Monochorionic twins with unequal placental sharing: why can the outcome still be favorable?
OBJECTIVE
In monochorionic diamniotic (MCDA) twin pregnancies, unequal placental sharing does not always lead to adverse outcomes. The aim of this study is to investigate how unequal placental sharing may be compensated by placental anatomical changes.


METHODS
Between January 2012 and July 2013, a total of 60 uncomplicated MCDA pregnancies ending in live birth of healthy twins were studied. Placentas were divided into two groups; an equally shared placenta group (placenta territory discordance ≤ 25%, N = 40) and an unequally shared placenta group (placenta territory discordance >25%, N = 20). Angioarchitecture, cord insertion type and the distance between two cord insertions were compared.


RESULTS
Vascular anastomoses were seen in all 60 placentas, and 58 placentas (96.7%) had arterioarterial anastomoses (AA). The overall diameter of the AA was larger in the unequally shared placenta group as compared to the equally shared placentas (0.27 ± 0.12 cm versus 0.19 ± 0.1 cm, p < 0.05). The distance between the cord insertions was shorter in the unequally shared group (14.5 ± 6.0 cm versus 18.3 ± 6.5 cm, p < 0.05).


CONCLUSION
The absence of adverse outcomes in unequally shared placenta group can be explained by the presence of large AA and shorter distance between cord insertions, protecting the twin with the smaller placental part against growth restriction and other pathology.
['Sun|Lu-Ming|LM|', 'Li|Ying|Y|', 'Zou|Gang|G|', 'Zhou|Fenghe|F|', 'Lei|Xiaoping|X|', 'Cram|David S|DS|', 'Oepkes|Dick|D|', 'Wu|Junqing|J|']
D000328:Adult D001163:Arteriovenous Anastomosis D001724:Birth Weight D004396:Coloring Agents D005260:Female D006801:Humans D010920:Placenta D021041:Placental Circulation D011247:Pregnancy D059285:Pregnancy, Twin D014430:Twins, Monozygotic D014470:Umbilical Cord
Monochorionic diamniotic uncomplicated placental anastomoses placental injection