see WHO classification of CNS tumors
All these tumors share...
The histological grading of prostate cancer has undergone many revisions, and for many years the primary system was the Gleason score, itself derived from the Gleason grade. In 2014, the Grade Group was introduced, and care must be taken to not confuse this with the Gleason grade.
The Gleason g...
Global testicular infarction is fortunately rare, and is most commonly seen in the context of testicular torsion. However rarely it can occur secondary to other causes.
surgery, e.g. inguinal hernia repair 7
Glomerulocystic disease (GCK) is a rare cystic kidney disease.
Histopathology typically shows normal-sized glomeruli with the enlarged Bowman’s space and tubular cystic changes. A proposed mechanism of glomerular cyst development is stenosis at the glomerulot...
The goblet sign, also known as the champagne glass sign, refers to the appearance of the ureter when it is focally dilated by an intraluminal mass. It is best seen when the ureter is opacified by retrograde contrast (retrograde ureterogram). Presence of this sign indicates the pathology to be ch...
The Goldman classification of urethral injuries is a more widely accepted classification than one proposed by the American Association for the Surgery of Trauma (AAST). The Goldman classification is based on the anatomical location of the urethral injury and was initially proposed by Colapinto a...
The gonadal arteries are the paired primary vascular supply to the ovaries in the female and the testes in the male. As the anatomy of the gonadal arteries differs substantially between the sexes, they are covered separately:
The gonadal veins are paired structures that drain the gonads in males and females. In males it is called the testicular vein (or internal spermatic vein) and in females it is called the ovarian vein. The gonadal veins ascend with the gonadal arteries in the abdomen along the psoas muscle anteri...
Gonadoblastomas are uncommon sex cord / stromal tumors. They are associated with disorders of sexual development (previously known as "intersex disorders").
The vast majority are found <30 years of age. Most are discovered in the perinatal period. May occur in phenotypic males or ...
Granulomatosis with polyangiitis (GPA), previously known as Wegener granulomatosis, is a multisystem necrotizing non-caseating granulomatous c-ANCA positive vasculitis affecting small to medium-sized arteries, capillaries, and veins, with a predilection for the respiratory system and kidneys.
The renal manifestations of granulomatosis with polyangiitis (GPA) are occult on imaging, especially when compared to the pulmonary changes.
For a general discussion of the condition, please refer to the main article on granulomatosis with polyangiitis (GPA). For other organ-specific radiograp...
Granulomatous epididymitis refers to a form of epididymitis secondary to a granulomatous process. It may or may not be associated with concurrent orchitis.
It is usually associated with
tuberculosis - tuberculous epididymitis
BCG - Bacillus Calmette-Guérin
Occasional cases are idiopathic, ca...
Granulomatous prostatitis is a nodular form of chronic prostatitis. It is usually diagnosed on biopsy.
Bacillus Calmette–Guérin (BCG) vaccine
Several classification sy...
The great vessel space is the fourth retroperitoneal space along with the anterior and posterior pararenal spaces, and the perirenal space 1,2. Unlike other retroperitoneal spaces, it is not well-defined by fascial planes and thus disease processes affecting other retroperitoneal spaces can also...
Growing teratoma syndrome is a rare complication after treatment for metastatic (or in the case of intracranial disease, primary) non-seminomatous germ cell tumors (NSGCT).
It was first described in the pediatric population with treated germ cell neoplasms, and represents enlarging masses at th...
Hematospermia (less commonly hemospermia) refers to the presence of blood in semen or ejaculatory fluid. It is a symptom that can cause great anxiety in patients despite usually being of benign etiology.
urogenital infections including sexually transmitted disease, ...
Hematuria occurs when blood enters the urinary collecting system and is excreted in the urine. There are many etiologies for hematuria, and they range from benign and transient to gravely concerning. Hematuria can derive from the kidneys, ureters, bladder, prostate (in men), or urethra. Imaging ...
Hematuria in a child is evaluated differently than in an adult in two main respects:
there is a lower likelihood of a malignancy (renal or bladder) causing the hematuria
preference is given to nonionizing radiation
Hematuria can be considered in three main forms:
Vascular access for haemodialysis when patients' with end-stage renal failure require renal replacement therapy. Options include temporary/permanent and non surgical vs surgical methods. This article will focus on surgical arteriovenous fistulae.
Types of vascular access
Hemolytic uremic syndrome (HUS) is a multisystem thrombotic microangiopathic disease characterized by the triad of renal failure, hemolytic anemia and thrombocytopenia. It is the most common cause of renal failure in infancy and childhood requiring dialysis.
There are two forms of this syndrom...
The hemorrhage exclusion sign can be a useful MRI finding following prostate biopsy.
The normal prostate produces high concentrations of citrate, which among other properties, acts as an anticoagulant 1. As tumor cells are dysfunctional, they will produce lower levels of citrate than...
The hairy kidney sign refers to the soft tissue ring of perirenal infiltration seen on cross-sectional imaging studies in Erdheim-Chester disease, and is considered to be pathognomonic of this disease. The ‘‘hairy’’ description refers to the associated thickening of the bridging perirenal septa ...
The H and M lines are reference lines for the pelvic floor on imaging studies and help detect and grade pelvic floor prolapse on defecography studies.
The H line is drawn from the inferior margin of the pubic symphysis to the posterior aspect of the anorectal junction, and represents the diamet...
Height adjusted total kidney volume (HtTKV) is used in patients with autosomal dominant polycystic kidney disease to predict the onset of renal insufficiency. There is strong evidence to indicate that baseline htTKV predicts, with good sensitivity and specificity, the development of renal insuff...
Hepatorenal syndrome refers to a form of acute kidney injury caused by changes in renal blood flow regulation due to liver pathology 1. Although the syndrome occurs mainly in cirrhotic livers it has been reported in patients with acute fulminant liver failure as well 1.
Hereditary angiopathy with nephropathy, aneurysms, and muscle cramps (HANAC) syndrome is an autosomal dominant monogenic COL4A1-related disorder.
The exact prevalence is unknown.
The cardinal features of HANAC syndrome are helpfully described in the name of...
Hereditary breast and ovarian cancer (HBOC) syndrome is caused by a mutation to either BRCA1 or BRCA2 genes. These patients have an increased risk of breast cancer, ovarian cancer, pancreatic cancer and prostate cancer. However, these gene mutations are not the only cause of hereditary breast ca...
Hereditary leiomyomatosis and renal cell carcinoma (HLRCC), also known as Reed syndrome, is an autosomal dominant tumor susceptibility syndrome.
It is characterized by:
predisposition to benign cutaneous and uterine leiomyomas (fibroids, myomas)
susceptibility to early-onset renal ...
Despite the vast majority of renal cancers being sporadic, there are a number of hereditary renal cancer syndromes:
von Hippel Lindau syndrome: predominantly clear cell type
tuberous sclerosis: predominantly clear cell type (also associated with angiomyolipoma)
Herlyn-Werner-Wunderlich (HWW) syndrome, is a rare anomaly characterized by Müllerian duct anomalies (MDA) associated with mesonephric duct anomalies 3. This entity is also known as obstructed hemivagina and ipsilateral renal anomaly (OHVIRA). It is not to be confused with the Wunderlich syndrom...
Hermaphroditism states are a result of abnormalities in embryonic development and may have mixed characteristics of each sex, with variable clinical manifestations. True hermaphroditism is deﬁned as the simultaneous presence in a single individual of both testicular and ovarian tissues, that may...
Hernias (or herniae) are a common pathological entity, in which an anatomical structure passes into an abnormal location via an opening.
The opening may be a normal physiological aperture (e.g. hiatus hernia: stomach passes through the diaphragmatic esophageal hiatus) or pathological. Iatrogeni...
Heterogeneous testicular echotexture at ultrasound may be the result of a variety of underlying pathology:
seminiferous tubular atrophy - can occur in around 14% of middle aged to elderly patients 2
Genitourinary manifestations of HIV/AIDS are protean and can be divided into:
renal diseases related to opportunistic infections: CMV, tuberculosis and MAC infections, fungal infections, pneumocystis carinii infection
drug-related renal diseases:
HIV-associated neoplasms are numerous and can be broadly divided into two groups:
associated but not AIDS defining malignancies
The development of these malignancies in HIV affected individuals generally implies progression to AIDS 4:
HIV-associated nephropathy (HIVAN) is commonly seen in patients with HIV/AIDS and leads to end-stage renal disease (ESRD). The diagnosis is not imaging-based and must be confirmed by renal biopsy.
HIVAN is seen in patients at advanced stages of HIV and AIDS, but it can also be see...
The hockey stick sign can refer to a variety of different signs and appearances:
hockey stick sign (thyroid hemiagenesis)
hockey stick sign (Creutzfeldt-Jakob disease)
hockey stick sign (ureters)
A horseshoe adrenal gland is a very rare anomaly. It is also sometimes referred to as a butterfly, fused or midline adrenal gland.
It is a solitary adrenal gland that is present in the midline of the fused portion either passing between the aorta and the inferior vena cava or posterior to the a...
Horseshoe kidneys are the most common type of renal fusion anomaly. They render the kidneys susceptible to trauma and are an independent risk factor for the development of renal calculi and transitional cell carcinoma of the renal pelvis.
Horseshoe kidneys are found in approximate...
Several normal anatomical structures and rare organ variants have been described as being horseshoe-shaped.
horseshoe pancreas 1
Hurley stick ureters refers to the widening of the distal ureters with abnormal lateral and upward curvature instead of normal oblique intramural course in excretory urogram. The appearance of distal ureter resembles hurley stick used in the traditional Iris game of hurling. This is seen in blad...
Hutch diverticula are congenital bladder diverticula, seen at the vesicoureteric junction, in the absence of posterior urethral valves or neurogenic bladder. They are thought to result from a weakness in the detrusor muscle anterolateral to the ureteral orifice.
They occur almost...
Hydroceles are acquired or congenital serous fluid collections between the layers of the tunica vaginalis surrounding a testis or spermatic cord. They are the most common form of "testicular" enlargement and present with painless enlargement of the scrotum. On all modalities, hydroceles appear a...
Hydrocele of the canal of Nuck is a rare condition in female children caused by a failure of complete obliteration of the canal of Nuck 1. The canal of Nuck is an abnormal patent pouch of peritoneum extending anterior to the round ligament of the uterus into the labia majora 2. Incomplete oblite...
Hydronephrosis (plural: hydronephroses) is defined as dilatation of the urinary collecting system of the kidney (the calyces, the infundibula, and the pelvis) 1.
Hydronephrosis in fetuses and newborns has specific causes that are covered in a separate article.
The term hydroureter...
Grading systems of hydronephrosis have been devised to communicate the degree of upper collecting system dilatation. The most common system used (Society of Fetal Urology, SFU) was originally designed for grading neonatal and infant hydronephrosis:
no dilatation, calyceal walls are app...
The causative factors leading to hydronephrosis can be recalled using this mnemonic :
R: retroperitoneal fibrosis
N: neoplastic mass (cervical cancer)
S: stenosis of pelvi-ureteric junction
Hydroureter refers to abnormal dilation (>3 mm) of the ureter and may occur in combination with hydronephrosis.
The term, megaureter, is usually reserved for ureters >7 mm in diameter. The term hydroureteronephrosis (or hydronephroureterosis) may be used when ureteric dilatation o...
The hymen (plural: hymens) is a thin fold of mucous membrane which extends across the vaginal opening, usually with some form of internal defect, which permits the free passage of normal menses.
It usually ruptures during coitus with the remnants, usually in the form of small tags of tissue ar...
Benign hyperattenuating renal cysts are also known as hyperdense renal cysts.
They are frequently found in patients with either acquired cystic renal disease or autosomal dominant polycystic renal disease 1.
homogeneously hyperattenuating (even when a narro...
Hyperparathyroidism is the effect of excess parathyroid hormone in the body. It can be primary, secondary, or tertiary. There are many characteristic imaging features, predominantly involving the skeletal system.
Hyperparathyroidism is supported biochemically by either an...
Hyperreninaemic hypertension may have many causes including:
renal artery stenosis
renal secreting tumor, e.g. renal cell carcinoma, reninoma
renal compression: large renal mass, subcapsular hemorrhage (Page kidney)
Columns of Bertin represent the extension of renal cortical tissue which separates the pyramids, and as such are normal structures. They become of radiographic importance when they are unusually enlarged and may be mistaken for a renal mass (renal pseudotumor).
Nomenclature of such enlarged col...
The hypogastric nerves are paired nerve bundles that are part of the autonomic nervous system and located in the pelvis.
origin: contain sympathetic fibers descending from the superior hypogastric plexus and parasympathetic fibers ascending from the inferior hypogast...
Hypospadias refers to a type of congenital malformation affecting the male external genitalia.
The estimated prevalence is ~2 (range 0.2-4.1) per 1000 live births.
The urethral meatus is abnormally positioned proximally and ventrally to its normal position.
It is thou...
Hypovitaminosis A results from inadequate intake of vitamin A, fat malabsorption, or liver disorders and produces a variety of epithelial alterations.
The World Health Organization currently estimates that 45-122 countries have a vitamin A deficiency of public health significance ...
Idiopathic retroperitoneal fibrosis, also known as Ormond disease or occasionally Albarran-Ormond syndrome 6, is a subtype of retroperitoneal fibrosis where no cause is found. It includes a spectrum of diseases which are characterized by fibroinflammatory tissue encasing the abdominal aorta and ...
Idiopathic scrotal calcinosis, sometimes called dystrophic scrotal calcinosis, is a rare benign condition characterized by superficial calcifications within the skin of the scrotum of unclear etiology. The condition is primarily cosmetic but may recur following excision of the calcified bodies.
IgA nephropathy (also known as IgA nephritis or Berger disease) is a form of glomerulonephritis.
IgA nephropathy is considered the most common glomerulonephritis worldwide and is a leading cause of chronic kidney disease and renal failure.
Primary IgA nephropathy is c...
An ileal conduit (or "Bricker conduit") was one of the original types of urinary diversions, and it is still in use today.
The conduit is most often placed after cystectomy (or cystoprostatectomy) for muscle-invasive bladder cancer. Although not a continent diversion, it may be prefe...
Ileal ureter interpositions are uncommon urologic reconstructions, using a loop of small bowel to replace a damaged ureter. The concept is similar to the formation of a neobladder from small bowel (e.g. ileal conduit), except one is forming a neo-ureter.
Variants include using colon as an inter...
Ileovesicostomy (also known as "cutaneous ileocystostomy", "ileal chimney", or "bladder chimney") is an uncommon urologic diversion in which a loop of small bowel is anastomosed/augmented to the dome of the bladder. This loop of bowel then exits through a urostomy. The diversion is not continent...
Imperforate hymen is a congenital condition in which the hymen lacks a normal opening.
It happens in 0.1% of the female population, usually an isolated finding.
Primary amenorrhea with cyclic lower abdominal pain during menarche age. An imperforate hymen c...
An incidentaloma is a radiological neologism to denote a lesion found incidentally and of dubious clinical significance. Although it can refer to any incidental lesion (e.g. pituitary 3, thyroid 4), it is most often used to denote an incidental adrenal lesion, which is commonly an adrenal adenom...
Increased renal echogenicity is a non-specific finding but can represent a number of underlying conditions.
chronic kidney disease: increased cortical echogenicity
sickle cell disease 4
echogenic renal pyramids - pediatric
The inferior adrenal (suprarenal) artery is one of three adrenal arteries that supplies the adrenal gland.
Ipsilateral renal artery (usually before the terminal division of the renal artery)
The course of the inferior suprarenal artery depends on its origin. Re...
The inferior hypogastric plexuses are autonomic nerve plexuses located in the pelvis.
location: lies in pelvis in extraperitoneal connective tissue on pelvic sidewall anterolateral to the mesorectum
origin: formed mainly from pelvic splanchnic branches (parasympathetic) and sacral spl...
The inferior rectal nerve, also known as the inferior anal nerve or inferior hemorrhoidal nerve, is a branch of the pudendal nerve which is derived from S2, S3 and S4 nerve roots of the sacral plexus. The nerve provides sensory innervation to the anal canal inferior to the pectinate line and mot...