BSNC 5000 - OB Questions and Answers with Verified Solutions |
Latest Update
QUESTION
Uteroplacental circulation
Answer:
- uterine arterial blood supply shown at right
- both the ovarian and uterine arteries supply the myometrium
- spiral arteries elongate as the endometrium cyclically thickens to accommodate the possibility
of implantation of a blastocyst
QUESTION
Intervillous space
Answer:
- the space in the placenta in which maternal blood bathes chorionic villi, allowing the exchange
of materials between the fetal and maternal circulations.
Divided into 3 parts:
- arterial circulation
- circulation in the intervillous space
- venous drainage
QUESTION
Hemodynamics of uteroplacental circulation
Answer:
Volume of placental blood flow - 600-700mL/min
Pressure in supplying uterine artery - 80-100 mmHg
Pressure in spiral arteries - 70mmHg
Pressure in draining uterine vein - 10mmHg
QUESTION
Maternal intravascular volume changes
Answer:
- plasma volume increases by up to 1L
- rise in #rbc/blood volume but to lesser extent (placental lactogen stimulates production of
erythropoietin)
- dilutional gap causes physiological anemia
, QUESTION
Blood pressure change in normal pregnancy
Answer:
- progesterone relaxes smooth muscle in the wall of blood vessels
- relaxin increases systemic arterial compliance (vasodilation) to reduce peripheral resistance
- decreases the effective circulating volume (same volume but larger space to fill) - effects of
vasodilation:
•non-osmotic release of vasopressin/ADH
•activation of SNS and RAAS increases plasma volume for adequate organ perfusion
QUESTION
Maternal cardiovascular changes
Answer:
- increasing volume -> increase in preload -> increased contractility.
- decrease in vascular resistance reduces afterload which increases cardiac output by nearly 50%
thereby increasing the efficiency of the heart.
QUESTION
Risk of thrombosis during pregnancy
Answer:
- increase in clotting factors increases risk of thrombosis about 2x
- platelet count decreases as pregnancy progresses
- diulutional effects
- sequestering in the intervillous spaces of the placenta
QUESTION
Postpartum risk of thrombosis
Answer:
- returns to normal 6-8 weeks postpartum
- risk of thrombosis increases 5.5x in postpartum period since platelets are no longer sequestered
by placenta
QUESTION
Basal metabolic rate during pregnancy
Answer:
- increases by about 14% over term of pregnancy
- causes an increase in oxygen consumption as pregnancy progresses to accommodate increase in
nutrition and energy use by both mother and fetus
Latest Update
QUESTION
Uteroplacental circulation
Answer:
- uterine arterial blood supply shown at right
- both the ovarian and uterine arteries supply the myometrium
- spiral arteries elongate as the endometrium cyclically thickens to accommodate the possibility
of implantation of a blastocyst
QUESTION
Intervillous space
Answer:
- the space in the placenta in which maternal blood bathes chorionic villi, allowing the exchange
of materials between the fetal and maternal circulations.
Divided into 3 parts:
- arterial circulation
- circulation in the intervillous space
- venous drainage
QUESTION
Hemodynamics of uteroplacental circulation
Answer:
Volume of placental blood flow - 600-700mL/min
Pressure in supplying uterine artery - 80-100 mmHg
Pressure in spiral arteries - 70mmHg
Pressure in draining uterine vein - 10mmHg
QUESTION
Maternal intravascular volume changes
Answer:
- plasma volume increases by up to 1L
- rise in #rbc/blood volume but to lesser extent (placental lactogen stimulates production of
erythropoietin)
- dilutional gap causes physiological anemia
, QUESTION
Blood pressure change in normal pregnancy
Answer:
- progesterone relaxes smooth muscle in the wall of blood vessels
- relaxin increases systemic arterial compliance (vasodilation) to reduce peripheral resistance
- decreases the effective circulating volume (same volume but larger space to fill) - effects of
vasodilation:
•non-osmotic release of vasopressin/ADH
•activation of SNS and RAAS increases plasma volume for adequate organ perfusion
QUESTION
Maternal cardiovascular changes
Answer:
- increasing volume -> increase in preload -> increased contractility.
- decrease in vascular resistance reduces afterload which increases cardiac output by nearly 50%
thereby increasing the efficiency of the heart.
QUESTION
Risk of thrombosis during pregnancy
Answer:
- increase in clotting factors increases risk of thrombosis about 2x
- platelet count decreases as pregnancy progresses
- diulutional effects
- sequestering in the intervillous spaces of the placenta
QUESTION
Postpartum risk of thrombosis
Answer:
- returns to normal 6-8 weeks postpartum
- risk of thrombosis increases 5.5x in postpartum period since platelets are no longer sequestered
by placenta
QUESTION
Basal metabolic rate during pregnancy
Answer:
- increases by about 14% over term of pregnancy
- causes an increase in oxygen consumption as pregnancy progresses to accommodate increase in
nutrition and energy use by both mother and fetus
