MCQ Obstetrics Answer 26

The correct answer is E.

Labor and delivery represents a process of stress for the fetus. With each uterine contraction, blood flow to the placenta decreases, and the fetus is exposed to transient hypoxia. As the labor progresses and more and more contractions occur, this hypoxia can eventually lead to a change from aerobic to anaerobic metabolism. This change can lead to a buildup of acid in the fetus, or fetal acidemia. However, most fetuses tolerate the stress of labor and delivery just fine.

The fetus has a variety of protective mechanisms, including a blood buffering system and the diving reflex (a lowering of the heart rate in times of hypoxic stress), to protect it from becoming dangerously acidemic. Electronic fetal monitoring is used to determine whether the fetus is becoming dangerously acidemic or "stressed" during labor so that delivery can occur prior to hypoxic damage to organs. Unfortunately, electronic fetal monitoring is not a very specific tool for identifying fetal acidemia.

Many fetuses with a non-reassuring fetal heart rate tracing do not have acidemia and are not in distress. However, it can be very difficult to distinguish non-acidemic fetuses with non-reassuring fetal heart rate tracings from acidemic fetuses with non-reassuring fetal heart rate tracings. Thus, the delivery of many fetuses is expedited because of the concern for fetal acidemia when, in fact, the fetus is not acidemic at all. Thus, it is most accurate to state, as is in this case, that the fetus was delivered because of the non-reassuring fetal heart rate tracing.

Fetal acidemia (choice A) is not the reason for delivery. In fact, there is a strong likelihood that this fetus is not acidemic at all.

Fetal distress (choice B) is not the reason for delivery. There is a strong likelihood that this fetus is perfectly healthy and will have high neonatal APGAR scores and no distress at all.

Fetal hypoxic encephalopathy (choice C) is not the reason for delivery. The desire to prevent hypoxic/acidemic damage to organs, including the brain, is the reason for expediting delivery. However, the non-reassuring fetal tracing does not indicate that hypoxic encephalopathy is necessarily occurring.

Low neonatal APGAR scores (choice D) can be a marker of fetal acidemia. However, many fetuses with non-reassuring fetal heart rate tracings do not have low neonatal APGAR scores.

Category: Obstetrics MCQs