Causes of increasing width of right anterior extrarenal space seen in ultrasonographic examinations.

The right anterior extrarenal space is composed of the perirenal fascia, the right anterior perirenal space, the right anterior pararenal space, and the liver capsule. To clarify the probable causes of an increasing width of the right anterior extrarenal space, the width was measured using ultrasonography for a period of 8 months. The right anterior extrarenal space was measured 3 cm from the superior renal pole and the smallest width obtained in several different scan planes was used. In 1,114 ultrasound examinations, 35 patients were found to have an increased width of the right anterior extrarenal space. Among the 35 cases, the common probable causes for such a condition were found in 27 cases. Eight patients had hyperchogenicity in the right pararenal space, a condition considered to be due to an acute inflammation, including acute pancreatitis, acute cecal diverticulitis, acute appendicitis, ischemic bowel, acute cholangitis, liver abscess, and penetrated duodenal ulcer. Chronic inflammations of an adjacent organ, a previous history of laparotomy, a malignancy with peritoneal metastases, and treatment with corticosteroid were considered the causes behind the condition in the 19 patients with normal echogenicity. For the remaining 8 patients, causes were not found during the follow-up period. This study indicates that life-threatening diseases, such as acute or chronic inflammatory diseases and malignancy of the abdomen, could be the cause of an increase in the width of this space.