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Member Research & Reports

Member Research & Reports

UAB Seeks to Identify Optimal Cervical Length for Placing Ultrasound-Indicated Cerclage

Dr. Jeff M. Szychowski, associate professor in the department of biostatistics at the University of Alabama at Birmingham—along with UAB co-investigator Dr. John Owen, professor in the department of obstetrics and gynecology—recently evaluated a sequence of cervical length (CL) cutoffs for ultrasound-indicated cerclage efficacy in women with a history of prior spontaneous preterm birth (PTB).


[Photo: Dr. Jeff M. Szychowski]

The team conducted a planned secondary analysis sponsored by the National Institute of Child Health and Human Development (NICHD) vaginal ultrasound cerclage trial. Using multivariable logistic regression, cerclage efficacy for preventing recurring PTB at under 35, 32, and 24 weeks gestation (GA) was assessed. The researchers also used bootstrap regression—which utilizes random sampling methods—to estimate odds ratios (ORs) and confidence intervals (CIs) for a range of CL cutoffs, with the 2.5 and 97.5 percentiles of bootstrapped ORs determining the CIs.

Dr. Szychowski says, “Of 301 women with CL of less than 25 mm, 142 underwent ultrasound-indicated cerclage and 159 did not. Few cases of CL of less than 10 mm limited evaluation to CL cutoffs between less than 10 and 25 mm. For the PTB less than the 35-week endpoint, statistically significant lower odds of PTB for CLs of less than 25 mm are demonstrated and efficacy was maintained for smaller CL cutoffs. Results were similar for PTB under 32 weeks. For the PTB under the 24-weeks endpoint, results differed, demonstrating that for CL cutoffs between less than 10 and 15 mm the ORs increased toward unity (no benefit) with wide CIs, attributed to few births under 24 weeks.”

In women with prior spontaneous PTB, ultrasound-indicated cerclage efficacy varies by CL action point cutoff, as well as by PTB GA endpoint. “Cerclage significantly reduces PTB under 35 and 32 weeks at CL cutoffs between less than 10 mm and 25 mm, reducing most for shorter CLs and affirming that women with prior spontaneous PTB and shortened CL are appropriate candidates for ultrasound-indicated cerclage,” conclude Dr. Szychowski and his colleagues.

“Can the Optimal Cervical Length for Placing Ultrasound-Indicated Cerclage Be Identified?” was published in August in the journal Ultrasound in Obstetrics & Gynecology.

Journal article: