contractions stress test (CST), ultrasound monitoring of fetal heart rate patterns during uterine contractions induced by exogenous oxytocin administration or endogenous oxytocin associated with nipple stimulation. Conceptually, decelerations (slowing) from the baseline fetal heart rate or fetal bradycardia are considered harbingers of placental insufficiency during the stress of labor. Management of such a “positive CST” depends on the nature of the altered fetal heart rate and the entire obstetric clinical situation. Indications for testing include maternal conditions (e.g., antiphospholipid syndrome, maternal cyanotic heart disease, systemic lupus erythematosus, chronic renal failure, insulin-treated diabetes, and hypertension) and pregnancy-related or fetal conditions (e.g., pregnancy-induced hypertension, preeclampsia, decreased fetal movement, oligohydramnios, polyhydramnios, intrauterine growth restriction [IUGR], postterm pregnancy, unexplained previous fetal demise, monochorionic diamniotic multiple gestation). See also fetal nonstress test, oxytocin challenge test, fetal biophysical profile.
