Is transabdominal sonography comparable to transvaginal sonography for eligibility assessment prior to medical abortion?
Awarded 2016
Complex Family Planning Fellowship Research
Caitlin Weber, MD
Columbia University

Ultrasound is frequently performed prior to medical abortion in order to determine whether a woman is eligible to receive mifepristone and misoprostol to induce abortion, which is available up to 70 days from the last menstrual period. Many providers routinely use transvaginal sonography, or TVS, yet numerous evidence-based guidelines do not recommend the routine use of ultrasound, much less a specific requirement for TVS. TVS requires the maintenance of expensive ultrasound probes in addition to high level disinfection (HLD), between patients. Meeting the HLD requirements set by the CDC can be time-consuming and costly to clinics. Transabdominal sonography (TAS) is an alternative approach that does not require these same HLD requirements and is also less invasive, as it is performed on the abdomen rather than by inserting a probe into the vagina. However, there is concern that TAS is not as effective as TVS in identifying early pregnancies in some patients. When an early pregnancy cannot be clearly identified using either method of ultrasound, providers often order additional tests to help clarify whether there is an early pregnancy, miscarriage, or ectopic pregnancy. Such additional testing may include a TVS in a person who initially just received TAS, a blood hCG test (measurement of pregnancy hormone level), a follow-up visit at a later date, or other testing.
One potential strategy to improve medical abortion access, reduce costs, and improve patient satisfaction is to perform TAS rather than TVS in most patients. Little information is available regarding how often women receive testing after TAS compared to TVS and there are no prior studies comparing patient acceptability between the two ultrasound modalities among women seeking abortion. This study compares how often additional testing is ordered for women who receive either TAS or TVS. We hypothesize that in the majority of patients, TAS will be adequate to determine eligibility for medical abortion. This study was as a non-inferiority trial, meaning that as long as eligibility could be determined without additional testing for at least 80% of participants receiving TAS, TAS would be considered non-inferior to TVS.
Women seeking medical abortion at 2 Columbia University Medical Center clinics and 8 Planned Parenthood of Northern, Central, and Southern New Jersey health centers were offered enrollment. Following a standard evaluation including history and examination, they were randomized to receive either TAS or TVS. Following ultrasound, providers (including physicians, nurse practicitioners, and certified nurse midwives) proceeded with either providing medical abortion to eligible women, or ordering additional testing first, as needed to confirm eligibility. Following completion of the clinic visit, all participants completed an acceptability questionnaire regarding the type of ultrasound used.
Data was analyzed for 630 participants across 10 study sites. Among those randomized to TAS, 19.8% received additional testing, compared to 4.8% among those randomized to TVS. Therefore, based on the pre-selected non-inferiority cutoff, TAS can be considered non-inferior to TVS. We also considered additional factors that might impact the proportion receiving additional testing, finding that women at earlier gestational ages and those seen by advanced practice nurses (rather than physicians), or by less experienced providers were more likely to receive additional testing. We did not find a difference in the proportion receiving additional testing among those with previous cesarean section, those with higher BMI, or when comparing the first third of participants enrolled to the last third of participants enrolled. Patient acceptability was higher among those who received TAS compared to those who received TVS. Approximately two-third of patients preferred to receive TAS in future care. Detailed analysis is still ongoing and will be updated here when available.
The results of this study suggest that in those clinics where TVS is currently being used routinely, switching to TAS for most patients is appropriate, and acceptable to patients. Additional research is needed to further clarify the relationship between additional testing and certain patient characteristics such as BMI, as not enough women were enrolled in this study to answer all questions regarding predictors of the need for further testing. These results may help clinics anticipate how often TVS may be required prior to medical abortion. Using TAS first in most patients may allow clinicians to provide more patient-centered and cost-effective care.