26 Obstetrics and Gynecology Board Review •••
❍ What increased concentrations of oxytocin receptors are found in the myometrium during pregnancy at term?
They are found to increase 300-fold as compared with prepregnancy.
❍ At what gestational age, does the uterus rise out of the pelvis?
About 12 weeks.
❍ During a term Cesarean section you are examining the uterus before making the uterine incision. What
direction of rotation are you most likely to see?
Dextrorotation (to the right)—usually results from the presence of the rectosigmoid.
❍ In late pregnancy what is the approximate rate of blood flow to the uterus?
450 to 650 mL/min.
❍ What are the three substances thought to take part in the regulation of uterine blood flow during pregnancy
and what are their effects on the uterine flow.
(1) Estrogen (vasodilation).
(2) Catecholamines (increased sensitivity even when controlled for blood pressure).
(3) Angiotensin II (vascular refractoriness).
❍ At term what percentage of uterine blood flow is directed toward the placenta?
80% to 90%.
❍ What mechanism is responsible for the increased maternal-placental and fetal-placental blood flow in
pregnancy?
Maternal-placental is principally caused by vasodilation of existing vessels; and fetal-placental is principally caused
by increasing numbers of placental vessels.
❍ During a strong contraction (50 mmHg) by how much is uterine blood flow reduced?
60%.
❍ What are the normal physical changes in the cervix during pregnancy?
Softening and cyanosis. This is known as Goodell sign.
❍ What is Chadwick sign?
This is described as a bluish discoloration of the vagina.
❍ Microscopically, how are the cervical changes during pregnancy manifested?
Increased vascularity and edema with hypertrophy and hyperplasia of cervical glands.
❍ What fraction of the cervical mass is composed of glands in the pregnant state?
50%