Nausea and vomiting of moderate intensity are especially common until about 16 weeks and occur in slightly over half of pregnant women. When severe and unresponsive to simple dietary modification and antiemetics, the condition is termed hyperemesis gravidarum. Hyperemesis is defined loosely as vomiting sufficiently severe to produce weight loss, dehydration, acidosis from starvation, alkalosis from loss of hydrochloric acid in vomitus, and hypokalemia. In some cases, transient hepatic dysfunction develops. There may be mild hyperbilirubinemia, and serum hepatic transaminase levels are elevated in up to half of women who are hospitalized. Enzyme levels seldom exceed 200 U/L. Hyperemesis appears to be related to high or rapidly rising serum levels of chorionic gonadotropin, estrogens, or both. An association with Helicobacter pylori—the causative agent of peptic ulcer disease—has been reported.
Outpatient management usually includes recommendations to eat small amounts at more frequent intervals and stopping short of satiation. It is also recommended to avoid foods that precipitate or aggravate symptoms. Treatment of nausea and vomiting in pregnancy with vitamin B6 or vitamin B6 plus doxylamine (Bendectin) is safe and effective and should be considered first-line pharmacotherapy. When these simple measures fail, antiemetics such as promethazine (25 mg every 6 hours orally), prochlorperazine, chlorpromazine, and ondanesetron are given to alleviate nausea and vomiting. For severe disease, metoclopramide (10 mg every 6 hours orally) may be given. This stimulates motility of the upper intestinal tract without stimulating gastric, biliary, or pancreatic secretions. Methylprednisolone has been reported to be ineffective in controlling severe hyperemesis.
Approximately one-fourth of women with hyperemesis require multiple hospitalizations. Vomiting may be prolonged, frequent, and severe. We have encountered women with severe azotemia with serum creatinine as high as 5 mg/dL. Serious complications may include Mallory-Weiss tears, esophageal rupture, bilateral pneumothoraces, pneumomediastinum, serious epistaxis caused by vitamin-K deficiency coagulopathy, and Wernicke encephalopathy from thiamine deficiency (blindness, convulsions, and coma).
Intravenous crystalloid solutions are used to correct dehydration, electrolyte deficits, and acid-base imbalances. This requires appropriate amounts of sodium, potassium, chloride, lactate or bicarbonate, glucose, and water, all of which should be administered parenterally until vomiting has been controlled. Parenteral drugs such as promethazine (25 mg every 6 hours intravenously) or metoclopramide (10 mg every 6 hours intravenously) may be administered.
With persistent vomiting, appropriate steps should be taken to diagnose and treat other diseases, such as gastroenteritis, cholecystitis, pancreatitis, hepatitis, peptic ulcer, pyelonephritis, and acute fatty liver of pregnancy. In some instances, social and psychological factors contribute to the illness. With the correction of these latter circumstances, the woman usually improves remarkably while hospitalized, only to relapse after discharge. Positive assistance with psychological and social problems is beneficial.
With prolonged vomiting, consideration is given for nutritional support, which is best provided by the enteral route if possible. In some women with persistent and severe disease, parenteral nutrition may be necessary. Thiamine supplementation should be considered in these women.
For further reading in Williams Obstetrics, 23rd ed.,
see Chapter 49, “Gastrointestinal Disorders.”