Understanding Abdominal Tuberculosis

Abdominal Tuberculosis

Abdominal Tuberculosis Introduction

Abdominal tuberculosis is a common extrapulmonary manifestation of tuberculosis. Disease is caused by Mycobacterium tuberculosis. Approximately 15–25% of cases with abdominal TB have concomitant pulmonary tuberculosis (TB) is a life-threatening disease which can virtually affect any organ system. Incidence in the West has also increased due to immigrant population and increased incidence of HIV infections. In India, extrapulmonary TB is also showing re-emergence due to incomplete treatment and occurrence of multidrugresistant strains.

Abdominal Tuberculosis Definition

The term abdominal tuberculosis includes tuberculous infection of gastrointestinal tract, mesenteric lymph nodes, peritoneum, omentum and solid organs related to gastrointestinal tract such as liver and spleen.

Abdominal Tuberculosis Classification

1. The commonly encountered four forms of tuberculosis are given below:
2. Tuberculous peritonitis
3. Tuberculous mesenteric lymphadenitis—glandular tuberculosis
4. Intestinal tuberculosis
5. Tuberculosis of solid viscera such as liver and spleen.

Routes of Spread of Infection and Pathogenesis

1. Intestinal tuberculosis is caused by Mycobacterium tuberculosis from swallowed sputum (pulmonary tuberculosis) or milk (milk-borne infection— Mycobacterium bovis). From intestinal tuberculosis, mesenteric nodes get involved and later, the peritoneum can get involved.
2. Blood spread: Infection from pulmonary tuberculosis can spread through blood during bacteraemic phase.
3. Lymphatic spread from tuberculosis of intestines.
4. Genitourinary tuberculosis: From here, cephalad spread occurs and thus, peritoneum gets affected.
5. From bile: Granuloma in liver. Bacilli are excreted in bile.

Pathology and Pathogenesis Investigations

It is important to realise that there are so many investigations for abdominal tuberculosis. Although it is essential to have a theoretical knowledge about all these investigations, all of them need not be done during clinical management.

To give an example: If chest X-ray and sputum AFB are positive, one should start ATT (need not do costly investigations such as CT scan or even diagnostic laparoscopy, etc.). Investigations done by the clinician should be complementary to each other.

1. Complete blood picture (CBP) which includes Hb%, TC, DC and ESR. Haemoglobin may be low indicating anaemiAnaemia has to be corrected before surgery.
2. ESR will help in equivocal cases. High values and the clinical situation may force the clinician to start antituberculous treatment in selected patients. However, with treatment, if ESR comes down and patient is symptomatically better with weight gain, settling fever, improving appetite, it suggests tubercular pathology.
3. Sputum AFB (acid-fast bacilli): Demonstrated by Zeihl-Neelsen methoMany patients, with abdominal tuberculosis will not have pulmonary tuberculosis. However, if sputum is present, it must be tested for AFB.
4. Chest X-ray may suggest tuberculosis in the form of cavity, calcification, etIn such patients, bronchoscopy washings or biopsy may clinch the diagnosis.
5. Mantoux test is nonspecific but a strong ulcerated Mantoux test result suggests tuberculosis.
6. Ultrasound, being a noninvasive investigation, is an imaging of choice.

• Ascites can be demonstrated and the aspirated fluid is sent for analysis.
• Focal ascites between loops of bowel—Club sandwich sign may be seen.
• Enlargement of mesenteric lymph nodes (common) and retroperitoneal nodes (uncommon) can be detected.
• Dilated loops and sometimes peritoneal tubercles are seen as echo-poor shadows.
• Thickening of omentum, mesentery, peritoneum can be found out. (However, ultrasound is not the best investigation to detect these findings.)
• Pseudokidney sign: Pulled caecum identified in the right hypochondrium.
• Hepatosplenomegaly may be present.

7. Ascitic fluid analysis: Ultrasound-guided fluid is aspirated and about 20–40 ml is sent for analysis.

8. CECT: Contrast enhanced CT scan of the abdomen: CT scan is objective. All the findings which can be detected by ultrasound can be confirmed by CT scan. Addition of the contrast is definitely more superior in detecting strictures, dilatations, perforations, and more importantly loculated ascites and intra-abdominal collections. CT-guided biopsy can be done. If distension or matting of loops and adhesions are present, it is not safe.

9. Barium studies: These are not done routinely. If diagnosis is possible by the various investigations mentioned above, there is no necessity to do them. In fact, it can harm the patient by precipitating obstruction and barium peritonitis, if there is a perforation. Few finding in barium studies can be:

• Small bowel enema—enteroclysis: Dilatation and narrowed segments in partial obstruction, narrowing of terminal ileum (Fleischner’s sign), fibrotic terminal ileum opening into the contracted caecum (Stierlin’s sign).
• Barium enema: Pulled up caecum, normal acute ileocaecal angle becomes obtuse or sometimes straightening of the ileocaecal angle.

10. Endoscopy: Upper gastroduodenoscopy may detect tubercles in the stomach or duodenum—rare.

1. Push enteroscopy also called small bowel enteroscopy: Ulcers in the proximal jejunum can be detected and biopsy can be taken—chances of perforation are high.
2. Colonoscopy can detect nodular lesions, ulcerations in the colon—caecum and terminal ileum (last 10 cm of ileum should be entered and biopsy should be taken).

11. Laparoscopy: This is a diagnostic investigation as it gives the tissue diagnosis. One can also evaluate all possible viscera, peritoneum, omentum and pelvic organs. Biopsy is possible under direct vision. Findings can be: Straw-coloured peritoneal fluid, abscesses secondary to perforation, rolled up omentum, tubercles on the peritoneal surface, matting of the loops of bowel, adhesions, bands, strictures and dilatations. Other findings which can be appreciated are: Shortened mesentery, caseation of lymph nodes (pseudomesenteric cyst), pulled up caecum and hepatosplenomegaly. Laparoscopy can also be therapeutic, if a stricture is identified, the diseased loop is isolated, brought out and resection and anastomosis/stricturoplasty done.

• Adhesiolysis can also be done.

12. Polymerase chain reaction (PCR)

• It is a technique used in medical and biological research labs.
• One can do functional analysis of genes; useful in the diagnosis of hereditary diseases.
• Helps in detection and diagnosis of infectious diseases, such as tuberculosis.
• Laparoscopically biopsied tissue can be sent for PCR. It can detect 1–2 organisms or 8 fg of mycobacterial DNA.
• Positive PCR indicates infection but it need not be active infection. Hence, it is inferior to tissue diagnosis.
• PCR has 97% sensitivity and 99% specificity.

Antituberculous Treatment

• Details are given in medicine textbooks. However, 4-drug regimen for 2 months followed by 3-drug regimen for 4 months is recommended as a first line of treatment.
• First line of drugs include INH, rifampicin, ethambutol and pyrazinamide given for 2 months. This is followed by rifampicin, ethambutol and INH for 4 months. Refractory cases are treated by kanamycin, ofloxacin, ciprofloxacin, amikacin, etsee clinical notes.