High vs Low Cervical Stitch: New Study
A secondary analysis of the C-STICH trial found no significant difference in pregnancy loss rates between high and low transvaginal cerclage techniques for
A new analysis of a major UK trial has compared two surgical techniques for placing a cervical stitch, or cerclage. The study found no significant difference in overall pregnancy loss rates between high and low vaginal cerclage. However, the high cerclage technique was linked to a small prolongation of pregnancy and fewer births before 32 weeks.
According to the research, published in BJOG: An International Journal of Obstetrics and Gynaecology, the choice between a high or low stitch is currently based on surgeon preference due to a lack of clear evidence. This secondary analysis of the C-STICH trial aimed to provide more data for clinicians and patients facing this decision.
What The Study Found
The analysis included 1,995 women from the C-STICH trial who had details of their cerclage height available. Of these, 24% received a high vaginal cerclage, which involves bladder dissection. The remaining 76% received a low vaginal cerclage, which does not.
The primary outcome was pregnancy loss, defined as miscarriage or perinatal mortality. The rates were similar between the two groups: 6.5% for the high cerclage group versus 7.3% for the low cerclage group. The adjusted risk ratio was 0.88, with a 95% confidence interval of 0.57 to 1.34.
While overall loss rates did not differ, the high cerclage technique showed benefits in extending pregnancy. It was associated with an increase in mean gestational age of 0.5 weeks. Crucially, it was linked to a lower rate of births before 32 weeks, with an adjusted risk ratio of 0.57.
Understanding The Two Techniques
A transvaginal cervical cerclage is a stitch placed around the cervix to prevent mid-trimester loss and preterm birth in high-risk women. It provides mechanical support and may help maintain barriers against infection.
The two main techniques are fundamentally different. A low vaginal cerclage, also called a McDonald cerclage, is a purse-string suture placed as high as possible on the vaginal cervix without dissecting the bladder. A high vaginal cerclage, or Shirodkar cerclage, involves dissecting the bladder to place the suture around the supravaginal cervix, and the suture thread is then buried.
Potential advantages of the low technique include requiring less surgical skill and being easier to remove. Advocates for the high technique suggest its placement closer to the internal os may offer better mechanical support. Burying the suture thread might also minimize disruption to the vaginal microbiome and lower infection risk.
Study Details and Patient Profile
The C-STICH trial originally investigated different suture materials. This secondary analysis used its data to compare surgical techniques. Women in the trial were eligible if they had an indication for a vaginal cerclage, were aged 18 or older, and had a singleton pregnancy.
Indications included a history of three or more previous mid-trimester losses or premature births, previous cervical stitches, a history of loss with a short cervix in the current pregnancy, or clinician concern. Women needing emergency procedures or non-vaginal cerclages were excluded.
| Outcome Measure | High Cerclage Group | Low Cerclage Group | Adjusted Risk Ratio (95% CI) |
|---|---|---|---|
| Pregnancy Loss | 6.5% | 7.3% | 0.88 (0.57-1.34) |
| Birth < 32 weeks | Lower rate | Higher rate | 0.57 (0.37-0.86) |
| Mean Gestational Age | Increased by 0.5 weeks | Baseline | Not provided |
The authors note this analysis was exploratory and the study was not formally powered to detect differences in pregnancy loss between the groups. The findings support the need for future research to determine the optimal surgical approach for an ideal birth in high-risk pregnancies. The final data point shows a clear reduction in very early preterm births with the high cerclage technique.
