Chapter 141

Nausea and Vomiting

Brad E. Franklin

Definition and Epidemiology

Nausea and vomiting significantly affect quality of life and are common presenting complaints in primary care.¹ One study of primary practice reported that nausea and vomiting ranked second to upper respiratory infections as presenting problems in primary care.² Nausea and vomiting present a diagnostic challenge to health care providers because of the varied causes such as infection, chronic medical conditions, and even treatment modalities. The health care provider needs not only to control the symptoms and to prevent complications but also to successfully diagnose and treat the underlying disease.²^,³

Nausea is defined as an unpleasant or queasy, but painless, sensation that one is about to vomit. Actual vomiting may or may not occur.¹^,⁴ Nausea usually lasts longer than vomiting and is generally relieved by vomiting. Vomiting, the forceful expulsion of liquid or food from the stomach through the mouth, should be differentiated from other symptoms that are often described by patients as vomiting, such as retching (rhythmic contractions of the respiratory and abdominal muscles without expulsion of gastric contents) or regurgitation (an effortless backward flow of food and liquids from the stomach to the mouth).⁴^,⁵ Vomiting is a protective mechanism from harmful ingested substances, but it can result from underlying disease affecting the gastrointestinal tract or surrounding structures, metabolic or endocrine function, or the central nervous system, or it can be an adverse effect of disease interventions (e.g., chemotherapy).¹^,²

Emergency consultation is indicated if nausea and vomiting are accompanied by pain, severe dehydration, acute abdomen, fever, neurologic changes, or a metabolic imbalance.

Pathophysiology

Vomiting is a reflex action controlled by two major central nervous system centers: the vomiting center (VC) and the chemoreceptor trigger zone (CTZ).²^,⁵^,⁶ The VC, a collection of neurons within the medulla, is stimulated by input from multiple mechanisms including pharyngeal, vagal, and midbrain afferents and the limbic system. Mechanical irritation can stimulate the pharyngeal afferents, leading to retching and then vomiting. The presence of noxious substances in the stomach and duodenum and the mechanical distention and contraction can sensitize chemoreceptors, and mechanical receptors can stimulate the vagal afferent pathways, which in turn stimulate the VC, leading to vomiting.⁵^,⁷

The CTZ, located on the floor of the fourth ventricle, is directly sensitive to chemical agents with known emetogenic potential. It is sensitive to stimulation from serotonin, dopamine, histamine, cholinergic, adrenergic, and opiate receptors. The pharmacologic basis of most antiemetics is to block these neurotransmitters. The CTZ identifies harmful substances and transmits the information to the VC, which then initiates the vomiting reflex. Neurotransmitters, vagal afferents, or noxious agents can stimulate the CTZ, resulting in the stimulation of the VC.⁵^,⁷

The Vomiting Reflex

No matter the cause of the stimulation of the VC, once stimulated it initiates a sequence of events that end with vomiting. There are three phases of vomiting: pre-ejection, ejection, and postejection. During pre-ejection, there is an increase in salivation and swallowing and a decrease in gastric tone; tachycardia, pallor, and diaphoresis occur. Relaxation of the proximal stomach and contraction of the small intestine ensue, leading to regurgitation of contents into the stomach. Pre-ejection is mediated by acetylcholine and the vagus nerve. In the ejection phase, abdominal muscles and the diaphragm contract and the lower esophageal sphincter relaxes, allowing contents into the esophagus and then into the mouth. The palate is elevated, thereby preventing propulsion of contents through the nasopharynx. Postejection is the period after expulsion of the stomach contents, usually resulting in some relief of the nausea.⁷

Clinical Presentation

Nausea and vomiting are common presenting symptoms in primary care and can be associated with a variety of clinical presentations. The vomiting act varies very little regardless of cause.² The symptoms can be mild and self-limited or severe and prolonged, which can result in anorexia, weight loss, dehydration, and malnutrition. Nausea and vomiting might dominate the presentation or may be only a part of a symptom complex.²

When obtaining history, the clinician must have a clear determination of the patient’s symptoms because a detailed history can provide clues to the diagnosis. The presentation of nausea and vomiting can vary from the gradual onset of symptoms noted with medication side effects, gastric retention, or early pregnancy to the abrupt episodes caused by viral gastroenteritis, food poisoning, increased intracranial pressure, or acute abdominal emergency.¹^,⁴ Associated symptoms can include pain, headache, dizziness, tinnitus, diarrhea, fever, mental status changes, anxiety, and other symptoms associated with pregnancy.¹^,²

History

A thorough history should include such details as the timing of the symptoms and their relation to meals, characteristics of the emesis, and any associated complaints. For example, early morning vomiting is associated with metabolic disturbances, alcoholic bingeing, and pregnancy. Vomiting that is triggered by meals is suggestive of pyloric channel ulcer, gastritis, or possibly a psychogenic problem. Learning the appearance of the vomitus is helpful (e.g., coffee-ground emesis suggests gastritis or ulcer disease, vomiting of gastric juice is suggestive of peptic ulcer disease and Zollinger-Ellison syndrome, and vomiting of feculent material is a sign of distal small bowel obstruction). Learning the onset, duration, and severity of symptoms is important.

The clinician should also ask about associated symptoms, past medical history, and psychosocial history. Inquiry should be made about the presence of abdominal pain, fever, jaundice, weight loss, dizziness, headache, visual disturbances, or abdominal surgery; a history of diabetes, cancer, irritable bowel syndrome, or heart disease is ascertained; and current medications and therapies including radiation therapy or chemotherapy are reviewed. Gentle questioning about eating habits (binge eating), self-image, and self-induced emesis should also be conducted. A woman of childbearing age needs to be asked about the last menstrual period and whether she is sexually active, with or without contraception. Essential epidemiologic data include a history of recent foreign travel,² any recent exposure to commonly contaminated foods, and any recent exposure to sick contacts. It is also necessary to determine the relationship of nausea and vomiting to food (Does it happen before, during, or after eating? Is it predictable?); the force of vomiting (projectile versus retching); and the quality of the emesis (bile, undigested food, coffee-ground emesis). Acute nausea and vomiting without warning signs can be indicative of infectious or iatrogenic causes. A 24-hour dietary review, with bowel symptoms (diarrhea versus constipation) and the time of the last void, should also be determined.¹^,²

Acute episodes of nausea and vomiting may be caused by viruses, bacterial food poisoning, or medication overdose. Acute emergencies, such as pancreatitis, appendicitis, bowel obstruction, peritonitis, or cholecystitis, may be accompanied by fever or pain. These symptoms can also occur in acute episodes of Crohn disease, colitis, and diverticulitis. Chronic or recurrent nausea and vomiting may be psychogenic or the result of radiation therapy or chemotherapy, gastric disorders, migraine headaches, diabetic gastroparesis, or a metabolic or endocrine abnormality.¹^,²

Physical Examination

A thorough physical examination should be directed toward searching for complications of nausea and vomiting and identifying any signs that might point to the cause. Each area of the abdomen assessed should help narrow the possible differential diagnoses specific to that region.⁸ The examination should focus on signs of dehydration, including evaluation of skin turgor, mucous membranes, and orthostatic vital signs (positional blood pressure, pulse). The general examination should include assessment of the skin for jaundice, moisture, rashes, or hyperpigmentation. Fingers should be assessed for calluses on dorsal surfaces suggesting self-induced vomiting. If self-induced vomiting is suspected, the clinician should examine the parotid gland for enlargement and check for the presence of lanugo hair and loss of tooth enamel; the patient should also be evaluated for signs of depression and anxiety. The head and neck should be assessed for evidence of dehydration, acute infection, lymphadenopathy, rigidity, or signs of thyrotoxicosis. A cardiovascular examination is necessary to determine the patient’s response to the illness or other signs of infection. The abdomen should be observed for distention, visible peristalsis, abdominal or inguinal hernias, and surgical scars; auscultated for bowel sounds (presence or absence, increased or sluggish) and succussion; then palpated for rigidity, tenderness or masses, and flank tenderness. When palpating, the provider begins in areas where no discomfort is reported. Abdominal wall rigidity is indicative of an acute surgical abdomen. A rectal examination is used to assess for fecal impaction and bleeding, if indicated. A neurologic examination including mental status, gait, muscle weakness, asterixis, and cranial nerve function is also an essential component of the evaluation, if neurologic involvement is suspected.¹^,²^,⁴

Diagnostics

There are currently no randomized controlled studies to guide the diagnostic evaluation; most recommendations are based on expert opinion.¹ The presentation of nausea and vomiting and the physical findings should guide diagnostic testing.³ Even though there are no specific tests to determine the cause of nausea and vomiting, laboratory tests can be used to evaluate for the complications as well as to determine the underlying causes. The laboratory tests may include urinalysis for specific gravity; erythrocyte sedimentation rate; serum glucose concentration; electrolyte values; serum levels of ketones; blood urea nitrogen (BUN), creatinine, and amylase concentrations; liver function tests (LFTs); and drug levels (if indicated). A serum level of human chorionic gonadotropin should be obtained in women of childbearing age. Urinalysis with culture and sensitivity, complete blood count (CBC), thyroid-stimulating hormone, or further endocrine studies may be indicated in some cases.¹^,⁴

Abdominal upright and plain x-ray films are necessary if an obstruction is suspected. An ultrasound examination, barium swallow study, computed tomography (CT) scan, or endoscopic examination may be indicated for masses, dysphagia, or suspected gastrointestinal bleeding or ulceration. If a cerebral hemorrhage or mass is suspected, the patient should be urgently referred to the nearest hospital where a head CT scan can be performed. Severe indigestion, epigastric pain, and vomiting could indicate a myocardial infarction.⁸ Electrocardiography is indicated if myocardial infarction suspected.

Diagnostics

Nausea and Vomiting

Laboratory