Abdominal Tuberculosis - Treatment Regimen

Standard Drug-Susceptible Regimen (First-Line)

"The preferred regimen for treating adults with TB caused by organisms not known or suspected to be drug resistant consists of an intensive phase of 2 months of INH, RIF, PZA, and ethambutol (EMB), followed by a continuation phase of 4 months of INH and RIF." - Murray & Nadel's Textbook of Respiratory Medicine

Drug Doses (Adult, Weight-Based)

When to Extend Duration

• 9 months total (2HRZE + 7HR): If there is cavitation on initial imaging AND positive culture at 2 months - both factors together suggest higher relapse risk.
• Consider extension in severely malnourished patients or those with delayed clinical response.
• Note: "Most forms of extrapulmonary TB in children can be treated with the same regimens as used in adults." - Murray & Nadel's

Adjunctive Corticosteroids

• Peritoneal TB: To reduce the risk of adhesions and stricture formation
• Ascites from TB: To hasten fluid reabsorption
• Intestinal TB (post-medical treatment): To decrease stricture formation and bowel obstruction risk

"Corticosteroids can be considered for children with... abdominal TB (to decrease the risk of strictures)." - Red Book 2021

Surgical Indications (Adjunct to Medical Therapy)

• Intestinal obstruction from strictures - strictureplasty or limited ileocolic resection
• Bowel perforation with peritonitis - resection + ileostomy (anastomosis avoided in active infection)
• Diagnostic laparoscopy when diagnosis is uncertain
• After medical treatment: re-image the small bowel; persistent/significant strictures need elective resection

Directly Observed Therapy (DOT)

Drug Resistance Considerations

• If drug-susceptible (INH + RIF sensitive confirmed): EMB can be dropped after susceptibility confirmed, and intensive phase uses only 3 drugs (HRZ).
• MDR-TB or XDR-TB requires specialist referral and completely different regimens.
• Never add a single drug to a failing regimen - always add 2-3 drugs to avoid amplification of resistance.

Monitoring During Treatment

Complications During ATT for Abdominal TB and Their Management

A. Drug-Related Complications

1. Hepatotoxicity (Most Common Serious Adverse Effect)

1. Stop ATT; rule out other causes (viral hepatitis, alcohol, biliary disease)
2. If patient is seriously ill/infectious: start a liver-sparing bridge regimen: Ethambutol + Levofloxacin + Aminoglycoside (streptomycin/amikacin)
3. Monitor ALT until it falls to <2x ULN, then restart sequentially:
   • RIF first (least hepatotoxic) ± EMB → wait 3-7 days
   • Then restart INH
   • If ALT remains stable: restart PZA (most hepatotoxic - omit if prior severe reaction)
4. If PZA cannot be restarted: extend total ATT duration to 9 months (2HRE + 7HR)

2. Peripheral Neuropathy (INH)

• Prevention (mandatory in high-risk): Pyridoxine 25-50 mg/day with each INH dose
• Some experts give pyridoxine to ALL patients on INH
• If neuropathy develops despite pyridoxine: increase dose to 100 mg/day
• If refractory: consider dose reduction or cessation of INH

• Hospitalize immediately
• IV pyridoxine (gram-for-gram if INH dose unknown) + antiepileptics (benzodiazepines)

3. Optic Neuritis (Ethambutol)

• Baseline visual acuity (Snellen) + color discrimination before starting EMB; repeat monthly
• Stop EMB immediately if any visual symptoms develop
• Refer to ophthalmologist promptly
• Recovery takes ~3 months on average but can be permanent if delayed
• Children too young to report visual changes: weigh risk-benefit carefully

4. Hyperuricemia and Gout (Pyrazinamide)

• Asymptomatic hyperuricemia: No treatment needed; monitor
• Symptomatic gout: Allopurinol (xanthine oxidase inhibitor) or other urate-lowering therapy
• Avoid aspirin (interferes with uric acid handling); use NSAIDs with caution
• PZA is contraindicated in acute gout
• Note: Ethambutol can also cause mild hyperuricemia

5. GI Symptoms (Nausea, Vomiting, Abdominal Pain)

• Take medications at bedtime to minimize symptoms
• Take with a light low-fat snack
• Antacids or proton pump inhibitors (PPIs)
• Antiemetics 30 min before ATT: ondansetron, metoclopramide, or promethazine

6. Skin Rash / Hypersensitivity

7. Rifampicin-Specific: Important Drug Interactions

• Oral contraceptives: Reduced efficacy - advise barrier contraception
• Antiretrovirals (HIV co-infection): Major interaction with protease inhibitors/NNRTIs - use rifabutin instead, or specialist-guided regimen
• Warfarin: Reduced anticoagulant effect - monitor INR closely, dose-adjust
• Corticosteroids: Reduced steroid effect - may need to increase steroid dose (relevant when using adjunctive steroids for peritoneal TB)
• Orange discoloration of urine, tears, saliva, skin - warn patients; harmless but distressing

B. Disease-Related Complications (During/After ATT)

8. Intestinal Obstruction from Strictures

• Pre-exist before ATT begins
• Paradoxically develop or worsen in the first 2-3 months after starting ATT (due to fibrosis during healing)

• After completing medical treatment, re-image the small bowel (barium follow-through or CT enterography)
• Persistent symptomatic strictures → surgical options:
  • Strictureplasty (single short stricture)
  • Limited ileocolic resection + anastomosis (ileocaecal hyperplastic disease)
  • Right hemicolectomy (extensive ileocolic disease)
  • "Surgical principles are similar to Crohn's disease - resections should be kept as conservative as possible." - Bailey & Love's Surgery, 28th Ed.

1. Vigorous IV resuscitation (correct dehydration, electrolytes, anemia)
2. Laparotomy: minimum life-saving procedure
   • Resection of obstructed segment + proximal ileostomy + distal mucus fistula (anastomosis avoided in acute infection - high leak risk)
   • Primary anastomosis only if the patient's general condition permits
3. Continue full 6-month ATT course post-operatively under combined physician-surgical care

9. Bowel Perforation

• Rare; from a perforated tuberculous ulcer in the small bowel
• Presents as acute peritonitis
• Requires emergency laparotomy, resection, and peritoneal lavage
• ATT continued post-operatively

10. Paradoxical Reactions (Immune Reconstitution)

• Worsening abdominal pain or ascites
• Enlarging mesenteric lymph nodes
• New or worsening bowel obstruction symptoms

• Rule out treatment failure and drug resistance first
• Continue ATT (do NOT stop)
• Corticosteroids (prednisolone 1-2 mg/kg/day) for severe paradoxical reactions, tapered over 4-8 weeks
• For IRIS: continue both ATT and ART; add steroids for severe cases

Summary Table