MCDA twin pregnancy: TAPS developed into twin-twin transfusion syndrome?

Twin–twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS) are diseases caused by imbalanced intertwin blood transfusion through placental anastomoses. TTTS and TAPS each have their unique characteristics. Here we report a rare monochorionic-diamniotic (MCDA) twin characterised by both features of TTTS and TAPS spontaneously. Ultrasound examination was performed on the MCDA pregnant woman during 3rd semester of pregnancy. The prenatal Ultrasound technique MVTM Flow was utilised to observe the placenta. Postnatal Computerised tomography (CT) scan was performed on the placenta injected with barium sulfate and 3D reconstruction was generated. The macroscopic placental examination was investigated after dye-injection. Clinical information was collected and the condition of the postpartum fetuses was observed. The ultrasound scan led to the diagnosis of TTTS (Stage 3), twin 1 (donor), and twin 2 (recipient). The placental echogenicity of twin 2 was significantly higher than that of twin 1. There was a 36% weight difference between the two fetuses. Two stillbirths were delivered. Twin 1 was born very plethoric with a birthweight of 1380g and twin 2 was very pale with a birthweight of 930g. The maternal side of the placenta displayed a plethoric placental share for twin 1 and a pale placental share for twin 2, similar to their skin colour, raising suspicion of TAPS. Both minuscule and large anastomoses could be found in the placenta. Although TTTS and TAPS are two separate diseases, this case adds to the knowledge of TAPS with TTTS. Spontaneous co-existing TAPS combining TTTS might be identical to the hypothesis that TTTS initially started with TAPS. It is unclear whether TAPS with TTTS represents a new spectrum of a clinical entity. More attention should be paid to this condition for future prenatal and postnatal diagnosis and treatment.