For pregnant women who have their cervix stitched closed to reduce miscarriage risk, rates of pregnancy loss do not differ after receiving either of the two most popular surgical sutures, according to findings from the first randomised control trial comparing pregnancy outcomes using the different approaches.
About 10%-15% of pregnancies end in miscarriage, and up to 5% of miscarriages occur within the second trimester, reports Medscape.
The American College of Obstetricians and Gynecologists (ACOG) recommends cervical cerclage for women with 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 is best to help women maintain their pregnancies.
According to ACOG, the superiority of one suture over another has not been established.
“Surgeons often have personal preferences on the equipment they use, and it's not standardised across procedures or hospitals or practices,” said Dr Scott Sullivan, director of maternal-foetal medicine at Inova Health in 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 Lancet. Data were included from August 2015 to January 2021 of roughly 2 000 pregnant women at 75 obstetric units in the UK 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 hypothesised 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. Most clinicians in the UK 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 the braided, both perform the same way,” said Sullivan, who was not involved with the research.
The findings also suggest that women may be less likely to have more serious complications from cerclage, such as prolonged infection, according to Dr Philip Toozs-Hobson, founding director of urogynaecology and pelvic floor medicine at the Birmingham Women’s Hospital, Birmingham in the 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.
His group now plans to study differences in outcomes between techniques used by surgeons, such as the McDonald cerclage, where 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.
Study details
Monofilament suture versus braided suture thread to improve pregnancy outcomes after vaginal cervical cerclage (C-STICH): a pragmatic randomised, controlled, phase 3, superiority trial
Victoria Hodgetts Morton, Philip Toozs-Hobson, Catherine Moakes, Lee Middleton,
Jane Daniels, Nigel Simpson, et al.
Published in The Lancet on 22 October 2022
Summary
Background
Miscarriage in the second trimester and preterm birth are significant global problems. Vaginal cervical cerclage is performed to prevent pregnancy loss and preterm birth. We aimed to determine the effectiveness of a monofilament suture thread compared with braided suture thread on pregnancy loss rates in women undergoing a cervical cerclage.
Methods
C-STICH was a pragmatic, randomised, controlled, superiority trial done at 75 obstetric units in the UK. Women with a singleton pregnancy who received a vaginal cervical cerclage due to a history of pregnancy loss or premature birth, or if indicated by ultrasound, were centrally randomised (1:1) using minimisation to receive a monofilament suture or braided suture thread for their cervical cerclage. Women and outcome assessors were masked to allocation as far as possible. The primary outcome was pregnancy loss, defined as miscarriage, stillbirth, or neonatal death in the first week of life, analysed in the intention-to-treat population (ie, all women who were randomly assigned). Safety was also assessed in the intention-to-treat population.
Findings
Between Aug 21, 2015, and Jan 28, 2021, 2049 women were randomly assigned to receive a monofilament suture (n=1025) or braided suture (n=1024). The primary outcome was ascertained in 1003 women in the monofilament suture group and 993 women in the braided suture group. Pregnancy loss occurred in 80 (8·0%) of 1003 women in the monofilament suture group and 75 (7·6%) of 993 women in the braided suture group (adjusted risk ratio 1·05 [95% CI 0·79 to 1·40]; adjusted risk difference 0·002 [95% CI –0·02 to 0·03]).
Interpretation
Monofilament suture did not reduce rate of pregnancy loss when compared with a braided suture. Clinicians should use the results of this trial to facilitate discussions around the choice of suture thread to optimise outcomes.
Medscape article – Could Suture Type for Stitching the Cervix Save a Pregnancy? (Open access)
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