Cervical Cerclage
Cervical incompetence (cervical insufficiency) is a nebulous condition characterized by pain-free dilatation and shortening of the cervix in the second or early third trimester of pregnancy (Fig. 49–1). This is followed by prolapse of the membranes through the cervix and, ultimately, by expulsion of the fetus with or without membrane rupture (Fig. 49–2). The diagnosis of cervical insufficiency depends primarily on an obstetric history of one or more pregnancy losses associated with painless labor and dilatation.
Once the diagnosis has been at least presumptively made, a decision must be reached about whether to suture the cervix. Most cerclage operations are performed via the vaginal approach. The technique of abdominal cerclage is described and shown in Unit I.
The Shirodkar surgical procedure is aimed at restoring the cervix to a nondilated state as well as lengthening the cervical canal. Essentially, in this operation a nonresorbable suture is placed at or above the level of the internal os of the cervix. If lengthening is to be achieved, then a portion of the corporal isthmus should be incorporated into the encompassing suture. This will eliminate the funnel effect of the membranes at the top of the cervical canal and will add 1 to 2 cm of length to the canal. Care must be taken to dissect the vagina away from the cervix and to retract it superiorly and anteriorly to avoid injury to the terminal ureter (i.e., at the uterovesical junction). As is noted in Section F Unit II, the ureters cross the vagina at the anterior and anterolateral fornices to gain entry to the bladder base (trigone).
The cervix is exposed by placing a weighted retractor into the posterior fornix. Small Dever retractors are placed in the lateral vaginal fornices, and a finger (small Richardson) retractor is placed in the anterior fornix. Sutures of 0 Vicryl are placed into the cervix at the 3 and 9 o’clock positions in figure-of-8 fashion for traction (Fig. 49–3A). These sutures should not be placed too far back into the lateral fornix because they can occlude the ureter. The sutures must be placed in the cervix forward of the vaginal reflection.
Next, 10 to 20 mL of normal saline is injected into the anterior cervix at the point of the vaginal reflection to create a plane of dissection. A similar injection is made into the posterior aspect of the cervix. A 2-cm incision is made with a scalpel into the vaginal reflection. The vagina is easily separated and dissected from the cervix. A similar procedure is carried out posteriorly. Retractors can now be placed between the cervix and the vagina (Fig. 49–3B, C).
