Specific Ultrasound Findings in Abdominal Tuberculosis in Children
The most specific ultrasound findings in pediatric abdominal TB include intra-abdominal lymphadenopathy (particularly mesenteric and retroperitoneal), high-density ascites, peritoneal/omental thickening, ileocecal wall thickening, and splenic microabscesses. 1, 2, 3
Primary Ultrasound Features
Lymphadenopathy (Most Common Finding)
- Enlarged mesenteric and retroperitoneal lymph nodes are present in approximately 78% of pediatric abdominal TB cases 2
- Nodes characteristically demonstrate low-density centers with multilocular appearance, representing caseous necrosis 3
- Calcified intra-abdominal lymph nodes are highly suggestive of TB and can be identified on point-of-care ultrasound 1
- Most commonly located in mesenteric, peripancreatic, periportal, and upper paraaortic regions 4
Ascites (Highly Characteristic)
- High-density ascites is present in approximately 67% of cases and is a distinguishing feature from other causes of ascites 2, 3
- The high protein content creates echogenic fluid on ultrasound, differentiating it from transudative ascites 3
- Often accompanied by peritoneal thickening and enhancement 2, 4
Peritoneal and Omental Involvement
- Thickening of the omentum or peritoneum occurs in approximately 67% of pediatric cases 2
- Appears as mottled low-density masses in the omentum or "smudgy omentum" pattern 3, 4
- Smooth peritoneal thickening is characteristic 4
Bowel Wall Changes
- Ileocecal region is the most commonly affected bowel segment 2, 4
- Circumferential bowel wall thickening without stratification and mild luminal narrowing 4
- Bowel wall thickening adjacent to mesentery 3
- Inflammatory masses may be present in approximately 33% of cases 2
Solid Organ Involvement
- Splenic microabscesses appear as multiple small hypoechoic lesions 1, 4
- Hepatic involvement presents as multiple microabscesses or pseudotumors in 13-16% of cases 3, 4
- Liver abscess may occasionally be seen 2
Diagnostic Algorithm Using Ultrasound
When ultrasound demonstrates the combination of intra-abdominal lymphadenopathy, ascites, mesenteric thickening, ileocecal thickening, and splenic microabscesses in the appropriate clinical context (fever, abdominal pain, weight loss), abdominal TB should be strongly considered. 1, 2
Clinical Context Integration
- Fever (90% of cases), abdominal pain (80%), and weight loss (89%) are the most common presenting symptoms 2
- History of TB exposure in household members is present in 60% of cases 2
- Abnormal chest radiography is present in 90% of pediatric abdominal TB cases 2
Important Caveats and Pitfalls
Ultrasound Limitations
- Ultrasound is operator-dependent and may yield equivocal results, necessitating follow-up with CT or MRI for definitive characterization 5, 6
- Bowel gas and patient body habitus can limit visualization 5
- Point-of-care ultrasound can facilitate bedside diagnosis in the emergency department when performed by experienced operators 1
Diagnostic Challenges
- Abdominal TB is a great mimicker of other abdominal pathology including Crohn's disease, lymphoma, and other infectious/inflammatory conditions 7, 4
- Diagnosis is frequently delayed 7-36 days after initial presentation because the condition is not suspected initially 2
- A high index of suspicion is essential, particularly in endemic areas or with known TB exposure 2, 7
When to Advance to CT/MRI
- If ultrasound findings are inconclusive but clinical suspicion remains high 6
- For comprehensive evaluation of bowel involvement and complications 2, 4
- CT demonstrates superior sensitivity for detecting peritoneal involvement, necrotic lymph nodes, and multi-focal bowel disease 3, 4
Confirmatory Testing
- Mycobacterium tuberculosis isolation rates are only 50% from ascites, 30% from gastric aspirates, and less than 50% from tissue specimens 2
- Laparoscopy or laparotomy may be required for definitive diagnosis in select cases 2
- Characteristic imaging findings combined with TB exposure history often justify empirical anti-tuberculous therapy without tissue confirmation 2, 7