Chapter 3. Recommendations and best practice statements across the continuum of abortion care

Clinical services Recommendation 10: Pre-abortion ultrasound scanning (3.3.5)

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).

CLINICAL SERVICES Recommendation 10: Pre-abortion ultrasound scanning

For both medical and surgical abortion: Recommend against the use of ultrasound scanning as a prerequisite for providing abortion services.*


  • Legal regulation that limits the availability of abortion by gestational age may require or result in ultrasounds being used to verify gestational age prior to abortion, even though this is not necessary from a clinical perspective. Removing legal gestational age limits on access to abortion (see Recommendation 3) should result in unnecessary pre-abortion ultrasound being avoided, and increase the availability of abortion in settings where ultrasound is difficult to access.

* On a case-by-case basis, there may be clinical reasons for using ultrasound scanning prior to abortion.

Source: Recommendation 12 carried forward from WHO (2012) (19). The wording has been revised to use the word “recommend against” to clarify that this is a strong recommendation against the intervention, and the former wording “routine” has been changed to use “prerequisite” for greater clarity, following discussion among the expert panel.

Not applicable.


  • Any information on gestational age should be complete, accurate and evidence based. It should not be provided with the aim of directing decision-making.
  • As a form of health information, information on gestational age should be of high quality, accurate and accessible. It should be presented in a respectful manner and acceptable to the person receiving it. It should not fuel stigma and discrimination.
  • Where information on gestational age is made available, it must be provided to individuals in a way that respects privacy and confidentiality.
  • The right to refuse such information when offered must be respected. This includes the right to refuse to view ultrasound images.

For further information and sources, please refer to Box 1.2 and Web annex A: Key international human rights standards on abortion.