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The differential diagnosis of nausea and vomiting is exhaustive, as pathology of almost every organ system may lead to nausea and vomiting (Table 72–2). A thorough history and physical examination will help guide the diagnostic approach to the patient presenting with nausea and vomiting.
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Identify the onset and duration of the symptoms. The evaluation for acute symptoms is quite different from the evaluation of a chronic problem. If the problem is chronic, asking the patient the results of any tests that have already been performed will help narrow the diagnostic possibilities. Chronic symptoms are defined as those symptoms present for >1 month.
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Frequency of the episodes is helpful to gauge the severity of illness. Ask how many times vomiting occurred and the interval between episodes. Timing of the episodes, such as increased number of episodes in the morning, may suggest pregnancy or a central nervous system cause, whereas postprandial vomiting suggests gastroparesis or gastric outlet obstruction.
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The content of the vomitus may be helpful to determine whether an obstruction is present and its location. Esophageal disorders produce vomitus with undigested food particles. Bile is often associated with a small bowel obstruction, whereas vomitus composed of food particles and devoid of bile often represents a gastric outlet obstruction. Large bowel obstruction often is composed of feculent material and has a foul odor.
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Because of the number of organ systems that are the potential cause of pathology, it is important to ask the patient about associated symptoms. The presence or absence of abdominal pain is a focal starting point. If pain is present, elicit its location and quality. Pain preceding the nausea and vomiting is most particularly associated with an obstructive process.2 Fever or, possibly, diarrhea suggests gastroenteritis. Ask about sick contacts or ingestion of food suspicious for a foodborne illness. A history of recent weight loss is associated with a malignancy or psychiatric component. Any central nervous system sign, such as headache, visual changes, vertigo, or neurologic deficits, may suggest a central cause for the nausea and vomiting. Obtain a thorough past medical history. Always ask about prior abdominal surgeries because the patient is at risk for bowel obstruction from adhesions. Review the patient's medication list to identify a medication with a common side effect of nausea and vomiting, such as nonsteroidal anti-inflammatory agents, cancer chemotherapeutic agents, various antibiotics, various antihypertensives and antiarrhythmics, and oral contraceptives. Other medications at toxic levels are known to cause nausea and vomiting. Examples include acetaminophen, salicylates, and digoxin.
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Assess vital signs for hypotension and tachycardia. Observe skin turgor, mucous membrane hydration, and capillary refill to assess for dehydration. In children, the most useful predictors of significant dehydration (>5% loss of body weight) are abnormal capillary refill, abnormal skin turgor, absent tears, and abnormal respiratory pattern.4 The abdominal examination is particularly important to assess for an emergent problem, as well as to help narrow the differential diagnosis to a possible gastrointestinal cause.5 Inspect, auscultate, and palpate the abdomen. (For further discussion of abdominal evaluation, see chapter 71, Acute Abdominal Pain.)
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Investigate any other important examination findings particular to various organ systems, as findings may provide valuable information regarding the cause of the nausea and vomiting (Table 72–3).
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