Neonatal hydronephrosis is most commonly diagnosed antenatally as fetal pylectasis, and in the majority of cases is due to pelvi-ureteric junction (PUJ) obstruction.
pelvi-ureteric junction (PUJ) obstruction (50% of cases 1,6)
vesicoureteric reflux (~20% of cases 5)
Nephroblastomatosis refers to diffuse or multifocal involvement of the kidneys with nephrogenic rests (persistent metanephric blastema).
Nephrogenic rest are found incidentally in 1% of infants.
Nephrogenic rests are foci of metanephric blastema that persist beyond 36 ...
Nephrocalcinosis, previous known as Anderson-Carr kidney or Albright's calcinosis, refers to the deposition of calcium salts in the parenchyma of the kidney. It is divided into several types, with differing aetiologies, based on the distribution:
medullary nephrocalcinosis: 95%
Nephroptosis, also known as floating or wandering kidney and ren mobilis, refers to the descent of the kidney more than 5 cm or two vertebral bodies when the patient moves from a supine to upright position during IVU 1-2.
Displacement can also occur medially across the midline, so-called medial...
Nephrostomy is a common urologic or interventional radiology procedure in which a tube/catheter is introduced into the renal collecting system (usually the renal pelvis).
Nephrostomies can either be
"open" nephrostomy: after a urological surgical procedure, such as a UPJ stone removal
Nephrotic syndrome (NS) results from loss of plasma proteins in the urine and characterised by hypoalbuminemia, hyperalbuminuria, hyperlipidemia, and oedema. It may be caused by primary (idiopathic) renal disease or by a variety of secondary causes.
Patients present with ...
Neuroblastomas are tumours of neuroblastic origin. Although they may occur anywhere along the sympathetic chain, the vast majority arise from the adrenal gland.
They represent the most common extracranial solid childhood malignancy and are the third commonest childhood tumour after leukaemia an...
There are two methods of neuroblastoma staging, one that is based on post-operative patients (INSS) and one developed for pre-treatment patients (INRGSS).
International Neuroblastoma Staging System (INSS)
This staging system is for post-operative patients and mainly for prognosis 1:
Both neuroblastoma and Wilms tumour occur in early childhood and typically present as large abdominal masses closely related to the kidneys. Distinguishing between the two is important, and a number of features are helpful.
calcification very common: 90%
encases vascular structu...
Neurocristopathy syndromes encompasses a group of conditions united by abnormal migration, differentiation, division or survival of neural crest cells 1.
neurofibromatosis type I (NF1)
Neurogenic bladder is a term applied to a dysfunctional urinary bladder that results from an injury to the central or peripheral nerves that control and regulate urination. Injury to the brain, brainstem, spinal cord or peripheral nerves from various causes including infection, trauma, malignanc...
Non-seminomatous germ cell tumours (NSGCT) is one of the main groups of germ cell tumours (the other being seminoma). Although they are made up of distinct histological entities, in general, they have similar radiographic appearances. They can, however, be found widely in the body, with variable...
This article serves as a resource for access to normal examples of imaging studies of the genitourinary tract.
KUB: example 1
abdominal x-ray: example 1
IVU: example 1
renal ultrasound: example 1
renal ultrasound: example 2
renal ultrasound: exa...
The normal size of kidneys in children will naturally depend on the age and size of the child. Based on the children's ages normal average renal length on ultrasound are as follows:
0 to 2 months: 5 cm (approximately 2 inches)
2 months to 6 months: 5.7 cm
6 months to 1 year: 6.2 cm (2.5 inche...
Normal kidneys size in adults varies depending on the height of the individual. Also, in general, it decreases with age and increases with body mass index (BMI).
The size of the kidneys is measured mainly sonographically, although both CT and MRI scans also can be used to estimate kidneys size....
Nutcracker syndrome is a vascular compression disorder and refers to the compression of the left renal vein between the superior mesenteric artery (SMA) and aorta. This can lead to renal venous hypertension, resulting in rupture of thin-walled veins into the collecting system with resultant haem...
Obstructive cystic renal dysplasia, or Potter type IV cystic renal disease, is a potential complication that can occur from prolonged obstruction of the bladder outlet or urethra during gestation.
Ureteric obstruction during active nephrogenesis results in cystic renal dysplasia; th...
An obstructive uropathy is a catch-all term encompassing any cause of complete or partial, congenital or acquired and permanent or intermittent obstruction to the urinary tract. Depending on the severity of obstruction and extent, it may result in permanent change in both the collecting system p...
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, Coxsac...
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 (plural: plexuses) is the venous network of approximately 10 veins draining the testis 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.
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...
A pelvic abscess refers to a walled-off collection of pus in the pelvis.
Some of the causes include:
pelvic inflammatory disease (tubo-ovarian abscess)
iatrogenic e.g. post surgical
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...
Pelviureteric 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 hydronephrosi...
Penile Doppler in erectile dysfunction or papaverine-induced colour duplex Doppler, is a highly accurate means of assessing patients with erectile dysfunction (ED).
Penile erection is a result of a complex interaction between the nervous, arterial, venous and sinusoidal systems. Any ...
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 are the presence of prominent perinephric septa. It is best appreciated on CT images.
The cobweb is considered to be due to engorged venous collaterals or due to oedema 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 forming the perirenal space.
It is a multi-laminated structure which is fused posteromedially with the muscular fasciae of the psoas a...
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). Fluorine-18 (F-18) is an unstable radioisotope and has a half-...
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 ...
Phaeochromocytomas 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
A phantom calyx is a solitary calyx which fails to opacify with contrast amidst an otherwise well-opacified pelvicalyceal system. It is due to an intrarenal process which has infiltrated and caused obliteration of the involved collecting system element.
It may be seen in:
tumour: especially tr...
Pie in the sky bladder refers to the appearance of a contrast-opacified floating bladder seen high in the pelvis due to the 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...
Polyarteritis nodosa (PAN) is a systemic inflammatory necrotising vasculitis that involves small to medium sized arteries (larger than arterioles).
Polyarteritis nodosa (PAN) is commoner in males and typically presents around the 5th to 7th decades. Twenty to thirty percent of p...
Polyorchidism (or supernumerary 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...
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...
Post-transplant lymphoproliferative disorder (PTLD), also referred as post-transplant lymphoproliferation disorder, represents a variety of conditions ranging from lymphoid hyperplasia to malignancy, included in the 2008 WHO classification of tumours of haematopoietic and lymphoid tissues. It ca...
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 f...
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 ischaemic low-flow priapism (95%) and non-ischaemic high-flow priapism (5%). In most cases only the corpora cavernosa are aff...
Primary cutaneous melanoma is the most common subtype of malignant melanoma, a malignant neoplasm that arises from melanocytes. Melanocytes predominantly occur in the basal layer of the epidermis but do occur elsewhere in the body. Primary cutaneous melanoma is by far the most common type of pri...
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, in most cases a urethral carcinoma, is a rare urological malignancy. It can be divided in female urethral cancer and male urethral cancer.
It has an incidence of 4.3 per million for males and 1.5 per million for females. It usually manifests in the fifth d...
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 a 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 non-cutaneous 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 ~30% of the...
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.
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...
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-RADS v2 6, ...