What is the next step for a patient at 38.5 weeks gestation with a reactive Non-Stress Test (NST) who reports decreased fetal movement?

Management of Decreased Fetal Movement with Reactive NST at 38.5 Weeks

Despite the reactive NST, this patient requires immediate ultrasound evaluation with umbilical artery Doppler assessment and amniotic fluid measurement, followed by delivery planning based on these findings, as a reactive NST alone cannot exclude fetal compromise and should never be used as the sole surveillance method in pregnancies with concerning symptoms. 1

Why a Reactive NST Is Not Sufficient

• A reactive NST indicates fetal well-being only for the immediate moment and predicts safety for approximately one week in low-risk pregnancies, but it does not exclude underlying placental insufficiency or fetal growth restriction 2, 3
• Normal fetal heart rate patterns occur in early or compensated fetal compromise while the fetus is still adapting to chronic hypoxemia through blood flow redistribution—heart rate changes appear late in the deterioration sequence, only after significant vascular changes are already present 1
• Case reports document severe fetal compromise including massive intracranial hemorrhage occurring despite reassuring biophysical profile scores, demonstrating the limitations of heart rate-based testing alone 4
• The reactive NST has high false-positive rates and should be integrated with other assessment modalities rather than viewed as a stand-alone test 3

Immediate Next Steps

1. Ultrasound Evaluation (Perform Immediately)

Obtain comprehensive ultrasound assessment including: 5

• Umbilical artery Doppler velocimetry - This is the primary surveillance tool that detects placental dysfunction before heart rate changes emerge and determines both timing and mode of delivery 1, 6
• Amniotic fluid volume measurement - Decreased amniotic fluid reflects chronic fetal hypoxemia from decreased renal perfusion and urine production 5
• Estimated fetal weight with growth percentile - To identify potential fetal growth restriction, which occurs in up to 10% of pregnancies and doubles the fetal death rate 1
• Biophysical profile components - Assess fetal breathing movements, body movements, and tone as indicators of acute fetal well-being 5

2. Interpretation Algorithm Based on Findings

If umbilical artery Doppler is normal AND amniotic fluid is normal: 1, 6

• Proceed with delivery planning at 38.5 weeks as this is appropriate timing for term pregnancy
• Induction of labor is reasonable with continuous electronic fetal monitoring throughout labor 1

If umbilical artery Doppler shows decreased diastolic flow (but not absent/reversed): 1, 6

• Delivery should occur immediately at 38.5 weeks—do not delay as recommended delivery timing is 37 weeks for this finding 6
• Consider cesarean delivery if other concerning features are present 6

If absent end-diastolic velocity (AEDV) is detected: 1, 6

• This represents severe placental dysfunction—delivery should have occurred by 33-34 weeks 6
• Cesarean delivery should be strongly considered as 75-95% of these pregnancies require cesarean for intrapartum fetal heart rate abnormalities 7, 6
• Proceed to immediate delivery regardless of the reactive NST 1

If reversed end-diastolic velocity (REDV) is detected: 1, 6

• This indicates critical placental failure—delivery should have occurred by 30-32 weeks 6
• Cesarean delivery is indicated due to high risk of fetal demise and inability to tolerate labor 6
• Proceed to urgent cesarean section 6

If oligohydramnios is present (AFI <5 cm or maximum vertical pocket <2 cm): 5, 7

• Oligohydramnios at term is an independent indication for delivery 5, 7
• The combination of decreased fetal movement with oligohydramnios significantly increases perinatal risk 7
• Proceed with delivery planning, with mode determined by Doppler findings and clinical scenario 7

Intrapartum Management Considerations

• Continuous electronic fetal monitoring is mandatory during labor as fetuses with any degree of compromise are at high risk for intrapartum hypoxia even when antepartum testing was reassuring 1
• If fetal growth restriction with abnormal Doppler is identified, expect 75-95% likelihood of requiring cesarean delivery for intrapartum fetal heart rate decelerations 7, 6
• Avoid augmentation of labor if contractions are already adequate, as increasing uterine activity worsens placental perfusion and accelerates fetal deterioration in compromised fetuses 6

Critical Pitfalls to Avoid

• Never rely on NST alone for fetal surveillance in pregnancies with concerning symptoms—the test has inherent limitations and provides only a narrow window to view fetal status 1, 3
• Do not delay delivery based on a reactive NST if Doppler abnormalities are identified, as Doppler findings take precedence over heart rate patterns in determining timing of delivery 1, 6
• Do not assume decreased fetal movement is benign simply because the NST is reactive—maternal perception of decreased movement warrants thorough evaluation as it may indicate early fetal compromise 8
• Recognize that biophysical profile scoring can also miss severe fetal compromise, so integration of multiple assessment modalities is essential 4