AAAAI: Unexplained Acute GI Pain Could be Hereditary Angioedema

SAN DIEGO, March 1 -- Severe acute abdominal pain, which may recur with no obvious clinical explanation, could be due to hereditary angioedema, reported investigators here.

The condition could even land patients in the operating room undergoing unnecessary surgery, noted Henry Li, M.D., Ph.D., from the Institute for Asthma and Allergy in Chevy Chase, Md., and colleagues, at the annual meeting of the American Academy of Allergy, Asthma, & Immunology meeting here.

Although hereditary angioedema is a rare condition, affecting between one in 10,000 and one in 50,000 patients, severe, recurrent abdominal pain and gastrointestinal symptoms lasting several days may be the first and/or only presenting symptoms, the authors noted in a poster presentation. It can recur for years or even decades.

"It's a very uncommon condition, even for the allergist, who is the primary caregiver for hereditary angioedema; average allergists may see one or two cases in their entire career, Dr. Li said. "For GI physicians it's probably even more uncommon."

Nonetheless, about 30% of all patients with this condition may have crampy abdominal pain, nausea, vomiting, and/or diarrhea, and will present to an emergency department or physician with no family history of the disease and no obvious edema.

"The tests usually take a few days to come back, and the emergency room has no way to assess -- the only thing they do usually is take an x-ray film or CT scans, which can show partial bowel obstruction, and that can be a surgical emergency, so they feel they may need to rescue the bowel," Dr. Li said.

Hereditary angioedema is characterized by relapsing, self-limiting episode of edema in subcutaneous tissue, the intestinal wall, and the larynx. Patients with abdominal attacks have severe pain, nausea, diarrhea and vomiting associated with intestinal wall edema. Attacks involving the larynx can result in airway constriction or closure and asphyxiation.

Prior to the advent of effective therapies for controlling the disease, the death rate was approximately 20% to 30%, primarily from airway obstruction.

"GI involvement appears to be segmental and transient, usually resolving in several days," Dr. Li and colleagues wrote. "Fever and leukocytosis are uncommon. Ascites has been observed in some patients during attacks. GI tract hereditary angioedema can go undiagnosed for decades, and patients may undergo unnecessary abdominal surgery."

The investigators conducted a retrospective chart review of all patients with hereditary angioedema at their center who reported abdominal pain as the initial or major presentation. They reviewed the diagnostic and therapeutic procedures the patients underwent prior to the diagnosis of hereditary angioedema.

They found that five of 28 patients had undergone exploratory abdominal operations for acute severe abdominal pain prior to their final diagnosis. Two of the patients had appendectomies, and one underwent several operations and procedures during her attacks, including multiple colonoscopies, appendectomy, cholecystectomy, and exploratory surgery for a presumed ectopic pregnancy.

"Education of healthcare professionals to increase familiarity with the differential diagnosis of hereditary angioedema when evaluating patients with recurrent severe abdominal pain is critical to help avoid unnecessary surgical interventions in these patients," the authors wrote.

Acknowledging the old medical maxim that "when you hear hoofbeats think horses, not zebras," Dr. Li said that it's still important for emergency physicians, gastroenterologists, and primary care physicians to be aware of the possibility of hereditary angioedema.

"If the patient has one episode, you need to check for the common things," he said, "but if the patient year in and year out has severe abdominal pain that you're not able to figure out, you need to look at other, uncommon causes," he said.