Antepartum fetal surveillance with serial tests (e.g., nonstress tests, biophysical profiles) is indicated in pregnancies in which the risk of antepartum fetal demise is increased.

• Indications of antepartum fetal surveillance (evaluation for fetal well-being)

◦ Amniotic fluid volume
◦ Fetal breathing movement
◦ Fetal movement
◦ Fetal tone

• 2 points per category if normal(maximum 10/10) • 0 points per category if abnormal | 8 or 10 points | • Equivocal: 6 points • Abnormal: 0, 2, or 4 points • Oligohydramnios | | Contraction stress test | External fetal heart rate monitoring during spontaneous or induced (eg, oxytocin, nipple stimulation) uterine contractions | No late or recurrent variable decelerations | Late decelerations with >50% of contractions | | Doppler sonography of the umbilical artery | Evaluation of umbilical artery flow in fetal intrauterine growth restriction only | High-velocity diastolic flow in umbilical artery | Decreased, absent, or reversed end-diastolic flow |

• First step in antepartum fetal surveillance is Nonstress test

Reactive NSTs are consistent with adequate fetal oxygenation and the risk of fetal acidemia is low (high NPV)

Nonreactive NSTs can be due to a benign cause (eg, fetal sleep cycle) or may indicate fetal hypoxemia and acidemia. Because a nonreactive NST result is nonspecific (high false-positive rate and low positive predictive value for fetal compromise) additional antepartum testing (eg, biophysical profile) is indicated

Most common cause of a nonreactive NST is a quiet fetal sleep cycle (which lasts ≤40 min).

A typical NST is 20 minutes, but a nonreactive NST is extended (eg, 40-120 min) to ensure that fetal activity outside of quiet sleep is captured. Due to a high false-positive rate and non-specificity, nonreactive NSTs are further evaluated with either a biophysical profile or contraction stress test before concluding that the fetus may be hypoxemic and needs intervention.

vibroacoustic stimulation→ wakes baby up

• A BPP includes an NST plus an ultrasound for amniotic fluid volume, fetal movement, tone, and breathing within 30 minutes.
• A CST is similar to an NST, but contractions are first induced with oxytocin or nipple stimulation. Patients with contraindications to uterine contractions (eg, placenta previa [as in this patient], history of uterine rupture) should not undergo a CST.  Therefore, the most appropriate next test for this patient is a BPP.
• Biophysical profile

Nonreactive NST result and normal BPP score (8-10) receive reassurance and routine care.

if BPP results are equivocal (ie, score of 6 of 10)→ contraction stress test is used to assess fetal well-being

abnormal BPP scores(particularly ≤4)→severe hypoxemia with imminent risk of stillbirth;  delivery is typically indicated.

Immediate delivery may be indicated for severe recurrent fetal heart rate decelerations, which typically indicate fetal hypoxia and acidemia. In contrast, a nonreactive NST result is followed by evaluation with a BPP. If the BPP result is also abnormal (eg, no fetal tone, no fetal movement), delivery may be indicated.

• Umbilical artery Doppler ultrasound

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