A Rare Dichorionic Triamniotic Triplet Pregnancy with Spontaneous Twin Anemia-Polycythemia Sequence between Two Dichorionic Fetuses.

Introduction: This report presents a rare case of spontaneous twin anemia-polycythemia sequence (TAPS) between two dichorionic fetuses in a spontaneous, homozygotic, dichorionic, triamniotic, triplet pregnancy treated with multiple intrauterine blood transfusions (IUTs) and partial exchange transfusions (PETs).

Case Presentation: The pregnancy was diagnosed with stage IV TAPS at gestational week 25+1. The patient was treated with laser surgery combined with multiple IUTs and PETs. The triplets were delivered at a planned caesarean section at gestational week 28+1 with postnatal hemoglobin values of 18.21, 26.43, and 11.92 g/dL in triplet 1, 2, and 3, respectively. At 4 years of age, triplet 1 is considered healthy, triplet 2 is diagnosed with mild mental retardation, and triplet 3 with profound mental retardation and dystonic cerebral palsy.

Discussion: This is an extremely rare case of TAPS between dichorionic fetuses in a triplet pregnancy, and routine surveillance with measurement of middle cerebral artery peak systolic velocity in dichorionic pregnancies may contribute to the detection of similar cases in the future. Furthermore, this case contributes with rare long-term follow-up data of children treated for high-stage TAPS with multiple IUTs and PETs.