Change in cervical length after prophylactic cerclage

The predictive value of sequential cervical length screening in singleton pregnancies after cerclage: a retrospective cohort study

Background

There are few valid predictors for preterm delivery after cerclage. Experience with a screening program that included four sequential cervical length measurements in singleton pregnancies after cerclage is reviewed.

Methods

In this retrospective cohort study, 88 singleton pregnancies after cerclage were included. Cervical length (CL) measurements were performed perioperatively and at weeks 16 + 0, 18 + 0, 20 + 0, and 22 + 0 by transvaginal ultrasound. Predictive factors for early preterm delivery included patient characteristics, obstetric history and CL measurements and were analyzed separately for women with ultrasound-indicated cerclage and those with history-indicated cerclage. Women with emergency cerclage were excluded.

Results

In women with delivery <35 weeks, CL declined from the 16 + 0 to the 22 + 0 weeks of gestation (p = 0.009). In univariate analysis, all CL measurements were predictive for delivery <35 weeks in women who underwent ultrasound-indicated cerclage and in women who received a history-indicated cerclage, whereas in multivariate analysis only CL three to six days after cerclage remained significant (odds ratio 0.85, 95 % CI 0.73–0.98). In women with ultrasound-indicated cerclage, optimized cut-off was ≤20 mm (specificity 83.8 %, sensitivity 84.2 %).

Conclusions

CL measured three to six days after cerclage placement provides the best information about the risk for delivery <35 weeks.

Transvaginal cervical cerclage: evidence for perioperative management strategies

The objective was to review the evidence supporting various perioperative technical and management strategies for transvaginal cervical cerclage. We performed MEDLINE, PubMed, EMBASE, and COCHRANE searches with the terms, cerclage, cervical cerclage, cervical insufficiency, and randomized trials, plus each technical aspect (eg, suture, amniocentesis, etc) considered. The search spanned 1966 through September 2012 and was not restricted by language. Each retrieved manuscript was carefully evaluated, and any pertinent references from the reports were also obtained and reviewed. All randomized trials covering surgical and selected perioperative, nonsurgical aspects of cerclage were included in the review. The evidence was assessed separately for history-, ultrasound-, and physical examination-indicated cerclage. Evidence levels according to the new method outlined by the US Preventive Services Task Force were assigned based on the evidence. There are no grade A high-certainty recommendations regarding technical aspects of transvaginal cervical cerclage. Grade B moderate-certainty recommendations include performing a fetal ultrasound before cerclage to ensure fetal viability, confirm gestational age, and assess fetal anatomy to rule out clinically significant structural abnormalities; administering spinal, and not general, anesthesia; performing a McDonald cerclage, with 1 stitch, placed as high as possible; and outpatient setting. Unfortunately, no other recommendations can be made regarding the other technical aspects of cerclage.

Role of ultrasound in screening patients at risk for preterm delivery

The ultrasound assessment of the cervix has contributed to the understanding of the pathways to preterm birth. Transvaginal ultrasound measurement of the cervix provides an objective and noninvasive tool for the evaluation of cervical status. Despite widespread use of this procedure, standardization of measurement indications, technique, and interval between examinations has not been achieved. The American College of Radiology has recently recommended that the cervix and lower uterine segment be imaged as part of every obstetric ultra-sound examination in the second trimester. These guidelines specifically suggest a search for a short cervix (less than 30 mm) or funneling. The expert panel on women's imaging further recommended evaluating the cervix sonographically on both the initial examination and all follow-up examinations for twin gestations. The American Institute of Ultrasound in Medicine guidelines indicate that evaluation of the uterus, including cervix, should be performed, but does not indicate specifically that the cervix should be measured. In contrast, the American College of Obstetricians and Gynecologists, although recognizing that cervical length assessment may be helpful in predicting the risk of preterm delivery (particularly from a negative predictive value), does not recommend routine use of cervical length measurement because of the lack of proved treatment or intervention methods. A review of the literature suggests that at the time of this writing the role of routine screening of low-risk women with cervical length assessment by ultrasound is not supported. In contrast, in women at risk for preterm delivery(eg, women with a prior history of preterm birth or women with multiple gestations) cervical length assessment may be useful for its negative predictive value. At present, however, there is no therapeutic intervention that has been proved to decrease the risk of preterm delivery in women with a documented cervix on ultrasound.

Does cerclage location influence perinatal outcome?

OBJECTIVE

The study was undertaken to measure cerclage location within the cervix and to determine whether placement closer to the internal os is related to perinatal outcome.

STUDY DESIGN

We analyzed data collected during a randomized trial of cervical cerclage versus no cerclage that was conducted at Lehigh Valley Hospital between May 1998 and June 2001 in women with ultrasound findings of short cervix less than 25 mm or funneling between 16 and 24 weeks' gestation. Women who were randomly assigned to the cerclage arm had cervical measurements performed before cerclage, including dilation of the internal os, depth of membrane prolapse into the endocervical canal, cervical length below any funnel (distal length), and total cervical length (including any funnel). Measurements obtained after cerclage placement included the distance from external os to cerclage (A), and a repeat of the same four measurements. The distance from the external os to the cerclage (A) was divided by the total cervical length (B) and a cerclage to cervical length ratio (A/B) was calculated. The relationship between these measurements and gestational age at birth was assessed by linear regression analysis.

RESULTS

Of 150 patients enrolled, 74 received a McDonald cerclage suture. Mean distal cervical length was 1.9+/-0.9 cm before and 2.9+/-1.0 cm after cerclage (P=.001). The mean distance between the cerclage and external os (A) was 1.8+/-0.6 cm; the total cervical length after cerclage (B) was 3.6+/-0.9 cm. The mean cerclage to cervical length ratio (A/B) was 0.5+/-0.1. Linear regression analysis did not demonstrate a correlation between either the cerclage to external os measurement (A) or the cervical length ratio (A/B) and gestational age at birth (R(2)=0.0006 and 0.008, P=.8 and.6, respectively).

CONCLUSION

The length of the cervix below the level of cerclage is not related to duration of pregnancy in women treated with cerclage because of ultrasound evidence of cervical effacement.

Changing trends in the obstetric indications for cervical cerclage

Cervical incompetence causes repeated mid-trimester miscarriage and preterm delivery with high fetal wastage. Since the introduction of cervical cerclage in 1951, it has undergone many changes with regard to the techniques, indications and postoperative care. The objective of this study is to review the changing trends in the current indications of cervical cerclage and subsequent perinatal outcome at the maternity hospital from January 1992 to December 1999. All the files of women who had had cervical cerclage were evaluated in terms of characteristics of the women, indications and obstetric outcome after cervical cerclage. Of 65539 who delivered in the hospital, 1021 women had had cervical cerclage, giving an incidence of 1.21%. There was a significant increase in the incidence of cervical cerclage, from 1.13% in 1992 to 1.40% in 1999 (P < 0.01). More women with multiple pregnancy in 1996 - 99 had cerclage than in 1992 - 94 period [22.7 vs. 8.5% (P < 0.01)]. It is clear that more cervical sutures are being performed in multiple pregnancies arising from assisted reproductive technology as well as after ultrasonographic evidence of cervical dilatation. A multicentre randomised clinical trial is therefore advocated to evaluate its effectiveness in these cases.

Comparison of two methods of cervical cerclage by ultrasound cervical measurement

OBJECTIVE

To compare the effects of cerclage performed with a modified Shirodkar procedure or with McDonald's technique using transvaginal ultrasound measurement of the distance between the external os and the suture.

MATERIALS AND METHODS

We performed a retrospective study of all patients who underwent a prophylactic cerclage with either the modified Shirodkar procedure or the McDonald's technique over a 3-year period. Physicians chose the cerclage technique according to their own preferences. Transvaginal ultrasound examination of the cervix was performed 2 weeks after the cerclage to measure its functional length and the distance between the external os and the cerclage.

RESULTS

During the study period, 14 patients had a cerclage with the modified Shirodkar procedure and 19 patients with the McDonald's technique. Twelve of these 33 patients (36.4%) delivered before 37 weeks. The obstetric characteristics of the patients in both groups were similar. There were no significant differences between the Shirodkar and McDonald groups as to the functional cervical length before (31.3 +/- 8.7 vs. 35.6 +/- 9.7 mm, respectively) or after (37.0 +/- 7.3 vs. 36.1 +/- 7.9 mm) cerclage, the distance between the external os and cerclage (16.7 +/- 3.8 vs. 14.0 +/- 5.2 mm), or the number of deliveries before 32 (0 vs. 2) and 34 (1 vs. 3) weeks.

CONCLUSION

The anterior colpotomy of the Shirodkar procedure increased the distance between the external os and the cerclage by a mean of 2.7 mm. This slight gain does not justify exposing the patient to the risks related to this procedure. When cerclage is necessary, McDonald's technique seems preferable.

Funneling to the stitch: an informative ultrasonographic finding after cervical cerclage

OBJECTIVE

The purpose of this study was to evaluate the utility of ultrasound surveillance after cerclage placement and to propose a rationale for cervical sonography in this setting.

SUBJECTS AND METHODS

This was a retrospective analysis of 53 women undergoing cervical cerclage by a maternal-fetal medicine specialist, regardless of indication, and delivering between January 1999 and April 2001. Transvaginal ultrasonographic assessment of cervical length and the degree of cervical funneling after cerclage were compared to preoperative values and to outcomes including gestational age at delivery. Funneling to the cerclage was defined as membranes prolapsing down the endocervical canal until they reached the plane of the cerclage.

RESULTS

Cervical cerclage resulted in a significant increase in cervical length from 2.1 +/- 1.2 cm to 2.9 +/- 0.8 cm after the procedure, P < 0.001; however, this measure was not correlated with gestational age at delivery. Funneling to the level of the cerclage was associated with an earlier gestational age at delivery 31.3 +/- 5.6 weeks vs. 36.8 +/- 2.8 weeks for those cases without this finding, P < 0.001. A statistically significant association between funneling to the cerclage and preterm delivery was identified irrespective of the indication (prophylactic or emergency) for the procedure. When descent of the membranes to the level of the cerclage was noted, it occurred by 28 weeks' gestation in all patients studied. The incidence of premature rupture of the membranes was also significantly greater postcerclage in women with descent of the membranes to the cerclage (52%) compared to those without this finding (9%) P= 0.002.

CONCLUSIONS

Funneling to the cerclage is significantly associated with earlier preterm delivery in patients who have undergone cervical cerclage. Serial sonography up to 28 weeks' gestation is useful in identifying patients at higher risk for premature rupture of the membranes and preterm delivery.

Cervical Incompetence Prevention Randomized Cerclage Trial (CIPRACT): effect of therapeutic cerclage with bed rest vs. bed rest only on cervical length

OBJECTIVE

To compare the effects of therapeutic cerclage and bed rest vs. just bed rest on cervical length and to relate these effects to the risk of preterm delivery.

DESIGN

Cervical length was measured in patients at high risk of cervical incompetence. When a cervical length < 25 mm was measured before 27 weeks' gestation, randomization for therapeutic cerclage and bed rest vs. just bed rest was performed. After randomization, cervical length was measured weekly. For statistical analysis, t-test and Fisher's exact tests were used and P < 0.05 was considered statistically significant.

RESULTS

Nineteen women were randomly allocated to receive a therapeutic cerclage and bed rest and 16 were allocated to receive bed rest only. Mean cervical lengths and mean gestational ages before randomization were comparable between both groups, overall 19.8 mm and 20.7 weeks. Cervical length was measured again at a mean gestation of 22.1 weeks. Mean cervical length (31 mm) was significantly (P < 0.0001) longer after cerclage than after bed rest only (19 mm). A cervical length > or = 25 mm was measured in 22 of the 35 included women, 16 in the cerclage group and six in the bed-rest group (P = 0.006). Of these 22 women, only one delivered before 34 weeks' gestation, which was significantly less frequent than six out of 13 women with a cervical length < 25 mm (P = 0.006).

CONCLUSIONS

Therapeutic cerclage with bed rest increases cervical length more often than bed rest alone. A postintervention cervical length > or = 25 mm reduces the risk of preterm delivery in women at high risk of cervical incompetence and a preintervention cervical length < 25 mm.

Transvaginal sonographic examination of the cervix in asymptomatic pregnant women: review of the literature

Different strategies have been developed to refine the prediction of the risk of preterm delivery in asymptomatic patients. Transvaginal sonography has been used for this reason to measure and examine the length and shape of the cervix. In this review, we focus on clinical studies involving transvaginal sonographic assessment of the cervix in asymptomatic women at high risk of preterm delivery and in the general pregnant population. Three ultrasound signs are suggestive of cervical incompetence, namely, dilatation of the internal os, sacculation or prolapse of the membranes into the cervix (with shortening of the functional cervical length) either spontaneously or induced by transfundal pressure, and short cervix in the absence of uterine contractions. Transvaginal sonography has clearly demonstrated that cerclage leads to a measurable increase in cervical length which may contribute to the success of this procedure in reducing the risk of preterm delivery. Several non-randomized interventional studies among patients with cervical incompetence have been published. They have defined a new group of patients requiring cerclage when the women show progressive cervical modifications on transvaginal sonography, while in other studies, cerclage performed on the basis of cervical changes on transvaginal sonography did not prevent premature delivery. One prospective randomized trial in asymptomatic high-risk women has shown two benefits of cerclage following indications for transvaginal sonography: (1) it would generate fewer prophylactic cerclages in high-risk women; (2) therapeutic cerclage before 27 weeks may reduce the incidence of premature delivery before 34 weeks. The risk of preterm delivery is inversely correlated with cervical length. Routine transvaginal sonography of the cervix performed between 18 and 22 weeks can help identify patients at risk of preterm delivery. However, given the low prevalence of preterm births, screening would generate either a high false-positive rate or a low sensitivity. One non-randomized interventional study among patients with a short cervix on routine ultrasound examination found a lower risk of delivery before 32 weeks in the cerclage group than in the expectant management group. However, to date, there have been no prospective randomized trials in a general population. Although evidence is still lacking, there does appear to be a benefit in performing a cerclage rather than continuing with expectant management in cases with sonographic appearance of cervical incompetence in asymptomatic women at high risk of preterm delivery. Ultrasound can be offered to reduce the indications of cerclage for cases in which the situation is uncertain. Within the general obstetric population, transvaginal sonography might help in the selection of asymptomatic but high-risk women. However, the benefit associated with cerclage for sonographic indication has not been demonstrated.

Cervical incompetence: the use of selective and emergency cerclage

OBJECTIVE

This prospective case series was performed in order to assess pregnancy outcome of women with tentative diagnosis of cervical incompetence undergoing selective and emergency cervical cerclage.

METHODS

Women recruited in this case series were divided into two groups. The selective group (n = 13) was chosen among pregnant women with a history suggestive of cervical incompetence, but no clinical evidence of threatened miscarriage. The definition of cervical incompetence was dilatation of internal cervical os with shortening of the cervix less than 25 mm and "funnelling" of 25% and more, found on the ultrasound examination of the cervix. The emergency group (n = 12) had clinical symptoms of threatened miscarriage. After exclusion of infection and in the absence of uterine activity they were counseled and offered cerclage.

RESULTS

After cervical cerclage all women were treated in the same way as per our clinical protocol and monitored until delivery. The median gestational age at delivery was 36 weeks (19-39) in the selective group and 33 weeks (22-38) in the emergency group. This difference is not statistically significant. There was 1 miscarriage (8%), 5 pre-term deliveries (38%) and 7 term deliveries (54%) in the selective group; and 4 miscarriages (33%), 3 pre-term deliveries (25%) and 5 term deliveries (42%) in the emergency group. Total neonatal survival was 19/20 (95%) if pregnancy exceeded 24 weeks, making perinatal mortality 5%. There was no differences between selective and emergency groups (1 of 12 in selective vs. 0 of 8 in emergency).

CONCLUSION

Overall, it can be concluded that both selective and emergency cerclage may have some benefits in patients with cervical incompetence. However, in the absence of a randomized-controlled study, these beneficial effects described cannot be considered as proved.