An oncocalyx is a dilated tumour filled renal calyx, typically seen in patients with transitional cell carcinomas of the renal pelvis.
Orchitis is an infection of the testicle, which is rarely isolated, and when in conjunction with the epididymis is called epididymo-orchitis.
Usually bacteria retrogradely seed into the testis from the bladder or prostate. Can also be secondary to viral infection (e.g. mumps, Coxsack...
Ossifying renal tumour of infancy (ORTI) is a rare renal tumour.
extremely rare, <<1% of paediatric renal neoplasms (17 cases reported)
6 days - 3 months
Histology reveals spindle cells and osteoblastic cells in a calcified osteoid matrix. It is thou...
Ovarian vein syndrome is a relatively rare condition where a dilated ovarian vein causes notching, dilatation, or obstruction of the ureter. This is usually secondary to varicoses of the ovarian vein or ovarian vein thrombosis and occurs at the point where the ovarian vein crosses the ureter.
Oxalosis results in supersaturation of calcium oxalate in the urine (hyperoxaluria), which in turn results in nephrolithiasis and cortical nephrocalcinosis.
This article focus on the secondary oxalosis, please refer to primary oxalosis for a specific discussion on this entity.
The paediatric cystic renal diseases comprises a group of conditions that are all either autosomal recessive or non-hereditary:
autosomal recessive polycystic kidney disease (ARPKD):
hyperechoic and enlarged kidney
multicystic dysplastic kidney (MCDK):
absence of functional parenchyma, urete...
The paediatric kidneys follow a growth curve. The measurements below are of the longest maximal dimension. Measurements in parentheses are one standard deviation.
0 months 1: female: 4.15 cm (0.35); male: 4.22 cm (0.32)
2 months: 5.28 cm (0.66)
6 months: 6.15 cm (0.67)
10 months: 6.23 cm (0...
Paediatric renal tumours and masses are another group of diseases (just like cystic renal diseases in both the adult and child) that are bewildering in their number, nomenclature and overlapping findings.
Wilms tumour: common in older children 1-8 years old
Paediatric urinary tract infections are common and are a source of significant imaging in young children.
Paediatric urinary tract infections affect up to 2.8% of all children every year, with approximately 2% of boys and 8% or more of girls developing a urinary tract infection at...
The British National Institute for Health and Care Excellence (NICE) published the “Urinary tract infection in under 16s: diagnosis and management” in 2007 as a guideline for paediatric urinary tract infection (UTI) management, including imaging, prophylaxis and follow-up 1.
This article inten...
Page kidney refers to the phenomenon of hypertension that develops following long-standing compression of renal parenchyma by subcapsular renal collection, e.g. haematoma, seroma, urinoma.
Compression of the renal parenchyma results in compression of the renal vessels, which leads to...
A paintbrush appearance describes the streaky appearances of dilated contrast filled tubules within the renal medulla on IVP or CT-IVU. This appearance is characteristic for medullary sponge kidneys.
bouquet of flowers appearance
The pampiniform plexus is the venous network of approximately 10 veins draining the testes and epididymis. The network surrounds the testicular artery in the spermatic cord and lies anterior to the ductus deferens. Each network coalesces to form the testicular veins.
Along with the cremaster an...
Pancake kidney (also known as discoid kidney, disc kidney, lump kidney, fused pelvic kidney or cake kidney) is a rare renal fusion anomaly of the kidneys of the crossed fused variety.
Pancake kidney may be an incidental finding. However, they can present clinically becaus...
Papillary cystadenomas of the epididymis are the second most common benign tumours of the epididymis after adenomatoid tumours. They are more common in young men. Approximately 30% of the patients have von Hippel Lindau disease and approximately 10% to 40% of patients with von Hippel-Lindau dise...
Papillary renal cell carcinoma (pRCC) is one of the subtypes of renal cell carcinoma.
This subtype may account 13-20% of all renal cell cancer. There is slightly increased male predilection.
As with other types of renal cell cancer, most are asymptomatic an...
The pararectal spaces are paired, triangular-shaped spaces in the posterior pelvis.
anterior: cardinal ligament
medial: rectal pillars
lateral: levator ani muscle, internal iliac arteries
The pelvic splanchnic nerves also known as nervi erigentes are preganglionic (presynaptic) parasympathetic nerve fibres that arise from S2, S3 and S4 nerve roots of the sacral plexus. These nerves form the parasympathetic portion of the autonomic nervous system in the pelvis.
Paratesticular lesions have a large list of differential diagnosis:
epididymal cyst (most common epididymal mass)
adenomatoid tumour (most common epididymal tumour)
scrotal tunica cysts
tunica vaginalis cyst
tunica albuginea cyst
A paratesticular mass may derive from a number of structures that surround the testicle within the scrotum; most commonly, they derive from the spermatic cord.
The masses can be categorised as benign (70%) or malignant (30%).
spermatic cord lipoma (most common pa...
The paravesical spaces are paired avascular spaces of the pelvis. The paravesical spaces generally contain fat, but can become filled with ascites, blood, or other substances during pathological processes.
superior: lateral umbilical folds
inferior: pubocervical fasc...
A patent urachus is one of the spectrum of congenital urachal anomalies. It has occasionally been termed "urachal fistula".
A patent urachus is often diagnosed in neonates when urine is noted leaking from the umbilicus. The umbilicus may also have an abnormal appearance o...
Pear-shaped (or tear-drop-shaped) bladder is one whose normal round or ovoid shape has been extrinsically compressed to resemble a pear. The pear may be inverted or upright, depending on how the excess pelvic tissue compresses the bladder.
Causes of a pear-shaped bladder i...
Pelvi-ureteric junction (PUJ) obstruction/stenosis, also known as ureteropelvic junction (UPJ) obstruction/stenosis, can be one of the causes of an obstructive uropathy. It can be congenital or acquired with a congenital PUJ obstruction being one of the commonest causes of antenatal hydronephros...
A pelvic abscess refers to a collection of pus in the pelvis,
Some of the causes include
pelvic inflammatory disease (tubo-ovarian abscess)
inflammatory bowel disease
pelvic actinomycosis infection
Pelvic congestion syndrome is a condition that results from retrograde flow through incompetent valves in ovarian veins. It is one of commonly missed and potentially treatable cause of chronic abdominal or pelvic pain.
It tends to be more common in multiparous, premenopausal wome...
Pelvic kidney (sometimes known as sacral kidney) is a kidney that is fixed in the bony pelvis or across the spine 1.
Pelvic ectopia is seen in 1 in 2100-3000 autopsies. It is considered the most common form of renal ectopia 4.
These patients are asymptomati...
Pelvic lipomatosis (also known as pelvic fibrolipomatosis) represents excessive deposition of fat in pelvis due to overgrowth of adipose cells leading to compression of pelvic organs.
The condition usually presents in patients 20-50 years of age. The condition is predominantly (2/...
The pelvic peritoneal space is the inferior reflection of the peritoneum over the fundus of the urinary bladder and the front of the rectum at the junction of its middle and lower thirds. In females, the reflection is also over the anterior and posterior surface of the uterus and the upper poste...
Penile Doppler (papaverine induced colour duplex Doppler) is an excellent and highly accurate means of assessing patients with erectile dysfunction.
Penile erection is a result of complex interaction between nervous, arterial, venous and sinusoidal systems. Any defect in one of these...
Penile fracture is a rare event, however requires emergency diagnosis and intervention.
It is a rupture of corpora cavernosa and penile sheath (tunica albuginea) caused by trauma to an erect penis, most commonly during sexual intercourse. What a urologist needs to known in such an emergency, is...
Penile implants are a surgically placed device to assist with erectile dysfunction. The device has inflatable components inserted in the penile shaft with a reservoir typically placed in the pelvis.
Penile Doppler in erectile dysfunction
medical devices in the a...
The penis is the most distal part of the male urogenital system.
The gross anatomy of the penis can be broken into five sections:
loosely connected to the tunica albuginea
distally folded to form the prepuce (foreskin) at the corona of the penis
the internal layer of th...
Percutaneous nephrolithotomy (PCNL) is a surgical procedure for the extraction of large renal calculi. It is usually performed in the operating theatre either by a urologist or combined urologist-radiologist team.
PCNL is used to destroy and remove renal calculi, typically over 2 cm...
Percutaneous nephrostomy is a technique in which percutaneous access to the kidney is achieved under radiological guidance. The access is then often maintained with the use of an indwelling catheter.
urinary tract obstruction
urinary diversion (e.g. ureteric injury; urine leak)
Percutaenous nephrostomy salvage and tube exchange are two procedures undertaken in those with long term nephrostomies. These patients are often either unsuitable or do not wish to have ureteric stenting to relieve their urinary tract obstruction.
Nephrostomy salvage is und...
The perineal nerve or the perineal branch of the pudendal nerve is the largest terminal branch of the pudendal nerve which is derived from S2, S3 and S4 nerve roots of the sacral plexus. The perineal nerve gives muscular branches to superficial and deep perineal muscles as well as the external ...
A perinephric abscess may result due to rupture of a renal abscess into the perirenal space, but usually it develops directly from acute pyelonephritis. However, any inflammatory process outside the Gerota's fascia may also result in perinephric abscess. Perinephric abscesses are associated with...
Perinephric fluid collections are commonly seen after renal transplantation. The appearance of a perinephric fluid collection is often nonspecific, and generating a differential often relies on when the transplant occurred.
Early post-transplant period
Perinephric stranding refers to the appearance of oedema within the fat of the perirenal space on CT or MRI. While a degree of symmetric bilateral perinephric stranding is common, particularly in the elderly, asymmetric or unilateral perinephric stranding is an important sign of renal inflammati...
The perineum is a diamond shaped region below the pelvic diaphragm and is divided by an imaginary line drawn between the ischial tuberosities into anteriorly the urogenital triangle and posteriorly the anal triangle.
The perineum is bounded by the pubis anteriorly, the ischial tu...
Perirenal cobwebs is the presence of prominent perinephric septae. It is best appreciated on CT images.
The cobweb is considered to be due to engorged venous collaterals or due to edema and fluid extravasation into the perirenal space 1.
Perirenal cobwebs may be seen in many benign ...
The perirenal fascia is a dense, elastic connective tissue sheath that envelops each kidney and adrenal gland together with a layer of surrounding perirenal fat.
It is a multi-laminated structure which is fused posteromedially with the muscular fasciae of the psoas and quadratus lumborum muscle...
Perirenal lymphocoeles are the most common cause of perinephric fluid collection. They can potentially occur in a post-transplant situation in up to 25% of cases.
Perirenal lymphocoele is usually asymptomatic but they can be large enough to cause hydronephrosis or venous ...
The perirenal space is the largest of the three divisions of the retroperitoneum and is the most easily identified. It contains the kidneys, renal vessels and proximal collecting systems, adrenal glands and an adequate amount of fat to allow identification on CT scanning.
The space is surrounde...
There are several peri-urethral cystic lesions. These include:
female genitourinary tract:
Gartner duct cyst
epidermal inclusion cyst of the vagina
Skene duct cyst
Bartholin gland cyst
endometrial cyst of perineal - vulval - vaginal region
Perlmann tumour of the kidney (also sometimes known as benign adenomatous multicystic kidney tumour) is often mistaken for a malignant neoplasm. Many now consider it synonymous with the more well-known multilocular cystic nephroma.
Persistent fetal lobulation is a normal variant seen occasionally in adult kidneys. It occurs when there is incomplete fusion of the developing renal lobules. Embryologically, the kidneys originate as distinct lobules that fuse as they develop and grow.
It is often seen on ultrasound, CT or MRI...
PET-CT is a combination of cross-sectional anatomic information provided by CT and the metabolic information provided by positron emission tomography (PET).
PET is most commonly performed with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG). F-18 is an unstable radioisotope and has a half-life of approx...
Peyronie disease is the most common cause of painful penile induration. Fibrous tissue plaques form within the tunica albuginea, causing painful deformity and shortening of the penis. Though clinical diagnosis is usually accurate, the role of imaging is to evaluate extension of plaques, whether ...
Phantom calyx is a calyx which fails to fill with contrast admist a well opacified remainder of pyelocalyceal system. It refers to an intrarenal process which has infilterated and caused obliteration of the involved collecting system element.
It may be seen in:
tumour: especially transitional ...
Pheochromocytomas are an uncommon tumour of the adrenal gland, with characteristic clinical, and to a lesser degree, imaging features. The tumours are said to follow a 10% rule:
~10% are extra-adrenal
~10% are bilateral
~10% are malignant
~10% are found in children
~10% are familial
Pie in the sky bladder refers to the appearance of contrast opacified floating bladder seen high in the pelvis due to a presence of a large pelvic haematoma. This sign should raise concern regarding the possibility of an underlying urethral injury.
A pine cone bladder or christmas tree bladder is a cystogram appearance in which the bladder is elongated and pointed with thickened trabeculated wall. It is typically seen in severe neurogenic bladder with increased sphincter tone (detrusor sphincter dyssynergia) due to suprasacral lesions (abo...
Polyorchidism (or supranumerary testes) refers to the presence of more than two testes and is a very rare congenital anomaly. The supernumerary testis can be usually located inside the scrotum (75% of the patients) or less commonly in the inguinal canal, the retroperitoneum, or the abdominal cav...
Post transplant lymphoproliferative/lymphoproliferation disorder (PTLD) is increasing in prevalence as the number and survival length of solid organ and bone-marrow transplant recipients also increases.
It represents a variety of conditions varying from lymphoid hyperplasia to malignancy but is...
The posterior pararenal space is the smallest and most clinically insignificant portion of the retroperitoneum.
It is filled with fat, blood vessels and lymphatics, but contains no major organs.
posteriorly: bound by transversalis fascia
anteriorly: bound by posteri...
Posterior urethral valves (PUVs), also referred as congenital obstructing posterior urethral membranes (COPUM), are the most common congenital obstructive lesion of the urethra and a common cause of obstructive uropathy in infancy.
Posterior urethral valves are congenital and only...
The Potter sequence is a constellation of findings demonstrated postnatally as a consequence of severe, prolonged oligohydramnios in utero.
It consists of
pulmonary hypoplasia: often severe and incompatible with life
growth restriction (IUGR)
abnormal facies (Potter fa...
Priapism is a term for a penile erection that occurs longer than desired. It may occur for multiple reasons, and the role of imaging in priapism is to distinguish between ischemic low-flow priapism (95%) and non-ischemic high-flow priapism (5%). In most cases only the corpora cavernosa are affec...
Primary hyperoxaluria, also referred as primary oxalosis, is a congenital autosomal recessive disease related to a liver enzyme deficiency leading to massive cortical nephrocalcinosis and renal failure.
Please, refer on secondary oxalosis for a discussion on the acquired form of hyperoxaluria....
Primary pigmented nodular adrenal dysplasia (PPNAD) is a rare benign adrenal condition characterised by ACTH-independent autonomous hypersecretion of cortisol, leading to Cushing syndrome.
PPNAD is inherited as an autosomal dominant trait, which has yet to be confidently mapped. ...
Primary melanoma of the prostate is rare, and usually cannot be diagnosed on imaging alone. In many cases, it is believed that in fact the tumour represents prostatic involvement by melanoma of the urethra.
Primary malignant melanoma of the prostate represent both a tiny fraction...
Primary urethral cancer staging often uses the TNM system and is as follows:
Primary tumour staging (T)
Tx: primary tumour cannot be assessed
T0: no evidence of primary tumour
Tis: carcinoma in situ
Ta: non-invasive papillary, polypoid, or verrucous carcinoma
T1: invasion of s...
Melanoma of the urethra is very rare tumour of the male urethra, and often presents as an invasive prostatic mass. As such it is usually referred to as primary prostatic malignant melanoma.
primary cutaneous melanoma
primary noncutaneous melanoma
The prostate gland is part of the male reproductive system and is the largest male accessory gland. It typically weighs between 20-40 grams with an average size of 3 x 4 x 2 cm. The prostate is comprised of 70% glandular tissue and 30% fibromuscular or stromal tissue 1-3 and provides approximate...
Transrectal ultrasound–guided biopsy is considered the standard approach for prostate biopsy and is most commonly performed on an outpatient with a positive screening for prostate cancer.
Nowadays, with the MRI capacity for depicting abnormal areas of the prostate, is possible to obtain target...
Prostate cancer staging can be thought of in terms of physical location or grading histologically. The TNM classification is used to determine spread, and the Gleason score is used to determine the histological type. Another staging system is the Jewett-Whitmore staging system.
Prostate cancer, also called carcinoma of the prostate or prostate carcinoma, is the commonest malignant tumour in men. It is primarily a disease of old age and many men remain asymptomatic.
This is a summary article; read more in our article on prostate cancer.
Prostate cystic disease encompasses a wide variety of pathologies that all result in cyst formation within the prostate.
midline cystic lesions / cyst like lesions
Mullerian duct cyst
prostatic utricle cyst
ejaculatory duct cyst (tends to be more paramidline 6)
cystadenoma of prostate
PI-RADS (Prostate Imaging Reporting and Data System) refers to a structured reporting scheme for evaluating the prostate for prostate cancer. It is designed to be used in a pre-therapy patient.
The original PI-RADS score was annotated, revised and published as the second version, PI-RADSv2 6 by...
Prostate peripheral zone T2 hypointensity is a common finding in pelvic MRIs that needs to be differentiated. A prostate directed MRI is usually performed using a multi-parametric technique to differentiate prostate cancer from more benign changes. This includes T2 weighted images, dynamic contr...
Prostatic sarcoma is an uncommon and heterogenous group of tumour arising from mesenchymal cells in and around the prostate.
In children the most common tumour type is a prostatic rhabdomyosarcoma, which accounts for approximately a third of all prostatic sarcomas 1.
In adults leiomyosarcoma...
Prostate specific antigen (PSA) is currently used as a tumour marker for prostate adenocarcinoma.
PSA is a 33 kilodalton glycoprotein produced in prostate epithelial cells. Its normal physiologic role is as a liquifying agent for seminal fluid and the normal amount in human serum is usually ver...
Prostate-specific membrane antigen (PSMA) is a type II transmembrane glycoprotein, that has become an increasingly prominent imaging biomarker 1. PSMA has emerged as a useful target in PET imaging of prostate cancer, especially in the evaluation of small volume lymph node and bone metastases 2.
Prostatectomy is a common procedure to remove the prostate gland, most often for prostate adenocarcinoma, although occasionally performed for benign prostatic hyperplasia. When performed for tumor, it is only indicated for tumors that are confined to the prostate.
There are two main types of pr...
Prostatic abscesses can be a rare complication of prostatitis.
It has become relatively uncommon in clinical practice due to antibiotic therapy in those with prostatitis. It tends to affect diabetic and immunosuppressed patients. Most patients tend to present in the 5th to 6th de...
Prostatic artery embolisation (PAE) is a minimally invasive procedure option utilised to treat the benign prostatic hyperplasia (BPH).
PAE has been used for controlling prostatic haemorrhage (such as those associated prostate cancer) since 1970. However, its use in the treatment o...
Prostatic calcification is a common finding, especially after the age of 50. They may be solitary but usually occur in clusters 7.
They are rare in children, infrequent below 40, and common in those over 50. Their number and size increase with age 8.
Prostatic carcinoma ranks as the most common malignant tumour in men and the second most common cause of cancer-related deaths in men. Prostatic adenocarcinoma is by far the most common histological type and is the primary focus of this article.
It is primarily a disease of the el...
Prostatic cystadenoma or multilocular cystadenoma of prostate is a rare benign neoplasm arising in the prostate gland.
If lesions are considerably large they may also be termed giant multilocular cystadenomas of the prostate.
Lesions are histologically characterised by glands and cy...
Prostatic infarction refers to necrosis of the prostate gland tissue from a lack of blood supply.
Histology slices on biopsy specimens may show reactive atypia 3.
prostatic artery embolisation
presumed pelvic ischaemia after
cross-clamping of the aorta for coron...
Prostatic utricle cyst (PUC) is an area of focal dilatation that occurs within the prostatic utricle.
They are midline cystic masses in the male pelvis and can be very difficult or impossible to distinguish from a Mullerian duct cyst.
Utricle cysts are most often detected in the ...
Prostatitis refers to an infection or inflammation of the prostate gland that presents as several syndromes with varying clinical features. Prostatitis is a clinical diagnosis and imaging is useful to evaluate abscess formation.
The National Institutes of Health (NIH) classified prostatitis in...
Prostatomegaly is a term used to generally describe enlargement of the prostate gland from whatever cause. Usually the prostate is considered enlarged on imaging when it measures beyond 30 cc (30 grams) in size.
The term prostatomegaly is often used interchangeably with benign pro...
Prune belly syndrome, also known as Eagle Barrett syndrome 3 or triad syndrome, is a rare anomaly comprising a specific constellation of features. It consists of three major findings:
gross ureteric dilatation
anterior abdominal wall underdevelopment (resulting in the "prune belly" appearance)...
Pseudobladder refers to a pelvic cystic mass that simulates the urinary bladder.
The location of the lesion should allow differentiation from the bladder but if doubt exists and clinical necessity arises, a delayed phase CT or MRI with excreted contrast or IDC-administered retrograde contrast f...
Pseudoenhancement is an artifact in postcontrast CT evaluation of renal cysts.
The distinction between cystic and solid lesions visualised in CT is primarily made on the basis of whether the lesion enhances with contrast administration. A renal cystic lesion is considered "enhancing" when there...
Pseudohydronephrosis refers to normal anatomy or non-significant pathologies that may mimic hydronephrosis. There is usually fluid-density material within a dilated of a part of the urinary tract, but without other signs of obstruction such as retroperitoneal fat stranding, renal perfusion abnor...
Pseudoureterocoeles are acquired dilatations of the submucosal portion of the distal ureter that mimic simple ureteroceles. The appearance of the radiolucent wall surrounding the dilated distal ureteral segment (cobra head sign) is an important differentiating point.
The distinction is importa...
A psoas hitch is a method of ureteric re-implantation following distal ureteric resection or injury.
The reconstruction is indicated when the distal ureter is injured or resected for cancer or stricture disease, and the remaining portion of ureter cannot reach the bladder for a ureteroneocystot...
Pulmonary-renal syndromes refer to a group of conditions that can affect the lung and kidneys. These conditions are typically characterised by diffuse alveolar haemorrhage and glomerulonephritis.
Diseases that can result in a pulmonary-renal syndrome includes:
certain pulmonary vasculitides
A putty kidney refers to a pattern of renal calcification associated with renal tuberculosis conventionally described on plain radiography. Calcification characteristically is very homogeneous and ground glass like, representing calcified caseous tissue 3-4. Premkumar et al labelled calcificatio...