What is the characteristic feature of a prolonged acceleration?

A prolonged acceleration is defined by its duration, specifically lasting longer than 2 minutes but less than 10 minutes. This characteristic distinguishes it from other types of fetal heart rate accelerations, which typically last for shorter periods. In the context of fetal monitoring, this duration indicates sustained fetal well-being, often associated with healthy neurological function and good oxygenation.

When evaluating the other options, it's clear that short durations (less than 15 seconds) do not meet the criteria for what defines a prolonged acceleration. Consistent heart rate drops instead describe decelerations, not accelerations, and an instant spike followed by a decline suggests a transient pattern rather than a prolonged one. Therefore, the time frame of more than 2 minutes but less than 10 minutes is what solidly characterizes a prolonged acceleration in fetal monitoring.