Acute inflammation of the small intestine (enteritis) often also affects the stomach (gastroenteritis) or the colon (enterocolitis). Involvement of regional lymph nodes is termed mesenteric adenitis. These usually self-limiting illnesses may be caused by viruses, bacteria, parasites, toxins, or unknown agents. These conditions are of importance to the surgeon when they mimic acute appendicitis or other problems that require operative treatment.
Gastrointestinal infections are frequent in AIDS patients. Enteric pathogens recoverable from these patients include Cryptosporidium and Campylobacter jejuni.
Many symptomatic patients have no identifiable intestinal pathogen, and there is evidence to support the existence of an enteropathy caused by the HIV itself. Intestinal perforation is a rare but devastating complication in these patients.
Much attention has focused on Yersinia enterocolitica; this pathogen may cause acute gastroenteritis, enterocolitis, colitis, mesenteric lymphadenitis, hepatic abscesses, and autoimmune processes – erythema nodosum and polyarthritis. Y enterocolitica has also been implicated in other disease (especially in women), including carditis, glomerulonephritis, Graves’ disease, and Hashimoto’s thyroiditis.
Acute gastroenteritis with fever, diarrhea, and sometimes vomiting is the clinical syndrome, especially in children. Acute mesenteric lymphadenitis and acute terminal ileitis are more frequent in adolescents. These infections may cause enough abdominal pain and tenderness that appendicitis seems a likely diagnosis. If operation is performed, large inflamed lymph nodes are found in the mesentery of the distal ileum, and the bowel itself may be grossly inflamed. In these circumstances, appendectomy is usually performed. Organisms can be cultured from stool, and antibody titers may rise and then fall in some patients. Y enterocolitica may respond to trimethoprim-sulfamethoxazole, and complicated Y enterocolitica infections should be treated. Fatal septicemia has been reported. No patient with Y enterocolitica enteritis has progressed to classic Crohn’s disease.
Campylobacter jejuni is now recognized as a cause of human illness. C jejuni infection is more common than infection by either salmonella or shigella. Raw milk, untreated drinking water, and undercooked poultry are recognized vehicles of transmission. Clinical features vary from mild abdominal pain, fever, emesis, and diarrhea indistinguishable from viral gastroenteritis to severe bloody diarrhea that resembles ulcerative or granulomatous colitis.
Darkfield microscopy of stool samples may reveal the characteristic of C jejuni and allow for a presumptive diagnosis. Stool and occasionally blood cultures are positive. Colonoscopy may reveal colonic lesions, and x-rays show inflammation of the small bowel.
Although C jejuni infection is in most patients and symptoms subside within a week, relapses occur in 20% of untreated patients. The appropriate antibiotic is erythromycin, ciprofloxacin, or doxycycline, depending on the results of sensitivity studies. Disease can be spread by symptomatic patients; once diarrhea subsides, transmission is unlikely.
Primary tuberculous infection of the intestine, caused by ingestion of the bovine strain of Mycobacterium tuberculosis, is rare in the USA. Secondary infection is due to swallowing the tubercle bacillus. About 1% of patients with pulmonary tuberculosis have intestinal involvement. Recent immigration from endemic areas has increased the incidence. Tuberculosis is prevalent in individuals infected with HIV.
The distal ileum is the site of disease. The bacillus localizes in the mucosal glands and spreads to Peyer’s patches, where inflammation, sloughing of tissue, and local attempts at walling off give rise to symptoms. Free perforation, fistula formation, or hemorrhage may occur in severe untreated disease.
Salmonella typhi may cause ulcers. Bleeding or perforation presents a formidable surgical challenge. Early operation offers the best hope for survival.
Enteropathy from Nonsteroidal Anti-Inflammatory Drugs
This drugs increase intestinal permeability within hours after ingestion, exposing the mucosa to macromolecules and toxins in the lumen. Bacterial invasion may contribute to inflammation. Perhaps 70% of patients of any age and either sex who have taken these agents for 6 months or longer develop enteropathy. Fewer than 1% of patients develop ulceration with submucosal fibrosis and circumferential diaphragmlike strictures. These patients may have obstruction, perforation, or anemia.
The drug should be withdrawn. Strictures require resection.
Aggressive radiation therapy for abdominal or pelvic cancer is almost always associated with some gastrointestinal injury, because proliferating intestinal epithelial cells are extremely radiosensitive. Degeneration of cells and edema of bowel wall may produce abdominal pain, vomiting, and sometimes bloody diarrhea during therapy or a few months later.
Carcinoma arising in irradiated small intestine is a rare late complication.
The incidence of significant bowel injury is dose-related and varies from 5% to 30%. Fixation of small bowel loops in the radiation field by adhesions from previous operations greatly increases the risk of complications. Absorbable polyglycolic acid mesh can be used to keep the small bowel out of the pelvis when radiation therapy is planned following pelvic surgery. Oral glutamine protects the small bowel mucosa from some of the morbidity of irradiation in preliminary animal studies.
Operation is required for obstruction due to stricture or entrapment in pelvic fibrosis, perforation with abscess or fistula formation, or hemorrhage from ulcerated mucosa. Symptoms should not be attributed to cancer until residual cancer is proved to be present.
The objective of operation is relief of symptoms. If resection of the involved segment is not possible, bypass is performed. It is imperative that normal bowel be used for anastomoses, because suture lines in irradiated bowel are likely to disrupt. The bowel is friable despite its thickness. If the distal colon and rectum are involved, diverting colostomy is the safest course.
The operative death rate is 10–15%, and the prognosis thereafter depends on the extent of involvement, short bowel syndrome, and cancer. Only 30–45% of patients with significant intestinal complications of radiation therapy are alive 5 years after operation.