160 Obstetrics and Gynecology Board Review •••
❍ What GI motility disturbances may occur during pregnancy?
(1) Abnormal esophageal motility with increased nonpropulsive motor activity and decreased contraction wave
amplitude and velocity.
(2) Decreased lower esophageal sphincter pressure.
(3) Decreased LES sensitivity to pharmacologic and physiologic stimulation.
(4) Decreased secretion of acid and pepsin by the stomach.
(5) Prolonged transit through the stomach and small bowel.
(6) Prolonged intervals between interdigestive small bowel myoelectric complexes.
(7) Increased villus height, gut hypertrophy, and increased activity of brush border enzymes in the small
intestine.
(8) Slower colonic transit.
(9) Enhanced colonic absorption of sodium and water.
(10) Slower gallbladder emptying.
❍ What is the differential diagnosis of nausea and vomiting in pregnancy?
(1) GI causes: Gastroenteritis, gastroparesis, achalasia, biliary tract disease, hepatitis, small bowel obstruction,
peptic ulcer disease, pancreatitis, and appendicitis.
(2) Genitourinary causes: Pyelonephritis, uremia, ovarian torsion, nephrolithiasis, kidney stones, and degenerating
fibroids.
(3) Metabolic disease: DKA, porphyria, Addison disease/crisis, and hyperthyroidism.
(4) Neurologic disorders: Pseudotumor cerebri, vestibular lesions, migraines, and CNS tumor.
(5) Pregnancy-related conditions: Acute fatty liver of pregnancy and preeclampsia.
(6) Miscellaneous: Drug toxicity/intolerance and psychological.
❍ Which hormones influence nausea and vomiting in pregnancy?
Peak levels of human chorionic gonadotropin (hCG) correlate temporally with the peak symptoms of nausea
and vomiting. The extent of its emetogenic stimulus may be increased in conditions where there is an increased
placental mass, such as in multiple gestation or molar pregnancy. Estrogen and progesterone levels are also
correlated with the frequency of nausea and vomiting. These hormones relax smooth muscle and slow GI transit
time. Estrogens^2 in oral contraceptive pills (OCPs) show a dose-response relationship for nausea and vomiting,
and women thus sensitized have an increased likelihood of exhibiting nausea and vomiting in pregnancy. Cigarette
smokers are less likely to have nausea and vomiting in pregnancy, which may be due to the associated lower levels
of both hCG and estradiol, compared with nonsmokers.
❍ What features are associated with a higher risk of nausea and vomiting of early pregnancy?
Primigravid status, multiple gestations, younger age, nonsmokers, obesity, <12 years of education, previous nausea
with OCP use, history of acid reflux, and corpus luteum primarily on the right ovary.
❍ What physical findings suggest that nausea and vomiting in a pregnant woman may be due to an
independent disease process?
Abdominal pain or tenderness that is worse than the mild epigastric discomfort that occurs after retching, fever,
headache, goiter, or an abnormal neurologic examination. A caveat: severe nausea and vomiting may rarely cause a
neurologic abnormality, such as thiamine-deficiency encephalopathy or central pontine myelinolysis.