Evaluation of nausea and vomiting: a case-based approach.

In the absence of acute abdominal pain, significant headache, or recent initiation of certain medications, acute nausea and vomiting is usually the result of self-limited gastrointestinal infections. Nausea and vomiting is also a common adverse effect of radiation therapy, chemotherapy, and surgical anesthesia. Other potential diagnoses include endocrine conditions (including pregnancy), central nervous system disorders, psychiatric causes, toxin exposure, metabolic abnormalities, and obstructive or functional gastrointestinal causes. The likely cause of acute nausea and vomiting can usually be determined by history and physical examination. Alarm signs such as dehydration, acidosis caused by an underlying metabolic disorder, or an acute abdomen warrant additional evaluation. Based on the suspected diagnosis, basic laboratory testing may include urinalysis, urine pregnancy testing, complete blood count, comprehensive metabolic panel, amylase and lipase levels, thyroid-stimulating hormone level, and stool studies with cultures. Imaging studies include abdominal radiography, ultrasonography, and computed tomography. Computed tomography of the head should be performed if an acute intracranial process is suspected. Chronic nausea and vomiting is defined by symptoms that persist for at least one month. Patients with risk factors for gastric malignancies or alarm symptoms should be evaluated with esophagogastroduodenoscopy. If gastroparesis is suspected, a gastric emptying study is recommended. In addition to functional causes, it is also important to consider psychiatric causes when evaluating patients with chronic nausea and vomiting.