Twin Anemia Polycythemia Sequence: Current Views on Pathogenesis, Diagnostic Criteria, Perinatal Management, and Outcome

• Published in: Twin research and human genetics Vol. 19; no. 3; pp. 222 - 233
• Main Authors: Tollenaar, Lisanne S. A., Slaghekke, Femke, Middeldorp, Johanna M., Klumper, Frans J., Haak, Monique C., Oepkes, Dick, Lopriore, Enrico
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01-06-2016
• Subjects: Anemia; Anemia - epidemiology; Anemia - etiology; Anemia - physiopathology; Anemia - therapy; Blood transfusion; Blood transfusions; Diagnosis; Epidemiology; Female; Fetofetal Transfusion - complications; Fetofetal Transfusion - physiopathology; Fetofetal Transfusion - therapy; Fetuses; Hemoglobin; Humans; Laser Coagulation; Lasers; Morbidity; Neonates; Pathogenesis; Placenta; Placenta - blood supply; Placenta - physiopathology; Placenta - surgery; Polycythemia; Polycythemia - epidemiology; Polycythemia - etiology; Polycythemia - physiopathology; Polycythemia - therapy; Pregnancy; Pregnancy, Twin; Prenatal care; Surgery; Twins; Twins, Monozygotic; Ultrasonic imaging; polycythemia; monochorionic twins; twin anemia polycythemia sequence; anemia
• ISSN: 1832-4274; 1839-2628
• DOI: 10.1017/thg.2016.18

Monochorionic twins share a single placenta and are connected with each other through vascular anastomoses. Unbalanced inter-twin blood transfusion may lead to various complications, including twin-to-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS). TAPS was first described less than a decade ago, and the pathogenesis of TAPS results from slow blood transfusion from donor to recipient through a few minuscule vascular anastomoses. This gradually leads to anemia in the donor and polycythemia in the recipient, in the absence of twin oligo-polyhydramnios sequence (TOPS). TAPS may occur spontaneously in 3–5% of monochorionic twins or after laser surgery for TTTS. The prevalence of post-laser TAPS varies from 2% to 16% of TTTS cases, depending on the rate of residual anastomoses. Pre-natal diagnosis of TAPS is currently based on discordant measurements of the middle cerebral artery peak systolic velocity (MCA-PSV; >1.5 multiples of the median [MoM] in donors and <1.0 in recipients). Post-natal diagnosis is based on large inter-twin hemoglobin (Hb) difference (>8 g/dL), and at least one of the following: reticulocyte count ratio >1.7 or minuscule placental anastomoses. Management includes expectant management, and intra-uterine blood transfusion (IUT) with or without partial exchange transfusion (PET) or fetoscopic laser surgery. Post-laser TAPS can be prevented by using the Solomon laser surgery technique. Short-term neonatal outcome ranges from isolated inter-twin Hb differences to severe neonatal morbidity and neonatal death. Long-term neonatal outcome in post-laser TAPS is comparable with long-term outcome after treated TTTS. This review summarizes the current knowledge after 10 years of research on the pathogenesis, diagnosis, management, and outcome in TAPS.