For what reason might a newborn infant with a cardiac defect, such as coarctation of the aorta, receive prostaglandin E?

A. Unruptured membranes: Internal fetal monitoring devices, such as a fetal scalp electrode or intrauterine pressure catheter, require rupture of membranes to access the amniotic fluid and fetal scalp. Attempting insertion with intact membranes increases the risk of trauma, infection, and procedural failure.

B. Cervix is dilated to 4 cm: A cervical dilation of 4 cm is typically sufficient for safe internal monitoring once membranes are ruptured. The degree of dilation itself does not prevent application, provided other criteria for internal monitoring are met.

C. External monitors are currently being used: External monitoring is noninvasive and can be used concurrently or as an initial step. The presence of external monitors does not contraindicate internal monitoring; internal devices are considered when more accurate fetal heart rate or contraction data are needed.

D. Fetus has a known heart defect: Some fetal heart defects may alter baseline heart rate or variability but do not automatically preclude the use of internal monitoring devices. Internal monitoring can still be applied safely if membranes are ruptured and other clinical criteria are met.

A. Blocking the opening to the cervix: Intrauterine devices are placed inside the uterine cavity and do not physically block the cervical opening. Cervical barriers such as diaphragms or cervical caps function at the level of the cervix rather than within the uterus. The contraceptive effect of an IUD occurs after sperm enter the reproductive tract.

B. Increasing the mobility of the uterus: Uterine mobility is not altered by the presence of an intrauterine device. IUDs do not affect uterine movement, peristalsis, or positioning. Their action is related to local inflammatory and biochemical effects within the uterine environment.

C. Preventing sperm from reaching the fallopian tubes: IUDs do not create a mechanical barrier that blocks sperm transport through the cervix or uterus. Sperm may still enter the uterine cavity, but their function and survival are impaired. Fertilization is prevented through changes in the uterine and tubal environment.

D. Not keeps sperm from reaching the egg by creating a hostile environment within the uterus: IUDs create a local inflammatory response in the uterus that is toxic to sperm and ova. Copper IUDs release ions that reduce sperm motility and viability, while hormonal IUDs thicken cervical mucus and alter the endometrium. These changes interfere with fertilization and implantation.