Diagnosis of abdominal tuberculosis: sonographic findings in patients with early disease

The diagnosis of abdominal tuberculosis is often difficult, because clinical manifestations and results of laboratory studies are nonspecific. If sonographic findings are sufficiently characteristic for diagnosis, sonography would be useful, especially in India, where abdominal tuberculosis is common and more expensive imaging techniques are not easily available. Accordingly, we performed sonography to establish the sonographic findings in cases of early tuberculosis in 56 patients with abdominal tuberculosis who had normal barium studies of the small bowel.

Fifty-six patients with clinical features suggestive of abdominal tuberculosis (history of fever, abdominal pain, and weight loss) with no history of intestinal obstruction and normal barium studies of the small bowel had abdominal sonography. All sonograms were independently assessed by three radiologists, and the findings were tabulated by consensus. Diagnosis of tuberculosis was confirmed by sonographically guided biopsy of mesenteric lymph nodes in 19 patients, analysis of aspirated ascitic fluid in 12, and response to antituberculous chemotherapy in 25. Sonography was repeated 1, 3, 6, and 12 months after antituberculous chemotherapy was begun. Abdominal sonograms were also performed in 30 healthy volunteers, and measurements of mesenteric thickness were recorded. The mesenteric thickness was statistically compared in two groups of patients: patients at presentation with patients at the end of antituberculous chemotherapy and patients at presentation with healthy individuals.

The mesenteric thickness in healthy individuals ranged from 5 to 14 mm. Sonographic findings in all patients with abdominal tuberculosis included an echogenic thickened mesentery (> or = 15 mm) with mesenteric lymphadenopathy. Other findings were dilated small bowel loops in 38 patients, minimal ascites in 17, matted small bowel loops in five, and omental thickening with altered echogenicity in three. Regression of these changes was noted on follow-up of all patients undergoing treatment.

The characteristic sonographic features of early abdominal tuberculosis are mesenteric thickness of 15 mm or more and an increase in the mesenteric echogenicity (due to fat deposition), combined with mesenteric lymphadenopathy. Presence of dilated small bowel loops and ascites further substantiate the diagnosis.