Abdominal TB is a broad term as the disease can be present in intestinal, nodal, peritoneal, visceral and disseminated forms, with almost one-third of patients having the involvement of more than one of these sites. Symptoms and signs vary as per the site. However, common symptoms are abdominal pain, fever, distension, weight loss and anorexia. On examination, doughy abdomen, ascites, omental mass, organomegaly may be seen. Isolated recurrent or chronic pain without any other symptom is usually not due to TB.

Multimodality evaluation, including clinical, laboratory, radiology, endoscopy, microbiology, histopathology, is needed to reach a definitive diagnosis of abdominal TB. Tissue diagnosis remains most reliable though it is often not feasible.  Plain X-Rays are not helpful for the diagnosis of abdominal TB. It may sometimes show non-specific features like enteroliths, perforation and features of intestinal obstruction.

 

 

 

Box 1. Characteristic Image Findings of Abdominal TB

 

Ultrasonography is recommended as an initial modality of choice and may pick up lymphadenopathy, peritoneal thickening, omental thickening, bowel wall thickening, and ascites. Non-specific bowel wall thickening, a small amount of fluid in the mesentery or dependent areas of the abdomen, or the presence of non-matted intra-abdominal lymphadenopathy can be misleading. Contrast-enhanced CT and CT enterography provide adequate cross-sectional imaging in depicting various forms of abdominal TB. Barium studies are gold standards in diagnosing strictures, fistulae, erosions etc. Typical imaging findings are detailed in the box.

For peritoneal TB diagnosis, peritoneoscopy has a very high sensitivity (93%) and specificity (98%). There are usually one of these three types of findings on peritoneoscopy, viz. Hyperemic peritoneum with ascites and whitish miliary nodules, hyperemic peritoneum with ascites and adhesions and markedly thickened parietal peritoneum with yellowish nodules multiple thickened adhesions. 

Diagnosis of abdominal TB is a challenge because of non-specific variable symptoms, low microbiological yield, need for multimodality investigations, complications of the wrong diagnosis. Many times, there is insufficient evidence to start ATT. Children with fever or failure to gain weight or functional abdominal pain often get diagnosed with abdominal TB as lymph nodes (usually around a centimetre in size) are detected on the USG abdomen. Chronic diarrhoea without proper evaluation is also often wrongly treated as TB abdomen.