title: Hematological characteristics in neonates with twin anemia-polycythemia sequence (TAPS).
abstract: OBJECTIVE
  To evaluate the neonatal hematological features of monochorionic twins with twin anemia-polycythemia sequence (TAPS) and to determine the additional diagnostic value of reticulocyte count measurement.
  
  
  METHODS
  A cohort of consecutive monochorionic twins with TAPS (n = 19) was included in the study and each twin pair was compared with two monochorionic twin pairs (n = 38) unaffected by TAPS or twin-twin transfusion syndrome (TTTS), matched for gestational age at birth. We measured full blood counts on day 1 and determined the incidence of anemia, polycythemia, reticulocytosis and thrombocytopenia.
  
  
  RESULTS
  Median inter-twin hemoglobin (Hb) difference in monochorionic twins with and without TAPS was 13.7 g/dL and 2.4 g/dL, respectively (p < 0.01). Median inter-twin reticulocyte count ratio in twins with and without TAPS was 3.1 and 1.0, respectively (p < 0.01). Thrombocytopenia (platelet count < 150 x 10(9)/L) occurred more often in the TAPS group than in the control group, 45% (17/38) versus 11% (11/38), respectively (p < 0.01). In the TAPS group, mean platelet count was significantly lower in recipients than in donors, 133 x 10(9)/L versus 218 x 10(9)/L, respectively (p < 0.01).
  
  
  CONCLUSIONS
  TAPS twins have a large inter-twin Hb difference in combination with a large inter-twin reticulocyte count ratio. Recipients are more often thrombocytopenic than donors, probably due to polycythemia.
authors.affiliation: Division of Neonatology, Department of Pediatrics, Leiden University Medical Centre, Leiden, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Lopriore
authors.forename: F
authors.initials: F
authors.lastname: Slaghekke
authors.forename: D
authors.initials: D
authors.lastname: Oepkes
authors.forename: J M
authors.initials: JM
authors.lastname: Middeldorp
authors.forename: F P H A
authors.initials: FP
authors.lastname: Vandenbussche
authors.forename: F J
authors.initials: FJ
authors.lastname: Walther
mesh_terms: D000328:Adult; D000740:Anemia / Q000097:blood / Q000150:complications / Q000175:diagnosis*; D004200:Diseases in Twins / Q000097:blood / Q000175:diagnosis*; D005260:Female; D005330:Fetofetal Transfusion / Q000175:diagnosis*; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007231:Infant, Newborn; D011086:Polycythemia / Q000097:blood / Q000150:complications / Q000175:diagnosis*; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000097:blood / Q000175:diagnosis; D017701:Reticulocyte Count; D014430:Twins, Monozygotic
chemical_list: D006454:Hemoglobins