Nausea and Vomiting During Early Pregnancy
Nausea and vomiting affect up to 80% of pregnant women. Symptoms are most common and most severe during the 1st trimester. Although common usage refers to morning sickness, nausea, vomiting, or both typically may occur at any point during the day. Symptoms vary from mild to severe (hyperemesis gravidarum).
Hyperemesis gravidarum is persistent, severe pregnancy-induced vomiting that causes significant dehydration, often with electrolyte abnormalities, ketosis, and weight loss.
Pathophysiology
Etiology
The most common causes of uncomplicated nausea and vomiting during early pregnancy (see table Some Causes of Nausea and Vomiting During Early Pregnancy) are
Occasionally, prenatal vitamin preparations with iron cause nausea. Rarely, severe, persistent vomiting results from a hydatidiform mole.
Vomiting can also result from many nonobstetric disorders. Common causes of acute abdomen (eg, appendicitis, cholecystitis) may occur during pregnancy and may be accompanied by vomiting, but the chief complaint is typically pain rather than vomiting. Similarly, some CNS disorders (eg, migraine, CNS hemorrhage, increased intracranial pressure) may be accompanied by vomiting, but headache or other neurologic symptoms are typically the chief complaint.
Some Causes of Nausea and Vomiting During Early Pregnancy
Cause |
Suggestive Findings |
Diagnostic Approach |
Obstetric |
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Morning sickness (uncomplicated nausea and vomiting) |
Mild, intermittent symptoms at varying times throughout the day, primarily during the 1st trimester Normal vital signs and physical examination |
Diagnosis of exclusion |
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Frequent, persistent nausea and vomiting with inability to maintain adequate oral intake of fluids, food, or both Usually, signs of dehydration (eg, tachycardia, dry mouth, thirst), weight loss |
Urine ketones, serum electrolytes, magnesium, BUN, creatinine If the condition persists, possibly liver function tests, pelvic ultrasonography |
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Larger-than-expected uterine size, absent fetal heart sounds and movement Sometimes elevated BP, vaginal bleeding, generalized edema, grapelike tissue from the cervix |
BP measurement, quantitative hCG, pelvic ultrasonography, biopsy |
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Nonobstetric |
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Acute, not chronic; usually accompanied by diarrhea Normal (benign) abdomen (soft, nontender, not distended) |
Clinical evaluation |
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Acute, usually in patients who have had abdominal surgery Colicky pain, with obstipation and distended, tympanitic abdomen May be caused by or occur in patients with appendicitis |
Abdominal imaging with flat and upright x-rays, ultrasonography, and possibly CT (if x-ray and ultrasound results are equivocal) |
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UTI or pyelonephritis |
Urinary frequency, urgency, or hesitancy, with or without flank pain and fever |
Urinalysis and culture |
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hCG = human chorionic gonadotropin. |
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Evaluation
Evaluation aims to exclude serious or life-threatening causes of nausea and vomiting. Morning sickness (uncomplicated nausea and vomiting) and hyperemesis gravidarum are diagnoses of exclusion.
History
History of present illness should particularly note the following:
Important associated symptoms include diarrhea, constipation, and abdominal pain. If pain is present, the location, radiation, and severity should be queried. The examiner should also ask what social effects the symptoms have had on the patient and her family (eg, whether she is able to work or to care for her children).
Review of systems should seek symptoms of nonobstetric causes of nausea and vomiting, including fever or chills, particularly if accompanied by flank pain or voiding symptoms (UTI or pyelonephritis), and neurologic symptoms such as headache, weakness, focal deficits, and confusion (migraine or CNS hemorrhage).
Past medical history includes questions about morning sickness or hyperemesis in past pregnancies. Past surgical history should include questions about any prior abdominal surgery, which would predispose a patient to mechanical bowel obstruction.
Drugs taken by the patient are reviewed for drugs that could contribute (eg, iron-containing compounds, hormonal therapy) and for safety during pregnancy.
Physical examination
Examination begins with review of vital signs for fever, tachycardia, and abnormal BP (too low or too high).
A general assessment is done to look for signs of toxicity (eg, lethargy, confusion, agitation). A complete physical examination, including pelvic examination, is done to check for findings suggesting serious or potentially life-threatening causes of nausea and vomiting (see table Relevant Physical Examination Finding in a Pregnant Patient With Vomiting).
Relevant Physical Examination Findings in a Pregnant Patient With Vomiting
Red flags
Interpretation of findings
Distinguishing pregnancy-related vomiting from vomiting due to other causes is important. Clinical manifestations help (see table Some Causes of Nausea and Vomiting During Early Pregnancy).
Vomiting is less likely to be due to pregnancy if it begins after the 1st trimester or is accompanied by abdominal pain, diarrhea, or both. Abdominal tenderness may suggest acute abdomen. Meningismus, neurologic abnormalities, or both suggest a neurologic cause.
Vomiting is more likely to be due to pregnancy if it begins during the 1st trimester, it lasts or recurs over several days to weeks, abdominal pain is absent, and there are no symptoms or signs involving other organ systems.
If vomiting appears to be pregnancy-related and is severe (ie, frequent, prolonged, accompanied by dehydration), hyperemesis gravidarum and hydatidiform mole should be considered.
Testing
Patients with significant vomiting, signs of dehydration, or both usually require testing. If hyperemesis gravidarum is suspected, urine ketones are measured; if symptoms are particularly severe or persistent, serum electrolytes are measured. If fetal heart sounds are not clearly audible or detected by fetal Doppler, pelvic ultrasonography should be done to rule out hydatidiform mole.
Other tests are done based on clinically suspected nonobstetric disorders (see table Some Causes of Nausea and Vomiting During Early Pregnancy).
Treatment
Pregnancy-induced vomiting may be relieved by drinking or eating frequently (5 or 6 small meals/day), but only bland foods (eg, crackers, soft drinks, BRAT diet [bananas, rice, applesauce, dry toast]) should be eaten. Eating before rising may help.
If dehydration (eg, due to hyperemesis gravidarum) is suspected, 1 to 2 L of normal saline or Ringer’s lactate is given IV, and any identified electrolyte abnormalities are corrected.
Certain drugs (see table Suggested Drugs for Nausea and Vomiting During Early Pregnancy) can be used to relieve nausea and vomiting during the 1st trimester without evidence of adverse effects on the fetus.
Vitamin B6 is used as monotherapy; other drugs are added if symptoms are not relieved.
Ginger (eg, ginger capsules 250 mg po tid or qid, ginger lollipops), acupuncture, motion sickness bands, and hypnosis may help, as may switching from prenatal vitamins to a children’s chewable vitamin with folate.
Key Points
Drugs Mentioned In This Article
| Drug Name | Select Trade |
|---|---|
Metoclopramide |
REGLAN |
Promethazine |
PROMETHEGAN |
Ondansetron |
ZOFRAN |
Doxylamine |
UNISOM |
