Cyclic vomiting is defined as episodes of vomiting interspersed with periods of wellness. Patients with cyclic vomiting have at least four episodes of vomiting per hour, but no more than two episodes per week. After testing, no cause of the vomiting is found. Previously, the vomiting has been attributed to migraine (so-called abdominal migraine), hypothalamic dysfunction or problematic parent-child relationships. Li and colleagues conducted a chart review of children who presented with an episodic pattern of vomiting to determine which disorders should be included in the differential diagnosis for a work-up of a child with cyclic vomiting.

Children who had an episodic pattern of vomiting with at least three discrete episodes were included in the study. Results of laboratory tests, radiographs and endoscopic biopsies, and clinical follow-up were reviewed. A structured telephone interview elicited a history of the pattern of vomiting, associated symptoms and possible trigger factors.

The mean occurrence of vomiting was 6.3 episodes per hour and 1.6 episodes per month. In slightly more than one half of the children (53 percent), a single diagnosis was determined to be the probable cause of the vomiting. Of these children, 88 percent were diagnosed with idiopathic cyclic vomiting syndrome, 7 percent were diagnosed with gastrointestinal conditions and 5 percent were diagnosed with extraintestinal problems.

When the treatments of children with multiple diagnoses were reviewed, 18 of 83 children responded, at least partially, to medication given for a diagnosed problem that was thought to have caused the vomiting (e.g., patients with vomiting and esophagitis partially responded to therapy with H₂ antagonists and cisapride). Twenty-six confirmed surgical disorders, such as small bowel malrotations, cholelithiasis and intracranial neoplasms, were believed to be associated with the vomiting. Various diagnostic tests, including blood counts, glucose levels, electrolyte studies and blood urea nitrogen levels, were performed in most patients during vomiting episodes. Forty-three percent of endoscopies yielded positive results, as did 38 percent of radiographs of the sinus, 28 percent of radiographs of the small bowel and 28 percent of computed tomographic scans or magnetic resonance images of the brain. As would be expected, patients who vomited more or had more frequent episodes of vomiting were tested more often than patients with less severe episodes.

The authors conclude that a rational laboratory evaluation of cyclic vomiting may be initiated based on the results of this study. The tests with the highest yield of positive results in this study were endoscopy and radiography of the sinus and small bowels. More specialized testing, such as determination of blood glucose, electrolytes, liver enzymes, pancreatic enzymes and ammonia levels, should be performed during the vomiting episode, when possible, to maximize the chance of detecting an intermittent or heterozygous disorder. Finally, surgical disorders are best detected by radiographs of the small bowel, abdominal imaging and cranial imaging.