Fetal anemia as a result of massive fetomaternal haemorrage: A case report

Background Fetal anemia is most commonly immune-related, resulting from red-blood-cell alloimmunization. Less common are non-immune causes, such as fetomaternal haemorrhage (FMH), Parvovirus B19 infection, hemoglobinopathies and complications in monochorionic twin pregnancies. Massive FMH happens in up to 1:1000 births. It is defined as transfusion of>20% of the fetal blood volume, leading to an increased morbidity and mortality in the perinatal period and is the assumed reason for around 3-5% of fetal deaths with no apparent reason.

Methods We present the case of a 16-year-old healthy primigravida with suspected fetal anemia at 30+4 weeks presenting after being followed for stable positive Anti-Cw (1:512) since the beginning of the pregnancy. She was referred with elevated middle cerebral artery peak systolic velocity (MCA-PSV) in the context of her regular follow-up for positive antibodies. As the stable titre of Anti-Cw was not a plausible cause of the fetal anemia, we also performed flow cytometry (FC), which demonstrated the presence of fetal blood cells (160ml) in the maternal blood.

Results The fetus required 4 cycles of intrauterine transfusions (IUT) and antenatal corticosteroid administration. The pregnancy resulted in preterm delivery via caesarean section of a healthy newborn, due to repeated elevated MCA-PSV and sinusoidal heart rate pattern in CTG.

Conclusion This case study shows how the cause of fetal anemia should not just be presumed, but always researched thoroughly.

In our case, the finding of the elevated MCA-PSV, although controlled for a different reason, resulted in the timely transfer to our tertiary perinatal center, where massive FMH was diagnosed and the further management was planned accordingly.

When reoccurring massive FMH, as in our case, is detected, repeated FBS and IUT as well as preterm delivery may be needed. Caesarean section is in this case the method of choice for delivery, due to less stress on the already weak placental circulation in comparison to vaginal delivery.

 

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Artikel online veröffentlicht:
16. Oktober 2025