Safety and accuracy of dating unwanted pregnancies and detecting ectopic pregnancy with the RCOG decision aid without routine ultrasound - a retrospective analysis form a large abortion service.

Background: Evidence suggests routine pre-abortion ultrasound is unnecessary for women with regular menstrual cycles and without symptoms or risk factors for ectopic pregnancy in early gestation.

Objectives: We evaluated the safety and accuracy of using the decision aid for early medical abortion without ultrasound developed by the RCOG Abortion Care group in a Finnish setting.

Method: Using gestational age (GA) expected by last menstrual period (LMP), cycle irregularities, use of hormonal contraceptives, breastfeeding and self-reported symptoms indicative of possible ectopic pregnancy, women were classified into 'no ultrasound needed' and 'ultrasound needed' with a cut-off of 10 + 0 weeks or 70 days. Findings on US were then evaluated to assess classification accuracy.

Results: Between September and December 2023, 494 women attending the abortion clinic at the Helsinki University Hospital were assessed. Correct classification of the necessity of an ultrasound was made in 491/494 (99.4%) cases before the women had a scan. The remaining three cases were one woman with an unexpected GA just above 10 + 0, one asymptomatic ectopic pregnancy and one asymptomatic pregnancy of unknown location with high plasma hCG, diagnosed as a partial molar pregnancy on pathology after diagnostic vacuum aspiration.

Conclusions: Use of the structured flowchart developed by the RCOG highly accurately identifies women needing an ultrasound examination. The few cases that would have been undetected highlight the importance of informing women and health care providers about symptoms of ectopic or abnormal pregnancy similar to practices in wanted pregnancies not routinely examined and dated before late first trimester.