192 Obstetrics and Gynecology Board Review •••
❍ What are two therapeutic options that might ameliorate polyhydramnios?
- Therapeutic amniotic fluid drainage via amniocentesis.
- Maternal indomethacin administration.
❍ What is the mechanism of action of prostaglandin synthetase inhibitors in decreasing amniotic fluid?
These medications stimulate fetal secretion of arginine vasopressin and facilitate vasopressin-induced renal
antidiuretic responses as well as reduced renal blood flow, thereby reducing fetal urine flow. These medications may
also impair production or enhance reabsorption of liquid in the lungs.
❍ What is the primary fetal concern with the use of indomethacin?
Constriction of the ductus arteriosus.
❍ Why should rapid decompression of a gravid uterus with polyhydramnios be avoided?
Rapid decompression may result in cord prolapse or placental abruption.