We've been doing cerclage for roughly half a century—but where's the evidence that it prevents preterm birth? The authors make the case for limiting this surgery to select patients, cautioning that for multiple gestations, it might just make things worse.
Does cerclage actually prevent miscarriage and pre-term birth (PTB) as intended? Our purpose here is to examine the scientific evidence that supports or refutes that premise, which as you will see suggests the procedure should only be done sometimes-and only in specific situations. The evidence also suggests a need to cut back on the estimated 40,000 cerclages placed each year in the United States-a number that translates into about 1% of pregnancies receiving cerclage annually.
One originator of this procedure in the early 1950s, Dr. V.N. Shirodkar, envisioned cerclage as appropriate for "women who abort repeatedly between the 4th and 7th month...where one can, by repeated internal examinations... find that the cervix is gradually yielding."1 Another pioneer, Dr. I.A. McDonald (Figure 1), saw cerclage as appropriate for "[women with] prior second-trimester miscarriages.... [who] presented with dilatation of the cervix and bulging of the forewaters during the second trimester."2 These investigators therefore agreed that two indications were needed for cerclage: a poor obstetrical history of repeated second-trimester losses, and cervical changes in the current pregnancy.
The diagnosis of cervical insufficiency is based on a history of painless dilation leading to recurrent second-trimester losses (STL).3 Therefore cervical insufficiency is one extreme on the continuum of PTB.4 Current proposed possibleindications for suturing the cervix closed include:
The terminology used in the past to describe the indications for cerclage has been very confusing. We avoid using terms like prophylactic, elective, salvage, therapeutic, urgent, emergent, and rescue. Instead, we recommend terms that more accurately describe the clinical situation, like history-indicated or U/S-indicated (Table 1).
Unfortunately, none of the three randomized trials evaluating history-indicated cerclage have focused on women with classical cervical insufficiency.5-7 Of the women studied, the only ones who appear to benefit from cerclage are those with three or more prior STL or prior PTBs.7 In this limited population, the number of PTBs declined by about 40% with cerclage compared to similar women who did not receive cerclage. Women with two STLs can also be considered for history-indicated cerclage, but there's no evidence that this does any good. The best time to place history-indicated cerclage is at around 11 to 13 weeks, before cervical changes occur.
A recent meta-analysis8 of the four randomized trials on U/S-indicated cerclage confirmed what Drs. Shirodkar (Figure 2) and McDonald had proposed roughly half a century ago: that the women who benefit from cerclage have both a prior history of PTB and early cervical change in the current pregnancy.9-12 Ultrasound-indicated cerclage helped to significantly reduce PTB, especially in women with a short TVU CL (<25 mm) and a previous PTB at 16 to 36 weeks (Table 2). This result needs to be confirmed by a randomized trial on this specific population. The good news is that such a trial is currently enrolling patients at 12 centers in the US. (For more information on the Vaginal Ultrasound Cerclage Trial, go to http://www.clinicaltrials.gov/ct/show/NC00059683?order=1, or contact John Owen, MD [PI] at 205-934-7343, or email@example.com, or Rachel Copper, MSN, CRNP, 205-934-4242, or firstname.lastname@example.org.)
Perinatal mortality was also reduced by 38% in women with both a short TVU CL and a previous PTB, but this result was not statistically significant, given the low incidence of this outcome. Too few women with other risks for PTB, like cone biopsy, two or more D&Es, müllerian anomalies, and DES exposure, have been studied to be able to make any meaningful recommendations.
Transvaginal ultrasound screening for cervical insufficiency in women with prior STL or PTB provides two key benefits: (1) It identifies which at-risk women might benefit from cerclage (Table 2); and (2) It identifies which ones might not benefit, given that more than 60% of at-risk women maintain a TVU CL of 25 mm or more between 14 and 23 6/7 weeks, and more than 90% of such women deliver at 35 weeks or later without any intervention.13
In the four studies that compared a policy of history-indicated cerclage with one of TVU CL screening (with U/S-indicated cerclage for TVU CL <25 mm at <24 weeks), the incidence of PTB was similar in the two groups.14-18 Since most women at risk for cervical insufficiency who actually deliver preterm have a short CL on TVU at an average of about 18 to 20 weeks (the gestational age of the anatomy scan), this is the best time to do one TVU CL screening examination. In certain high-risk groups, serial screening every 2 weeks with TVU CL can be suggested between 16 and 23 6/7 weeks. Consider earlier screening, starting at 12 to 14 weeks, only for women with multiple STLs or very large (>2 cm) cone biopsies.13,19
Only one randomized trial has compared cerclage to expectant management in women found at 20 to 24 weeks to have membranes at or beyond the internal os as confirmed by physical exam.20 This trial included only 23 women, seven of whom were carrying twins. The women who received the physical exam-indicated cerclage gained 1 additional month compared to similar women who did not receive cerclage-a finding confirmed by the largest retrospective series on this topic in the literature.21 Even so, it's important to emphasize that TVU is a more effective screen for cervical shortening and the risk of PTB than bimanual cervical exams.22
There's little evidence to indicate that transabdominal cerclage prevents PTB; in fact, there's been only one controlled, nonrandomized trial.23 When women with a history-indicated transvaginal cerclage who'd experienced a PTB before 33 weeks underwent a transabdominal cerclage in the next pregnancy, 82% gave birth at 35 weeks or more, compared to 58% of similar women who instead had another trans-vaginal cerclage the second time around. This greater than 80% success rate is confirmed by more than 22 case series of transabdominal cerclage.
Unfortunately no other indication for transabdominal cerclage has been properly evaluated. It's unclear what the best management is for women in whom no vaginal portion of the cervix remains due to cone biopsy or other cervical trauma. Transabdominal cerclage is usually performed at around 11 weeks, which is past the period of early miscarriages, and allows for U/S assessment at 11 weeks for nuchal translucency (NT).
Some researchers have advocated prepregnancy transabdominal cerclage. However, there are no RCTs of prepregnancy versus first-trimester transabdominal cerclage. Laparoscopic transabdominal cerclages have been placed (usually pre-pregnancy) in some centers, with limited reports, usually including a small number of cases, making this approach promising but still experimental.24 Figure 3 shows basic steps for performing a transabdominal cerclage.
Reinforcing cerclage is defined as one placed in a woman with a cerclage already in place for more than 1 day. So far, the literature contains only one controlled study of such a cerclage.25 In women with a history-indicated cerclage already in situ and a short CL less than 25 mm at 14 to 23 6/7 weeks on TVU, the placement of a reinforcing (second or repeat) cerclage is associated with a greater number of PTBs and pre-viable deliveries. Therefore rein-forcing cerclage should not be performed in clinical practice outside of controlled research.
The only randomized trial on cerclage performed solely because of multiple gestation was one that involved twins. It showed no reduction in PTB.26 Moreover, a meta-analysis of U/S-indicated cerclage showed that women carrying twins who develop a short CL less than 25 mm between 14 and 23 6/7 weeks on TVU have a greater number of PTBs with cerclage compared to the "no cerclage" controls (Table 2).8 Therefore, at this point there's no evidence that cerclage should be performed in any woman carrying a multiple gestation.
Contraindications to this surgery include severe fetal anomaly, intrauterine infection, active bleeding, active PTL, preterm premature rupture of membranes (PPROM), and non-viability. It is of utmost importance to always perform a detailed U/S before cerclage placement to ensure viability and normal anatomical survey appropriate for gestational age (GA).
Q. How short should the CL on TVU be before I offer cerclage?
A. A TVU CL shorter than 25 mm at 14 to 23 6/7 weeks is the current accepted cutoff for a heightened risk of PTB. Among women with singleton gestations and a previous PTB, cerclage reduces PTB to a similar extent both in women with a CL shorter than 25 mm and in those with a CL of 15 mm or less.8
Q. How late in gestation should I offer a cerclage?
A. Be guided by two important considerations that affect the GA limit of performing a cerclage. First, due to tremendous improvements in neonatology care, the GA of viability is now earlier, with survivals being achieved at 22 to 23 weeks, though usually with substantial perinatal morbidity. Second, the later in gestation that you detect cervical changes, the more likely the uterus is to be contracting. In fact, most women with a short CL before 24 weeks have contractions.27 While there's no strong evidence to support or refute the value of cerclage after 23 weeks, for U/S-indicated cerclage, the earlier the short CL is detected, the more effective the cerclage might be at preventing PTB.8
Q.Does a term delivery eliminate the risk of previous "cervical insufficiency?"
A. If a patient has a previous PTB or STL but this is followed by a pregnancy in which, with no particular intervention, a term delivery occurs, the subsequent recurrent risk of PTB is usually slim-less than 10%. Therefore no particular screening is recommended.
Q. What about women with LEEPs?
A. For women who've had LEEP procedures or cone biopsies where a minimal amount of tissue is removed (<2 cm), the rates of cervical shortening and of PTB are low, so cerclage is probably not justified solely for this indication.28
Q. Should I perform an amniocentesis prior to the cerclage?
A. For history-indicated or transabdominal cerclages, usually performed at 11 to 13 weeks, the risk for intra-amniotic infections is very low, since the cervix is closed and long. Therefore amniocentesis to rule out infection is not indicated and would be detrimental.
For U/S-indicated cerclages, usually performed at 14 to 23 6/7 weeks, the percentage of intra-amniotic infections is only 1% to 2%.9 Therefore amniocentesis cannot be universally recommended before cases of U/S-indicated cerclage unless there are signs or symptoms of infection. But it's a different story when it comes to physical exam-indicated cerclage in women with some cervical changes on bimanual or speculum exam. For these patients, the incidence of subclinical intra-amniotic infection can be more than 10% to 20%. The risk of intra-amniotic infection detected by amniocentesis is even greater (about 50%) for women with a cervix dilated 2 cm or more.29,30 Therefore you should consider an amniocentesis for women with cervical changes on physical exam before cerclage placement, even in the absence of clinical symptoms of intra-amniotic infection.
Q. Which technique?
A. There is no randomized trial comparing the McDonald (Figure 1) and Shirodkar (Figure 2) cerclage techniques.1,2 Most surgeons prefer the McDonald technique because it's the easiest to perform and studies show that it is effective in certain clinical situations.8,18
Q. Which suture?
A. Only one study compared Mersilene, Tevdek, and Prolene as sutures used in a McDonald cerclage.31 Overall incidences of PTB were similar in the three groups. Therefore, in the absence of extensive evidence, the choice of suture can be left to the physician's preference.
Q. Which anesthesia?
A. While there are no controlled studies on this issue, regional is preferable to general anesthesia for placing a transvaginal cerclage. Spinal anesthesia is usually the preferred regional technique. Trans-abdominal cerclage can also be safely performed under regional anesthesia.
Q. Should I use tocolytics?
A. Once again, there's no clear evidence that tocolytics at the time of cerclage placement improve outcomes. Active contractions and PTL are contraindications to placement of a cerclage. There's been one randomized trial on U/S-indicated cerclage in women at high risk for PTB because of both their prior history and a short TVU CL that showed fewer PTBs in those who received both U/S-indicated cerclage and indomethacin compared to those who received neither.10 Whether it was the cerclage, the indomethacin, or the combination of the two that improved outcomes needs further research.
Q. Should I use antibiotics?
A. Not according to the evidence. There's no study that proves that antibiotics should be given at the time of cerclage placement. Intra-amniotic infection is a contraindication to placement of a cerclage. If the candidate for cerclage has risk factors for infections (in particular sexually transmitted ones), appropriately screen for and treat those specific infections.
Q. Should activities be restricted?
A. There's no evidence that decreased activity like bed rest prevents PTB. In fact, there is evidence that prophylactic bed rest in the hospital increases PTB in twins.32 Standing (versus lying down) has been shown to unmask or increase cervical shortening. You should inform women placed on restricted activity that not only is there no proven benefit to this management, but there are potential risks like thromboembolism.
Q. Is outpatient as good as inpatient cerclage?
A. Most history-indicated cerclages can be safely performed on an outpatient basis. For women with cervical changes on physical exam who are at higher risk for infection and PTL, especially if detected after 20 weeks, you might consider a brief 24-hour postop stay for observation.
Complications of cerclage placement can include bleeding, infection (especially endometritis), cervical trauma, PPROM, and suture displacement. As we've said, evidence suggests that cerclage can increase PTB in multiple gestations. Before doing a cerclage, make sure you've appropriately counseled the woman about potential benefits and complications and obtained written consent.
Although there are no controlled studies on the best time to remove a cerclage, we do know that severe cervical injuries can occur if women have prolonged labor with a cerclage in place. Because of this concern, and the fact that there are minimal risks to neonates born after 36 weeks, most experts advocate removing cerclages at around 36 weeks at the latest. For patients with cerclage in place and PPROM, you must weigh the potential risks for maternal and fetal infection against the risk of prematurity to the fetus. Cerclage management with PPROM depends on GA:
A cerclage should be done only for very specific indications. If a woman has previously received this surgery for unclear or inappropriate indications, and delivered at term, she does not have to have a cerclage in her next pregnancy. Two controlled series showed that the rate of PTB in women with a prior cerclage for unclear or inappropriate indications is similar whether or not the cerclage is placed in the subsequent pregnancy.34,35
Evidence suggests that cerclage prevents PTB in the clinical situations shown in Figure 4: women (1) with three or more PTB/STL (history-indicated cerclage best placed between 11 and 13 weeks); (2) with a prior PTB at 16 to 36 weeks and TVU CL 25 mm or less in the current pregnancy (U/S-indicated cerclage at 14 to 23 6/7 weeks); or (3) with recurrent STL, a prior history-indicated cerclage, and PTB before 33 weeks despite the cerclage (consideration for transabdominal cerclage by an expert surgeon).
Evidence is weaker for the effectiveness of cerclage among women with physical exam-detected cervical changes and/or prolapsed membranes in the second trimester (physical exam-indicated cerclage at 14 to 23 6/7 weeks). There's also less evidence for the effectiveness of cerclage among women with recurrent (two) STL (history-indicated cerclage) with no apparent cause other than cervical insufficiency. Evidence suggests that cerclage may not prevent but in fact increases PTB in women with a short CL who are carrying multiple fetuses.
It's important to remember that cerclage is but one of many interventions for preventing PTB-which is a complex condition. As with other complex problems like cardiac disease, some interventions may be helpful in certain situations and detrimental in others. Cerclage should still be an available intervention used in selected cases for prevention of PTB, but clinicians should restrict its use based on the available evidence.
1. Shirodkar VN. A new method of operative treatment for habitual abortions in the second trimester of pregnancy. Antiseptic. 1955;52:299-300.
2. McDonald IA. Suture of the cervix for inevitable miscarriage. J Obstet Gynaecol Br Emp. 1957;64:346-350.
3. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin: Cervical Insufficiency. 2003;102: 1091-1099.
4. Iams JD, Johnson FF, Sonek J, et al. Cervical competence as a continuum: a study of ultrasonographic cervical length and obstetric performance. Am J Obstet Gynecol 1995;172:1097-1106.
5. Rush RW, Isaacs S, McPherson K, et al. A randomized controlled trial of cervical cerclage in women at high risk of spontaneous preterm delivery. Br J Obstet Gynaecol. 1984;91:724-730.
6. Lazar P, Gueguen S, Dreyfus J, et al. Multicentred controlled trial of cervical cerclage in women at moderate risk of preterm delivery. Br J Obstet Gynaecol. 1984;91: 731-735.
7. Final report of the Medical Research Council/Royal College of Obstetricians and Gynaecologists multicentre randomized trial of cervical cerclage. MRC/RCOG Working Party on Cervical Cerclage. Br J Obstet Gynaecol. 1993; 100:516-523.
8. Berghella V, Odibo AO, To MS, et al. Cerclage for short cervix on ultrasonography: meta-analysis of trials using individual patient-level data. Obstet Gynecol. 2005; 106:181-189.
9. Rust OA, Atlas RO, Reed J, et al. Revisiting the short cervix detected by transvaginal ultrasound in the second trimester: why cerclage therapy may not help. Am J Obstet Gynecol 2001;185:1098-1105.
10. Althuisius SM, Dekker GA, Hummel P, et al. Final results of the Cervical Incompetence Prevention Randomized Cerclage Trial (CIPRACT): therapeutic cerclage with bed rest versus bed rest alone. Am JObstet Gynecol. 2001;185:1106-1112.
10. To MS, Alfirevic Z, Heath VC, et al. Cervical cerclage for prevention of preterm delivery in women with short cervix: randomised controlled trial. Lancet. 2004;363: 1849-1853.
12. Berghella V, Odibo AO, Tolosa JE. Cerclage for prevention of preterm birth in women with a short cervix found on transvaginal ultrasound examination: a randomized trial. Am J Obstet Gynecol. 2004;191:1311-1317.
13. Berghella V, Bega G, Tolosa JE, Berghella M. Ultrasound assessment of the cervix. Clin Obstet Gynecol. 2003;46:947-962.
14. Althuisius SM, Dekker GA, van Geijn HP, et al. Cervical incompetence prevention randomized cerclage trial (CIPRACT): study design and preliminary results. Am J Obstet Gynecol. 2000;183:823-829.
15. Kelly S, Pollock M, Maas B, et al. Early transvaginal ultrasonography versus early cerclage in women with an unclear history of incompetent cervix. Am J Obstet Gynecol. 2001;184:1097-1099.
16. To MS, Palaniappan V, Skentou C, et al. Elective cerclage vs. ultrasound-indicated cerclage in high-risk pregnancies. Ultrasound ObstetGynecol. 2002;19:475-477.
17. Berghella V, Haas S, Chervoneva I, et al. Patients with prior second-trimester loss: prophylactic cerclage or serial transvaginal sonograms? Am J ObstetGynecol. 2002; 187:747-751.
18. Berghella V, Baxter J, Berghella M. Cervical Insufficiency. In: Apuzzio JJ, Iffy L, Vintzileos AM, eds. Operative Obstetrics. Oxford, UK: Taylor & Francis, 2005. In Press.
19. Berghella V, Talucci M, Desai A. Does transvaginal sonographic measurement of cervical length before 14 weeks predict preterm delivery in high-risk pregnancies? Ultrasound Obstet Gynecol. 2003;21:140-144.
20. Althuisius SM, Dekker GA, Hummel P, et al. Cervical incompetence prevention randomized cerclage trial: emergency cerclage with bed rest versus bed rest alone. Am J Obstet Gynecol. 2003;189:907-910.
21. Pereira L, Cotter A, Berghella V, et al. Cervical cerclage compared to expectant management in women with a dilated cervix in the 2nd trimester: results from the GNPRH international cohort study. Am J Obstet Gynecol. 2005;193;abstract # 436.
22. Berghella V, Tolosa JE, Kuhlman KA, et al. Cervical ultrasonography compared with manual examination as a predictor of preterm delivery. Am JObstet Gynecol. 1997;177:723-730.
23. Davis G, Berghella V, Talucci M, et al. Patients with a prior failed transvaginal cerclage: a comparison of obstetric outcomes with either transabdominal or transvaginal cerclage. Am J Obstet Gynecol. 2000;183:836-839.
24. Cho CH, Kim TH, Kwon SH, et al. Laparoscopic transabdominal cervicoisthmic cerclage during pregnancy. J Am Assoc Gyn Laparosc. 2003;10:363-366.
25. Baxter J, Airoldi J, Berghella V. Short cervical length after history-indicated cerclage: is a reinforcing cerclage beneficial? Am J Obstet Gynecol. 2005;193:1204-1207.
26. Dor J, Shalev J, Mashiach S, et al. Elective cervical suture of twin pregnancies diagnosed ultrasonically in the first trimester following induced ovulation. Gynecol Obstet Invest. 1982;13:55-60.
27. Lewis D, Pelham J, Sawhney H, Berghella V, et al. Most asymptomatic pregnant women with a short cervix on ultrasound are having uterine contractions. J Matern Fetal Neonatal Med. 2005. In press.
28. Berghella V, Pereira L. Gariepy A, et al. Prior cone biopsy: prediction of preterm birth by cervical ultrasound. Am J Obstet Gynecol. 2004;191:1393-1397.
29. Pereira L, Gomez R, Ness A, et al. Amniocentesis should always be performed in women with a dilated cervix in the 2nd trimester: results from the GNPRH international cohort study. Ultrasound Obstet Gynecol. 2005. In press.
30. Romero R, Gonzalez R, Sepulveda W, et al. Infection and labor. VIII. Microbial invasion of the amniotic cavity in patients with suspected cervical incompetence: prevalence and clinical significance. Am J Obstet Gynecol. 1992;167:
31. Pereira L, Levy C, Lewis D, Berghella V, et al. Effect of suture material on the outcome of emergent cerclage. Am J Obstet Gynecol. 2004;103(4):35S.
32. Crowther CA. Hospitalisation and bed rest for multiple pregnancy. The Cochrane Database of Systematic Reviews. 2005, Issue 2.
33. Jenkins TM, Berghella V, Shlossman PA, et al. Timing of cerclage removal after preterm premature rupture of membranes-maternal and neonatal outcomes. Am J Obstet Gynecol. 2000;183:847-852.
34. Fejgin MD, Gabai B, Goldberger S, et al. Once a cerclage, not always a cerclage. J Reprod Med. 1994;39: 880-882.
35. Pereira L, Levy C, Lewis D, Berghella V, et al. Effect of suture material on the outcome of emergent cerclage. Am J Obstet Gynecol. 2002;187(6):S115. Abstract No. 199.