title: Twin Anemia Polycythemia Sequence: Current Views on Pathogenesis, Diagnostic Criteria, Perinatal Management, and Outcome.
abstract: 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 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.
authors.affiliation: Division of Fetal Medicine,Department of Obstetrics,Leiden University Medical Centre,Leiden,the Netherlands.
authors.forename: Lisanne S A
authors.initials: LS
authors.lastname: Tollenaar
authors.affiliation: Division of Fetal Medicine,Department of Obstetrics,Leiden University Medical Centre,Leiden,the Netherlands.
authors.forename: Femke
authors.initials: F
authors.lastname: Slaghekke
authors.affiliation: Division of Fetal Medicine,Department of Obstetrics,Leiden University Medical Centre,Leiden,the Netherlands.
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Middeldorp
authors.affiliation: Division of Fetal Medicine,Department of Obstetrics,Leiden University Medical Centre,Leiden,the Netherlands.
authors.forename: Frans J
authors.initials: FJ
authors.lastname: Klumper
authors.affiliation: Division of Fetal Medicine,Department of Obstetrics,Leiden University Medical Centre,Leiden,the Netherlands.
authors.forename: Monique C
authors.initials: MC
authors.lastname: Haak
authors.affiliation: Division of Fetal Medicine,Department of Obstetrics,Leiden University Medical Centre,Leiden,the Netherlands.
authors.forename: Dick
authors.initials: D
authors.lastname: Oepkes
authors.affiliation: Division of Neonatology,Department of Pediatrics,Leiden University Medical Centre,Leiden,the Netherlands.
authors.forename: Enrico
authors.initials: E
authors.lastname: Lopriore
mesh_terms: D000740:Anemia / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy; D005260:Female; D005330:Fetofetal Transfusion / Q000150:complications / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D017075:Laser Coagulation; D010920:Placenta / Q000098:blood supply / Q000503:physiopathology* / Q000601:surgery; D011086:Polycythemia / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy; D011247:Pregnancy; D059285:Pregnancy, Twin; D014430:Twins, Monozygotic
keywords: anemia; monochorionic twins; polycythemia; twin anemia polycythemia sequence