Cervical cerclage technique: what do experts actually achieve?

Abstract

Cervical cerclage is a recognised intervention in the management of women who are at risk of preterm birth and mid-trimester loss. The mechanism of action of cerclage is unclear and the technique has been poorly researched. We aimed to evaluate cerclage technique amongst experienced obstetricians, using a cerclage simulator we previously developed and evaluated. This prospective experimental simulation and observational study used identical simulators for 28 Consultant Obstetricians who were asked to perform their normal cerclage. Suture type, height, knot site and free thread length were recorded. Using computerised tomography, depth of bite and tension (by reduction in area of cervix) were calculated. Fifty-two cervical cerclages were completed (Mersilene tape n=20, monofilament suture n=32). Mean suture height was 33mm (SD 7.7mm) and was greater with monofilament suture than Mersilene tape and was associated with smaller needle size. Mean depth of bite and mean reduction of starting area did not differ by suture type. Seven procedures showed one or more suture bites that had entered the cervical canal once or more. In the first study of cerclage technique by experienced obstetricians using simulator and CT imaging we demonstrate wide variation in technique; this may affect the efficacy of the procedure. Further work should include establishing optimal technique and a consensus agreed for training and clinical practice.