Management of spontaneous fetomaternal hemorrhage (FMH)

FHR: fetal heart rate; MCA-PSV: middle cerebral artery peak systolic velocity reported in MoMs; MoMs: multiples of the median; K-B: Kleihauer-Betke acid elution assay; FMH: fetomaternal hemorrhage; BPP: biophysical profile; GA: gestational age.
* A nonreassuring biophysical profile score in this setting is generally an indication for prompt delivery because of the increased risk of fetal demise with expectant management; however, this decision must be made on a case-by-case basis taking into account factors such as gestational age and other findings (eg, ultrasound and laboratory results; maternal medical, obstetric, and family history).
¶ Refer to the UpToDate topic on spontaneous massive fetomaternal hemorrhage for information on how to determine the presence and volume of fetomaternal bleeding. Either a Kleihauer-Betke acid elution assay or flow cytometry can be used.
Δ Refer to the UpToDate topic on nonimmune hydrops.
◊ In a nonanemic fetus with a reassuring biophysical profile score, the possibility of a pseudosinusoidal pattern should be considered. There is no consensus on the exact definition. This pattern may be related to maternal opioid or sedative administration and is typically transient and associated with a good fetal outcome.
§ The combination of MCA-PSV ≥1.5 and FMH >20% of fetal blood volume suggests moderate or severe fetal anemia due to fetomaternal bleeding.
¥ 5 percentage point increase (eg, from 20 to 25%).
‡ These cases are rare, and no guidelines for antepartum fetal surveillance exist. The author performs a nonstress test or biophysical profile twice weekly and Doppler ultrasound MCA-PSV weekly until delivery in an attempt to identify recurrent significant FMH.
† The decision to deliver or perform intrauterine transfusion assumes appropriate resources are available. If unavailable, consultation with maternal-fetal medicine and/or neonatology specialists at another hospital should be initiated to discuss potential transfer.
** Repetitive MCA-PSV ≥1.5 or 5% increase in FMH indicates ongoing FMH. We suggest delivery for these patients because repetitive intrauterine transfusions may not be sufficient to prevent fetal mortality.