title: Pre-Operative Twin Anemia/Polycythemia in the Setting of Twin-Twin Transfusion Syndrome (TTTS).
abstract: BACKGROUND
  Twin-twin transfusion syndrome (TTTS) and twin anemia-polycythemia sequence (TAPS) are classified as distinct clinical disorders associated with unbalanced blood flow through placental vascular communications. Typically, TAPS placentas demonstrate few <1 mm arteriovenous (AV) communications, and at fetoscopy the twins are visibly pale and plethoric.
  
  
  METHODS
  In a cohort of TTTS patients who underwent laser surgery, those with preoperative findings suggestive of anemia/polycythemia (AP) were compared to those with TTTS alone. AP was defined as middle cerebral artery peak systolic velocity in one twin >1.5 multiples of the median (MoM), and <1.0 MoM in the other.
  
  
  RESULTS
  Of 369 TTTS patients, 9 (2.4%) met criteria for preoperative AP. The mean number (±SD) of AV communications in the TTTS + AP group was 5.6 ± 5.7, compared with 8.8 ± 4.8 in the TTTS-alone group (p = 0.013). Five TTTS + AP patients (56%) had a few thin AV communications (mean 2.8 ± 1.6); all 5 had visibly pale and plethoric twins. The remaining 4 (44%) had large or numerous anastomoses (mean 10.5 ± 6.8); none had fetal skin color discordance.
  
  
  CONCLUSIONS
  Preoperative AP affected 2% of TTTS patients. Of these, approximately half had placental and skin color findings typically reported with isolated TAPS.
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Keck School of Medicine, University of Southern California, Los Angeles, Calif., USA.
authors.forename: Kristi R
authors.initials: KR
authors.lastname: Van Winden
authors.forename: Ruben A
authors.initials: RA
authors.lastname: Quintero
authors.forename: Eftichia V
authors.initials: EV
authors.lastname: Kontopoulos
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Korst
authors.forename: Arlyn
authors.initials: A
authors.lastname: Llanes
authors.forename: Ramen H
authors.initials: RH
authors.lastname: Chmait
mesh_terms: D000740:Anemia / Q000150:complications* / Q000601:surgery; D005260:Female; D005330:Fetofetal Transfusion / Q000150:complications* / Q000601:surgery; D005332:Fetoscopy; D006801:Humans; D053685:Laser Therapy; D010920:Placenta / Q000098:blood supply; D011086:Polycythemia / Q000150:complications* / Q000601:surgery; D011247:Pregnancy; D059285:Pregnancy, Twin; D057234:Preoperative Period; D016896:Treatment Outcome