Answer of November 2013

Clinical History:

This 60-year-old lady presented with several days of abdominal distention and vomiting. She has known polycystic renal disease on haemodialysis, following previously failed peritoneal dialysis.

Diagnosis:

Sclerosing encapsulating peritonitis, complicated by subacute small bowel obstruction.

Discussion:

Sclerosing encapsulating peritonitis (SEP), also known as encapsulating peritoneal sclerosis, is an uncommon but important complication of continuous ambulatory peritoneal dialysis (CAPD). The exact cause is unknown, but recurrent episodes of bacterial peritonitis and use of glucose-based dialysate are thought to play a contributing role. The risk of SEP increases significantly with the duration of dialysis, with quoted incidences reaching 19% in patients on CAPD exceeding 8 years.

Macroscopically, both the parietal and visceral peritoneum becomes markedly thickened and fibrotic, with a ‘tanned’ or ‘leathery’ appearance. Small bowel often becomes encased with a ‘coccooned’ or ‘encapsulated appearance’, and a static position of bowel loops may be noticed on serial examinations. Intra-abdominal collections or loculated ascites is an unspecific feature, and may markedly increase in volume as disease progresses.

Widespread peritoneal calcification can often be identified on KUB radiographs, though they are not always present. Calcification can be smooth or nodular. Other imaging differential diagnoses to consider with diffuse peritoneal calcification would include pseudomyxoma peritonei, tuberculosis, peritoneal mesothelioma, and calcified peritoneal carcinomatosis. Most of these conditions are associated with nodular rather than sheet-like calcifications, with prominent soft-tissue nodular components which are not found in SEP. Pseudomyxoma peritonei is further characterized by scalloping of the liver and splenic capsules. Tuberculosis is more likely in the presence of other intra-abdominal features such as calcific lymphadenopathy, dense ascites, and segmental enteritis or colitis.

Because of the tendency to encase or encapsulate small bowel loops, there is a risk of progression to acute or subacute small bowel obstruction - the main cause for morbidity and mortality in SEP. The diagnosis is often delayed because clinical features are unspecific and insidious. Increased awareness of SEP may allow early imaging diagnosis and prompt management with cessation of CAPD and peritonectomy.