Regional Guidelines for the ultrasound surveillance of twin pregnancies


1. Diagnosis of Chorionicity
An attempt should be made to diagnose chorionicity using the following guidelines at the first scan in any multiple pregnancy, or any further scans when the diagnosis is not already established

Scardo+, 1995; Sepulveda, 1997

For all chorionicity examinations, make notes of:
" Placental structure (ie single placental mass or separate placentas)
" Lambda sign
" Membrane thickness


2. Dating according to the ultrasound scan


3. Ultrasonographic surveillance during pregnancy



4. Inform Multiple Pregnancy Survey


* Calculate EFW discordance as (EFW larger twin-EFW smaller twin)*100 / EFW smaller twin

S.N. Sturgiss 2002

Review date 2005

This guideline was drawn up by the Special Interest Group in Maternal/Fetal Medicine, Northern deanery. Queries about this guideline or problems arising from its use should be directed to Dr S.N. Sturgiss, Royal Victoria Infirmary, Newcastle NE1 4LP
Tel: 0191 2825833, Fax: 0191 2275194, E-mail: