oxytocin challenge test

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a hypothalamic hormone stored in and released from the posterior pituitary; it may also be prepared synthetically or obtained from the posterior pituitary of domestic animals. It acts as a powerful stimulant to the pregnant uterus, especially toward the end of gestation, and also causes milk to be expressed from the alveoli into the lactiferous ducts during breastfeeding. Injection of oxytocin may be used to induce labor or strengthen uterine contractions during labor, to contract uterine muscle after delivery of the placenta, and to control postpartum hemorrhage. It must be administered with care to avoid trauma to the mother or infant by hyperactivity of uterine muscles during labor. Oxytocin also may be administered intravenously by slow drip or applied to the mucous membranes of the nasal cavity to be absorbed into the bloodstream.
oxytocin challenge test (OCT) a type of contraction stress test to assess placental reserve for transmitting oxygen to the fetus and detecting insufficiency by observing the fetal heart rate response to oxytocin-induced contraction. See also fetal monitoring.

oxytocin challenge test

a contraction stress test accomplished by administration of intravenous dilute oxytocin solution to stimulate contractions.

oxytocin challenge test

a stress test for the assessment of intrauterine function of the fetus and the placenta. It is performed to evaluate the ability of the fetus to tolerate continuation of pregnancy or the anticipated stress of labor and delivery. A dilute IV infusion of oxytocin is begun, regulated by an infusion pump. The uterine activity is monitored with a tocodynamometer, and the fetal heart rate is monitored with an ultrasonic sensor as the uterus is stimulated to contract by the oxytocin. The amount of solution infused is increased as necessary to cause the uterus to contract for 30 to 40 seconds three times every 10 minutes. The fetal heart rate is observed for variability and for the timing of any marked variation from the normal in relation to uterine contractions. Decelerations of the fetal heart rate in certain repeating patterns may indicate fetal distress. One quarter of the infants diagnosed by this method as being in distress are normal. Therefore, other tests of fetal well-being are recommended before performing an emergency cesarean section or induction of labor.

ox·y·to·cin chal·lenge test

(ok'si-tō'sin chal'ĕnj test)
A contraction stress test accomplished by administration of intravenous dilute oxytocin solution to stimulate contractions.
Synonym(s): contraction stress test.