The renal pelvis (or, more rarely, the renal infundibulum) forms part of the pelvicalyceal system of the kidney and is the connection between the calyces and the ureter.
The renal pelvis is triangular in shape, lies posteriorly in the renal hilum surrounded by fat and vessels and...
A renal pseudotumour is a mass that will simulate a tumour on imaging but is composed of non-neoplastic tissue. There are many examples 1:
prominent column of Bertin
persistent fetal lobulation
cross-fused renal ectopia
renal hilar lip
Renal replacement lipomatosis is a rare condition characterised by fatty tissue proliferation in the renal sinus and perinephric space with marked destruction/atrophy of renal parenchyma (due to chronic inflammation).
Patients usually present with non-specific complaints ...
Renal replacement therapy (RRT) (also called renal dialysis or just dialysis) is used to supplement renal function in patients with either end-stage chronic kidney disease or medically-refractory acute renal impairment.
Haemodialysis refers to the diffusion of solutes in solution across...
The renal sinus is a fat-filled compartment of the kidney.
The renal sinus is a fatty compartment located within the medial aspect of the kidney. It communicates with the perinephric space. It contains the renal hilum and is bordered by renal parenchyma laterally.
Renal sinus cysts are simple renal cysts that lie within the renal sinus.
It is worth noting that some authors 5,6 use the term renal lymphangiectasia interchangeably. It is likely that true renal lymphangiectasia is a separate and rare disorder, and is thus discussed separately.
Renal sinus lipomatosis refers to a condition where there is excessive renal sinus fat replacement.
It results from renal parenchymal atrophy, inflammation, calculous disease, ageing or exogenous or endogenous steroids.
There is usually no or rarely little mass effect on collecting ...
Renal sympathetic denervation (RSDN), also known as renal denervation, is an interventional procedure that uses radiofrequency ablation to destroy the nerve endings in the wall of the renal arteries. Endovascular (trans-catheter) techniques are an alternative to surgical sympathectomy.
This is a basic article for medical students and other non-radiologists
Renal tract calculi, also known as urolithiasis, refer to renal stone formation at any point along the renal tract (from kidneys to bladder and urethra).
This is a summary article; read more in our artic...
Renal transplantation is one, if not the most, common transplant procedures undertaken worldwide. Consequently, purposeful and incidental imaging of renal transplants and renal transplant-related complications are increasingly common. These include acute renal transplant rejection and chronic re...
Renal transplant rejection is one of the feared complications of renal transplantation.
In terms of onset, this can be broadly divided into two groups
acute renal transplant rejection
chronic renal transplant rejection: usually after one year post transplantation (at least after 3 months)
The recipients of renal transplants are susceptible to a number of complications. Incidence of each is variable and partially subject to specific surgical transplantation techniques and management patterns 3.
Renal transplant complications
These can be broadly categorised as periren...
The central approach of renal transplant ultrasound is to evaluate for possibly treatable surgical or medical complications arising in the transplanted kidney.
Institutions vary in the exact schedule of renal transplant ultrasound assessment, but it is common to obtain an initial ultrasound 24-...
Renal trauma can result from direct, blunt, penetrating and iatrogenic injury.
Renal injuries account for ~10% of abdominal trauma, and thus the demographic of affected individuals reflects that population. The incidence of renal injuries increases in pre-existing congenital or ac...
Renal tuberculosis, a subset of genitourinary tuberculosis, accounts for 15-20% of extra-pulmonary tuberculosis and can result in varied and striking radiographic appearances.
Tuberculosis can involve both the renal parenchyma and the collecting system (calyces, renal pelvis, ureter, bladder a...
Renal tubular acidosis (RTA) refers to defects in the renal tubular transport of hydrogen ions, bicarbonate ions, or both, in the kidneys resulting in a normal anion gap metabolic acidosis.
The exact prevalence of renal tubular acidosis is unknown but the entity is probably u...
Renal tubular ectasia is an incidental finding that is seen more commonly on intravenous pyelography (IVP), but which can also occasionally be seen on CT urography (CTU).
Renal tubular ectasia is also known as benign renal tubular ectasia. The term "benign" was used to differentiat...
Renal tumours (for the purposes of this article taken to broadly mean neoplastic lesions) should be distinguished from renal pseudotumours.
Whilst renal tumours can be broadly divided into primary and secondary (metastatic), benign and malignant or adult and paediatric tumours, they are more fo...
Renal vascular pedicle injury is a severe form of renal trauma, which if not recognised and treated expediently with lead to the loss of the kidney.
Contrast enhanced CT is the Imaging modality of choice. On CT it is recognised as a non-enhaning kidney. Perirenal ha...
The renal veins are asymmetric paired veins that drain the kidneys.
The renal vein is formed by the union of two-to-three renal parenchymal veins in the renal sinus. It emerges from the renal hilum anterior to the renal artery and drains into the inferior vena cava at th...
There are several variations in renal venous anatomy. Some of these are specific to the left renal vein.
Left renal vein anomalies are generally classified into four types 2:
the ventral pre-aortic limb of the left renal vein is obliterated, but the dorsal retro-aortic limb persists a...
Renal vein thrombosis can be either from "bland" thrombus or tumour thrombus (extension of tumor into the vein). There are numerous aetiologies for bland thrombus, but it most commonly occurs in the hypercoagulable nephrotic syndrome. Renal vein thrombus is commoner on the left side, presumably ...
Renal vein varices develop for various reasons and are usually asymptomatic.
Renal vein varices are usually asymptomatic. Some patients may present with flank pain and/or haematuria.
chronic renal vein thrombosis
Renovascular hypertension (RVH) is a type of secondary hypertension, where high blood pressure develops secondary to renal artery disease.
Approximately 2.5% (range 0.5-5%) of hypertensive patients will have RVH as a cause 2,3.
There are a number of condit...
Retroaortic left renal vein (RLRV) is a normal anatomical variant where the left renal vein is located between the aorta and the vertebra, and drains into the inferior vena cava.
Its recognition is important in order to avoid complications during retroperitoneal surgery or interventional proced...
Retrograde pyelography (also known as retrograde pyeloureterography) is a method of imaging the upper urinary collecting system. After IVU and CTU were developed, it has been rarely performed as a primary study, but it still has a few potential indications as a secondary study.
Retroperitoneal fibrosis (RPF), is a condition that has previously been described as chronic periaortitis. It is an uncommon fibrotic reaction in the retroperitoneum that typically presents with ureteric obstruction.
The disease is part of a spectrum of entities that have a common pathogenic pr...
Retroperitoneal haemorrhage can be a source of significant yet occult blood loss.
The clinical features are varied depending on the amount of hemorrhage present, rate of onset and ability of the surrounding structures to contain the hemostatic system. The classical featur...
The retropubic space (also known as the prevesical space or cave of Retzius) is an extraperitoneal space located posterior to the pubic symphysis and anterior to the urinary bladder. It is separated from the anterior abdominal wall by the transversalis fascia and extends to the level of the umbi...
Rhabdoid tumour of the kidney is a rare, highly aggressive malignancy of early childhood, closely related to atypical teratoid/rhabdoid tumours (AT/RT) of the brain (see rhabdoid tumours)
Rhabdoid tumours occur exclusively in children, with 60% occurring before the age of 1 year o...
Rhabdomyosarcomas of the genitourinary tract are uncommon tumours occurring in pelvic organs. It is a disease nearly exclusive to the paediatric population.
For a general discussion of this type of tumour, please refer to the article on rhabdomyosarcomas.
The peak incidence of ...
Right iliac fossa mass is a common clinical presentation and has a range of differentials that need to be excluded. Radiology plays an important role in this differentiation.
The rim sign can be seen in association with chronic hydronephrosis.
In patients with chronic hydronephrosis, in all forms of contrast-enhanced imaging of the obstructed kidney, enhancement may occur in the residual, but markedly atrophic, renal parenchyma, surrounding the dilated calyces and ...
Rim sign in renal vascular compromise is seen in major renal vascular compromise.
It can be seen in:
renal artery obstruction from embolism, thrombosis or dissection
renal vein thrombosis
acute tubular necrosis
At contrast-enhanced CT or MRI, a thin (1-3 mm) rim of su...
Risk factors for testicular germ cell tumours (GCT) include:
Caucasians at higher risk than African Americans (9:1)
10-40x increased risk
around 10% of all tumours are associated with undescended testis
higher risk if intra-abdominal testis compared with intra-inguinal
Robson staging of renal cell carcinoma (RCC) is simple but has largely been replaced by the TNM system (see renal cell cancer staging article). Robson staging revolves around the relationship to Gerota's fascia, involvement of renal vein and regional nodes.
stage I: limited to kidney
The salt and pepper sign is used to refer to a speckled appearance of tissue. It is used in many instances, but most commonly on MRI. Please note that pathologists also use the term.
Used to describe some highly vascular tumours which contain foci of ha...
Sarcoidosis is a systemic inflammatory disease of unknown origin characterized by the formation of non-caseating granulomas. Virtually any organ system may be involved. Although the involvement of abdominal viscera is less frequent than pulmonary and mediastinal disease when it occurs, it may m...
Sarcomatoid renal cell carcinomas (sRCC) may develop when one of the more common subtypes of renal cell carcinoma degenerates into a sarcoma.
On imaging, they are generally large masses, with irregular contours, and malignant-appearing, but do not have specific imaging features.
Schiller-Duval body is a perivascular structure that can be found in 50% of testicular yolk sac tumours also known as endodermal sinus tumours. If present it is considered pathognomonic.
A central vessel is surrounded by tumour cells, and the cell-vessel complex is contained in a cy...
Schistosomiasis (also referred to as bilharzia or snail fever) is the result of infection by blood fluke (trematode worm) of the Schistosoma species.
Schistosomiasis is very common, affecting over 200 million people, with the vast majority (85%) in Africa. It is prevalent in tropi...
Bladder schistosomiasis, also known as bilharzia of the bladder, is a major health problem in developing parts of the world predisposing individuals to squamous cell carcinoma.
Schistosomiasis is very common, affecting over 200 million people, with the vast majority (85%) in Afric...
Sciatic hernia is a rare type of pelvic floor hernia, which occurs through either the greater or lesser sciatic foramina.
curlicue ureter sign
Scleroderma, also known as systemic sclerosis, is an autoimmune connective tissue disorder characterised by multisystem fibrosis and soft tissue calcification. As such, it affects many separate organ systems, which are discussed separately:
musculoskeletal manifestations of scleroderma
Renal manifestations of scleroderma are common, affecting up to 25% of patients. Some patients (5-10%) can present with a scleroderma renal crisis (SRC). These patients have abrupt onset of hypertension, acute renal failure 4.
For a general discussion of scleroderma, please refer to the parent...
Scrotal cystocoeles are a type of urinary bladder hernia, where the bladder herniates into the scrotum.
Scrotal sac will contain fluid. Emptying of a scrotal cystocoele with voiding is an ...
Scrotal filariasis is a manifestation of filariasis and refers to scrotal involvement from parasitic nematodes of the superfamily filarioidea.
Known disease of the tropics and sub-tropics and a cause of morbidity in Asia, Africa and the Western Pacific regions 2.
Scrotal haematocoeles are collections of blood within the scrotal sac, but outside of the testis.
A haematocoele normally occurs following trauma to the scrotum, or on occasion following surgery. Some think that a varicocoele is a risk factor for developing a haematocoele 4.
The scrotum and its content are subject to a number of infective processes including:
Scrotal pyoceles are purulent fluid collections in the scrotal sac, that generally occur in conjunction with epididymo-orchitis.
Scrotal pyoceles are typically a complication of epididymo-orchitis or testicular abscess but can also occur following trauma or surgery. The purulent flui...
Scrotal scintigraphy is a radio-isotope examination of the scrotal contents, primarily in patients presenting with scrotal pain.
Although, ultrasound remains the mainstay of scrotal imaging, scintigraphy can be used where the diagnosis is unclear, since ultrasound appearances for s...
Scrotal tunica cysts are paratesticular cystic lesions. They include:
tunica vaginalis cysts
tunica albuginea cysts
Typically seen as a simple appearing paratesticular cystic lesion not in the region of the epididymis.
Scrotoliths, also known as scrotal pearls, are benign incidental extra testicular macro-calcifications within the scrotum. They frequently occupy the potential space of the tunica vaginalis or sinus of the epididymis. They are usually of no clinical significance 1,2.
The scrotum (plural: scrota or scrotums) is a dual-chambered protuberance of skin and muscle that contains the testes, epididymides, and spermatic cord. It consists of two chambers separated by a septum. It is an extension of the perineum, and is located between the penis and anus.
Segmental renal hypoplasia, also known as the Ask-Upmark kidney, is a type of renal hypoplasia. It is often found in young females with severe hypertension. The aetiology is unknown but has been postulated to be congenital or a sequelae of pyelonephritis. It is associated with severe juvenile hy...
Segmental testicular infarctions are uncommon testicular lesions that usually result from arterial embolisation or thrombosis (as opposed to testicular infarction from torsion, which may originate from venous occlusion).
The causes of a segmental testicular infarct include:
The seminal vesicles are paired accessory sex glands of the male reproductive system. The seminal vesicle produces over two-thirds of the ejaculate and is very high in fructose.
The seminal vesicle is actually a 10-15 cm long tubular structure but is coiled tightly so it only me...
Seminal vesicle cysts can be congenital or acquired.
It is the presence of cysts within the seminal vesicles since birth. It is seen rarely and occurs probably due to an obstruction at the junction of the seminal vesicle and ejaculatory duct. It is associated with many other urogeni...
Seminal vesiculitis is an uncommon entity characterised by inflammation of the seminal vesicles. It is most commonly infective in aetiology, and often associated with concurrent infection elsewhere in the male genital tract, forming part of the spectrum of male accessory gland inflammation 4. It...
Sertoli cell tumours of the testis are uncommon sex cord stromal tumours. They are less common than Leydig cell tumours of the testis.
May present in both paediatric and adult males, depending on the histologic subtype.
Testicular mass or firmness. May occ...
Sex cord stromal tumours of the testis are uncommon testicular neoplasms. Although ~90% of these tumours are benign, they cannot be differentiated from testicular malignancies on imaging, and are therefore usually discovered after orchiectomy.
Leydig cell tumour of the testis (most common, ~30%...
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 haemoglobin (a haemoglobinopathy), which manifests as multisystem ischaemia and infarction, as well as haemolytic anaemia.
There is no recognised gender predilection. ...
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 colour Doppler and is safer.
Sildenafil citrate is a popular vasodilator drug used in treatment o...
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 oedematous ureteric wall. Phleboliths on the other hand usually have imperceptible walls (although up to 8% m...
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 refers to the presence of a linear worm like filling defect within a contrast opacified bladder. This linear filling defect is considered to represent blood clot extruded from the ureter and thereby moulded in the tubular shape. It is seen in patients with gross haematuria. Pr...
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 tumour 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 extra-testicular 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 ...
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 paediatric patients with Spigelian hernias will have ipsilateral cryptorchidism 1,2.
Along with Spigelian hernia and cryptorch...
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 haematuria 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 f...
A spoke wheel pattern in renal imaging refers to a vascular appearance seen with certain renal tumours, 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 th...
Spontaneous retroperitoneal haemorrhage (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 abdomin...
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 ischaemia or necrosis, as a result of small vessel occlusion. This abnormal perfusion pattern ...
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 ...