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Cervical Insufficiency and Mid-trimester Delivery

This article was originally published in the Austin Perinatal Associates newsletter.

David L. Berry, M.D., F.A.C.O.G.

One of the most devastating diagnoses in pregnancy is that of cervical insufficiency or incompetent cervix. During the mid-trimester, an otherwise normally progressing pregnancy may turn devastatingly lethal. Classically, cervical insufficiency occurs with little or no warning. Between 18 and 24 weeks’ gestation, spotty vaginal bleeding, sudden and severe pelvic pressure, explosive rupture of the membranes (PROM) and rapid delivery of a pre-viable fetus occurs. These deliveries can occur at home, in the car, in the Emergency Department or in the toilet of a Labor and Delivery unit. There is no reliable historical presentation or risk factor that is predictive of cervical insufficiency.

Among obstetric care providers, much disinformation has led to the demonization of this diagnosis as one of exclusion, and cerclage has been described as “voodoo medicine” technique. The American College of Obstetrics and Gynecology (ACOG) still defines cervical insufficiency as a potential diagnosis AFTER three or more unexplained mid-trimester losses when associated with painless cervical dilatation. ACOG, also, misleadingly states the operative complication rate of elective cerclage is as high as 16.6%(1.) (SEE ADDENDUM BELOW)

One of the most under-diagnosed conditions, cervical insufficiency can be mistaken as intra-amniotic infection (chorioamnionitis), PROM, abruptio placenta, preterm labor, or just bad luck. If we examine the causes of chorioamnionitis, clearly, ascending polymicrobial infection is responsible. Where and why, you may ask, does an ascending infection occur in the face of a normal cervix and an intact mucus barrier filled with secretory IgA antibodies? Why do intact membranes rupture without provocation, stress or bacterial collagenase that weakens membranes? Why would a normal cervix melt away with neither pain, nor symptoms of true, raging labor? Unfortunately, clinical research in obstetrics has failed to answer any of these questions adequately. We do know, however, that the treatment of failure of cervical integrity is quickly, easily and effectively treated with first trimester cervical cerclage.

Cervical insufficiency has, for decades, been associated with cervical surgeries (LEEP, biopsy or multiple D&C procedures), diethyl stilbesterol exposure or Mullerian anomalies. More recently, hypotheses have included vitamins C and E deficiencies. None of these theories have proven reliable. Unfortunately, all patients with any combination of an array of past obstetrical histories can fall victim to cervical insufficiency. We at Austin Perinatal have cared for many patients with cervical insufficiency including the G1 with no previous cervical procedures, patients with 6 or more previous mid-trimester losses, and patients with 3 previous term C-sections followed by a 20-week loss from clear cervical insufficiency.

McDonald originally described a simple purse-string suture requiring no vaginal wall dissection in 1957(2.) This suture is easily removed to allow for vaginal delivery at term. Many modifications have been done since. TeLinde’s Operative Gynecology still describes tying a McDonald cerclage over a 5 mm Hegar’s dilator to prevent cervical stenosis(3.) This technique has proven in my hands to fail. Most patients will accept a very small increased risk of Cesarean section for the benefit of not prolapsing their membranes via that iatragenic 5 mm opening in their cervix. Approximately 90% of cerclages performed in this office are modified McDonald-type cerclages using 5 mm Mersilene (#1 Prolene or Ethibond which also have shown to fail).

The original Shirodkar cerclage was described in 1955 by Dr. V.N. Shirodkar in Bombay, utilized an allografted strip of tensor fascia lata harvested from the lateral thigh of the patient(4.) This type of cerclage, which now uses synthetic Mersilene suture, is reserved for those who have significant tissue loss of the cervix from previous operative procedures or for those with a previous failed McDonald cerclage.
Abdominal cerclage is a more invasive procedure involving 2 – 3 days of hospitalization and an incision similar to that of a Cesarean delivery. Bowel, bladder, ureteral injury and excessive blood loss can occur with an abdominal cerclage, and it is, therefore, reserved for a very select group of patients.

Rescue cerclage is a controversial technique that may be appropriate for the acute care patient who is incidentally found to have a foreshortened cervix with membrane prolapse between 18 and 24 weeks. Rescue cerclages are wrought with exceptionally high risks of PROM, infection, labor and pre-viable delivery in up to 50% of cases. The more heroic the maneuvers at the time of surgery, the more likely it is that the patient will experience poor perinatal outcomes. Patients must be individualized for consideration of this “emergency” or “rescue” procedure. Generally, these patients are admitted for 48-hours of observation and given broad-spectrum antibiotics. Deep Trendelenberg position and pre-operative Foley catheters are of little added value since the stress upon the cervix originates from the elasticity of the gravid uterus and is not gravitational. If the membranes are less that 2 x 2 cm out of the external os, there is no bleeding or signs of infection or labor, a rescue cerclage would be considered.

Up to 1 - 2% of all pregnancies (40,000 – 80,000/year in the U.S. and 200 - 400/year in Austin alone) are complicated by cervical failure. It is the policy of APA to evaluate all patients with the history of even one mid-trimester loss, regardless of the reason, for the potential for cervical insufficiency. We individualize patient care depending upon risk factors, personal and family history. Frequently, a patient with a single loss between 18 and 24 weeks will qualify for cervical cerclage.

Dr. Berry has personally performed over 900 procedures in 17 years with a 0% operative complication rate, a 0.1% anesthetic complication rate, a 99% fetal survival rate and a 96% term delivery rate. Of note is the national preterm delivery rate in the uncomplicated pregnancy is 12%, while Dr. Berry’s preterm delivery rate in the complex patient with cerclage is only 4%. Clearly, there are additional benefits in prevention of prematurity other than just the reinforcement of a weak cervix. Most likely, there are added benefits of preventing membrane prolapse and physical strain on the membranes overriding the cervix, the prevention of ascending infection by reinforcing the immunologic mucus barrier, in addition to the emotional and psychological benefit of avoiding the feared unattended delivery without warning signs as happens with cervical insufficiency without cerclage.

ADDENDUM, February 19, 2014

In February of 2014, ACOG finally changed their 2003 stated position on cerclage. The new Practice Bulletin states that, now, cerclage should be considered in any patient with any single previous mid-trimester delivery, especially with silent cervical dilation(5).

  1. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin. Cervical insufficiency. Obstet Gynecol 2003 (Nov); 102 (5 Pt 1): 1191 – 9.
  2. McDonald IA: Suture of the cervix for inevitable miscarriage. J Obstet Gynecol Br Commonw 64:346, 1957.
  3. Thompson JD, Rock JA: TeLinde’s Operative Gynecology 7th ed. 322 – 6.
  4. Shirodkar VN; A new method of operative treatment for habitual abortions in the second trimester of pregnancy. Antiseptic 52:299, 1955.
  5. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin. Cerclage for the management of cervical insufficiency. Obstet Gynecol. 2014 Feb;123(2 Pt 1):372-9.

Dr. David Berry and his staff at Austin Perinatal Associates are pleased to offer to you consultation in this regard as well as a comprehensive array of services for the complex and high-risk pregnancy.

Dr. David L. Berry

A 4th generation physician and Austinite since 1978, Dr. Berry is board certified by the American Board of Obstetrics and Gynecology both in OB/GYN and maternal-fetal medicine.

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