QATAR MEDICAL JOURNAL | VOL. 17 / NO. 2 / DECEMBER 2008 CASE REPORT Bilateral Urinothorax Following Spontanious Extravasation from the Kidney-Speculation of an Anatomical Pathway for the Transport of Extravasated to the Pleural Cavities: A case report and review of the literature *Muzhrachi A.,**Prasad K.V. * Radiology Department and ** Section, Surgery Department Hamad Medical Corporation, Doha, Qatar Abstract: the patient underwent further investigations. A pre-contrast The pathway of extravasated urine from the retroperi- CT scan of the abdomen, five days after admission, showed toenum to the ipsilateral and contralateral in retroperitoneal collection of fluid in the posterior pararenal cases of urinothorax has been of debate in the literature. area, starting at the hilum of the right kidney and extending We present a proposed route for the extravasated urine upwards above the upper pole of right kidney, well separated pathway from the retroperitoenum to both pleural cavities from the posterior surface of the kidney by perirenal fat and based on radiological evidence. in close contact with postero-medial part of the right dome of diaphragm (Figure 1). A thick sheet like structure of fluid Introduction: density was demonstrated on either side of para-spinal space, Collection of urine in the thoracic cavity has been reported which was thicker on the right side, starting from the level of following urinary tract obstruction^1"4). The majority of thoracic the urinoma and extending upwards along the inner surface urine collections have been confined to the same side as that of of the crura of the diaphragm into the posterior mediastinal urinary tract obstruction(5). Many pathways have been proposed space (Figure 2). A tube like structure was also seen in front in the past to trace the passage of urine from the retroperitoenum of the spine and just behind and to the right side of abdominal to the pleural cavity(5' 6). We suggest an anatomical pathway of aorta (Figure 2). Images about 10 cms cranial to this image passage of urine from the retroperitoenum to the pleural cavity showed bilateral and the right sided sheet like with the aid of Computed Tomographic (CT) scan images in a fluid density now appeared as a lobulated structure extending case of bilateral urinothorax following laterally along the inner surface of the posterior wall of the from the right kidney. chest separated from the right pleural effusion by a thin line of fat density suggesting extra-pleural fat (Figure 3). Case Report: A 49-year old male Arabic patient presented to the physician with recent onset of right-sided and vomit- ing. He gave past history of anorexia and weight loss of six months duration. On evaluation he was found to have renal insufficiency with electrolyte disturbances. An Ultrasound Scan (US) of the abdomen on admission showed normal sized kidneys with mild bilateral dilatation of pelvicalyceal system. An ill-defined hypo-echoic area was seen posterior to the upper pole of right kidney with volume of 194 ml. The patient was initially treated by the physician for the renal failure and his renal parameters improved. Urologist was then consulted and

Figure 1: This non-enhanced CT image at the level of upper l/3rd of right kidney revealing a large fluid collection (urinoma) at postero-medial part of posterior pararenal space, Address for correspondence: separated from posterior surface of right kidney by fatty Krishna Prasad V. tissue in the perirenal space. The urinoma is in direct contact Urology Section, Surgery Department with postero-medial part of inferior surface of right dome of Hamad Medical Corporation, P. O. Box 3050, Doha, Qatar diaphragm (arrow). Fax: +974 4392915; E-mail: [email protected]

QATAR MEDICAL JOURNAL | VOL. 17 / NO. 2 / DECEMBER 2008 71 Bilateral Urinothorax Following Spontanious Extravasation from the Kidney . Prasad K.V., et. al.

drainage, another CT scan at the same levels showed in addi- tion to previously described changes in Figure 4 and 5, the contrast was now seen on the left side of para spinal, retrocrural spaces and posterior mediastinum. The contrast was also seen in the lobulated sheet along inner surface of the posterior part of left chest wall. This sheet was separated from the left pleural effusion by the extra-pleural fat. The density of the pleural effu- sion had increased (Figure 6) compared to the previous scan. The contrast media in the posterior mediastinum had extended upward to the level of the mid dorsal spine.

Figure 2: This image is a few cms cranial to the Figure 1 at the level of the upper part of the urinoma. There is a sheet like structure of fluid density (arrows) present on either side of paraspinal areolar tissue and along the inner surface of crura of diaphragm. The domes of diaphragm appear as thin dense lines.

Figure 4: This image is at the same level of Figure 2, but 50 minutes after I. V. contrast injection. The urinoma has filled with contrast. The sheet on right side of paraspinal areolar tissue is full of contrast extending anteriorly along inner surface of right crus of diaphragm. Contrast is also seen within the rounded structure anterior to right part of vertebral body, possibly cisterna chyli (arrow).

Figure 3: This CT cut is at the level of base of chest showing bilateral pleural effusion. The fluid in prevertebral soft tissue extended upward into superior mediastinum and also surrounded the lower l/3rd of oesophagus (arrow) along the posterior part of right wall of the chest as lobulated thickened sheet separated from right pleural effusion by thin line of fat density of extrapleural fat.

CT scan images fifty minutes after injection of intravenous contrast material at almost the same levels of pre-contrast scanning revealed contrast filled urinoma and the fluid density Figure 5: This image is about 5 cms above Figure no. 4 sheet on the right side of the para spinal, retrocrural space and and shows that the contrast filled sheet along right side of posterior mediastinum. The lobulated sheet along the inner posterior mediastinum has now extended laterally along the surface of the posterior part of right wall of the chest and the inner surface of posterior part of right chest wall separated from pleural effusion by fat density line (? extrapleural tube like structure in front of the spine has now become dense fat). Contrast is also present anterior and to right of and loaded with contrast media(Figure 4 and 5). vertebral body. No such changes are seen on the left side of Drainage of the bilateral pleural effusion and right peri- mediastinum. Dense fluid is surrounding the lower part of nephric urinoma was performed the next day. Just before the oesophagus.

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Figure 7: Nephrostogram showing extravasation of contrast (arrow) from the upper minor calyx of the right kidney ascending upwards into urinoma. Figure 6: This CT scan image is at the same level of Figure No. 5, but 24 hours later. The urinoma is still filled with Discussion: contrast media. There is now contrast filled sheets on either side of paraspinal space extending upwards into the left and The term Urinothorax has been adopted to describe in- right sides of posterior mediastinum and extending laterally trapleural fluid collections that are associated with perirenal along the inner surface of posterior part of both left and right extravasation, and to differentiate these from other causes of wall of the chest. Contrast is also seen anterior to left and pleural effusion. The fluidin these cases is inferred to be urine as right parts of vertebral body (arrows). The pleural effusion is now denser than CT images 24 hours earlier. it disappears rapidly after drainage of the perinephric collections or relief of obstruction and on basis of biochemical evidence of raised creatinine content in the pleural fluid compared to This patient was diagnosed to have bilateral urinothorax the serum values(7). and right perinephric urinoma following right renal fornicial Various postulates have been made on the subject of the rupture. This happened as a result of due pathway of urine from the retroperitoenum to the pleural cav- to . The retroperitoneal fibrosis started ity(5,6) ancj many authors described their speculation concerning down from just below the renal hilum and became extensive the urine pathway. We here would like to mention our specula- down towards the bifurcation of the aorta. tion about such pathway. This is based on tracing the passage On percutanious drainage, four liters of fluid from the right of contrast from the urinoma in the retroperitoenum up to the pleural cavity and three liters from left pleural cavity were pleural cavities in the CT scan images, and on screening most drained. About 100 ml of fluid in the right posterior pararenal of the published literature on this subject. space was also drained and catheter left in place. The samples Peritoneal serosal membrane contains sub-serous lymphatic were sent for cytological and biochemical analysis. Cytological plexus. The lymphatic plexus associated with parietal perito- examination of the pleural fluid did not reveal any malignant neum is not well developed except on the undersurface of the cells. Light microscopy of the centrifuged pleural fluid did not diaphragm. In this situation "stomata" have been described reveal any acid-fast bacilli. Biochemical analysis of the aspirat- through which the sub-diaphragmatic lymphatics are in free ed pleural fluid showed urea content of 13.1 mmol/L, creatinine and open communication with the peritoneal cavity. Whether content of 468 Umol/L in the left side and 13.2 mmol/L and 460 these stomata are present or not, there is no doubt that particles Umol/L respectively in the right side. Analysis of blood samples ranging in size from granules of India ink to red blood cells obtained on the same day showed BUN of 10.4 mmol/L and the can readily pass from the peritoneal sac into lymphatics under serum creatinine of 280 Umol/L. The renal functions improved the diaphragm and be found in the lymph vessels above the further and bilateral percutanious (PCN) were diaphragm. It has also been reported that there are communica- performed. Nephrostogram showed extravasation of contrast tions between peritoneal and pleural cavities(8,9). The posterior from the upper minor calyx of the right kidney into urinoma intercostal lymphatic vessels passing backward in the intercostal (Figure 7). He underwent antegrade stenting on both sides and spaces traverse one or two posterior intercostal nodes near the was medically treated for retroperitoneal fibrosis from which head of the ribs and for most part enter the thoracic duct. They he gradually improved. do so either directly or in the case of lower intercostal vessels

73 QATAR MEDICAL JOURNAL | VOL. 17 / NO. 2 / DECEMBER 2008 Bilateral Urinothorax Following Spontanious Extravasation from the Kidney . Prasad K.V., et. al. by means of a trunk, which descends on each side of vertebral These two mechanisms of transfer of urine from the uri- column through diaphragm to open into Cisterna chyli. noma into pleural cavity may operate together or only one at The sheet like structure noted in the CT scan images in the a time. It is noted that the pleural effusion is usually on the areolar tissue of the paraspinal, retrocrural spaces and poste- same side of urinoma or is more prominent on same side in rior mediastinum in our case probably represents the dilated case of bilateral pleural effusion. It is our presumption that, lymphatic channels (Figure 3). The cause of dilatation of the when the lymphatic system is not obstructed, the passage of lymphatic vessels in our case is probably due to the obstruc- urine through the diaphragm into ipsilateral pleural cavity is tion of the lymphatic vessels at the region of the hilum of the the more probable mechanism in these cases. We feel that the kidney by retroperitoneal fibrosis or because these vessels are normal non-obstructed lymphatic system could easily deal with overloaded with urine transferred from the urinoma in the ret- the amount of urine extravasated. roperitoneal space. The sheet is seen to be filled with contrast However, in case of lymphatic obstruction or when the large shortly after IV contrast infusion and after urinoma becomes amount of urine gets accumulated in pararenal space as in our filled with contrast gives the impression that urine with the con- case, the lymphatic system may become overloaded with urine trast, is transferred by lymphatic vessels in paraspinal region, and develop retrograde flow into intercostal lymphatics on either closely related to the urinoma on the right side. The urine with side of the chest wall resulting in bilateral pleural effusion. This contrast was then probably retrogradly drained by lymphatics could, in our opinion, explain the fact that bilateral urinothorax through retrocrural space up into posterior mediastinum and is very uncommon and much less than unilateral urinothorax. then through the lobulated sheet, which is extending laterally in the extrapleural part of the intercostal spaces. We speculate In the normal circumstances urinary extravasations, if that, urine is now transferred from these loaded intercostal discovered early enough get treated immediately and thus lymphatics into the pleural cavity in the same mechanism of prevents late complications like bilateral pleural effusions. congestive heart failure where the pressure increase in the Due to various reasons, the treatment in our case was delayed lymphatic system produce bilateral pleural effusion. The tube for about a week even though contrast imaging was done. This like structure in front of vertebral and intervertebral spaces at resulted in our obtaining progressive CT scan images of the path upper part of lumbar spine is likely to be representing the dilated of contrast from the retroperitoneum to the pleural cavities. overloaded Cisterna chyli. We were thus able to postulate, albeit indirectly, an anatomi- cal pathway for the passage of urine from pararenal space into The findings in the CT images confirm the Barons (7) sugges- tion of mediastinal route of transfer of urine from retroperitoneal pleural cavities. This pathway resulting in bilateral urinothorax urinoma to pleural cavity. The urinoma in the retroperitoenum differs from the mechanisms postulated earlier in the commoner is closely related to inferior surface of postero-medial part of type of ipsilateral urinothorax following spontaneous urinary dome of diaphragm and urine could easily pass through spaces extravasation from a kidney. between muscular bundles and come into direct contact with This view, based on a single case report, obviously needs parietal pleura along the superior surface of the diaphragm and to be corroborated by more rigorous tracing studies. But since then pass into the pleural cavity in same mechanism where fluid such cases are very rare we thought this report would be useful in peritoneum transferred up into pleural cavity. for those interested in the subject. References: 1. Corriere JN MW, Murphy JJ. Hydronephrosis as a cause of 6. Gurtner B. (Urine in the wrong place: urothorax). Schweiz pleural effusion. Radiology 1968; 90: 79-84. Rundsch Med Prax 1994; 83: 30-35. 2. Belis J A, Milam DF. Pleural effusion secondary to ureteral 7. Stark DD, Shanes JG, Baron RL, Koch DD. Biochemical features obstruction. Urology 1979; 14:27-29. of urinothorax. Arch Intern Med 1982; 142:1509-1511. 3. Barek LB, Cigtay OS. Urinothorax - An unusual pleural effusion. 8. Salcedo JR. Urinothorax: report of 4 cases and review of the Br J Radiol 1975; 48: 685-686. literature. J Urol 1986; 135: 805-808. 4. Carcillo J, Jr., Salcedo JR. Urinothorax as a manifestation of 9. Moss G, Genant. Thorax and Neck. In: Computed Tomography nondilated obstructive uropathy following renal transplantation. of the body with Magnetic Resonance Imaging, 2nd edn ed: Am J Kidney Dis 1985; 5: 211-213. W.B. Saunders: 261. 5. Ralston MD, Wilkinson RH, Jr. Bilateral urinothorax identified by technetium-99m DPTA renal imaging. J Nucl Med 1986; 27:56-59.

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