At the end of my last post, I mentioned that the McDonald cerclage procedure is the type I have preferred for many years for most routine and ‘rescue cerclages’, but I also mentioned that if the suture is not placed highly enough, deeply enough, or tied tightly enough, it is at risk for failure. The first caveat, “highly enough,” is readily apparent but still often not done adequately. When I explain this to patients, I ask them to approximate the tips of their thumb and index fingers on one hand and imagine this to be the cervix with the surface of contact being the cervical canal. Then take the other thumb and index finger and squeeze the first two together. By compression even 2 cm up our surrogate cervix, and squeezing snugly, we can restore 3 to 4 cm of ‘cervical length.’
“Deeply enough” and “tightly enough” were technical components of good cerclage placement that I learned on my own early in my career and were actually contrary, especially the latter, to the classical approach to cerclage placement that I had been taught. I found that by placing the cerclage deeply into the cervical stroma, it is much more secure, less likely to dislodge, and goes beneath the major blood supply to the cervix so that when you tie the knot “tightly enough”, you do not run the risk of strangulating the cervix. Indeed, when I was originally taught to perform a cerclage I was specifically instructed never to tie the knot too tightly and to place either a finger or a small diameter dilator into the cervical canal and to tie the knot down against that. “Don’t close up an abscess” was the mantra that was drilled into my head. But, as I soon learned, patients with true cervical insufficiency would use the opportunity of the slight opening this left in the cervical canal to eventually ‘balloon’ their membranes past the point of the cerclage.
With these points in mind, my step-by-step approach to cerclage placement in the patient who is having this done prophylactically at 13-14 weeks is the following:
1) Perform an ultrasound and offer combined first trimester screening for aneuploidy at 11-12 weeks
2) Evaluate the cervix by speculum examination to determine the amount of cervix present in the vagina (portio vaginalis)
3) During the latter, send diagnostic studies for Chlamydia and gonorrhea if appropriate and evaluate the vaginal fluid for evidence of bacterial vaginosis
4) Evaluate the urine for evidence of a urinary tract infection
5) Treat any cervical, vaginal, or urinary tract infections before cerclage placement
6) Prophylactic antibiotics and tocolytic agents are usually not used for prophylactic early cerclages
7) The procedure itself is usually performed under regional (epidural or spinal) anesthesia
8) The patient is placed in the dorsal lithotomy position and the perineum and vagina prepped with a betadine solution
9) The bladder is emptied or a foley catheter is placed after the patient is prepped
10) A weighted speculum is placed in the vagina and the cervix is visualized with retractors – good assistance and visualization is very important to adequate cerclage placement
11) The cervix is grasped at the 12:00 o’clock position with a sponge stick and downward traction applied to ascertain the junction between the vaginal mucosa and the cervix – in and out movement of the sponge stick while holding the cervix can help to readily identify this anatomical landmark
12) A double-strand of #5 Ethibond is loaded on a free CT-1 needle and the tails are together held with a hemostat
13) Using the edge of the needle to push up on the junction between the cervix and vaginal mucosa (this will often give an additional cm or more of cervical length) the cerclage is begun at the 12:00 o’clock position by deeply seating (about two-thirds of the depth of the cervical stroma) the suture, angling the needle somewhat cephalad with each ‘bite’ of the cervix, and exiting between 9:00 and 10:00 o’clock.
14) The sponge stick is then moved to 9:00 o’clock, the retractors are repositioned, the next ‘bite’ of the cervix is begun right where the needle last exited (being careful not to place the needle between the double-strand of suture), and then exited between 7:00 and 8:00 o’clock.
15) The next stitch is VERY important (and also very risky once there has been cervical change later in the pregnancy). The cervix is grasped at 6:00 o’clock and the cervix pulled upward, retractors repositioned, and the next bite is placed as high as possible posteriorally on the cervix exiting between the 4:00 and 5:00 o’clock positions.
16) Movement of the sponge stick to 3:00 o’clock is done, the next stitch exited at 2:00 to 3:00 o’clock and then one more time brings the suture back to the 12:00 o’clock position (As you can see, I typically use a “five point” approach to cerclage placement with significant support brought to the posterior aspect of the cervix)
17) The next step is also VERY important. Before tying the knot, I cinch the suture material up snugly by grasping both ends of the suture and moving it through the tissue 3-4 times, seating the suture material even more deeply
18) I then tie the knot TIGHTLY with 6-7 knots – enough to cause slight cyanosis of the cervix before I leave the operating room
19) Irrigate the vagina with warm (not hot) saline (not squirting this into the cervical canal) and then DRY the vagina completely with sponges
20) The cervix should be slightly cyanotic at this point and ‘pouting’ at you; if the cerclage is well-placed, this pouting should be very symmetrical
21) The patient is not discharged until she can void on her own (and I will often leave the catheter in place until her full sensation to void has returned to avoid overdistention of the bladder and a call from the operating room nurse informing me that the patient has “ruptured membranes,” usually leaking urine from an overly full bladder)
22) The patient is given a prescription for ibuprofen 600 mg q 6 hour, instructed to use this for the expected cramping sensation she will experience, and told to call if she needs to use the medication for more than 72 hours.
23) She is scheduled for a tranvaginal ultrasound 2-3 weeks following the procedure to assess cervical length, integrity at the internal os, and the level of the cerclage placement
I fully realize that some components of my approach to cerclage placement may be controversial, but I can assure all of you who read this that this approach has worked well and has been accompanied by virtually no complications in the prophylactic cerclages I have performed for more than 20 years. In the next post, I will go through my approach to ‘rescue cerclage’ placement….