Differential appendicitis diagnoses
The most common alternate diagnoses for appendicitis (see lower table, above) originate in adjacent organs, e.g., ileocolitis due to acute infection or inflammatory bowel disease. Bacterial enteric infections that commonly mimic appendicitis are those due to salmonella, Campylobacter, Shiga toxin-producing Escherichia coli (E. coli O157:H7), and Yersinia enterocolitica. These infections involve the ileocolonic areas in the right lower quadrant. Yersinia also causes a mesenteric adenitis that produces right lower-quadrant pain. Yersinia pseudotuberculosis can cause both appendicitis and a pseudo-appendicitis picture. Other pathogens with a predilection for the ileocecal area are Mycobacterium tuberculosis and Entamoeba histolytica. Tuberculosis usually presents with chronic pain.
Viruses—measles, adenovirus, and cytomegalovirus—have rarely been associated with appendicitis. Fungi are also uncommon, but Histoplasma capsulatum, aspergillus, and actinomyces may account for a very small number of cases. Parasite worms or eggs can cause appendicitis by occluding the lumen—Enterobius vermicularis (pinworm) and Ascaris lumbricoides have been reported but are usually an incidental finding.
In women, symptoms similar to those of appendicitis can be due to pathology of the ovary, fallopian tubes, and uterus, including ruptured ovarian cysts, ectopic pregnancy, and pelvic inflammatory disease. These possibilities contribute to a negative appendectomy rate as high as 20% in women. (The rate in men can be as low as 10%.)
Colonic adenocarcinoma or, less likely, lymphoma in the cecum can present with right lower-quadrant pain, as can right-sided diverticulitis and Crohn’s ileocolitis.
Urinary disease, including kidney stones and pyleonephritis, should also be excluded. Uncommon differentials are osteomyelitis of the iliac bones and abscess of the psoas or gluteal muscles.
Therapy—and the role of antibiotics Appropriate management requires accurate early diagnosis and surgical intervention. Because the consequences of missed appendicitis are perforation, abscess, and possible death, an aggressive surgical approach is usual. Overall mortality is low—1%.
Postsurgical antibiotics are given for prophylaxis of wound infection only if the appendix is not perforated. Patients with perforation and abscess whose symptoms have lasted five days or longer at presentation may have their surgery delayed for a few days to allow broad-spectrum antibiotics, IV fluids, and bowel rest. This delay is intended to decrease morbidity due to local inflammation.
A recent study questioned the need for surgery in 252 men aged 18-50 years who had acute appendicitis and were planning to undergo appendectomy. Study participants were randomized to surgery or antibiotics. Outcomes were similar for hospital stay, but evidence from this trial is not strong enough to change clinical practice. An excellent editorial by Søreide analyzing the article found a statistical error. Søreide concludes that surgery remains the gold standard of care for patients with acute appendicitis.
For the primary-care or emergency physician, careful evaluation as well as early surgical consultation is important, especially to help distinguish surgical from nonsurgical cases. A gastroenterologist should be consulted if Crohn’s disease is in the differential, but endoscopic procedures should be avoided if there is a possibility of acute appendicitis, as air from colonoscopy could perforate the appendix. There does appear to be an entity that could be described as “chronic appendicitis.” Not much is known about this condition, which is characterized by recurrent acute right lower-quadrant pain. In patients who have undergone appendectomy, histologic findings included chronic inflammation of the appendiceal wall or fibrosis of the appendix.