Off Target But Hitting the Mark

A 32-year-old woman presented to the emergency department (ED) with 3 months of abdominal pain and 1 week of vomiting.

The differential diagnosis of abdominal pain is broad. This presentation could be caused by disorders of the gastrointestinal (GI), gynecologic, urinary, or, less likely, the neuromuscular systems. The presence of vomiting supports a GI cause. Pregnancy should be excluded in any woman of childbearing age presenting with abdominal pain.

Characteristics of the pain, including location, temporal characteristics, severity, and aggravating and alleviating factors, can narrow the differential diagnosis. The past medical history, including prior surgeries, menstrual, and obstetric history, is also critical.

Approximately 3 months prior to presentation, she reported a tick bite that had evolved into a circumferential targetoid rash. Her primary care provider performed serologic testing for Lyme disease, which was negative, and prescribed doxycycline, which she stopped after a week because of nausea and diffuse, achy, and constant abdominal pain. After initial improvement, symptoms recurred a week prior to presentation. The nausea was now associated with intractable vomiting and anorexia. She denied hematemesis or coffee ground emesis. Her abdominal pain intensified and radiated to her back. She lost 10 pounds over the past week. She denied headache, constipation, diarrhea, blood per rectum, melena, dysuria, vaginal discharge, or rash. She reported chills and temperatures up to 37.8 ° C at home.

She had a history of migraine headaches for which she took ibuprofen occasionally but took no other prescription or over-the-counter medications. She had never smoked, consumed 2 alcoholic beverages a month, and denied illicit drug use. She lived with her boyfriend on a farm in Indiana where she raised chickens, rabbits, and ducks.

The patient dates the onset of nausea and abdominal pain to a course of doxycycline, presumably prescribed for early Lyme disease, which was stopped after only 1 week. GI side effects, including nausea, vomiting, and upper abdominal pain, are common with doxycycline and may account for the early symptoms. However, these symptoms typically resolve promptly with drug discontinuation. Doxycycline may rarely cause esophageal and gastric ulcers, which could explain her symptoms.

Fewer than half of patients with erythema migrans caused by Lyme disease are seropositive at presentation, as there has been insufficient time for antibodies to develop. Lyme disease typically affects the skin, joints, heart, and nervous system and only rarely affects the GI tract. Acute Lyme disease can cause intestinal pseudoobstruction, splenomegaly, and mild hepatitis. Although Lyme disease is unlikely to be the cause of the current symptoms, serologic testing should be repeated and should be positive if the patient now has early disseminated disease.

Patients with Lyme disease are occasionally coinfected with a second organism. Ixodes scapularis, the tick that transmits Lyme disease in the Northeast and Midwest, can be coinfected with Babesia microti, a red cell parasite. Babesiosis can persist for months and presents with fever, malaise, and many other nonspecific symptoms, including some that this patient has: anorexia, weight loss, abdominal pain, and vomiting.

The history of migraine and intractable vomiting suggests the possibility of cyclic vomiting syndrome. This syndrome is characterized by episodic bouts of vomiting lasting from hours to as long as a week. The vomiting is often accompanied by abdominal pain and occasionally headaches. Episodes are separated by asymptomatic periods that may last months. Cyclic vomiting syndrome can occur at any age but is more common in children, those with a personal or family history of migraines, and heavy users of cannabis. At least 3 stereotypical episodes are required to make the diagnosis, so a history of prior similar symptoms should be explored.

The differential diagnosis of abdominal pain and vomiting should stay broad until a comprehensive physical exam and initial laboratory tests are performed. Volume status should be assessed by estimating jugular venous pressure and by obtaining supine and standing blood pressure measurements. The abdomen should be examined carefully, and the presence or absence of hepatomegaly, splenomegaly, masses, and ascites should be specifically noted. The presence of bradycardia, oligoarticular arthritis, or neuropathy could provide supporting evidence for Lyme disease. Pregnancy is less likely given the diffuse and persistent nature of the pain but should still be excluded.