1st Trimester Normal Measurements

First Trimester Mean sac diameter (MSD) is the preferred method for measuring gestational sac size The relationship between MSD and human chorionic gonadotropin should be used to aid assessment of the uterus and endometrial cavity in early pregnancy CRL should be used for gestational age assessment once a fetal pole us detected Discriminatory values for pregnancy viability in the 1st trimester: Fetal pole must be seen when MSD ≥ 18 mm (TV) or ≥ 25 mm (TA) Fetal heart activity must be seen when CRL ≥ 5 mm on TV or >9mm on TA TABLES TO BE ADDED

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