ABDOMINAL TUBERCULOSIS

Introduction

• TB can involve any part of GIT from mouth to anus, peritoneum & pancreatobiliary system.

• Very varied presentation possible

TB of GIT- 6th most frequent extrapulmonary site.

Pathogenesis

• Mechanisms by which M. tuberculosis reach the GIT:– Hematogenous spread from primary lung focus

– Ingestion of bacilli in sputum from active pulmonary focus.

– Direct spread from adjacent organs.

– Via lymph channels from infected LN

• Most common site - ileocaecal region– Increased physiological stasis– Increased rate of fluid and electrolyte absorption– Minimal digestive activity – Abundance of lymphoid tissue at this site.

Distribution of tuberculous lesions

Ileum > caecum > ascending colon > jejunum

>appendix > sigmoid > rectum > duodenum

> stomach > oesophagus

• More than one site may be involved

• Peritoneal involvement occurs from : – Spread from LN

– Intestinal lesions or

– Tubercular salpingitis

• Abdominal LN and peritoneal TB may occur without GIT involvement in ~ 1/3 cases.

Peritoneal tuberculosis occurs in 3 forms.

• Wet type - ascitis.

• Encysted (loculated) type - localized swelling.

• Fibrotic type - masses composed of mesenteric &

omental thickening, with matted bowel loops.

Pathology:

Three types of intestinal lesion are seen;•Ulcerative, • Stricturous, •Hypertrophic,

though the three may co-exist.

(1) The ulcerative form of TB is seen in approximately 60% of patients. Multiple superficial ulcers largely confined to the epithelial surface. This is considered a highly active form of the disease with the long axis of the ulcers perpendicular to the long axis of the bowel.

(2) The stricturous form shows multiple or single stricture, often very tight.(3) The hypertrophic form is seen in approximately 10% of patients and consists of thickening of bowel wall with scarring, fibrosis, and a rigid, mass-like appearance that mimics carcinoma.

The ulcerohypertrophic form is a subtype seen in 30% of patients. These patients have a combination of features of the ulcerative and hypertrophic forms.

The serosal surface may show nodular masses of tubercles. In some cases, aphthous ulcers may be seen in the colon.

Caseation may not always be seen in the granuloma, especially in the mucosa, but they are almost always seen in the regional lymph nodes.

HIV & TB

• Before era of HIV infection > 80% TB confined to lung

• Extrapulmonary TB increases with HIV • 40 –60% TB in HIV+ pt - extrapulmonary• Globally, propotion of coinfected pt > 8 % • ~ 0.4 million people in India coinfected. • 16.6% abdominal TB pt in Bombay HIV +.

Incidence severity of

abdominal TB will increase with

the HIV epidemic

Clinical Features

• Mainly disease of young adults

• ~ 2/3 of pt. are 21-40 yr old

• Sex incidence equal.

• Clinical presentation Acute / Chronic / Acute on Chronic.

• Constitutional symptoms – Fever (40%-70%)– Weight loss (40%-90%)– Anorexia– Malaise

• Pain (80%-95%) – Colicky (luminal stenosis)– Continous ( LN involvement)

• Diarrhoea (11%-20%)• Constipation• Alternating constipation and diarrhoea

Tuberculosis of esophagus

• Rare ~ 0.2% of total cases

• By extension from adjacent LN

• Low grade fever / Dysphagia / Odynophagia / Midesophageal ulcer

• Mimics esophageal Ca

Gastroduodenal TB

• Stomach and duodenum each ~ 1% of total cases

• Mimics PUD - shorter history, non response to t/t

• Mimics gastric Ca.

• Duodenal obstruction - extrinsic compression by tuberculous LN

• Hematemesis / Perforation / Fistulae / Obstructive jaundice

• Cx-Ray usually normal

• Endoscopic picture - non specific

Ileocaecal tuberculosis

• Colicky abdominal pain

• ‘Ball of wind’ rolling in abdomen

• Borborygmi

• Right iliac fossa lump - ileocaecal region, mesenteric fat and LN

Obstruction• Most common complication

Pathogenesis– Hyperplastic caecal TB

– Strictures of the small intestine--- commonly multiple

– Adhesions

– Adjacent LN involvement traction, narrowing and fixation of bowel loops.

Perforation

• 2nd commonest cause after typhoid

• Usually single and proximal to a stricture

• Clue - TB Chest x-ray, h/o SAIO

• Pneumoperitoneum in ~ 50% cases

Malabsorption

• Pathogenesis– bacterial overgrowth in stagnant loop

– bile salt deconjugation

– diminished absorptive surface due to ulceration

– involvement of lymphatics and LN

Segmental / Isolated colonic tuberculosis

• Involvement of the colon without involvement of the ileocaecal region

• 9.2% of all cases

• Multifocal involvement in ~ 1/3 (28% to 44%)

• Median symptom duration <1 year

Colonic tuberculosis

• Pain --- predominant symptom ( 78%-90% )

• Hematochezia in < 1/3 - usually minor

Overall, TB accounts for ~ 4% of LGI bleeding

• Other features--- fever / anorexia / weight loss / change in bowel habits

Rectal and Anal Tuberculosis

• Hematochezia - most common symp. Due to mucosal trauma by stool

• Constitutional symptoms

• Constipation

• Rectal stricture

• Anal fistula – usually multiple

Diagnosis and Investigations

• Non specific findings---

– Raised ESR

– Positive Mantoux test

– Anemia

– Hypoalbuminaemia

Immunological Tests

• ELISA

Response to mycobacteria variable & reproducibility poor

Value of immunological tests remain undefined

Ascitic fluid examination

• Straw coloured

• Protein >3g/dL

• TLC of 150-4000/µl, Lymphocytes >70%

• SAAG < 1.1 g/dL

• ZN stain + in < 3% cases

• + culture in < 20% cases

Adenosine Deaminase (ADA)

Aminohydrolase that converts adenosine à inosine

• ADA increased due to stimulation of T-cells by mycobacterial Ag

– Serum ADA > 54 U/L

– Ascitic fluid ADA > 36 U/L

– Ascitic fluid to serum ADA ratio > 0.985

• Coinfection with HIV normal or low ADA

Endoscopy may show,•Ulcers, •Nodules, •Deformed cecum and ileocecal valve, •Strictures, •Multiple fibrous bands, and•Polypoid lesions

Barium examination:

A small-bowel barium study may show dilated loops, thickened folds or even a stricture.

USG:

•Intra-abdominal fluid, free or loculated; clear or complex with septae or debris •Inter loop ascites.•Lymphadenopathy, discrete or conglomerated, •Bowel wall thickening, and •Pseudo kidney sign.

CT : •The CT features suggestive of abdominal TB include, •Irregular soft-tissue densities in the omentum,•Low-attenuating masses surrounded by thick solid rims, •Low-attenuating necrotic nodes, •High-attenuating ascitic fluid and bowel loops forming poorly defined masses. •Splenomegaly and hepatomegaly with nodules, •Pleural effusion, •Intrahepatic, intrasplenic, and intrapancreatic masses.

In clinical practice, typical GI symptoms mentioned above with USG evidence of either terminal ileal involvement or ascites are reasonable evidence in a proper set up.

Further confirmation is by diagnostic ascitic tapping and endoscopic biopsy.

Differential Diagnosis:

•Crohn’s disease,•Gastrointestinal malignancy, •Sarcoma, •Amebiasis, •Yersinia infection, and •Periappendiceal abscess

Management

• ATT for at least 6 months including 2 months of Rif, INH, Pzide and Etham

• However in practice t/t often given for 12 to 18 months

• 2 recent reports obstructing lesions may relieve with ATT alone

However most will need surgery

Surgery in TB:

Surgery is required if there is a tight fibrotic stricture which is symptomatic. Resection anastomosis or stricturoplasty are the standard approaches. Results are excellent.

Clinical Pearls

• Abdominal tuberculosis (TB) is very common in the developing world but it is rarely seen in western countries.

• Its reappearance has increased in association with the acquired immunodeficiency syndrome (AIDS).

• The occurrence of abdominal TB is dependent of pulmonary disease in most patients.

• In patients with abdominal TB, the highest incidence of disease was noted in the gastrointestinal tract and in the peritoneum, followed by the mesenteric lymph nodes.

• Within the gastrointestinal tract, the ileocecal area is the most common site of involvement.

• A third of patients will report a family history of tuberculosis. • TB can occur in persons of any age, although it is uncommon in

children and in older persons whose immune systems are weak.

• The mode of spread is either through hematogenous spread from active pulmonary or miliary tuberculosis, swallowing of infected sputum or ingestion of contaminated milk or food, and contiguous spread from adjacent organs.

• Most cases of abdominal tuberculosis involve the intestine with the commonest site being the ileocecal region due to abundance of lymphoid tissue (Payer’s patches).

• Ileocecal junction is involved in 80-90% of the patients. • Proximal small intestinal disease is seen more commonly with

Mycobacterium avium-intracellulare (MAI) complex infection, predominantly one involving the jejunum.

• Three types of intestinal lesion are seen; Ulcerative, Stricturous and hypertrophic.

• Patients may present with non-specific abdominal pain, with ascites, alteration in bowel habit, diarrhea, constipation or together, malabsorption, rectal bleeding etc.

• Colonic TB rarely is associated with ileal TB. • Subacute or acute intestinal obstruction due to stricture is

the commonest complication.• Hemorrhage and perforation are recognized

complications of intestinal TB, and free perforation is more frequent than in Crohn’s disease.

• TB never involve rectum and isolated rectal involvement suggests rectal malignancy.

• A small-bowel barium study is the main radiographic method for the evaluation of intestinal TB in regions of the world where the disease is endemic.

• However, because peritonitis is common in GI TB, abdominal CT may be performed as a preferred examination, which nearly always suggest the diagnosis in the presence of necrotic lymph nodes or changes suggestive of TB peritonitis.

• Early changes on barium examinations reveal nodular thickening of mucosal folds with loss of symmetry in fold pattern.

• Definitive diagnosis is by showing AFB microbiologically by culture or by both smear and PCR positivity.

• If the diagnosis of TB is not possible using both of these methods, a clinical diagnosis of TB is ruled out.