Cervical Cerclage

Updated: Oct 03, 2023
  • Author: Allahyar Jazayeri, MD, PhD, FACOG, DACOG, FSMFM; Chief Editor: Ronald M Ramus, MD  more...
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Cerclage is usually done transvaginally as either a McDonald [1] or a Shiradkor [2] procedure. [3] When these 2 procedures are unsuccessful or difficult to perform, the transabdominal cerclage procedure is done. [4]

McDonald’s Cerclage

The McDonald’s cerclage is performed using a permanent suture. It was originally described as follows: "The bladder having been emptied, the cervix is exposed and grasped by Allis' or Babcock forceps. A purse string suture of No. 4 Mersilk on a Mayo needle is inserted around the exo-cervix as high as possible to approximate to the level of the internal os. This is at the junction of the rugose vagina and smooth cervix. Five or six bites with the needle are made, with special attention to the stitches behind the cervix. These are difficult to insert and must be deep...The stitch is pulled tight enough to close the internal os, the knot being made in front of the cervix and the end left long enough to facilitate subsequent division."

The author usually uses a Prolene #1 suture placed in a purse string fashion. Under regional anesthesia, the cervix is visualized by placing a long weighted speculum posteriorly, and curved or right angle retractors anteriorly and laterally as needed. With patient in stirrups and in the lithotomy position, the author uses an Allis to grasp the cervix as high in the vagina as possible, first at the 10 o'clock position. This Allis is used to retract cervical tissue inferiorly and laterally, to ensure that only cervical tissue is included in the bite and that the cervical canal is not violated or entered. The suture is placed immediately below the Allis clamp, hugging the clamp as the curved needle is rotated through. This maneuver is then repeated at the 8, 4, and 2 o'clock positions.

A surgeon's knot is placed, the knot is cinched down tightly, and several additional throws are placed (see the image below). The ends are cut long to allow identification at term and facilitate removal. Several different modifications have been described, including placement of a second suture above the first if the surgeon feels the cervical length (which should be more than 10 mm) below the first suture is inadequate.

Suture placement. Suture placement.

Shiradkor Technique

The original technique was described as follows:

I. A strip of fascia lata 1/4 inch wide and 4 1/2 inches long, is removed from the outer side of the thigh, and each end of this strip is transfixed with a linen suture.

2. The cervix is pulled down, a transverse incision is made above the cervix as in anterior colporrhaphy, and the bladder is pushed well up above the internal os.

3. The cervix is then pulled forward, toward the symphysis pubis, and a vertical incision is made in the posterior vaginal wall, again at and above the internal os, going only through the vaginal wall.

4. Through the right and left corner of the anterior incision an aneurysm needle is passed between the cervix and the vaginal wall until its eye comes out of the posterior incision.

5. The linen attached to each end of the fascia is passed through the eye of the aneurysm needle, and the right end of the fascia is pulled retrovaginally forward into the anterior incision. The same thing is done from the left side.

6. The two ends of the strip cross each other in front of the cervix and are tightened to close the internal os. The operator's left index finger in the internal os will indicate how much to pull on the strips. The assistant should be holding one end of the strip with an artery forceps.

7. The two ends are stitched together by a number of stitches that take a bite of the muscle fibers of the lowest part of the lower uterine segment, using a small curved needle and fine linen.

8. Extra portions of the fascia are cut out, and the anterior and posterior incisions are closed with chromic catgut No. 0.

Many modifications have been made, but in general the Shiradkor technique involves dissection of the vaginal mucosa and retraction of the bladder and rectum to expose the cervix at the level of the internal os. Usually, a curved Allis clamp is used to grasp the lateral edges of the anterior and posterior aspects of the transverse incisions and some paracervical tissue. The suture is then placed using a 5 mm tape suture with a double blunt needle at each end. The suture is placed anteriorly and tied posteriorly or placed posteriorly and tied anteriorly. If the patient is to be delivered by cesarean, the suture can be buried under the vaginal mucosa, which is then re-approximated using absorbable suture, or the knot can be left exposed for easy removal if vaginal delivery is planned.

Caspi et al described a modification using a single transverse incision in the anterior fornix. [5] A monofilament suture is passed on each side, under the mucosa at the level of the internal os, from the anterior incision to exit through the mucosa of the posterior cervix, and is then tied. The procedure was compared with the modified technique of Shirodkar in a randomized fashion in 90 subjects with previous failed McDonald procedure or with cervical anatomy felt to be unfavorable for McDonald cerclage placement. [6] Similar pregnancy outcomes were reported. The investigators believed that this modification has the advantages of simplicity, ease of removal, and lower incidence of severe vaginal discharge.

A retrospective study by Kindinger et al that included 678 women who received cervical cerclage reported that compared to monofilament suture, braided cerclage was associated with increased intrauterine death (15% vs 5%; P = 0.0001) and preterm birth (28% vs 17%; P = 0.0006). A prospective, longitudinal, follow-up study of the vaginal microbiome in women at risk of preterm birth because of short cervical length (≤25 mm) also found that braided suture induced a persistent shift toward vaginal microbiome dysbiosis. Although these results are preliminary and we need additional studies to confirm these findings, it appears that monofilament synthetic non-absorbable sutures like Prolene may be advantageous to braided sutures in the setting of cervical cerclage in pregnant women. [7]

Authors' preference

The patient is placed in the lithotomy position in stirrups. The vagina is prepped with Betadine. A long, weighted speculum is placed in the posterior vagina. The posterior lip of the cervix is grasped with ring forceps or tenacula. Care should be exercised not to lacerate the cervix.

Since bleeding from the anterior mucosal incision often obscures the operator's view of the posterior cervix, the posterior mucosal incision is made first. A small (2-cm) vertical incision is begun approximately 2.5 cm above the external os and carried proximally. The plane between the vaginal mucosa and the cervix is entered and developed using blunt dissection.

The cervicovesical reflection is identified. The anterior mucosal incision, approximately 2 cm long is made transversely at the cervicovesical reflection, and blunt dissection is used to develop the appropriate plane approaching as close to the internal os as possible.

A curved Allis clamp is used to bring the mucosa and paracervical tissue laterally. One blade of the clamp is inserted in the anterior incision and the other in the posterior incision. As the clamp is closed, the tissue is drawn away from the substance of the cervix.

Five mm Mersilene tape on a curved needle is used. It is placed similarly to what is described above for the McDonald's procedure. The needle is rotated against the clamp hugging the tip of the clamp opposite the curvature of the cervix. This ensures avoiding the cervical canal and membranes. It is best to enter posteriorly first so the knot ends up posterior and not anteriorly against the bladder. The exact procedure is performed on the opposite side driving the needle in the anterior to posterior direction.

A small permanent suture such as 3-0 Prolene can then be used to anchor the suture anteriorly at the level of internal os, or an absorbable suture can be used. Placing the permanent suture to anchor the tape anteriorly through the vaginal mucosa allows easy removal if the cerclage is to be removed later.

The cerclage can then be tied posteriorly. The ends are left long and through the posterior incision. The edges of the posterior and anterior incision are approximated by interrupted 3-0 chromic.

The advantage of Shiradkor is placement close to the level of the internal os and that most of the suture is buried (see image below); the disadvantages include bleeding when it is performed during pregnancy and difficulty in removal at term.

Cervical cerclage. Cervical cerclage.

Abdominal Cerclage

Some patients manifest severe cervical injures, and others have apparent congenital absence of the cervix, rendering Shirodkar or McDonald cerclage technically difficult or impossible. Benson and Durfee described an abdominal approach to cerclage, a procedure that was applied to congenitally short or surgically amputated cervices. [8]

Novy popularized this procedure and added the indications of "wide or extensive cervical conization, cervico-vaginal fistulas following abortion, or a previously failed vaginal approach to cervical cerclage." [9] In addition, Novy suggested using this procedure in pregnant patients with cervical effacement that precluded high placement of a vaginal cerclage. Novy later reported on 16 patients treated with transabdominal cerclage during a 14 year interval, including 22 pregnancies, 21 of which resulted in living children. [10]

Guidelines for patient selection include the following:

  • Previous failed vaginal cerclage with scarring or lacerations rendering vaginal cerclage technically very difficult or impossible

  • Absent or very hypoplastic cervix with history of pregnancy loss fitting classical description of cervical insufficiency

Advantages to abdominal cerclage include the following:

  • It can be performed in patients who cannot be treated successfully with vaginal cerclage.

  • The cerclage can be placed higher on the cervix, at the level of the internal os.

The main disadvantages of abdominal cerclage are:

  • The patient must undergo two laparotomies, one for the cerclage placement and another for the cesarean delivery.

  • The pregnancy that results in fetal death or preterm labor prior to viability after abdominal cerclage will need a hysterotomy even though no living child will result.

This the procedure is reserved for highly selected cases. The following approach to abdominal cerclage is based upon Novy's descriptions: [9, 10, 11]

  1. The procedure is planned at the end of the first trimester or the early second trimester, after fetal viability has been documented and initial ultrasound evaluation of the pregnancy has ruled out any major congenital malformation. It is important to wait until the risk of spontaneous first trimester abortion has passed, so that a second laparotomy to remove a nonviable pregnancy is not necessary.

  2. Either regional or general anesthesia can be employed. A catheter is placed in the bladder. Both Pfannenstiel and vertical abdominal incisions have been advocated, but transverse incision is adequate in most cases.

  3. The peritoneal cavity is opened, and the bladder flap is incised transversely for approximately 5 cm at its reflection on the uterus, just above the level of internal cervical os. The bladder flap is advanced downward bluntly for about 5 cm

  4. The uterus is wrapped in a laparotomy pad moistened with warm saline. The uterus is elevated through the abdominal incision, putting the cervix on traction. The uterine artery on each side is identified and retracted laterally. The avascular space between the ascending and descending branch is visualized and then this space is further expanded by gentle lateral retraction.

  5. A 5-mm Mersilene tape on a needle is then placed through the avascular space from anterior to posterior.

  6. The same process is repeated on the other side of the uterus except that the needle carrying the Mersilene tape is now passed from posterior to anterior so that the knot can be placed anteriorly.

  7. Care must be taken to insure that the Mersilene tape is flat all the way around and not twisted. A square knot is placed anterior to the internal os, compressing the cervical tissue but not too tightly. The free ends of the tape are secured with 3-0 Prolene sutures placed approximately 1 to 2 cm distal to the knot. The remaining free ends are then cut away . The posterior portion of the band passes around the isthmus of the uterus at about the level of insertion of the uterosacral ligaments and is easily palpable and visible from behind as the uterus is drawn into the incision. Later it will become encased in scar tissue.

  8. The peritoneal cavity, and abdominal incision are closed.

Emergency Cerclage

All 3 of the above procedures for cervical insufficiency are best performed prior to cervical dilation and effacement. However, many patients do not have the classic history that indicates prophylactic cerclage in the late first or early second trimester. Such patients are managed expectantly, with cerclage reserved for those who manifest cervical change demonstrated clinically or by ultrasound.

Therefore, many cerclage procedures are performed emergently rather than prophylactically. The most important step in performing emergency cerclage is making the diagnosis. Other causes of premature cervical dilation must be ruled out, specifically preterm labor, premature rupture of membranes and chorioamnionitis.

If regular uterine contractions are present, tocolysis may be considered. Abruptio placentae should be part of the differential diagnosis, especially with bleeding and is considered a relative contraindication to tocolysis and probably an absolute contraindication to cerclage.

In patient with contractions, emergency cerclage should only be considered if uterine contractions can be successfully inhibited and the clinician is convinced that preterm labor was the result of cervical dilation rather than the cause of it. In my experience, the McDonald procedure has worked well. Prolene no. 0 or 1 suture is used, and multiple small bites are taken. One or two circumferential sutures are placed and tied anteriorly.

While ruptured membranes are clear contraindication to a cerclage, a number of investigators have published descriptions of approaches to the dilated cervix with bulging, unruptured membranes. McDonald suggested using a moistened swab on a sponge forceps to reduce the bulging membranes. [1] Goodlin suggested transabdominal amniocentesis to reduce the tension in the amniotic cavity and allow retraction of "hourglassing" membranes. (see image below) [12] The author has used this approach on occasion, but it usually does not reduce the prolapsed portion of the membranes, and other techniques are needed.

Cervical cerclage. Cervical cerclage.

Olatunbosun and Dyck recommended the placement of patients in steep Trendelenburg position under general anesthesia and the use of 6 to 10 cervical stay sutures of no. 00 silk, then using traction on these sutures to cause the membranes to fall back into the uterine cavity before placing the cerclage. [13]

Katz and Chez suggested that filling the bladder by instilling 400 to 500 cc of normal saline may lead to a retraction of the amniotic sac into the uterine cavity, thus facilitating cerclage placement. [14]

I have used a foley catheter with a large balloon at the tip. With a full bladder, and the patient in steep Trendelenburg, the catheter is introduced in the cervix and the balloon gently inflated. The membrane usually retracts back inside the uterine cavity and the cerclage can be completed. The balloon is then deflated and the Foley is removed.

Charles and Edwards recommended the use of prophylactic antibiotics when emergency cerclage is performed. [15] They found a 2.6-fold increase in chorioamnionitis when cerclage was performed after, compared to before, 18 weeks' gestation and a tripling in the likelihood of preterm PROM. The use of antibiotics should be individualized to specific cases. Please see the ACOG 2011 recommendations above. The use of tocolysis after an emergency cerclage also needs to be individualized.




Cervical insufficiency, previously known as cervical incompetence, is a term used to describe an underlying cervical structural defect that contributes to early delivery of an otherwise healthy pregnancy. A classical diagnosis of cervical insufficiency is made based on historical information in which cervical dilatation occurs without contractions in one or more pregnancies. In most cases, this leads to delivery in the second trimester of pregnancy.

Cervical insufficiency can be treated with either activity restriction or surgically with cerclage. [16] Limited data are also available on use of vaginal pessary and progesterone therapy in treatment of selected patients. [17, 18, 19, 20, 21] Controversy exists as to whether such interventions are effective for cervical insufficiency. The biggest obstacle in this area of research is the accurate diagnosis of cervical insufficiency. Most authorities agree that cervical cerclage improves outcome in patients with true cervical insufficiency. The controversy comes from many studies and routine practice often including patients without a clear diagnosis who likely do not have true cervical insufficiency. [22]

Cervical cerclage is a surgical procedures in which sutures or synthetic tape is used to reinforce the cervix. The purpose of cervical cerclage is to increase the mechanical strength of the cervix, thereby preventing painless passive dilatation and premature delivery prior to viability.

Incompetent cervix can result in the following:

  • Preterm delivery, preterm labor, preterm premature rupture of membranes

  • Prolapse of the fetal membranes beyond the cervix into the vagina

  • Chorioamnionitis

  • Pregnancy loss


Cerclage should be placed in patients whose obstetrical history is consistent with cervical insufficiency. This includes patients with at least one delivery in the second trimester resulting from painless dilatation of cervix. [23, 24] The timing of cerclage placement is sometimes controversial, with some advocating placement between 12-14 weeks. Others argue that cervical insufficiency does not manifest itself prior to mid second trimester, around 18-20 weeks and consequently the optimal time to place a cerclage should be between 16-18 weeks when the vast majority of spontaneous pregnancy losses have already occurred and where ultrasound anatomical evaluation of the fetus can exclude pregnancies with major congenital abnormalities incompatible with life. No literature indicates early cerclage is advantageous over placement at 16 weeks.

A cerclage is also indicated in patients who are discovered during pregnancy to have a dilated or shortened cervix (see images below). Depending on the dilatation and effacement of the cervix, the procedure is categorized as urgent/indicated or emergent. Most experts agree that such an approach may be advantageous if the patient has had a prior preterm delivery. Recent studies have provided some support for this approach. [25, 26]

Prolapsed membrane. Prolapsed membrane.
Stages of incompetent cervix. Stages of incompetent cervix.

In rare circumstances, a cerclage may be placed prior to pregnancy. If the cervix has a large traumatic laceration, a cervical cerclage may be placed either abdominally or transvaginally. Placing in a nonpregnant patient may allow dissection of vaginal mucosa and cervix with less complications and blood loss than may occur in pregnancy. In these cases, a procedure described by Lash and Lash may be used to repair the cervical laceration. Preconception cerclage may complicate the management of first and early second trimester pregnancy loss or pregnancies complicated with major congenital malformations incompatible with life. The potential for these complications should be discussed with the patient. [27]

Elective cerclage is usually performed between 12-18 weeks. Emergency and urgent cerclage may be placed up to viability but are rarely used after 24-28 weeks. Risks associated with cerclage as well as the risks of premature delivery need to be carefully considered and each case evaluated and individualized based on the circumstances. After 24 weeks, expectant management and rest may be just as effective but can be associated with their own risks including, maternal deep venous thrombosis.


Both absolute and relative contraindications to cerclage exist.

Absolute contraindications include the following:

  • Active labor

  • Active vaginal bleeding

  • Abruptio placenta

  • Premature rupture of membranes

  • Chorioamnionitis

Relative contraindications include the following:

  • Prolapsed membranes

  • Vaginal spotting

Patients with relative contraindications should be observed from several hours to a day to ensure that no evidence of absolute contraindication exists prior to placement of a cerclage.



In general, regional anesthesia is used. In certain cases, general anesthesia may be more suitable, particularly if significant amounts of maternal positional manipulation, uterine relaxation, or airway protection are needed. [28]


The following equipment is needed for McDonald's cerclage:

  • Asepto syringe for irrigation

  • Suction tubing

  • Yankauer suction tip

  • Heaney retractors

  • Doyen retractors

  • Extra long blade weighted speculum

  • 1" Deaver retractor

  • Heaney and straight needle holders

The following equipment is needed for Shiradkor cerclage:

  • All equipment used for McDonald's cerclage

  • Cautery with short and long tip

  • Scalpel handle and # 10 blade available

The following equipment is needed for abdominal cerclage:

  • Standard laparotomy tray


Dorsal lithotomy position allows optimal exposure. Allen type or "candy cane" stirrups may be used. The surgeon must protect vulnerable neurologic, vascular, and bony points of the lower extremities. The buttocks should be positioned at the end of the table, with the table level with the floor. Hyperflexion of the hips should be avoided, as this can cause femoral neuropathy. Padding should be used at all potential pressure points.

Once positioned, and after appropriate anesthesia is obtained, the patient is then prepped and draped with the stirrups positioned to allow for assistants to be able to visualize the operative field. A bladder catheter may be inserted or the bladder may be emptied with a straight catheter; some surgeons prefer a distended bladder.

Patients are placed in the supine position for abdominal cerclage.

Preoperative evaluation

The fetus needs to be evaluated prior to placement of a cerclage. This is best done after 16 weeks with a combination of maternal serum screening and targeted ultrasound examination of the fetus. If the cerclage is being placed prior to that time, first trimester screening and nuchal translucency as well as limited fetal evaluation transvaginally and transabdominally looking for major congenital malformations such as anencephaly should be considered. In all surgical cases, fetal life should be documented before and after the procedure.

The use of antibiotics prior or after the cerclage is controversial. In elective cerclage, prophylactic antibiotics are not used. In urgent or emergency cerclage, the membranes have been exposed to the vaginal flora, and hence the pregnancy and the mother are both at risk of infection. In these cases, a single dose of antibiotics may be used to provide broad coverage. In some cases, antibiotics may be used for a short period of time. No study exists that indicates the use of antibiotics in these cases improves outcome or prolongs latency to delivery. Therefore, each case should be individualized to maximize benefits to the pregnancy and minimize emergence of antibiotic resistance. In 2011, ACOG Practice Bulletin #120 stated the following: [29]

" Evidence is insufficient to recommend perioperative antibiotic prophylaxis at the time of prophylactic or emergency cervical cerclage. Few studies have specifically evaluated the use of prophylactic antibiotics during the performance of a prophylactic cervical cerclage. Because the rate of complications (including infectious complications) after prophylactic cerclage (when performed before any evidence of cervical dilation or shortening) is low (1–5%), a study with a sufficiently large sample size to determine whether prophylactic antibiotic therapy is of benefit would be extremely difficult to implement.

Cerclage performed later in pregnancy, and when cervical dilation and effacement are present, has a high rate of complications, including chorioamnionitis and rupture of membranes. In addition, the risk of pre-existing, often subclinical, chorioamnionitis as a cause of the cervical insufficiency is significant, averaging approximately 33%. Randomized trials of cerclage in both high-risk individuals and low-risk individuals with cervical shortening have not uniformly included antibiotic prophylaxis as part of their protocols and, therefore, the current evidence is insufficient to recommend antibiotic prophylaxis for either prophylactic or emergency cerclage. If prophylaxis is used in such a situation, it should be guided by the general principles previously outlined, particularly a focused-coverage spectrum and short duration.

Similarly, consistent data are lacking regarding the use of antibiotic prophylaxis for abdominal cerclage. When performed via laparotomy, however, routine prophylaxis would not be indicated, in accordance with recommendations for other gynecologic surgical procedures that do not involve the vagina. Similarly, in cases where this procedure is performed laparoscopically, antibiotic prophylaxis, as for other laparoscopic procedures, is not indicated."

Some practitioners advocate amniocentesis in all cases of urgent or emergent cerclage to rule out chorioamnionitis or PROM. Amniocentesis can also be used therapeutically to reduce the amniotic fluid volume to allow an urgent or emergency cerclage when the membranes are protruding through the cervix. Not all providers do this, and need for amniocentesis should be determined on a case by case assessment of risk versus benefit. Amniocentesis may cause uterine irritability, making it more difficult to perform an emergency cerclage or to retain the cerclage in place. It can also be associated with PROM.

Amniocentesis should be considered in cases of cervical dilatation in excess of 4 cm with membranes and fetal parts prolapsed into the vagina. It should be considered in all cases when PROM or chorioamnionitis cannot be ruled out with certainty by clinical criteria, or when it can assist in reducing the membranes back above the cervix.

Tocolysis is used by some clinicians prior and for a few days after a cerclage to minimize uterine irritability immediately after the cerclage placement. It is not clear if this approach is associated with improved outcome. [30] Indomethacin is usually used; rectal suppositories are no longer available and oral tablets can be used when needed.

Patients with prolapsed membranes who do not undergo an amniocentesis should be observed for several hours to ensure that they are not infected, ruptured, or in preterm labor. Prolapsed membranes in patients with cervical insufficiency are often associated with excessive vaginal discharge and exudate, which in many cases can continue after cerclage placement. This can be distinguished from amniotic fluid by measurement of intrauterine amniotic fluid with ultrasound.

Mid-second trimester PROM of clinical significance is associated with oligohydramnios or anhydramnios. Preterm labor is diagnosed by painful, regular uterine contractions, and chorioamnionitis is diagnosed by fever, fetal tachycardia and uterine tenderness. Almost all patients with prolapsed membranes have elevated white blood cell count, and this laboratory value alone should not be used to define chorioamnionitis.




Complications at time of elective cerclage are uncommon and occur in less than 10% of procedures. [31] The frequency of complications is higher with increasing gestational age and cervical dilatation. PROM after elective cerclage occurs in approximately 2% of cases. [32] Rupture of membranes intraoperatively or in the immediate postoperative period is a major concern in nonelective cerclage, especially if done in the presence of advanced cervical dilation or prolapsed fetal membranes. This complication has been reported in up to 58% of nonelective procedures.

The frequencies of chorioamnionitis has been reported to be as much as 2-3 fold higher in non-elective cerclage. [15] The new ACOG practice bulletin #120 gives a figure of 33% for chorioamnionitis and others have reported a rate between 5-80% for emergent cerclage. [33]

Women who have undergone cerclage placement have an increased frequency of uterine contractions, but the presence of uterine irritability is not highly predictive of an increased risk of preterm birth. Cervical dystocia or cervical trauma in labor have been reported in fewer than 5% of patients. Excessive bleeding, maternal sepsis, and fistula formation are rare.

A systematic review by Alani et al found that the most common long-term complication of cervical cerclage is fistula formation, particularly vesicovaginal fistula. The researchers estimated that the incidence of vaginal erosion or fistula formation is 1 per 1000 cervical cerclage placements. [34]

Postoperative Care

Elective cerclage is typically an ambulatory procedure. The patient is discharged after recovery from the anesthetic and when she is able to ambulate and void.

Acetaminophen alone usually provides adequate analgesia for most women. Patients are told to report any leakage of fluid from the vagina so that they can be evaluated for preterm PROM. They should also be told to expect some spotting, cramps, and dysuria.

There is no evidence that coitus adversely affects prenatal outcome. Coitus should be avoided immediately after the procedure and individualized for each patient. In a nonelective cerclage, patients should be managed conservatively; physical activity and coitus should be avoided until a favorable gestational age of at least 32 to 34 weeks is reached.

Women are followed as outpatients on a regular basis with frequent (weekly or biweekly) visits for cervical checks. Transvaginal ultrasound assessment of the cervical length and dynamics (changes in length with and without pressure) may be useful for identifying those patients at highest risk for preterm birth. [35, 36]

A cerclage may fail as the uterus enlarges resulting in cervical dilatation. This may be an indication for a rescue cerclage, or treatment of preterm labor when appropriate.

Cerclage Removal

The cerclage is usually removed at 36-37 weeks of gestation or with the onset of premature labor to avoid cervical laceration or uterine rupture. Whether to remove the cerclage in the setting of PPROM is controversial.

A McDonald cerclage can usually be cut and removed in the office without analgesia. A Shiradkor cerclage often requires a return to the operating room for removal, either because the knot is buried under the vaginal epithelium or the Mersilene has become infiltrated by cervical granulation tissue.

As discussed above, a Shirodkar cerclage does not have to be removed if cesarean delivery is anticipated and future pregnancies are planned. There is a theoretical risk of reduced fertility from inflammation or infection of the cervix due to the foreign body and a risk of erosion into adjacent tissue.