title: Comparison Between Monochorionic and Dichorionic Placentas With Special Attention to Vascular Anastomoses and Placental Share.
abstract: Placental vascular anastomoses in twins lead to a shared circulation and may subsequently enable the development of severe complications such as twin-twin transfusion syndrome (TTTS) and twin anemia-polycythemia sequence (TAPS). The presence of vascular anastomoses has frequently and systematically been studied in monochorionic (MC) placentas, but only rarely in dichorionic (DC) placentas. The aim of this study was to compare the prevalence of vascular anastomoses and evaluate the sharing discordance in MC and DC placentas. All consecutive placentas of MC and DC twins delivered at the Leiden University Medical Center (the Netherlands) and Medical University of Warsaw (Poland) from 2012 to 2015 were routinely injected with colored dye and included in the study. We excluded twin pregnancies treated with fetoscopic laser surgery. A total of 258 placentas were analyzed in this study, including 134 MC placentas and 124 DC placentas. Vascular anastomoses were present in 99% (133/134) of MC placentas and 0% of DC placentas (p < .01). Placental share discordance between MC twins was significantly larger compared to DC twins, 19.8 (interquartile range [IQR] 8.1-33.3) and 10.8 (IQR 6.2-19.0), respectively (p < .01). Vascular anastomoses associated complications occurred in 16% (22/134) MC twins. Our findings show that vascular anastomoses are almost ubiquitous in MC placentas, but non-existent in DC placentas. In addition, unequal placental sharing appears to be more common in MC than in DC placentas.
authors.affiliation: Fetal Medicine Unit & Prenatal Diagnosis Center,Department of Obstetrics,Shanghai First Maternity and Infant Hospital,Tongji University School of Medicine,Shanghai,China.
authors.forename: Depeng
authors.initials: D
authors.lastname: Zhao
authors.affiliation: 1st Department of Obstetrics and Gynecology,Medical University of Warsaw,Warsaw,Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Lipa
authors.affiliation: 1st Department of Obstetrics and Gynecology,Medical University of Warsaw,Warsaw,Poland.
authors.forename: Miroslaw
authors.initials: M
authors.lastname: Wielgos
authors.affiliation: Department of Pathology,Leiden University Medical Center,Leiden,the Netherlands.
authors.forename: Danielle
authors.initials: D
authors.lastname: Cohen
authors.affiliation: Division of Fetal Medicine,Department of Obstetrics,Leiden University Medical Center,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 Center,Leiden,the Netherlands.
authors.forename: Dick
authors.initials: D
authors.lastname: Oepkes
authors.affiliation: Division of Neonatology,Department of Pediatrics,Leiden University Medical Center,Leiden,the Netherlands.
authors.forename: Enrico
authors.initials: E
authors.lastname: Lopriore
mesh_terms: D000328:Adult; D000740:Anemia / Q000453:epidemiology / Q000235:genetics / Q000503:physiopathology*; D005260:Female; D005330:Fetofetal Transfusion / Q000453:epidemiology / Q000235:genetics / Q000503:physiopathology*; D005865:Gestational Age; D006801:Humans; D009426:Netherlands; D010920:Placenta / Q000098:blood supply / Q000503:physiopathology*; D011044:Poland; D011247:Pregnancy; D059285:Pregnancy, Twin; D014429:Twins, Dizygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics
keywords: dichorionic placenta; monochorionic placenta; unequal placental share; vascular anastomoses