title: Twin anemia polycythemia sequence: a report of three cases.
abstract: BACKGROUND
  Vascular anastomoses in monochorionic placentas are the key factor in the develop- ment of several complications, including twin anemiapolycythemia sequence (TAPS). TAPS is an uncommon form of chronic fetofetal transfusion, characterized by large intertwin hemoglobin (Hb) differences in the absence of amniotic fluid discordances.
  
  
  METHODS
  We report 3 unusual cases of spontaneous TAPS. Looking to the intertwin Hb differences, each case fits in a different stage of postnatal twin anemia-polycythemia classification. Five of the 6 twins had a good outcome despite major hemodynamic changes.
  
  
  CONCLUSIONS
  Spontaneous TAPS is by far more infrequent than its postlaser counterpart. Our report is somewhat uncommon due to the fact that the 3 cases were spontaneous, consecutive, and each one fit as an example of the various degrees of severity according to the described classifications of this condition.
authors.affiliation: Department of Obstetrics and Gynecology,  Porto Hospital Center, Poro, Portugal. joaomiguelcasanova@gmail.com
authors.forename: Joao
authors.initials: J
authors.lastname: Casanova
authors.forename: Catarina
authors.initials: C
authors.lastname: Paiva
authors.forename: Carmen
authors.initials: C
authors.lastname: Carvalho
authors.forename: Ana C
authors.initials: AC
authors.lastname: Cunha
mesh_terms: D000328:Adult; D001163:Arteriovenous Anastomosis; D017809:Fatal Outcome; D005260:Female; D005315:Fetal Diseases / Q000628:therapy; D005330:Fetofetal Transfusion; D005331:Fetomaternal Transfusion; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007231:Infant, Newborn; D010920:Placenta / Q000098:blood supply / Q000473:pathology; D011086:Polycythemia; D011247:Pregnancy; D014427:Twins
chemical_list: D006454:Hemoglobins