Module 4: Point of care ultrasound in first trimester abortion (POCUS)
11. Further reading and resources
In an evidence review to support the National Institute for Health and Care Excellence (NICE) Abortion care guideline (NG140), it is stated that:
“Initiating medical or surgical abortion before a definitive diagnosis of pregnancy can be made on ultrasound introduces the possibility of missing an asymptomatic ectopic pregnancy. This may have serious consequences and lead to emergency care/hospital admission, potentially impacting future fertility. Missed diagnosis of ectopic pregnancy and need for emergency care/hospital admission were therefore selected as a critical outcomes.
The committee also agreed to prioritise patient satisfaction as a critical outcome for decision-making as abortion is an area where women are known to have strong preferences for prompt resolution. Time to completion of treatment was included as an important outcome because the possibility of having an abortion before ultrasound evidence compared to having to wait 2 to 3 weeks until the pregnancy is visible on ultrasound is likely to further influence patient preference. The need for repeat doses of misoprostol, ongoing pregnancy and complete abortion without the need for (repeat) surgical intervention were included as important outcomes due to the impact that needing a second appointment and intervention will have on both the patient and on available resources.
The evidence showed that there were no clinically important differences in the rates of complete abortion without the need for (repeat) surgical intervention between women with definitive evidence of an IUP on ultrasound compared to women who had an ultrasound but where an IUP could not be confirmed whereas for missed diagnosis of ectopic pregnancy and ongoing pregnancy, it was unclear whether or not there was a clinically important difference. The committee noted the evidence from the review on “What factors help or hinder the accessibility and sustainability of a safe termination of pregnancy service?” which showed that women had clear preferences not to prolong waiting times, and therefore they agreed that the recommendation should be to offer immediate treatment if that was the patient’s preferred option.
In this respect the committee wanted to clarify that this recommendation does not imply that all women have to have an ultrasound scan before initiating an abortion, only that if an ultrasound has been performed that shows no definitive evidence of an intrauterine pregnancy, then the abortion can still go ahead.
However, although the committee agreed that an abortion at this stage should only be offered to women who did not have any signs or symptoms of an ectopic pregnancy and whilst the committee were aware of other evidence that shows there is a lower incidence of ectopic pregnancy in the population requesting a termination (0.8, 0.9, 5.9 /1000 in Bizjak, Heller, and Edwards respectively) compared with an overall rate of 11/1000 in the general population (NICE, 2012), nevertheless it remains a possibility and diagnosis can be delayed if symptoms are attributed to recovery following an abortion. Whilst rare, the consequences of a missed ectopic pregnancy can be serious.
The committee therefore agreed it was essential that women were made aware of the importance of the potential need to participate in follow-up appointments if completion of the abortion could not be confirmed at the time of treatment to facilitate early intervention, the nature of the follow-up should be decided locally given the variation in nature of provider. They noted that commonly used protocols included the use of blood tests to check that serum βhCG is declining, or urinary pregnancy testing to ensure this becomes negative after the procedure.
If there are signs and symptoms of ectopic pregnancy (e.g., pain, bleeding) referral to an Early Pregnancy Assessment Unit (EPAU) to rule out this diagnosis should be pursued before treatment is provided. The committee were also aware of previous national guidance from the Royal College of Obstetricians and Gynaecologists (2011) recommending that surgical procedures could be used in abortions before ultrasound evidence of pregnancy if there are appropriate safeguards, including inspection of aspirated tissue. Whilst the study included in this review did not give cause for concern, the committee agreed that in the surgical group a similar follow-up programme to those used in the medical abortion group is needed where a gestation sac was not clearly identified in the aspirate in order to exclude an on-going pregnancy or missed ectopic pregnancy.”
Pedersen, J.K., Sira, C., Trovik, J. (2021) Handheld transabdominal ultrasound, after limited training, may confirm first trimester viable intrauterine pregnancy: a prospective cohort study. Scand J P Health Care 39:123–130. Available from: https://doi.org/10.1080/02813432.2021.1910643
“During week 6 handheld abdominal POCUS yielded a sensitivity of 63% in detecting vitality while the negative predictive value was 33%, demonstrating that a positive finding confirms a vital pregnancy, but a negative finding cannot confirm that the pregnancy is pathological. From week 7, the sensitivity was excellent: 94% in confirming vitality and a negative predictive value of 79% in confirming pathological pregnancy.”