36 Obstetrics and Gynecology Board Review •••
❍ Is gastric emptying time increased or decreased during pregnancy?
In nonpregnant patients 60% of a meal is emptied in 90 min. This time is found almost double during pregnancy.
❍ In normal pregnancy, what two components of the liver function test change appreciably and in which
directions?
Alkaline phosphatase increases, while albumin levels decrease.
❍ If a healthy pregnant woman were to undergo a liver biopsy, what would you see histologically?
Normal liver morphology even with electron microscopy.
❍ What is the regulator of gall bladder contraction and why is it compromised in pregnancy?
Cholecystokinin (CCK) causes gall bladder contraction and pancreatic enzyme release. It is formed in the type
I mucosal cell of the duodenum and proximal jejunum. High levels of estrogen and progesterone inhibit CCK
action on smooth muscle cells in the gall bladder causing impaired contraction and high residual volume.
❍ Name two GI disorders of pregnancy that most commonly present in the third trimester.
Acute fatty liver of pregnancy and cholestasis of pregnancy.
❍ Hyperplasia of the pituitary occurs in pregnancy. How large does the pituitary grow?
The pituitary enlarges by 135% compared with nonpregnant controls. This does not compress the optic chiasm.
❍ Is it possible to maintain a pregnancy after a hypophysectomy?
Yes. The pituitary gland is not necessary for the maintenance of pregnancy. Women have undergone
hypophysectomy and completed pregnancy with replacement of glucocorticoids, thyroid hormone, and
vasopressin.
❍ Which thyroid function tests reflect true thyroid function in pregnancy?
TSH, free T3, and free T4 are the three tests not affected by pregnancy after the first trimester. The other
parameters (total T4, total T3, and T3 uptake) are altered due to the increase in thyroid-binding globulin that
occurs as a result of the high estrogen state.
❍ Name the thyroid hormones that cross the placenta.
Thyroid-releasing hormone can cross the placenta and may stimulate the fetal pituitary to secrete TSH. There
is minimal transfer, if any, of thyroxine, triiodothyroxine, or reverse triiodothyroxine from the maternal to the
fetal compartment. The fetal thyroid function is independent of the maternal thyroid status except in the case of
autoimmune thyroid disease when stimulatory or inhibitory IgG crosses the placenta and affects the fetal thyroid.
❍ Describe the trend of TSH in pregnancy. Does it cross the placenta.
TSH decreases in the first trimester then normalizes throughout the rest of the pregnancy. TSH does not cross the
placenta.
❍ What is the correlation between TSH and hCG levels during pregnancy?
TSH levels are inversely correlated with hCG levels.