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Abstract: Placental vascular anastomoses in monochorionic twins may lead to acute or chronic inter-twin transfusion. We report an uncommon form of chronic inter-twin transfusion, referred to as twin anemia–polycythemia sequence (TAPS), with severe anemia in one twin and polycythemia in the other, without the characteristically associated twin oligo-polyhydramnios sequence (TOPS) seen in the classical twin-to-twin transfusion syndrome (TTTS). The clinical course and placental characteristics of two pairs of monochorionic twins with TAPS born at, respectively, 33 and 34 weeks'' gestation were reviewed. Serial fetal ultrasound examinations revealed no signs of TOPS. At birth, both donor twins were severely anemic requiring blood transfusion and both recipients were polycythemic, one requiring partial volume exchange transfusions. Inter-twin difference in reticulocyte counts was extremely high, suggesting a chronic form of inter-twin blood transfusion. Placental injection studies revealed a preponderance of very small (<1mm) arterio-venous anastomoses in one direction. In conclusion, chronic inter-twin transfusion may lead to an uncommon form of inter-twin transfusion, named TAPS, not associated with TOPS, resulting in severe fetal or neonatal hematological complications. We hypothesize that TAPS is mediated through minuscule unidirectional anastomoses. TAPS can be diagnosed antenatally with Doppler studies and postnatally by hemoglobin and reticulocyte measurements. [Copyright &y& Elsevier]

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a disease in pregnancy characterized by maternal alloantibodies directed against the human platelet antigen (HPA). These antibodies can cause intracranial hemorrhage (ICH) or other major bleeding resulting in lifelong handicaps or death. Optimal fetal care can be provided by timely identification of pregnancies at risk. However, this can only be done by routinely antenatal screening. Whether nationwide screening is cost-effective is still being debated. HPA-1a alloantibodies are estimated to be found in 1 in 400 pregnancies resulting in severe burden and fetal ICH in 1 in 10.000 pregnancies. Antenatal treatment is focused on the prevention of fetal ICH and consists of weekly maternal IVIg administration. In high-risk FNAIT treatment should be initiated at 12–18 weeks gestational age using high dosage and in standard-risk FNAIT at 20–28 weeks gestational age using a lower dosage. Postnatal prophylactic platelet transfusions are often given in case of severe thrombocytopenia to prevent bleedings. The optimal threshold and product for postnatal transfusion is not known and international consensus is lacking. In this review practical guidelines for antenatal and postnatal management are offered to clinicians that face the challenge of reducing the risk of bleeding in fetuses and infants affected by FNAIT. [ABSTRACT FROM AUTHOR]