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We present the unusual case of a 45-year-old lady who developed a perirenal urinoma secondary to a complex pelvic cyst.    

Keywords: perirenal urinoma formation, complex pelvic cyst
Authors:

A.Ona-Olapo, T.Oke, S.Surenthiran
Queen Elizabeth Hospital, Woolwich, UK           

Corresponding Author: Rebecca Dale E-mail: rebecca.dale@doctors.org.uk, annette.ona-olapo@doctors.org.uk

Introduction

Perirenal urinoma formation is a rare occurrence most commonly associated with ureteric obstruction by calculi, trauma or iatrogenic injury. We present the unusual case of a 45-year-old lady who developed a perirenal urinoma secondary to a complex pelvic cyst. Resection of the pelvic cyst and placement of a JJ stent led to resolution of the urinoma and a full recovery. 

Case Report

A 45-year-old lady presented to accident and emergency with acute lower abdominal pain, vomiting and rigors. On examination she had a mildly distended abdomen with suprapubic tenderness and signs of lower abdominal peritonism. Blood tests revealed a white cell count of 1.01(normal range 3.9-11.1 x 109), neutrophils of 0.77 (1.7-7.5 x 109), CRP less than one, creatinine of 113 (44-80umol/l) and urea of 6.2 (2.1-7.1mmol/l). All other blood results were within the normal range. Her abdominal and chest x-rays were unremarkable with no evidence of bowel obstruction or perforation.
Her past medical history included laparotomy and adhesiolysis the previous year, sigmoid colectomy for diverticular disease three years previously, total abdominal hysterectomy for abnormal uterine bleeding due to a bicornate uterus five years previously and a laparotomy for pneumo-peritoneum of unknown origin seven years previously. She was also under out-patient investigation for persistent diarrhoea and an MRI enteroclysis performed four weeks earlier had shown a complex 15cm pelvic cystic mass (Figures 1 & 2). 
Figure 1 MRI saggital view of pelvis illustrating complex pelvic cyst


Figure 2 MRI axial view of complex pelvic cyst 



The same study showed a solitary right kidney with a simple renal cyst (Figure 3) and mild hydronephrosis (Figure 4).         
Figure 3 MRI coronal view demonstrating simple renal cyst

   
Figure 4 MRI axial view illustrating mild hydronephrosis


A presumptive diagnosis of sepsis was made and after fluid resuscitation and empirical antibiotics had been started a repeat MRI was performed. This showed persistence of the complex pelvic cyst with resolution of the hydronephrosis but the new development of a right sided urinoma extending into the retroperitoneal space (Figures 5 & 6). The diagnosis of acute sepsis secondary to an infected urinoma was made.       
Figure 5 MRI coronal view demonstrating the presence of urinoma 


Figure 6 MRI axial view of urinoma 


At laparotomy a large thin walled cyst with multiple daughter cysts was found arising from the pelvis. As there were no clear tissue planes the cyst was deroofed and a sample of the fluid and cyst wall was sent for histological examination. Both ovaries were also noted to be cystic, and the largest cysts were deroofed and tissue samples from both ovaries were sent for analysis. A 7 channel JJ stent was inserted to relieve the obstruction of the right kidney. 
Histological examination of the pelvic cyst wall revealed portions of omentum exhibiting a lining of reactive connective tissue surrounding a cystic region consistent with a peritoneal pseudocyst. The right ovarian tissue showed a benign mesothelial inclusion cyst, and the left showed a haemorrhagic ovarian cyst suggestive of a previous follicular cyst. There was no evidence of an associated neoplasm, and the patient went on to make a full and uneventful recovery.

Discussion

A urinoma is a collection of urine in a body cavity or soft tissue resulting from the extravasation of urine from the urinary tract . It may occur at any point between the kidney and the external urinary meatus. A perirenal urinoma forms when the point of extravasation of urine is the collecting system of the kidney. Friedenberg et al  proposed that in order for a urinoma to form then four criteria must be met. Firstly the kidney affected must have adequate function and be capable of concentration and diuresis, secondly there must be chronic partial obstruction, thirdly the renal calyces or fornices when under increased intrapelvic pressure must be capable of pyelosinus extravasation and fourthly the renal hilus must allow this extravasated urine into the perirenal space. Urine collecting in the perirenal space may then follow the anatomical plane and extend into the retroperitoneum. 

Perirenal urinoma formation is a rare occurrence and is most commonly associated with ureteric obstruction by calculi causing increased intrapelvic pressure. Trauma and iatrogenic injury may also result in urinoma formation either through increase in the intrapelvic pressure secondary to obstruction or by causing anatomical disruption of the drainage system. Rare cases of urinoma have also been reported secondary to malignancy (including rectal , cervical  and ovarian  cancer), benign conditions such as benign prostatic hypertrophy  and congenital abnormalities such as the presence of posterior urethral valves in boys . 

Clinical presentation depends on the location of the urinoma and its size and the presence or absence of infection. Urinomas forming within the soft tissue may present with a mass effect. Large perirenal urinomas may present with flank swelling, but smaller ones tend to present more insidiously with pain and flank tenderness4. Infected urinomas may present with signs of systemic sepsis. 

Diagnosis involves biochemical measurement of renal function and imaging of the affected kidney most commonly by IVP, USS or CT4. In our case, MRI was used to allow comparison of the previous study in this modality.

Treatment is dependent on the cause of the urinoma, the patient’s condition and function of the affected kidney4. In our case report, management was directed towards treating the cause of the obstruction by excising the pelvic cyst at laparotomy and inserting a JJ stent to aid drainage and allowed spontaneous resolution of the urinoma. In cases where the obstruction cannot be relieved with a stent or surgery, diversion by percutaneous nephrostomy  or rarely nephrectomy may be required.

In conclusion, patients with renal cysts and lower urinary tract obstruction need prompt treatment to avoid complications. Although rare, it is important to be aware of perirenal urinomas as a potential complication of pelvic pathology. 

References

1. Austin T, Williamson M, Meeks R. Urinoma of the mons pubis associated with a suprapubic catheter. J Pelvic Med Surg. 2004;10:219-222
2.  Friedenberg RM, Moorehouse H, Gade M. Urinomas secondary to pyelosinus backflow.  Urol Radiolol. 1983:5;23
3. Sayeed R, Nyamekye I, Kinder R. Unsuspected rectal adenocarcinoma causing a urinoma. Int J Urol. 1997;4/1:99-100
4. Spurlock JW et al. Calyceal rupture with a perirenal urinoma in a patient with cervical carcinoma. Obstet Gynaecol. 1987:70;511-513 
5. Cormio G et al. Calyceal rupture and perirenal urinoma as a presenting sign or recurrent ovarian cancer. Gynae Onc. 2001:83;415-417
6. Urbain et al. Perirenal urinoma secondary to prostatic obstruction. J Urol. 1985;134/5:967-968
 7. Patil KK, Wilcox DT, Samuel M, et al. Management of urinary extravasation in 18 boys with posterior urethral valves. J Urol. 2003:169:1508-1511
8. Lang EK, Glorioso L, Management of urinomas by percutaneous drainage procedures. Radiol Clin North Am. 1986;24:551-559



Date added to bjui.org: 10/09/2010 (publication information)
This content is exclusive to bjui.org website.

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CASE REPORTS:
Perirenal urinoma formation in a patient with a complex pelvic cyst