reactive NST
A normal non-stress test result showing appropriate fetal heart rate accelerations in response to fetal movement.
Full Definition
A reactive non-stress test (NST) demonstrates fetal well-being through the presence of adequate fetal heart rate accelerations associated with fetal movement. The criteria for reactivity include at least two accelerations of 15 beats per minute above baseline lasting for 15 seconds within a 20-minute period (15×15×2 rule). For pregnancies less than 32 weeks, the criteria are modified to 10 beats per minute above baseline for 10 seconds (10×10×2 rule). A reactive NST suggests intact fetal neurologic function and adequate oxygenation, while a non-reactive NST requires further evaluation through extended monitoring, vibroacoustic stimulation, or additional testing such as a biophysical profile.
Usage
Usage note: Always specify 'reactive' or 'non-reactive' when documenting NST results. Include specific criteria met when possible.
In Context
- "The NST was reactive with three appropriate accelerations noted during the 20-minute monitoring period." — Antepartum testing report
- "Given the reactive NST and normal amniotic fluid volume, routine surveillance was continued." — Maternal-fetal medicine consultation