Characterisation of vascular anastomoses in monochorionic placenta by vascular casts

Abstract

This study aims (1) to delineate vascular anatomy in monochorionic (MC) twin pregnancies by casting methods and (2) to compare naked eye identification with vascular casting of arteriovenous anastomosis (AVA). Monochorionic placentae and control singleton placentae collected immediately after delivery were washed thoroughly with calcium-free isotonic solution mixed with sodium nitroprusside to remove all blood products. All AVAs were identified by naked eye after colour-coded vascular resins were injected into each individual umbilical vessel. The resins then hardened for 24 hours at room temperature, immersed in concentrated hydrochloric acid and washed until all tissues were dissolved. Intact vascular networks could be identified on all MC and singleton placentae. Anastomotic casts were visualised. We visualised ≥1 AVA not identified by naked eye inspection in each of the MC placentae.