Could Suture Type for Stitching the Cervix Save a Pregnancy?

For pregnant women who have their cervix stitched closed to reduce the risk for miscarriage, rates of pregnancy loss do not differ after receiving either of the two most popular surgical sutures, according to findings from the first randomized control trial comparing pregnancy outcomes using the different approaches.  

Approximately 10%-15% of pregnancies end in miscarriage, and up to 5% of miscarriages occur within the second trimester, according to the March of Dimes.

The American College of Obstetricians and Gynecologists (ACOG) recommends cervical cerclage for women who have a history of miscarriages, a previous pre-term birth, or those who have a dilated cervix early in their pregnancy. However, clinicians have not had clear guidance on what type of surgical suture would be best to help women maintain their pregnancies. According to ACOG, the superiority of one suture over another has not been established.

Dr Scott Sullivan

“Surgeons often have personal preferences on the equipment they use, and it’s not standardized across procedures or hospitals or practices,” said Scott Sullivan, MD, director of maternal-fetal medicine at Inova Health in Falls Church, Virginia, and professor of medicine at the University of Virginia. “If there’s not a proven superior method, then doctors use what they prefer.”

Personal preference now has much needed support from data published in the October 22 issue of The Lancet . Data was included from August 2015 to January 2021 of roughly 2000 pregnant women at 75 obstetric units in the United Kingdom who were considered high risk because of a history of pregnancy loss or preterm birth, or based on an ultrasound of their current pregnancy. The women were randomly assigned to undergo a cervical cerclage using either a monofilament suture or a braided suture thread.

The researchers hypothesized that a monofilament suture would be superior to a braided suture in preventing pregnancy loss, which they defined as miscarriage, stillbirth, or neonatal death in the first week of life. A majority of clinicians in the United Kingdom prefer to use a braided thread, because of the ease of the suture method and the concerns that monofilament may be more difficult to remove, according to the study. 

The researchers found that pregnancy loss occurred in 8% of women who underwent the monofilament suture and in 7.6% in the braided suture, suggesting one method was not superior to the other, with an adjusted risk difference of .002 (95% CI, -0.02 to 0.03; P =.73).

“This study helps reassure surgeons that whether they use monofilament or whether they use braided, that they both perform the same way,” said Sullivan, who was not involved with the current research.

The findings also suggest that women may be less likely to have more serious complications from cerclage, such as prolonged infection, according to Philip Toozs-Hobson, MD, founding director of urogynecology and pelvic floor medicine at the Birmingham Women’s Hospital, Birmingham, UK, and co-author of the study.

Toozs-Hobson said surgical technique, along with medical interventions such as the administration of antibiotics to reduce the risk for serious infections, are among the reasons pregnancy loss is so rare among women who receive a cerclage. 

Toozs-Hobson said his group now plans to study differences in outcomes between techniques surgeons use, such as the McDonald cerclage, in which the suture is placed around the cervix like a purse-string, or the Shirodkar cerclage, in which the suture is put in the higher part of the cervix, closer to the uterus. 

Sullivan said scientific evidence also hasn’t established that one method is more beneficial than the other, or which women with what type of anatomy may benefit from either method. 

The study was funded by the National Institute of Health Research Health Technology Assessment Programme. Co-author Victoria Hodgetts Morton, PhD, reports having received an honorarium from Hologic. Co-author Jane E. Norman, MD, is a paid consultant for DILAFOR. Co-author R. Katie Morris, PhD, is a paid clinical advisory board member for Surepulse.

Lancet. Published online October 22, 2022. Full text

Lara Salahi is a freelance journalist based in Boston.

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