Cervical cerclage technique: what do experts actually achieve?

Cervical cerclage is a recognized intervention in the management of women at risk of preterm birth and midtrimester loss. The mechanism of action of cerclage is unclear, and the technique has been poorly researched.This study aimed to evaluate cerclage technique among experienced obstetricians, using a previously developed and evaluated cerclage simulator.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 computed tomography, depth of bite and tension (by reduction in area of cervix) were calculated.A total of 52 cervical cerclages were completed (Mersilene tape, n=20; monofilament suture, n=32). Mean suture height was 33 mm (standard deviation, 7.7 mm), greater with monofilament suture than with Mersilene tape, and associated with smaller needle size. Mean depth of bite and mean reduction of starting area did not differ by suture type. Seven procedures showed ≥1 suture bite that had entered the cervical canal once or more.This study assessed cerclage technique of experienced obstetricians using simulators and computed tomography imaging, and demonstrated wide variation in technique; this may affect the efficacy of the procedure. Further work should establish optimal technique and consensus for training and clinical practice.