|Year : 2015 | Volume
| Issue : 1 | Page : 78-80
Subcutaneous urinoma: A rare sequelae to percutaneous nephrolithotomy
Rishi Philip Mathew1, Gouri B Kaveriappa1, Manjunath Shetty2, Hadihally B Suresh1
1 Department of Radio-Diagnosis, Father Muller Medical College, Mangalore, Karnataka, India
2 Department of Urology, Father Muller Medical College, Mangalore, Karnataka, India
|Date of Web Publication||8-Dec-2014|
Rishi Philip Mathew
Department of Radio-Diagnosis, Father Muller Medical College, Kankanady, Mangalore - 575 002, Karnataka
Source of Support: None, Conflict of Interest: None
Urinomas are formed when urine leaks outside its normal pathway of flow from the kidney to the urethra. In most cases it is found in the retroperitoneal space, around the perinephric region. Urinomas are formed secondary to obstruction (such as calculi, fibrosis, malignancy, etc.), or from trauma (blunt, penetrating or iatrogenic). Subcutaneous urinomas are extremely rare and to the best of our knowledge only two cases have been documented, both of which have resulted from renal trauma, secondary to renal transplantation and ureterocutaneostomy. We present the first and only known case of subcutaneous urinoma occurring as a sequelae to percutaneous nephrolithotomy (PCNL) with computed tomography (CT) correlation.
Keywords: Iatrogenic, percutaneous nephrolithotomy, subcutaneous urinoma
|How to cite this article:|
Mathew RP, Kaveriappa GB, Shetty M, Suresh HB. Subcutaneous urinoma: A rare sequelae to percutaneous nephrolithotomy. Muller J Med Sci Res 2015;6:78-80
|How to cite this URL:|
Mathew RP, Kaveriappa GB, Shetty M, Suresh HB. Subcutaneous urinoma: A rare sequelae to percutaneous nephrolithotomy. Muller J Med Sci Res [serial online] 2015 [cited 2019 Nov 13];6:78-80. Available from: http://www.mjmsr.net/text.asp?2015/6/1/78/146472
| Introduction|| |
Urinomas are formed when urine leaks out from its pathway from the kidneys to the bladder. They are either a sequelae to obstruction or trauma (blunt, penetrating or iatrogenic). In most cases, urinomas form in the retroperitoneal space around the perinephric region. Subcutaneous urinomas are very rare and are almost always due to iatrogenic trauma. 
| Case Report|| |
A 35-year-old man presented with chief complaints of a swelling near the left renal angle since five years. He had undergone PCNL of the left kidney for a renal calculus five years back. Two months later he noticed a swelling in the same area. On examination, the swelling was smooth and the transillumination test was positive. An abdominal ultrasound revealed gross left hydroureteronephrosis with diffuse thinning of the renal cortex. The right kidney was normal. The ultrasound examination of the swelling revealed a uniloculated, anechoic, non-vascular cystic lesion, located in the subcutaneous plane in the left lumbar region. A tract was seen communicating between the left kidney and the cystic lesion. A plain abdominal CT revealed a grossly hydronephrotic left kidney with thinned out parenchyma [Figure 1]a. A contrast-enhanced CT (arterial and venous phases) revealed a gross hydronephrotic left kidney, with diffuse, thinned out, poorly enhancing parenchyma. A tract measuring 3 cm in length and 7 mm in width was seen communicating from the mid calyx of the dilated calyceal system to the subcutaneous cystic lesion with a Hounsfield unit (HU) value of 5 [Figure 1]b, [Figure 2]a and b. On delayed post-contrast scans, there was no extravasation of contrast into the cystic lesion, probably due to poor functioning of the left kidney [Figure 3]. The creatinine value of the aspirate obtained from the subcutaneous cystic lesion was 15 mg/dl, as compared to the serum creatinine, which was 1.1 mg/dl. With these findings, along with his history, a subcutaneous left urinoma, secondary to left PCNL, was considered. He underwent a renal scintigraphic study, which confirmed the non-functional status of the left kidney (function <20%). Two weeks later the patient underwent left nephrectomy with excision of the urinoma [Figure 4]. He was discharged later with stable vitals.
|Figure 1: (a) Non-contrast axial CT of the abdomen showing a normal appearing right kidney and a grossly hydronephrotic left kidney with a thinned out cortex (b) Contrast-enhanced CT (arterial phase), axial section showing a grossly hydronephrotic left kidney with a tract communicating to a cystic lesion located in the subcutaneous plane|
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|Figure 2: (a) Contrast-enhanced CT (venous phase), axial section showing a grossly hydronephrotic left kidney communicating with a cystic lesion located in the subcutaneous plane (b) Contrast-enhanced CT (venous phase), sagittal section showing a grossly hydronephrotic left kidney communicating with a cystic lesion located in the subcutaneous plane|
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|Figure 3: Contrast-enhanced CT (delayed phase), axial section showing a grossly hydronephrotic left kidney communicating with a cystic lesion located in the subcutaneous plane through a tract. There was no extravasation of the contrast into the subcutaneously located cyst due to a poorly functioning left kidney|
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| Discussion|| |
Urinomas are defined as a collection of urine formed outside its normal pathway from the kidneys to the urethra. It may be contained, encapsulated or present as free fluid. Urinomas may form anywhere in the body from the upper abdomen to the pelvis, secondary to a number of etiologies. The most common cause of urinomas are trauma (blunt, penetrating or iatrogenic) and obstruction of the ureter, with a forniceal rupture.  In neonates, the posterior urethral valves are the major cause of urinomas and are seen in 15% of the cases, while in older children the pelviureteric junction (PUJ) obstruction is the main etiology. Trauma (blunt or penetrating) may cause perinephric urinoma in two ways Ϳ by directly disrupting the pelvis or collecting system or by degeneration of tissue that is not viable. Symptomatic urinomas are seen in 17% of the blunt trauma cases in children. Common iatrogenic causes include, surgical damage to kidneys, ureter or bladder. Urinomas may also result secondary to leakage from a technically inadequate or dehisced anastomotic site. Urinomas may occur following procedures such as, percutaneous nephrostomy, stone basketing, and extracorporeal shock wave lithotripsy. Most urinomas are either perinephric or subcapsular in location. Intraperitoneal urinomas are a result of iatrogenic or penetrating injuries. Subcutaneous urinomas, in general, are very rare. Although two cases of subcutaneous urinomas have been documented, both have been secondary to post-renal (allograft) transplantation and ureterocutaneostomy (for urinary diversion). , To the best of our knowledge, ours is the only known case of subcutaneous urinoma presenting as a sequelae to PCNL clearly documented with ultrasound and CT correlation. Other rare locations of urinomas include extravasation into the thorax, causing urinothorax and urinomas extending into the buttocks and scrotum. ,
Urinomas may be incidentally detected. However, when large, because of their mass effect, they may cause discomfort or pain. They can also cause urinary obstruction by compressing the ureters, and when located in the upper abdomen, they may compress the diaphragm and cause respiratory problems. 
On ultrasound and CT, urinomas appear as cystic lesions. CT is the imaging modality of choice in the diagnosis of urinomas. CT protocols in these patients involve scanning the abdomen and pelvis before and after intravenous (IV) contrast administration of about 100-150 ml. Delayed phase images obtained 20 minutes after contrast administration are important, as they show the leakage, as attenuation of urinoma increases with time. Ultrasonography (USG)/CT alone may not be able to differentiate urinomas from other cystic collections such as lymphocele or seroma. Patients in whom contrast administration is contraindicated (i.e., high serum creatinine levels, allergic history, patients who have received renal transplants) renal scintigraphy may play an important role. In situations where diagnoses of urinoma remains uncertain even after diagnostic imaging, examining the urinoma aspirate may help, as urinomas have high creatinine and low glucose levels, as compared to the serum levels. ,,
The treatment primarily consists of dealing with the main factor that causes the urinoma. If the urinoma is caused by renal trauma, where the leak is secondary to a devitalized tissue, healing may not occur. In the past, this was treated by partial nephrectomy. However, newer options include embolizing the artery in the renal parenchymal region, from where the urine leak is originating. In conditions where there is a defect leading to the formation of urinoma, diversion of urine may be necessary so that the rent heals. This will also prevent further flow into the urinoma. If obstruction is a causative factor then it needs to be sorted out. Benign conditions such as posterior urethral valves (PUV) may be easily treated. However, conditions such as malignant ureteral obstruction or strictures may require nephrostomy or ureteral stenting to provide urinary drainage. Small urinomas need not be drained separately as they will be reabsorbed. However, they may require drainage when they become infected and cause fever and leukocytosis or when they compress the adjacent structures or cause pain. In patients who cannot be taken up for surgery, cyanoacrylate glue may be used for occluding the persistent leak. Radiologists play a vital role in diagnosing urinomas and urine leaks, and in majority of the cases their role ends there. However, their role may be extended when image-guided interventions such as catheter insertion or stenting are required. ,
| Conclusion|| |
Urinomas are formed secondary to obstruction or trauma. They generally form in the retroperitoneal space around the perinephric region. Subcutaneous urinomas are extremely rare and are secondary to trauma. In most cases urinomas are asymptomatic. However, if urinomas become infected they may cause fever and when they enlarge they may cause obstruction or pain. CT is the imaging modality of choice. In situations where urinomas cannot be differentiated from seromas or lymphoceles on diagnostic imaging, examining the creatinine and glucose levels of the urinoma aspirate will be helpful. The role of radiologists in urinomas in most situations stops with diagnosis, but it may extend further when image-guided interventional management is required. ,
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]