What is the main reason why a woman who is older than 35 years may have difficulty achieving pregnancy?

Choice A reason: Vibroacoustic stimulation is a technique that uses sound to stimulate the fetus and elicit a response. It is sometimes used in conjunction with the nonstress test (NST), not the CST. The NST measures the fetal heart rate (FHR) in response to fetal movement, while the CST measures the FHR in response to uterine contractions.

Choice B reason: A negative CST result means that the FHR does not show any late decelerations during at least three contractions in a 10-minute period. Late decelerations are decreases in the FHR that begin after the peak of a contraction and return to the baseline after the contraction ends. They indicate uteroplacental insufficiency, which means that the placenta is not delivering enough oxygen and nutrients to the fetus. A negative CST result is reassuring and suggests that the fetus is well-oxygenated and can tolerate labor².

Choice C reason: The CST is not an invasive test, as it does not involve inserting any instruments or devices into the uterus or the fetus. However, it does require stimulating contractions, either by giving the pregnant woman oxytocin (a hormone that causes uterine contractions) or by having her rub her nipples (which also releases oxytocin). The contractions can be uncomfortable and may trigger preterm labor in some cases.

Choice D reason: The CST is not more effective than the NST if the membranes have already been ruptured. In fact, the CST is contraindicated (not recommended) in women who have ruptured membranes, as it can increase the risk of infection and bleeding. The NST is a safer and simpler alternative to the CST, as it does not require stimulating contractions. However, the NST may not be as reliable as the CST in detecting fetal compromise.

Choice A reason: Amniocentesis for fetal lung maturity is not an expected diagnostic procedure for a pregnant woman with bright red, painless vaginal bleeding. It is a procedure that involves inserting a needle into the amniotic sac to obtain a sample of amniotic fluid, which can be used to assess the fetal lung development. It is usually done in late pregnancy or preterm labor, not in the second trimester.

Choice B reason: Contraction stress test (CST) is not an expected diagnostic procedure for a pregnant woman with bright red, painless vaginal bleeding. It is a test that involves stimulating uterine contractions, either by nipple stimulation or oxytocin infusion, to evaluate the fetal heart rate response. It is used to assess fetal well-being and placental function, not to diagnose the cause of bleeding.

Choice C reason: Internal fetal monitoring is not an expected diagnostic procedure for a pregnant woman with bright red, painless vaginal bleeding. It is a method of measuring the fetal heart rate and uterine contractions using electrodes or catheters that are inserted through the cervix and attached to the fetal scalp or the amniotic sac. It is usually done during labor, not in the second trimester.

Choice D reason: Ultrasound for placental location is an expected diagnostic procedure for a pregnant woman with bright red, painless vaginal bleeding. It is a test that uses sound waves to create an image of the uterus, the placenta, and the fetus. It can help to determine the position and attachment of the placenta, which can be the cause of bleeding if it is low-lying or covering the cervix (placenta previa).

Choice E reason: None of the above is not a correct answer. There is one expected diagnostic procedure for a pregnant woman with bright red, painless vaginal bleeding, which is ultrasound for placental location.