Termination of pregnancy at very early gestation without visible yolk sac on ultrasound

Requests for termination of pregnancy (TOP) at very early gestation (≤6 weeks) can prove challenging for abortion services as the ultrasound feature usually accepted as definitive evidence of an intrauterine pregnancy (IUP), the presence of a yolk sac within a gestational sac, may not yet be evident. In 2011 the Edinburgh TOP service introduced a protocol permitting women to proceed to treatment without further investigations provided that ultrasound showed the features of an eccentrically placed gestational sac (≥3 mm) with a decidual reaction, and there were no signs, symptoms or risk factors for ectopic pregnancy.

A retrospective audit was conducted of outcomes of women presenting for TOP at ≤6 weeks' gestation over a 2-year period using the hospital computerised database.

A total of 1155 women presented for TOP with an ultrasound gestational age of ≤6 weeks. Of these, 1030 (89%) had ultrasound evidence of a yolk sac. Eighty-seven women (7.5%) had an eccentrically placed gestational sac with a decidual reaction. All 87 women fulfilled our criteria to proceed to medical TOP, and 66 did so. In the remaining 21 cases, further investigations were performed before they proceeded to medical TOP. Two (0.17%) medical TOPs failed, both in women whose initial ultrasound had shown a yolk sac.

Women with ultrasound features consistent with a very early IUP (≥3 mm eccentrically placed gestational sac with a decidual reaction) and without signs, symptoms or risk factors for ectopic pregnancy can proceed directly to medical TOP without the need for delay for further ultrasonography.