The fetal cerebral Doppler in the last weeks of pregnancy can select very small fetuses unlikely to present intrapartum compromise.

Abstract

Objective: To evaluate whether, in late pregnancy, the cerebral Doppler can identify very small fetuses that are less likely to experience intrapartum compromise (IC).

Material and methods: This was a retrospective study of 282 singleton pregnancies that underwent an ultrasound scan at 32 + 0- 40 + 6 weeks and were delivered after induction, or spontaneous onset of labor. Very small fetuses were defined as fetuses with estimated weight less than the 3rd centile. IC was diagnosed in case of abnormal intrapartum fetal heart rate or intrapartum fetal scalp pH < 7.20, requiring urgent cesarean section, neonatal pH below 7.10 and Apgar score at 5 min <7. The ability of the cerebral Doppler, middle cerebral artery pulsatility index, and cerebroplacental ratio, expressed in multiples of the median (MCA PI MoM and CPR MoM), to rule out the risk of IC was evaluated alone and combined with other sonographic and clinical parameters by means of logistic regression and ROC curve analyses.

Results: The only significant parameters determining IC were parity, MCA PI, and CPR MoM. [AUC 0.62 (95% CI 0.54-0.71, p = 0.012), 0.62 (95% CI 0.53-0.71, p = 0.008), 0.60 (95% CI 0.51-0.69, p = 0.020), respectively], while the best prediction was obtained combining parity with MCA PI or CPR [AUC 0.68 (95% CI 0.60-0.76), 0.67 (95% CI 0.60-0.75), p < 0.0001 for both]. Moreover, 90% of IC cases had MCA PI and CPR values below 1.1 MoM, while 100% had MCA and CPR values below 1.5 and 1.3 MoM. Finally, the negative predictive value was 82% for any combination of parameters that included either the MCA MoM or CPR MoM.

Conclusion: The cerebral Doppler can select a group of very small fetuses that are less likely to experience IC. These fetuses might be to some extent constitutionally small and might be candidates for a more conservative and individualized management.