Abdominal tuberculosis

Abdominal tuberculosis
Other names: Tuberculosis of abdomen[1]
Top:Tuberculosis of the ileum showing serosal tubercles Bottom:Peritoneal tuberculosis(granulomas on the abdominal aspect of the diaphragm)[2]
Specialty	Infectious disease,gastroenterology
Symptoms	Abdominal pain, diarrhea, fever, weight loss[3]
Complications	Intestinal obstruction, peritonitis[3]
Causes	Spread of TB bacteria[3]
Diagnostic method	Blood tests,stool tests, endoscopy[3]
Treatment	Isoniazid, rifampin, pyrazinamide(surgery is possible)[3][4]

Abdominal tuberculosis is a type of extrapulmonary tuberculosis which involves the abdominal organs such as intestines, peritoneum and abdominal lymph nodes. It can either occur in isolation or along with a primary focus (such as the lungs) in patients with disseminated tuberculosis.^[5] PCR and CT scan(of abdomen) may be used for diagnosis^[3]

Treatment is with anti-tuberculosis drugs and/or surgery.^[3]Higher incidence exists in TB-endemic regions such as South Asia, sub-Saharan Africa, and parts of Latin America.Lack of mandatory organ-specific reporting in EPTB misrepresents true burden estimates^[6][7]

Types

• Tubercular lymphadenopathy: Abdominal lymphadenopathy is the most common manifestation of abdominal tuberculosis. The commonly involved lymph nodes are mesenteric nodes and omental nodes. They usually have central areas of caseous necrosis.^[4][3]
• Peritoneal tuberculosis: Peritoneal tuberculosis most often presents as abdominal pain and ascites. It can occur most commonly following re-activation of a latent focus of tuberculosis.^[3][8]
• Intestinal tuberculosis: Tuberculosis of the intestine can affect multiple areas of the bowel simultaneously. The bacilli penetrate the mucosa, cause caseous necrosis and scarring.^[4][3]
• Visceral tuberculosis: This type involves the solid organs in the abdomen, either in isolation or as part of a more widespread infection. Common organs affected include the liver, spleen, and pancreas, as well as the genitourinary system (kidneys, bladder)^[3][9][4]

Symptoms and signs

The symptoms of abdominal tuberculosis depends on the sites of involvement, the most common symptoms and signs of abdominal tuberculosis are abdominal pain, ascites. Other clinical features are fever, altered bowel habits, and loss of weight.Night sweats, nausea, loss of appetite, constipation, diarrhoea are some of the rare symptoms of abdominal tuberculosis.^[10][3]

Complication

As to complications in the affected individual we find the following may occur:^[3]

• Anemia

• Obstruction of gastrointestinal lumen

• Intussusception

• Lower gastrointestinal bleeding

• Perforation

• Malnutrition

Risk factors

The risk factors for abdominal tuberculosis are immunocompromised states such as HIV infection, diabetes mellitus and underlying malignancy. Liver cirrhosis and use of peritoneal dialysis are also risk factors for abdominal tuberculosis.^[11][3][12]

Pathophysiology

There are several ways by which tuberculosis can infect the abdomen. The tubercle bacteria many enter the abdomen via the consumption of infected milk. Those with existing pulmonary tuberculosis can have abdominal tuberculosis through the ingestion of infected sputum.^[4] When the gastrointestinal tract is infected with the bacteria, epitheloid tubercles are formed in the lymphoid tissue of the submucosal layer. Subsequently, caseous necrosis of the tubercles can occur, leading to ulceration of the mucosa. At this stage, the bacili can spread to adjacent lymph nodes and deeper layers of the peritoneum.^[4] Tuberculosis can also spread through the blood from the primary focus to elsewhere in the abdomen. Abdominal solid organs, kidneys, lymph nodes and peritoneum can be affected this way.^[4] Tuberculosis is also reported to spread to the peritoneum directly from adjacently situated infected foci, such as from the fallopian tubes, adnexa, psoas abscess or secondary tuberculous spondylitis.^[4] It can also spread from infected lymph nodes via lymphatic channels.^[4]

Diagnosis

The clinical presentation of abdominal tuberculosis is often atypical, tissue samples for confirmation of diagnosis can be difficult to procure and conventional diagnostic methods have poor yield.^[5] Therefore, the diagnosis is often delayed.^[5] The diagnosis is often suspected clinically with relevant manifestations or epidemiological factors such as known prior tuberculosis and possible TB exposure.^[13] A high index of suspicion of TB should be maintained in immunocompromised individuals.^[13] Those with extra-abdominal tuberculosis should undergo evaluation for abdominal involvement in case of clinical suspicion. The definitive diagnosis can be established by demonstrating Mycobacterium tuberculosis in peritoneal fluid or in a biopsy specimen. The histopathologic findings of tuberculosis in biopsy, such as caseous granuloma, can be suggestive of tuberculosis, but is not pathognomic.^[13] CT scan offers evaluation of involvement of the liver or other organs, as well as for the presence of ascites, lymphadenopathy and peritoneal involvement.^[13] Ultrasound scan is useful for demonstrating lymphadenopathy and ascites.^[14]

• 
  a,b)CT of abdominal tuberculosis^[15]
• 
  Histopathology of tuberculosis of the duodenum. Numerous rod shaped tuberculosis bacilli can be seen.

Differential diagnosis

As to the DDx of abdominal tuberculosis we find the following:^[3]

• Esophageal cancer

• Gastric ulcers

• Colorectal cancer

• Hepatic granulomatosis

• Spontaneous bacterial peritonitis

• Colitis

Management

Abdominal tuberculosis most often responds to treatment with anti-tuberculosis drugs.^[4]

Treatment using anti-tuberculous drugs can cause resolution in fever, ascites and bleeding in a few weeks after the start of the therapy.^[13]

Surgical management

Surgery may be warranted in abdominal tuberculosis in case of complications such as perforation, abscess, bleeding, fistula or obstruction.^[13]

There are three types of surgeries usually performed in abdominal tuberculosis. The first type of surgery is to bypass the affected segments of the bowel. The second type is a more extensive surgery called hemicolectomy, where a large portion of the bowel is removed.^[4]

The third type is stricturoplasty which is done for relieving the luminal obstruction caused due to intestinal tuberculosis.When bowel perforations occur in tuberculosis, it is usually treated by the resection of the involved segments.^[4][16]

Prognosis

With treatment, the prognosis is good.Untreated abdominal TB has a mortality rate of 6 to 20 percent and can lead to complications that may require surgical intervention^[3]

Epidemiology

Abdominal tuberculosis accounts for up to 5 percent of the tuberculosis cases worldwide.^[5][18] It makes up for less than 11–15 percent of all tuberculosis cases in immunocompetent individuals.^[5]

Approximately 20 percent of individuals with abdominal tuberculosis have active tuberculosis. The incidence of abdominal tuberculosis has increased in the last few decades due to the increased incidence of HIV infection, which makes individuals vulnerable to tuberculosis.^[19][20][21]

History

Ancient history indicates that symptoms resembling abdominal TB were described in Egyptian, and Chinese texts as early as 2000–3500 years ago.^[22]

As to recent history Logan and Paustian's postulates in the mid-20th century, helped distinguish abdominal TB from Crohn's disease, which it often mimics^[22]

Research

In terms of research we find molecular methods, particularly those targeting Mycobacterium tuberculosis DNA, remain the most significant area of progress due to their high specificity and turnaround time.A 2022 review indicates the potential of multiplex Polymerase Chain Reaction, which amplifies multiple DNA targets in a single reaction. This technique has shown a superior sensitivity compared to simple PCR or GeneXpert assays for detecting the low bacterial load often found in abdominal TB tissue samples^[23]

References