LAS VEGAS – Universal cervical length screening by transvaginal ultrasound in a low-risk cohort resulted in a significant reduction in spontaneous preterm births.
In a single-center retrospective cohort study of more than 13,000 deliveries, the overall preterm birth rate decreased from 3.8% to 2.4% on implementation of universal cervical length screening (P less than .001).
Screening reduced the numbers of both early and late preterm birth rates. Preterm births occurring earlier than 28 weeks’ gestation dropped from 0.3% to 0.1% (P = .04); preterm births before 34 weeks dropped from 1% to 0.5% (P less than .001); and preterm births before 37 weeks dropped from 2.5% to 1.8% (P = .004).
The data were presented by Alex Argyelan, MD, an ob.gyn. resident at St. Joseph Mercy Hospital–Ann Arbor, Mich., at the Annual Pregnancy Meeting sponsored by the Society for Maternal-Fetal Medicine. Dr. Argyelan noted that the current Society for Maternal-Fetal Medicine (SMFM) position regarding cervical length screening is that it should not yet be universally mandated for singleton pregnancies without a prior history of preterm birth. However, a 2016 SMFM guideline stated, “Nonetheless, implementation of such a screening strategy can be viewed as reasonable and can be considered by individual practitioners.” This statement was made, he said, in recognition of the fact that “a sonographic short cervix is a powerful predictor of spontaneous preterm birth,” and that progesterone administration for gravid women with shortening cervixes can, for many, forestall spontaneous preterm labor.
First author Pooja Mittal Green, MD, a maternal-fetal medicine specialist at St. Joseph Mercy Hospital, and her associates looked at preterm delivery data before and after implementation of a universal cervical length screening protocol at a single tertiary referral center. The data collection period spanned from January 2013 to May 2014, with implementation of universal cervical length screening in October 2014.
A total of 13,396 women were included in the study, with a small minority of just 0.5% having experienced a prior spontaneous preterm birth. The mean patient age was just under 30 years; most patients were white, mirroring the demographics of the county where the study took place. Pre- and postintervention patient characteristics did not vary significantly.
Almost all patients agreed to cervical length screening by ultrasound, with the numbers climbing from 93% during the first year after implementing the universal screening protocol, to 99.2% in 2016.
All of the sonographers participating in the study were Cervical Length Education and Review (CLEAR) certified, and the institution’s lead sonographer carried out a ongoing quality assurance program.
A shortened cervix (25 mm or less) was found in a total of 114 women (1.7%) who underwent cervical length screening. According to the protocol, if maternal cervical length was 25 mm or less, women were offered treatment to attempt to stave off preterm delivery, according to the usual standard of care.
For women with no prior history of preterm delivery, treatment was vaginal progesterone. For women who had a prior preterm birth, cervical cerclage was offered, as well as vaginal progesterone if the patient was not already on 17-alpha-hydroxyprogesterone caproate.
The determination whether spontaneous preterm birth had occurred was made by reviewing labor and delivery birth logs, with a subsequent individual chart review to make sure that the delivery happened after either spontaneous labor or preterm premature rupture of membranes.
Only women who received prenatal care at the study institution were included in the study, and women who had not received any prenatal care were excluded.
Dr. Argyelan and his colleagues did not see any significant differences between the preterm and term delivery groups in maternal age, body mass index, or ethnicity.
“Among spontaneous preterm deliveries in low-risk women, the proportion of deliveries before 34 weeks was decreased” after the intervention, said Dr. Argyelan, who reported seeing a decrease from 28% early (less than 34 weeks’ gestation) preterm births before the intervention to 17% after the intervention.
In response to an audience question, Dr. Argyelan noted that his institution charges $186 for an ultrasound examination that includes assessment of cervical length, saying, “We have not had significant issues being reimbursed.”
Another audience member asked what the institution policy had been before the universal screening program was implemented. “Before the universal screening study, there was a policy of screening those with a history of preterm birth; also, if sonographers saw what looked like a short cervix on transabdominal exam, then they would do a transvaginal scan to further assess the cervix,” Dr. Argyelan said.
Dr. Argyelan reported having no financial disclosures.
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