Shirodkar Cerclage Technique
The Shirodkar cerclage is a surgical procedure for cervical insufficiency that involves placing a suture high at the level of the internal cervical os, with the suture buried beneath the vaginal mucosa.
Surgical Steps
Preoperative Preparation
- Positioning: Place patient in dorsal lithotomy position under regional or general anesthesia
- Bladder management: Empty bladder and consider Foley catheter placement
- Cervical exposure: Use weighted speculum for adequate visualization
Step-by-Step Procedure
1. Anterior Incision and Bladder Mobilization
- Make a transverse incision over the anterior lip of the cervix at the level of the bladder reflection 1
- Carefully dissect and separate the bladder from the anterior cervix using sharp and blunt dissection
- Push the bladder superiorly to expose the cervicovesical space
2. Posterior Fornix Incision
- Create a small transverse incision in the posterior vaginal fornix
- This allows access to the posterior paracervical tissues
3. Suture Placement
- Material selection: Use non-absorbable suture material (Mersilene band or monofilament nylon 0.6mm) 2, 3
- Lateral passage: Using curved forceps (such as White tonsil forceps), create a submucosal tunnel laterally on each side of the cervix at the level of the internal os 3
- Pass the suture material through these lateral tunnels, encircling the cervix as high as possible near the internal os
- The suture should pass through paracervical tissues bilaterally, staying submucosal to avoid bladder or rectal injury
4. Knot Tying
- Tie the knot anteriorly with moderate tension to close the internal os without excessive constriction 1
- Some surgeons prefer tying posteriorly in the posterior fornix for easier removal 2
- Facilitating removal: Pass a silk thread around the tape in the posterior fornix to mark location and facilitate later removal 1
5. Closure
- Close the vaginal mucosa over the suture with absorbable sutures
- The cerclage should be completely buried beneath the mucosa (distinguishing feature from McDonald technique)
- Ensure hemostasis
Key Technical Points
Critical Differences from McDonald Technique
- Submucosal placement: Suture is buried beneath vaginal mucosa (vs. McDonald which is visible)
- Higher placement: Positioned at internal os level for maximum effectiveness
- More complex: Requires bladder mobilization and mucosal incisions 4
Modifications to Facilitate Removal
Modern modifications address the historical difficulty of suture removal 2:
- Use monofilament nylon instead of braided material to reduce vaginal discharge (52% with Mersilene vs 0% with nylon) 2
- Place knot posteriorly in fornix rather than anteriorly
- Use auxiliary marking sutures to locate the cerclage at term 5
Advantages Over McDonald
- Higher placement allows better closure at internal os level
- More effective in preventing preterm birth <32,34, and 35 weeks (RR 0.91 for delivery <37 weeks) 4
- Longer cerclage-to-delivery interval and increased birthweight 4
- Particularly indicated when McDonald has failed or cervix is too short/lacerated for McDonald placement 2, 6
Clinical Context and Indications
When to Consider Shirodkar vs McDonald:
- Prior McDonald cerclage failure (63.6% of Shirodkar cases have this history) 6
- Very short cervix where McDonald placement would be too low
- Severely lacerated cervix with poor anatomy 2
- Need for placement at true internal os level
Important Caveat: Current guidelines recommend against routine cerclage in patients without prior preterm birth history who have short cervix (10-25mm) without cervical dilation 7. Cerclage may be considered at cervical length <10mm based on shared decision-making 7.
Outcomes
- Success rate: >90% delivery beyond 24 weeks in experienced hands 6
- Median delivery GA: 38 weeks 6
- Neonatal survival: 90.6% 6
- Vaginal delivery rate: 70.3% possible after removal 6