The American Association for the Surgery of Trauma (AAST) renal injury scale, most recently updated in 2018, is the most widely used grading system for renal trauma.
The 2018 update incorporates "vascular injury" (i.e. pseudoaneurysm, arteriovenous fistula) into the imaging criteria for viscera...
AP oblique supine radiograph is normally performed when localizing foreign bodies or lines within the abdominal cavity. Additionally, the oblique abdominal series can be utilized in the assessment of the upper intestinal tract during barium studies.
the patient is laying 30 de...
PA prone radiograph is rarely performed, often utilized when a patient is unable to lay supine. The projection is adequate for the examination of the abdominal cavities, however, not as practical for the renal structures due to magnification.
the patient is prone, either on th...
Abdominal and pelvic anatomy encompasses the anatomy of all structures of the abdominal and pelvic cavities.
This anatomy section promotes the use of the Terminologia Anatomica, the global standard for correct gross anatomical nomenclature.
Abnormal renal rotation (renal malrotation) refers to an anatomical variation in the position of the kidneys, in particular to anomalous orientation of the renal hilum. It may occur unilaterally or bilaterally. It is almost always an asymptomatic incidental finding.
Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1:
a central core consisting of necrotic inflammatory cells and local tissue
peripheral halo of viable neutrophils
surrounded by a 'capsule' with dilated blood vessel...
Accessory renal arteries are a common variant and are present in ~25% (range 20-30%) and are bilateral in ~10% of the population 7. Their proper identification is of utmost importance for surgical planning prior to live donor transplantation 2,3 and renal artery embolization for various reasons ...
Acquired cystic kidney disease (ACKD) is a condition that occurs in patients with end-stage renal disease (ESRD), especially when on dialysis treatment. They do not have a history of other cystic renal disease.
Its incidence increases with the amount of time a patient is azotemic...
Acute idiopathic scrotal edema (AISE) is a self-limiting condition characterized by marked edema of the skin and dartos fascia without involvement of the deeper layers, testes, or epididymis. It is an important condition to recognize in order to avoid unnecessary surgical exploration.
Acute pyelonephritis is a bacterial infection of the renal pelvis and parenchyma most commonly seen in young women. It remains common and continues to have significant morbidity in certain groups of patients.
The incidence of acute pyelonephritis parallels that of lower urinary tr...
Acute tubular necrosis is a common type of acute kidney injury, particularly in hospitalised patients.
Acute tubular necrosis is characterized by renal tubular cell damage and death and is usually caused by ischemic or nephrotoxic insults. Deposition of cellular debris within the tu...
Adenocarcinoma of the urinary bladder is rare and accounts for only ~1% of all bladder cancers (90% are transitional cell carcinomas).
Metaplasia of urinary bladder induced by chronic irritation or infection can lead to adenocarcinoma. Pathological types of adenocarcinoma of the urin...
Adenomatoid tumors of the scrotum are benign, solid extratesticular lesions that can originate from the epididymis, tunica vaginalis, or spermatic cord (90% derived from the funiculus).
They are the most common extratesticular neoplasm, and most common tumor of the epididymis, and...
Adrenal abscesses are rare lesions affecting the adrenal glands and are usually encountered in the setting of disseminated infection.
Although cases have been described in both neonates and adults, no systematic literature is available on the epidemiology of adrenal abscesses.
Adrenal adenomas are the most common adrenal lesion and are often found incidentally during abdominal imaging for other reasons. In all cases, but especially in the setting of known current or previous malignancy, adrenal adenomas need to be distinguished from adrenal metastases or other adrenal...
The adrenal glands are supplied by three adrenal (suprarenal) arteries:
superior adrenal artery: arises from ipsilateral inferior phrenic artery
middle adrenal artery: arises from lateral side of abdominal aorta
inferior adrenal artery: arises from the ipsilateral renal artery
Adrenal calcification is not a rare finding in healthy asymptomatic people and is usually the result of previous hemorrhage or tuberculosis. Addison disease patients only occasionally develop calcification.
sepsis: Waterhouse-Friderichsen syndrome
An adrenal collision tumor or collision tumor of the adrenal gland is an uncommon condition where two histologically distinct tumors abut each other or are in close proximity in the same adrenal gland.
Collision tumors have been reported in nearly every organ, for example, collision ...
Primary adrenal cortical carcinoma is a highly malignant but rare neoplasm. It may present as a hormonally active or an inactive tumor.
Although men and women are affected equally, functioning tumors are more common in females, who are also more likely to have an associated endoc...
Adrenal cysts are rare lesions and are commonly incidental findings.
Adrenal cysts are reported to be rare with an incidence of <1% 1.
Patients can present with pain or swelling, although a significant portion (~40%) are incidental findings 1,3.
The adrenal (suprarenal) glands are paired organs of the endocrine system, often asymmetric in shape.
Each gland is enclosed in the perirenal fascia and each has a body and two limbs: a medial limb and a lateral limb. However, the right adrenal gland is usually more pyramidal in...
Adrenal gland trauma most commonly results from blunt force trauma.
Adrenal gland trauma is present on 1-2% of CT imaging in blunt trauma although the occurrence is thought to be much higher as injury has been demonstrated at 28% in one autopsy series 1-4.
The right adrenal glan...
Despite its small size, the adrenal gland is affected by a relatively large number of neoplastic entities:
adrenal cortical carcinoma
adrenal lesions: for a more general list of...
Adrenal hemangiomas are rare benign tumors that are usually incidentally identified (one example of an adrenal incidentaloma). Its significance mainly relates to the difficulty in differentiation from other malignant lesions.
Although these can be found at any age, they are most ...
Adrenal hemorrhage can result from a variety of traumatic and non-traumatic causes. When unilateral, it is often clinically silent. In contrast, bilateral adrenal hemorrhage can lead to catastrophic adrenal insufficiency.
The large majority of patients with unilateral adr...
Adrenal hyperplasia refers to nonmalignant growth (enlargement) of the adrenal glands and is a rare cause of ACTH-independent Cushing syndrome, with unilateral adrenal cortical adenomas being the commonest. Approximately 20% of Conn syndrome cases are secondary to adrenal hyperplasia. In diffuse...
Adrenal insufficiency refers to inadequate secretion of corticosteroids (glucocorticoids and mineralocorticoids).
It may occur from partial or complete destruction of the adrenal cortex, in which case it is termed primary adrenal insufficiency (also known as Addison disease). Secon...
Adrenal lesions cover a broad spectrum from benign to neoplastic entities. Due to increased use of cross-sectional imaging they are frequently detected as incidental lesions (incidentalomas). If found incidentally, please refer to the Management of Incidental Adrenal Masses: American College of ...
Adrenal lymphangiomas, also known as cystic adrenal lymphangiomas, are rare, benign cystic adrenal lesions.
Adrenal lymphangiomas are extremely rare; prevalence is estimated at 0.06% 8. They can occur at any age, with a peak incidence between the 3rd and 6th decades of life. Accor...
Adrenal metastases are the most common malignant lesions involving the adrenal gland. Metastases are usually bilateral but may also be unilateral. Unilateral involvement is more prevalent on the left side (ratio of 1.5:1).
They are present at autopsy in up to 27% of patients with ...
Adrenal myelolipomas are rare benign and usually asymptomatic, tumors of the adrenal gland characterized by the predominance of mature adipocytes.
On imaging, they usually present as large masses with a variable amount of fat-containing components.
Rare tumors with estimated aut...
Adrenal pseudocysts account for ~40% of adrenal cysts and are more likely than simple adrenal cysts to be symptomatic.
Pseudocysts do not have an epithelial lining and typically arise after an episode of adrenal hemorrhage. There is an ~7% association with malignancy (e.g. from hemor...
Adrenal vein sampling (AVS) is a procedure where blood is collected from the adrenal veins via catheter to confirm autonomous hormone production, if it is unilateral or bilateral, and to guide further treatment.
AVS is commonly performed in primary aldosteronism, being indicated to ...
Adrenal washout can be calculated using the density value of an adrenal mass on non-enhanced, portal venous phase and 15 minutes delayed CT scans (density measured in Hounsfield units (HU)). It is primarily used to diagnose adrenal adenoma.
[(HUportal venous phase) - (HUdelaye...
Adrenocorticotropin independent macronodular adrenocortical hyperplasia (AIMAH) is considered a rare form of macronodular adrenal hyperplasia. It is an uncommon cause of primary adrenal hypercortisolism.
Patients with AIMAH tend to present 10 years earlier on average than...
Adult cystic renal disease comprises multiple distinct hereditary and non-hereditary disease processes.
adult polycystic kidney disease (APCKD), a.k.a. autosomal dominant polycystic kidney disease (ADPCKD)
medullary cystic kidney disease
von Hippel-Lindau dis...
Aggressive angiomyxomas are rare tumors that arise in the pelvis and typically cross the levator ani muscles. Despite its name, it is essentially a benign tumor and the term "aggressive" is given due to a predilection for local recurrence. Only rarely does it metastasize.
It is se...
Alport syndrome is an X-linked dominant disease characterized by progressive sensorineural hearing loss, renal disease and, at times, ocular lesions.
sensorineural hearing loss: typically high frequency 2
anterior lenticonus: most common...
The anal triangle forms the posterior half of the diamond-shaped perineum. The triangle's three corners are defined by the tip of the coccyx posteriorly and both ischial tuberosities anterolaterally. The anterior border is the transverse perineal muscles and the posterolateral borders are the sa...
The anatomy curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core anatomy knowledge for radiologists and imaging specialists.
Head and neck anatomy
Abdominal and pelvic anatomy
Androgen insensitivity syndrome (AIS), also known as the testicular feminisation syndrome, results from end-organ resistance to androgens, particularly testosterone. AIS may be complete or incomplete with variable imaging findings.
The incidence may vary depending on whether it i...
Angiomyofibroblastoma-like tumor of the scrotum is a rare, well-defined, slow growing mesenchymal extratesticular nonepididymal tumor rarely seen in the perineum or scrotum of older male patients. A similar tumor can occur in females in the vulval region.
In males, they are seen ...
The angular interface sign is used to characterize an exophytic renal mass, in which the exophytic renal mass has an angular interface with the renal parenchyma. In other words, the exophytic lesion has a tapered pyramidal contour or definite apex within the renal parenchyma.
Due to its high se...
Antegrade ureteric stents are performed under fluoroscopic guidance, typically by an interventional radiologist or urologist. It is performed via percutaneous access from the kidney. It is usually performed using the access from a prior percutaneous nephrostomy, a so-called two-step procedure, a...
The anterior pararenal space is the portion of the retroperitoneum that lies between the posterior surface of the parietal peritoneum and the anterior reflection of the perirenal fascia.
It contains the duodenum, pancreas and retroperitoneal segments of the ascending and descendi...
Antopol-Goldman lesions are very rare presentations of subepithelial hemorrhage in the renal pelvis, presenting as discrete mass-like hematomas.
The cause of these lesions is uncertain, although long-term anticoagulation, non-steroidal anti-inflammatory drugs (NSAIDs) overuse, trauma...
Artificial urethral sphincters, also known as inflatable artificial sphincters and urinary control systems, are devices used for the treatment of urinary stress incontinence (e.g. due to pelvic floor dysfunction in female or prostate surgery in male) and are sometimes used in combination with a ...
Asbestos related disease, in particular affecting the lung, comprise of a broad spectrum of entities related to the inhalational exposure to asbestos fibers. They can be divided into benign and malignant changes 1-3.
Benign pleural and parenchymal lung disease
asbestos related benign pleural d...
Atypical small acinar proliferations (ASAP) are premalignant lesions of the prostate, which can be found in as many as 5% of prostate biopsies. They are suspicious glands without adequate histologic atypia to establish a definitive diagnosis of prostate cancer. Some studies showed that there is ...
The aubergine sign (also known as egg-plant sign or deformity) is a clinical sign of a fractured penis. Hemorrhage beyond the tunica albuginea produces swelling and bruising of the penis simulating the appearance of an aubergine.
Autosomal dominant polycystic kidney disease (ADPKD), also sometimes more vaguely referred to as "adult polycystic kidney disease", is as the name would suggest, a hereditary form of adult cystic renal disease.
Autosomal dominant polycystic kidney disease is one of the most commo...
Autosomal recessive polycystic kidney disease (ARPKD) is one of many pediatric cystic renal diseases.
On imaging, it usually presents on ultrasound with enlarged echogenic kidneys with multiple small cysts. Liver involvement with coarse echotexture, biliary tract cystic changes, and portal hype...
The avascular plane of Brodel is the section of renal parenchyma between 2/3 anterior and 1/3 posterior kidney on the cross-section that is relatively avascular. The reason for its relative avascularity is that it represents the plane where the anterior and posterior segmental renal artery branc...
Azoospermia refers to complete absence of sperm in the semen. It accounts for 5-10% of male infertility 1.
It can be obstructive or non-obstructive, e.g. primary testicular failure. This differentiation is of utmost importance, as obstructive azoospermia can be corrected by surgical ...
Bähren classification of left varicoceles:
type 0: no evidence of venous reflux in internal spermatic vein (ISV)
type I: single ISV with insufficient or absent valve
type II: single ISV with ≥ 2 ostia to renal vein; may be branches to ascending lumbar/retroperitoneal veins
IIa: insufficient ...
Balkan nephropathy refers to a degenerative interstitial nephropathy endemic to the Balkan states, which is associated with a very high rate of transitional cell carcinomas of the renal pelvis and upper ureter.
The condition is largely restricted to the villages along the Danube ...
The balloon on a string sign refers to the appearance of the ureter on intravenous urography in ureteropelvic junction obstruction. It is seen due to the high and eccentric point of the exit of ureter from a dilated renal pelvis.
Bardet-Biedl syndrome (BBS), previously known as the Laurence-Moon-Bardet-Biedl syndrome (LMBBS), is a rare autosomal recessive hereditary condition.
The clinical spectrum includes:
retinal anomalies: similar to that of retinitis pigmentosa
Bartholin gland cysts are located in the posterolateral inferior third of the vagina and are associated with the labia majora.
Most patients are asymptomatic 4.
infection: may turn into Bartholin gland abscesses
rare instances of development of adenocarc...
The Bartholin glands, also known as greater vestibular glands, are paired pea-sized structures, lying on either side of the vaginal opening, and are homologous to the bulbourethral (Cowper) glands in the male. They form part of the vulva.
These glands are described as less than 1...
Bartter syndrome is a rare inherited renal disorder.
Bartter syndrome is characterized by hyperplasia of the juxtaglomerular cells along with:
hypotension or normotension
elevated plasma renin
Batson venous plexus, also known as Batson veins, are a network of veins with no valves that connect deep pelvic veins draining the bladder, prostate, and rectum to the internal vertebral venous plexus 1. These veins are important because they are believed to provide a route for spread of pelvic...
The bear paw sign is seen in xanthogranulomatous pyelonephritis and refers to the cross-sectional appearance of the kidney which is said to resemble the paw of a bear. The renal pelvis is contracted whereas the calyces are dilated, mimicking the toe-pads of the paw.
Behçet disease is a multisystemic and chronic inflammatory vasculitis of unknown etiology.
The mean age at which Behçet disease occurs is 20-30 years. The disease is most prevalent in the Mediterranean region, Middle East and East Asia. The highest incidence has been reported in T...
A bell clapper deformity is a predisposing factor in testicular torsion in which the tunica vaginalis joins high on the spermatic cord, leaving the testis free to rotate. Bell clapper deformity predisposes to intravaginal torsion of the testis.
Benign prostatic hyperplasia (BPH) or benign prostatic enlargement (BPE) is an extremely common condition in elderly men and is a major cause of bladder outflow obstruction.
The term benign prostatic hypertrophy was formerly used for this condition, but since there is actually an ...
A bifid ureter, or ureter fissus, is an example of incomplete duplication of a duplex collecting system.
Present in ~5% (range 1-10%) of the population 1-2.
A bifid ureter is formed when there is a duplex kidney (separate pelvicalyceal collecting systems) drain i...
The differential for bilaterally enlarged adrenal glands is relatively limited:
micronodular adrenal hyperplasia
macronodular adrenal hyperplasia
adrenocorticotropin (ACTH)-independent macronodular adrenocortical hyperplasia (AIMAH) 2
Bilateral renal enlargement can arise from a number of causes which include 1:
diabetic nephropathy (common)
renal involvement with lymphoma
acute interstitial nephritis
vasculitis / autoimmune
autosomal recessive polycystic kidneys (ARPKD)
adult dominant polycys...
Bilateral testicular lesions have a relatively limited differential diagnosis.
lymphoblastic leukemia (acute or chronic)
primary testicular lymphoma is rare but the testes are often the site of lymphoma/leukemia recurrence due to ...
Bilobed testis, also known as incomplete unilateral polyorchidism, is a very rare variant in children.
The exact etiology is unknown but is thought be a form of incomplete polyorchidism. It has been proposed that bilobed testis results from incomplete division of the urogenital ridge...
Birt-Hogg-Dubé (BHD) syndrome or folliculin gene-associated syndrome is a genetic multisystemic disease mainly characterized by:
multiple lung cysts and secondary spontaneous pneumothoraces
multiple bilateral renal tumors (particularly chromophobe renal cell cancer and oncocytoma)
Bladder and ureteric tuberculosis (TB) refers to infection of ureters and urinary bladder with Mycobacterium tuberculosis.
characteristic beaded appearance due to alternate areas of strictures and dilatation (chronic state)
acute: ureteral wall thic...
A simple mnemonic to recall the common causes of bladder calcification is:
C: cytotoxic: see radiation- and chemotherapy-induced cystitis
R: radiation: see radiation- and chemotherapy-induced cystitis
I: interstitial cystitis
Bladder calculi occur either from migrated renal calculi or urinary stasis. Bladder calculi can be divided into primary and secondary stones:
primary: stones form de novo in the bladder
secondary: stones are either from renal calculi which have migrated down into the bladder, or from concretio...
Bladder exstrophy (also known as ectopia vesicae) refers to a herniation of the urinary bladder through an anterior abdominal wall defect. The severity of these defects is widely variable.
The estimated incidence of bladder exstrophy is 1:10,000-50,000 live births 4,6. There is a ...
A commonly used classification scheme used by urologists and rehabilitation specialists, described by Wein, classifies bladder impairment following spinal cord injury according to the level of injury:
suprasacral (infrapontine) bladder - upper motor neuron lesion, releasing the sacral micturiti...
Bladder inflammatory pseudotumour is a non-neoplastic proliferation of cells.
This entity is more common in adults, with a mean age at diagnosis of 38 years.
Patients present most commonly with an ulcerating bleeding mass, hematuria, and voiding symptoms.
Neuroanatomy of the bladder is complex, described here is a summary of the co-ordination of micturition.
The bladder acts as a reservoir normally storing 400-500 mL of urine under low pressure (<15 cmH2O) before voluntary voiding can occur at a socially-convenient time. Bladder filling and empt...
Bladder outlet obstruction can arise from a number of conditions affecting the urethra and/or bladder outlet.
Patients often present with difficulty in urination, retention and urinary discomfort 2.
Obstruction can be caused by multiple etiologies but is most...
A mnemonic for the causes of bladder wall calcification is:
C: cystitis post radiation therapy/chemotherapy/chronic infection
E: eosinophilic cystitis
Differential diagnosis for bladder wall thickening depends on whether the bladder is adequately distended. The bladder wall may be thickened if:
>3 mm when distended
>5 mm when nondistended
If the bladder is not distended, then it is difficult to exclude artifactual thickening from a collapse...
A Boari bladder flap is one of the options for ureteric reimplantation when the diseased ureteric segment is long (e.g. more than 5 cm). It is useful in the management of lower ureteric strictures and can be performed as either an open or laparoscopic procedure. It involves tubularisation of a f...
The Bosniak classification system of renal cystic masses divides renal cystic masses into five categories based on imaging characteristics on contrast-enhanced CT. It is helpful in predicting a risk of malignancy and suggesting either follow up or treatment.
A bouquet of flowers appearance is a description given to the appearances of medullary sponge kidney on a traditional intravenous pyelogram (IVP) study. The ectatic distal collecting ducts contain the microcalcifications typical of the disease. This is also known as the bunch of grapes appearanc...
Brachytherapy, also known as sealed source radiotherapy or endocurietherapy, is a form of radiotherapy where a radioactive source is placed, under the guidance of imaging, within or next to the area requiring treatment.
Brachytherapy has been used to treat:
breast cancer (ofte...
Brachytherapy seed migration to the lung is a known complication of radioactive seed therapy. These seeds are used for localized treatment of malignancies, most commonly prostate cancer.
Regarding staging, nearly 79% of the cases are localized, 12% are regional and 5% present with distant disea...
Branchio-oto-renal (BOR) dysplasia is a rare syndromic disorder characterized by:
can involve the outer, middle, and inner ear associated with conductive, sensorineural, or mixed hearing impairment
branchial fistulae and branchial cleft cysts
The bulbospongiosus is a muscle found in the superficial perineal pouch which covers the bulb of the penis in males and the bulb of the vestibule in females.
origin: median raphe and perineal body
insertion: dorsum of penis/clitoris, perineal membrane
innervation: pudendal nerve
The bulbourethral glands or Cowper glands are paired small pea-sized glands of the male reproductive tract, analogous to the female Bartholin glands.
The bulbourethral glands are located in the deep perineal pouch posterolateral to the membranous portion of the male urethra and c...
Bullet and bodkin sign is the appearance of the ureter when there is an abrupt transition in the ureteral caliber. Bullet in the name is represented by the dilated proximal ureteric segment which appears to be perched on the constricted / non-dilated encased ureter which gives an appearance of a...
Burned-out testis tumors may be present if there is metastatic retroperitoneal lymphadenopathy, but the primary testicular tumor is a relatively occult, scarred intratesticular focus. Approximately 50% of the "burned-out" tumors continue to harbor malignant cells.
Calciphylaxis, or calcific ureamic arteriolopathy, is a rare condition which manifests as subcutaneous vascular calcification and cutaneous necrosis (small blood vessels of the fat tissue and the skin). Some authors describe as a syndrome of vascular calcification, thrombosis and skin necrosis.