Bilateral Spontaneous Urinoma in a Patient with Primary Hypothyroidism

Urinomas are a rare entity involving collection of urine in the perinephric and adjacent spaces resulting from disruption of the urinary collecting system at any level from the calyx to the urethra. Among other causes, blunt trauma to the abdomen is one of the commonest causes. Literature regarding medical causes leading to urinomas is scarce. We report a case of a patient with spontaneous bilateral urinoma with co-incident hypothyroidism.

Urogenital trauma is the most common cause of urinary leaks from the kidney, ureter, bladder and urethra. 1 The formation of urinomas is insidious initially and may lead to complications such as abscess formation and electrolyte imbalances if not promptly diagnosed and appropriately managed. 2 Urinomas have been reported in literature in association with pelvic masses, urinary calculus, p osterior urethral valves, ureteropelvic junction (UPJ) obstruction, congenital anomalies, chronically distended bladder resulting in obstructive uropathy. 3Though data of spontaneous urinomas in association with medical diseases like hypothyroidism are scarce, a rare case of hypothyroid ascites responding to thyroxine replacement has been reported. 4Possible pathophysiology of spontaneous urinoma is r aised intrapelvicalyceal pressure resulting in back-flow of urine with subsequent multiple rupture or porosities at calyceal fornices and extravasation of urine through sinus and renal capsule. 3

Case report
A 40-year-old female presented t o outpatient department with two weeks history of pain in both flanks.It was dull aching and continuous in nature with no constitutional symptoms like fever, dysuria or increased frequency of m icturition.There was no history of antecedent trauma, diabetes, tuberculosis, hypertension or any significant surgical or medical past history.Physical examination revealed normal vitals.There was mild pallor but no cyanosis, jaundice or thyromegaly.There was no abdominal t e nderness, organomegaly or ascites.
Baseline investigation revealed hypochromic microcytic anemia with haemoglobin of 9.1 gm%, m e an corpuscular volume (MCV) 72, m e an corpuscular haemoglobin concentration (MCHC) of 25 and mean corpuscular haemoglobin (MCH) 24.Renal function tests and liver function tests were normal.Urine routine examination was normal and urine culture was sterile.Electrocardiography and chest radiography were normal.Transabdominal ultrasonography r e vealed bilateral p e rinephric collection with a m aintained corticomedullary differentiation, normal hepatobiliary system and no ascites..08 mg% confirming it to be urine.Patient was managed conservatively with monthly follow-up during which transabdominal sonography was done each time for consecutive three months.Patient was incidentally found to be hypothyroid on routine investigations for which he was put on thyroxine 75 µg/day.At the end of three months there was complete resolution of the collection.

Fig 4. USG of abdomen showing complete resolution of collection
Whether the resolution was affected b y t hyroxine replacement for hypothyroidism warrants further study, as there was no other medical or surgical comorbidity that may be correlated with presentation of urinoma in this patient.

Discussion
A urinoma, also called p ararenal p seudocyst, is an encapsulated collection of extravasated fluid and typically found in the area adjacent to the kidneys 5,6 or extends into the retroperitoneum 7 .A urinoma is the result of a breach of the integrity of the pelvis or calices of the kidney or of the ureter. 8The urine collection in the perirenal fat causes an inflammatory r e sponse with lipolysis resulting in its fibrous encapsulation.Urinomas are usually caused by blunt trauma to the kidneys.While extravasation of urine is common as a result a severe blunt trauma (2-18%), spontaneous resolution is typical and urinoma formation develops only in few instances. 9][7] Urinomas tend to develop gradually.Symptoms depend on size and location of the lesion. 7Eventually local pain and p r essure symptoms m ay b e come apparent.
Biochemical t e sting of r e nal function is indicated.Imaging (IVP, ultrasonography, CT scan) will identify the lesion.Image-guided percutaneous needle aspiration is both diagnostic and therapeutic. 6If left untreated, complications may arise including abscess formation, peritonitis, sepsis and damage to the urinary tract by fibrosis and granuloma formation.It is recommended, as a first step, to drain the lesion with ultrasound or CT guidance. 5,6If a patient has an underlying obstructive problem, it needs t o b e addressed according t o its aetiology.

Fig 2 .
Fig 2. Contrast enhanced CT of abdomen and pelvis showing bilateral perinephric collection