twin anemia-polycythemia sequence twin anemia-polycythemia sequence twin anemia-polycythemia sequence (taps) is a form of chronic inter-twin transfusion. it is distinguished from classic twin-to-twin transfusion syndrome by differing red blood cell counts between the fetuses, a relative lack of symptoms and a lack of oligohydramnios or polyhydramnios among the fetuses. twin anemia-polycythemia sequencetwin anemia-polycythemia sequence is a monochorionic twin condition characterized by a large intertwin hemoglobin difference.specialtyobstetrics monochorionic twin pregnancy complication diagnosis and staging diagnosis by doppler ultrasound measurement of the middle cerebral artery—peak systolic velocity (mca-psv) different stages of taps are identified using the criteria as shown in the following tables. postnatal classification postnatal stageintertwin hemoglobin difference (g/dl) stage 1>8.0 g/dl stage 2>11.0 g/dl stage 3>14.0 g/dl stage 4>17.0 g/dl stage 5>20.0 g/dl treatment the use of the so-called solomon technique or dichorionization in fetoscopic laser therapy for twin-to-twin transfusion syndrome is proven to be beneficial in preventing post-laser taps. with this technique, not only all anastomoses are coagulated (closed) but also a line is drawn between those in order to coagulate anastomoses that might not (yet) be visible during fetoscopy. it should be stressed that the success of such a technique is highly dependent on the specific situation. for example, when one of the fetuses obstructs the view on the vascular equator (the part of the placenta where the anastomoses need to be coagulated), complete dichorionization by the solomon technique might not be possible. perinatal outcome