3.3.5 Determining gestational age of pregnancy

Determining the gestational age of the pregnancy is a preliminary step before selecting the most appropriate abortion method. There are multiple ways to determine gestational age. Pregnancy dating can be done based on last menstrual period (LMP) alone or in combination with the use of a validated tool (i.e. mobile app, checklist or pregnancy wheel), thus enabling the option of self-assessment of gestational age. When LMP is uncertain, gestational age can be determined by way of a clinical/physical examination (i.e. bimanual pelvic and abdominal examination) or by ultrasound, both of which are used to assess the size of the uterus, estimated in weeks, that corresponds to a pregnant uterus of the same gestational age dated by LMP. In general, the least invasive method that is appropriate in the circumstances and available in the setting should be used.

Routine screening for ectopic pregnancy is not necessary prior to medical abortion. The incidence of ectopic pregnancy is lower in abortion seekers then in the general population (130). Even for continuing pregnancies, WHO only recommends one ultrasound scan before 24 weeks of gestation (early pregnancy ultrasound) to estimate gestational age, improve detection of fetal anomalies and multiple pregnancies, reduce induction of labour for post-term pregnancy, and improve a woman’s pregnancy experience (128).