Abdominal Tuberculosis

Aetiology and Epidemiology

• Causative organism: Mycobacterium tuberculosis (human type predominates); M. bovis (bovine type) is linked to unpasteurized dairy consumption
• Common in resource-limited countries; incidence is rising in developed nations due to migration and immunosuppression
• HIV co-infection is a major risk factor; M. avium intracellulare becomes increasingly prevalent in HIV-positive patients
• M. bovis and M. fortuitum can also cause intestinal TB via unpasteurized dairy and present similarly

Routes of Infection

Classification

1. Intestinal Tuberculosis

2. Tuberculosis of Mesenteric Lymph Nodes

3. Tuberculous Peritonitis

4. Solid Organ TB (liver, spleen, pancreas - less common)

1. Intestinal Tuberculosis

Pathological Types

(a) Ulcerative Type

• Results from swallowing sputum in active pulmonary TB
• Organism colonises the lymphatics of the terminal ileum
• Produces transverse ulcers with characteristic undermined edges
• Serosa studded with tubercles
• Histology: caseating granuloma with Langhans' giant cells (see histology image below)
• Healing leads to fibrosis and multiple strictures - a major cause of intestinal obstruction
• Perforation is unusual because the serous coat over the ulcer becomes thickened

Fig. Histology of ileocaecal TB showing epithelioid cell granuloma (arrows) with central caseation (star). - Bailey & Love's Short Practice of Surgery, 28th Ed.

(b) Hyperplastic (Hypertrophic) Type

• Occurs when host resistance overcomes organism virulence
• Marked inflammatory reaction causes hyperplasia and thickening of the terminal ileum and caecum
• Fibrosis leads to shortening of bowel with the caecum pulled up into a subhepatic position, widening the ileocaecal angle beyond 90°
• Macroscopically may resemble Crohn's disease
• Presents as a right iliac fossa mass with features of subacute obstruction

Both types may coexist with marked mesenteric lymphadenopathy

Clinical Features

Symptoms

• Abdominal pain (most common) - cramping, worse after meals; right iliac fossa or central
• Weight loss and anorexia
• Diarrhoea (with or without blood/mucus) or alternating bowel habits
• Fever - classically low-grade, evening rise
• Nausea; change in bowel habits
• Night sweats, malaise

Signs

• Palpable right iliac fossa mass in hyperplastic type (may mimic carcinoma or Crohn's)
• Tenderness in the right iliac fossa
• Ascites and abdominal distension (in peritonitis)
• Features of intestinal obstruction (distension, high-pitched bowel sounds)

Differential Diagnoses

• Crohn's disease (most important - very similar clinically and radiologically)
• Carcinoma of the caecum/colon
• Appendicitis / appendix mass
• Amoebic colitis
• Yersinia ileitis
• Lymphoma

2. Tuberculosis of Mesenteric Lymph Nodes

• Mainly seen in children
• Bacilli enter lymph nodes through Peyer's patches of the terminal ileum
• Bovine and human types both implicated

1. Chronic abdominal pain - central dull discomfort; enlarged nodes palpable right of umbilicus as firm, discrete, round nodules
2. General symptoms only - weight loss, anorexia, pallor, low-grade fever
3. Intestinal obstruction - adherence of small bowel to a caseating node
4. Mimics appendicitis - pain and tenderness in the RIF; distinguished by persistent nature, negative Rovsing's sign, no high pulse/leucocytosis
5. Pseudomesenteric cyst - caseation with cold abscess forming between mesenteric leaves

3. Tuberculous Peritonitis

Types

Clinical Features

• Insidious onset: abdominal pain, distension, weight loss, fever, night sweats
• Ascites
• Coexistence with cirrhosis can obscure diagnosis
• Distinction from diffuse peritoneal metastases is often difficult and requires biopsy

CT Findings in TB Peritonitis

Fig. Axial CT abdomen showing mesenteric lymphadenopathy and ascites in tuberculous peritonitis. - Bailey & Love's Short Practice of Surgery, 28th Ed.

Investigations

Laboratory

• Raised inflammatory markers (ESR, CRP)
• Anaemia (normochromic normocytic)
• Positive sputum AFB smear/culture (if concurrent pulmonary TB)
• Interferon-gamma release assays (IGRA) - useful for subclinical infection detection
• Mantoux/tuberculin skin test - may be positive

Ascitic Fluid Analysis (TB Peritonitis)

• Straw-coloured exudate (protein >25-30 g/L)
• White cells >500/mL with lymphocyte predominance (>40%)
• Adenosine deaminase (ADA) - high sensitivity (93%) and specificity (96%) for TB peritonitis
• AFB smear: low sensitivity (rarely positive)
• Culture: positive in only ~50% but increases with large volume submission (takes 4-8 weeks)

Imaging

• Chest X-ray: pulmonary infiltrates or miliary pattern in ~50%
• Abdominal USS: loculated ascites, lymphadenopathy, bowel wall thickening
• CT abdomen: bowel wall thickening, lymphadenopathy with central necrosis (hallmark distinguishing from IBD), peritoneal thickening, omental caking, ascites
• Barium meal and follow-through: multiple small bowel strictures; subhepatic caecum (caecum pulled up due to fibrosis); non-filling or inadequate filling of terminal ileum and caecum ("Stierlin's sign" area)

Fig. (a, b) Barium meal and follow-through showing strictures in ileum with subhepatic caecum. - Bailey & Love's Short Practice of Surgery, 28th Ed.

Endoscopy

• Colonoscopy is particularly valuable: visualizes lesions and allows biopsy
• Findings pointing to TB: terminal ileitis with ulceration, pseudodiverticulosis, stricture mucosa
• Histopathology provides diagnosis in 40-55% of specimens; culture yield 20-50%
• Xpert MTB/RIF assay on tissue samples: sensitivity up to 80%; preferred initial diagnostic option

Laparoscopy

• Gold standard when other investigations fail
• Allows direct visualization of characteristic appearances (peritoneal tubercles) and peritoneal biopsy
• Couples typical visual appearance with histopathological confirmation

Treatment

Medical (First-Line Anti-TB Chemotherapy)

• Intensive phase (2 months): Isoniazid (H) + Rifampicin (R) + Pyrazinamide (Z) + Ethambutol (E) - 2HRZE
• Continuation phase (4 months): Isoniazid + Rifampicin - 4HR
• Total duration: 6 months for uncomplicated cases; some centres extend to 9 months for abdominal TB
• Note: Multidrug resistance (MDR-TB) may be higher for abdominal than pulmonary TB; DST should guide therapy
• Supportive care: nutritional rehabilitation and hydration are essential components

Surgical Management

• Patient often severely ill: dehydrate, malnourished, anaemic, possibly with active pulmonary TB
• Vigorous resuscitation first
• Minimum life-saving procedure: resection of diseased segment + proximal ileostomy + distal mucus fistula (avoids high-risk anastomosis in presence of active infection)
• One-stage resection and anastomosis only if general condition permits

Surgical principles mirror those in Crohn's disease - keep resections as conservative as possible. Post-operatively, complete the full course of anti-TB chemotherapy (6-12 months).

Key Distinguishing Features: TB vs Crohn's Disease

Complications

• Intestinal obstruction (most common)
• Intestinal perforation (less common due to serosal thickening, but occurs)
• Fistula formation (entero-enteric, entero-cutaneous)
• Malabsorption
• Haemorrhage
• Mesenteric cyst formation
• Constrictive peritonitis

Recent Evidence

• Bailey and Love's Short Practice of Surgery, 28th Ed., pp. 1110-1112 & pp. 109-111
• Harrison's Principles of Internal Medicine, 22nd Ed., pp. 1431-1432
• Murray & Nadel's Textbook of Respiratory Medicine, pp. 1422-1432
• S Das: A Manual on Clinical Surgery, 13th Ed., pp. 517-518

Abdominal Tuberculosis in Pediatrics

Epidemiology and Risk Factors

• Predominant age group: adolescents are most commonly affected; however, cases have been reported from neonates (congenital TB) to young adults
• Female preponderance noted in large case series
• Highest burden in TB-endemic regions (South Asia, sub-Saharan Africa)
• Key risk factors in children:
  • Close household contact with an adult with active pulmonary TB (most important source of exposure)
  • HIV co-infection (dramatically increases susceptibility)
  • Malnutrition and poverty
  • Unpasteurized milk consumption (bovine-type TB, M. bovis)
  • Absence of BCG vaccination

Pathogenesis - How it Differs in Children

Classification (Same as Adults - with Different Frequency)

1. Mesenteric lymph node TB - most common form in children
2. Intestinal TB (ulcerative or hyperplastic)
3. Tuberculous peritonitis
4. Solid organ TB (hepatic, splenic, pancreatic) - rare but reported

Clinical Presentation

Symptoms (Most Common to Less Common)

• Fever (low-grade, evening rise) - most frequent complaint
• Abdominal pain - can be acute, subacute, or chronic; central or right iliac fossa
• Abdominal distension - often from ascites or matted loops
• Weight loss / failure to thrive - chronic cases
• Anorexia
• Constipation or diarrhea (alternating or one predominant)
• Vomiting
• Ascites

From the AIIMS prospective study (2025, PMID 40978883), abdominal TB was found to be "a common cause of acute abdomen in the pediatric population" - it should be actively considered whenever a child in an endemic region presents with abdominal pain, fever, and weight loss.

Unusual/Atypical Presentations Reported in Children

• Splenic microabscess (especially in HIV-positive cases)
• Liver abscess (HIV co-infection)
• Deep vein thrombosis (hypercoagulable state from TB inflammation)
• Mesenteric artery stenosis
• Intracranial sinus thrombosis
• Neonatal/congenital abdominal TB (rare - from haematogenous spread in utero)

Why Children are Frequently Misdiagnosed

• No single clinical feature reliably predicts ATB - clinical features alone are insufficient for diagnosis
• Ascites and abdominal distension were more common in misdiagnosed children (confused with nephrotic syndrome, cirrhosis, malignancy)
• The symptoms overlap significantly with:
  • Appendicitis / appendix mass
  • Malignancy (lymphoma, neuroblastoma)
  • Inflammatory bowel disease
  • Nephrotic syndrome
  • Acute mesenteric adenitis
  • Amoebic liver abscess
  • Typhoid abdomen

The study concluded: "Clinical characteristics alone are not reliable indicators for diagnosing ATB... early suspicion and timely diagnostic evaluation in TB-endemic regions is crucial."

Investigations

Microbiological

• Mycobacterial culture: 50-75% positivity in pediatric series (higher than in adults due to tissue sampling)
• CB-NAAT / Xpert MTB/RIF: increasing use in children; preferred initial test; sensitivity ~80%
• AFB smear: low sensitivity
• Gastric aspirate: used when sputum cannot be obtained (particularly in infants and young children) for concurrent pulmonary TB detection

Immunological

• Mantoux test (TST): supportive but not diagnostic; may be negative in severely malnourished/immunocompromised children
• Interferon-gamma release assays (IGRA): better specificity than TST; useful for subclinical TB infection; preferred in BCG-vaccinated children
• Adenosine Deaminase (ADA) in ascitic fluid or tissue: An authoritative meta-analysis (Zhou et al., 2022, PMID 36211645) demonstrated pooled sensitivity 93% and specificity 95% for abdominal TB diagnosis - ADA is an excellent diagnostic biomarker

Blood Tests

• Raised inflammatory markers: elevated ESR, CRP
• Anaemia (normochromic normocytic) - very common in children
• Leucocytosis (mild, non-specific)
• Low albumin in chronic cases
• Lymphopenia in severe disease

Imaging

Chest X-Ray

• Look for pulmonary infiltrates, miliary pattern, pleural effusion, mediastinal lymphadenopathy
• Abnormal in up to 50% - even when child has no pulmonary symptoms

Abdominal Ultrasound (first-line in children)

• Mesenteric lymphadenopathy
• Free or loculated ascites
• Bowel wall thickening
• Omental thickening
• Hepatosplenic involvement (granulomas appear as small hypoechoic foci)

CT Abdomen (gold standard imaging)

• Lymphadenopathy with central necrosis - highly specific for TB vs. other causes
• Bowel wall thickening (especially terminal ileum and caecum)
• Peritoneal thickening and enhancement
• Omental caking - seen in peritoneal TB
• Ascites (free or loculated)
• Calcified lymph nodes in healed/old mesenteric TB (also visible on plain X-ray)

Barium Studies

• Multiple small bowel strictures
• Subhepatic caecum (caecum pulled superiorly by fibrosis)
• Incomplete filling or hypermotility of terminal ileum ("Stierlin's sign")
• Less commonly used now; CT/MRI preferred

MRI

• Preferred in children to avoid radiation
• Excellent for soft tissue delineation and peritoneal disease

Endoscopy/Laparoscopy

• Colonoscopy with biopsy - visualises ileocaecal lesions; histopathology diagnostic in 40-55%
• Laparoscopy: gold standard for peritoneal TB; allows direct visualization + biopsy; typical appearance of small white peritoneal tubercles
• All attempts for tissue diagnosis (imaging-guided biopsy, endoscopic, laparoscopic, surgical) should be made

Definite vs. Probable Abdominal TB (Diagnostic Categories)

Treatment

Medical Management (First-Line)

CNS/miliary TB (if coexistent): uses 6-9 month single-phase treatment with higher-dose Isoniazid (15-20 mg/kg) and ethionamide instead of ethambutol, per 2024 South African pediatric guidelines.

• Fixed-dose combination (FDC) tablets are preferred for ease of administration and adherence
• Pyridoxine (vitamin B6) supplementation is recommended with isoniazid in children to prevent peripheral neuropathy
• Regular LFT monitoring (hepatotoxicity risk with H, R, Z)
• Nutritional rehabilitation is a critical component of management - malnutrition worsens prognosis and impairs drug metabolism
• Duration may be extended to 9 months for extensive or complicated abdominal TB

HIV Co-Infected Children

• Start anti-TB therapy first; initiate ART within 2-8 weeks
• Drug interactions between rifampicin and antiretrovirals require careful management (rifampicin reduces lopinavir/ritonavir levels significantly)
• Higher doses of some drugs may be needed
• MDR-TB must be actively excluded

Surgical Management

• Medical management is always tried first; obstruction may resolve with anti-TB therapy alone
• Emergency cases: severely ill children (dehydrated, anaemic, malnourished) need vigorous resuscitation before operating
• Preferred emergency approach: limited resection + proximal ileostomy + distal mucus fistula (avoids high-risk anastomosis in the presence of active infection and poor general condition)
• Anastomosis may be performed at a second-stage operation once the child has recovered
• Post-operatively, complete the full anti-TB course (6-12 months) under combined pediatric medicine and surgical care

Complications

• Intestinal obstruction (most common)
• Intestinal perforation
• Fistula formation
• Malabsorption and growth failure
• Mesenteric cyst formation
• Constrictive peritonitis
• Adhesive obstruction post-surgery
• DVT / vascular complications (rare)
• Disseminated/miliary TB
• Drug-induced liver injury (from ATT)

Prognosis

• Good prognosis with early diagnosis and prompt initiation of ATT
• Delayed diagnosis significantly worsens outcomes - complications (perforation, obstruction) increase mortality
• Children in endemic regions with non-specific symptoms require a high index of suspicion
• The AIIMS 2025 study emphasizes: "early detection through recognition of common clinical features, guided imaging, and timely sampling for confirmation is vital for initiating ATT and improving outcomes"

Summary: Key Pediatric-Specific Points

1. Mesenteric lymph node TB is the most characteristic form in children (rare in adults)
2. Haematogenous spread and primary TB are more prominent pathways in children
3. Fever + abdominal pain + weight loss in a child from an endemic area = suspect TB until proven otherwise
4. No single clinical feature reliably distinguishes ATB from other abdominal conditions - early suspicion and multi-modal workup are essential
5. ADA (pooled sensitivity 93%, specificity 95%) is an excellent biomarker
6. Intestinal perforation is the primary indication for surgery in children (cf. obstruction in adults)
7. Nutritional rehabilitation is as important as ATT
8. 6-month HRZE/HR regimen is standard; weight-based dosing is mandatory in children
9. Unusual presentations (splenic abscess, DVT, neonatal TB) must be recognized
10. BCG vaccination provides significant protection against disseminated and extrapulmonary TB in children

• Raj V, Sharma S. Abdominal tuberculosis in children: a systematic review on current advances. Pediatr Surg Int, 2025. [PMID 40533676]
• Siddiqui MJ et al. Clinical characteristics leading to misdiagnosis of abdominal TB in children. Front Pediatr, 2025. [PMID 40963962]
• Zhou R et al. Diagnostic performance of ADA for abdominal TB: meta-analysis. Front Public Health, 2022. [PMID 36211645]
• S Das: A Manual on Clinical Surgery, 13th Ed., p. 517
• Bailey and Love's Short Practice of Surgery, 28th Ed., pp. 109-111
• WHO/South African National Guideline: Management of TB in Children and Adolescents, 2024-2025