A 28-year-old woman, gravida 2 para 1, at 35 weeks gestation comes to the office for evaluation of decreased fetal movement. Over the past 12 hours, the patient has felt only 4 or 5 fetal movements. She rested for an hour and felt only 2 movements, prompting her to come to the office. The patient has had no contractions, vaginal bleeding, or leakage of fluid. She has no chronic medical conditions and has had no complications during this pregnancy. The patient does not use tobacco, alcohol, or illicit drugs. Blood pressure is 136/84 mm Hg and pulse is 84/min. Fetal heart rate is 145/min on Doppler. Fundal height is 35 cm and a slight fetal movement is palpated through the abdominal wall. The remainder of the physical examination is unremarkable. Which of the following is the best next step in management of this patient?
Nonstress test | |
Reactive |
|
Nonreactive |
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Initial maternal awareness of fetal movement typically occurs at 16-20 weeks gestation, and maternal monitoring of fetal movement (eg, kick counts) begins in the third trimester (≥28 weeks gestation). Monitoring of fetal movement is a simple method for evaluating fetal activity (eg, tone, limb extension and flexion) because normal fetal activity (eg, ≥10 movements in 2 hours) typically indicates a normal fetal acid-base status and low risk of fetal demise. In contrast, hypoxemic or acidemic fetuses have reduced fetal activity as a compensatory mechanism to divert blood flow from peripheral tissues to preserve oxygen for the CNS. Therefore, maternal sensation of decreased fetal movement requires further evaluation of fetal status (Choice D). The best next step in patients with decreased fetal movement is a nonstress test (NST), a noninvasive method of tracking fetal heart rates over time (eg, 20-40 minutes).
Reactive NSTs (eg, ≥2 accelerations, baseline 110-160/min, moderate variability) are consistent with a normal fetal acid-base status.
Nonreactive NSTs (eg, <2 accelerations) may indicate fetal hypoxemia and acidemia. Additional antepartum testing (eg, biophysical profile) is indicated in these patients.
(Choice A) An amniotic fluid index is performed in patients with decreased fetal movement if the NST is nonreactive or if fetal decelerations are present to evaluate for oligohydramnios, which may indicate chronic uteroplacental insufficiency and impending fetal compromise.
(Choice B) Induction of labor is indicated in patients at ≥39 weeks gestation with persistent decreased fetal movement due to the risk of unexplained stillbirth in these patients. It can also be performed at earlier gestation if significant signs of fetal distress (eg, late fetal decelerations) or maternal deterioration are present.
(Choice E) Umbilical artery Doppler ultrasound is used to monitor fetal status in pregnancies complicated by maternal hypertension or fetal growth restriction. It is not used in the evaluation of decreased fetal movement.
Educational objective:
The maternal sensation of decreased fetal movement may be due to fetal hypoxemia or acidemia and is concerning for increased risk of demise. Patients with decreased fetal movement require further investigation of fetal status with nonstress testing.