ARDMS (American Registry for Diagnostic Medical Sonography) Practice Test

In obstetric imaging, how is "viability" commonly assessed?

1. By measuring the size of the fetus

2. By detecting the fetal heartbeat

3. By evaluating the amniotic fluid level

4. By assessing maternal blood pressure

The correct answer is: By detecting the fetal heartbeat

In obstetric imaging, assessing "viability" primarily involves detecting the fetal heartbeat. The presence of a heartbeat is a critical indicator that the fetus is alive and developing normally. It signals that the cardiovascular system is functioning, which is essential for proper growth and development. Other methods, such as measuring the size of the fetus or evaluating amniotic fluid levels, can provide useful information about the pregnancy's progress and health. However, these methods do not directly confirm the presence of life. For instance, a fetus may be measured and found to be within the expected size range, but without a heartbeat, viability cannot be confirmed. Maternal blood pressure, while important for maternal and fetal health, does not directly correlate with the viability of the fetus. Thus, detecting the fetal heartbeat serves as a reliable and definitive way to assess the viability of a pregnancy, providing clear evidence that the fetus is alive.