Efficacy of transvaginal cervical cerclage in women at risk of preterm birth following previous emergency cesarean section

Prediction of spontaneous preterm birth in women with previous full dilatation cesarean delivery

BACKGROUND

A previous term (≥37 weeks' gestation), full-dilatation cesarean delivery is associated with an increased risk for a subsequent spontaneous preterm birth. The mechanism is unknown. We hypothesized that the cesarean delivery scar characteristics and scar position relative to the internal cervical os may compromise cervical function, thereby leading to shortening of the cervical length and spontaneous preterm birth.

OBJECTIVE

This study aimed to determine the relationship of cesarean delivery scar characteristics and position, assessed by transvaginal ultrasound, in pregnant women with previous full-dilatation cesarean delivery with the risk of shortening cervical length and spontaneous preterm birth.

STUDY DESIGN

This was a single-center, prospective cohort study of singleton pregnant women (14 to 24 weeks' gestation) with a previous term full-dilatation cesarean delivery who attended a high-risk preterm birth surveillance clinic (2017-2021). Women underwent transvaginal ultrasound assessment of cervical length, cesarean delivery scar distance relative to the internal cervical os, and scar niche parameters using a reproducible transvaginal ultrasound technique. Spontaneous preterm birth prophylactic interventions (vaginal cervical cerclage or vaginal progesterone) were offered for short cervical length (≤25 mm) and to women with a history of spontaneous preterm birth or late miscarriage after full-dilatation cesarean delivery. The primary outcome was spontaneous preterm birth; secondary outcomes included short cervical length and a need for prophylactic interventions. A multivariable logistic regression analysis was used to develop multiparameter models that combined cesarean delivery scar parameters, cervical length, history of full-dilatation cesarean delivery, and maternal characteristics. The predictive performance of models was examined using the area under the receiver operating characteristics curve and the detection rate at various fixed false positive rates. The optimal cutoff for cesarean delivery scar distance to best predict a short cervical length and spontaneous preterm birth was analyzed.

RESULTS

Cesarean delivery scars were visualized in 90.5% (220/243) of the included women. The spontaneous preterm birth rate was 4.1% (10/243), and 12.8% (31/243) of women developed a short cervical length. A history- (n=4) or ultrasound-indicated (n=19) cervical cerclage was performed in 23 of 243 (9.5%) women; among those, 2 (8.7%) spontaneously delivered prematurely. A multiparameter model based on absolute scar distance from the internal os best predicted spontaneous preterm birth (area under the receiver operating characteristics curve, 0.73; 95% confidence interval, 0.57-0.89; detection rate of 60% for a fixed 25% false positive rate). Models based on the relative anatomic position of the cesarean delivery scar to the internal os and the cesarean delivery scar position with niche parameters (length, depth, and width) best predicted the development of a short cervical length (area under the receiver operating characteristics curve, 0.79 [95% confidence interval, 0.71-0.87]; and 0.81 [95% confidence interval, 0.73-0.89], respectively; detection rate of 73% at a fixed 25% false positive rate). Spontaneous preterm birth was significantly more likely when the cesarean delivery scar was <5.0 mm above or below the internal os (adjusted odds ratio, 6.87; 95% confidence interval, 1.34-58; P =.035).

CONCLUSION

In pregnancies following a full-dilatation cesarean delivery, cesarean delivery scar characteristics and distance from the internal os identified women who were at risk for spontaneous preterm birth and developing short cervical length. Overall, the spontaneous preterm birth rate was low, but it was significantly increased among women with a scar located <5.0 mm above or below the internal cervical os. Shortening of cervical length was strongly associated with a low scar position. Our novel findings indicate that a low cesarean delivery scar can compromise the functional integrity of the internal cervical os, leading to cervical shortening and/or spontaneous preterm birth. Assessment of the cesarean delivery scar characteristics and position seem to have use in preterm birth clinical surveillance among women with a previous, full-dilatation cesarean delivery and could better identify women who would benefit from prophylactic interventions.

Emergency caesareans are associated with an increased risk of recurrent early preterm birth: a commentary

This article includes Author Insights, a video abstract available at: https://vimeo.com/733549553.

Outcomes following elective cerclage versus ultrasound surveillance in women with one prior preterm event

OBJECTIVE

Preterm birth, defined as delivery before 37 weeks' gestation, is a major obstetric challenge and is associated with serious long-term complications in those infants that survive. Preventative management includes cervical cerclage, either as an elective procedure or performed following transvaginal ultrasound surveillance and shortening of the cervix (≤25 mm). Significant questions remain regarding the optimal management, target population and technique. Therefore, this study aimed to assess differences in risk factors and pregnancy outcomes for women who received an elective cerclage versus ultrasound surveillance, following one prior premature event (spontaneous preterm birth/second trimester loss).

STUDY DESIGN

Women were retrospectively identified from St Thomas's Hospital Preterm Birth Clinical Network Database. Women who had one prior premature event (between 14+0 and 36+6 weeks' gestation) were included and they were separated into those that an elective cerclage and those who underwent ultrasound surveillance to assess differences in demographics, pregnancy risk factors and preterm birth outcomes. We excluded women who received other preventative therapies. We also separately analysed those women who required an ultrasound-indicated cerclage, comparing the differences between women that delivered preterm and term.

RESULTS

We collected data from 1077 women who had a prior preterm event. 66 women received an elective cerclage. 11.4% of women who had ultrasound surveillance received an ultrasound indicated cerclage. Women with a prior history of mid-trimester loss, instead of preterm birth, were more likely to receive an elective cerclage. The mean gestational age of delivery was similar between those women who received an elective cerclage and those who had ultrasound surveillance with and without an ultrasound-indicated cerclage (38+1 vs 37+1), however, preterm birth rates <37 weeks' were twice as high in this ultrasound group (OR 2.3 [1.1-4.5], p = 0.02). In those women that do require an ultrasound-indicated cerclage, 50.4% deliver preterm.

CONCLUSIONS

In conclusion, this study shows that in women with one prior preterm event, both history-indicated cerclage and ultrasound surveillance are appropriate management options. The majority of women undergoing ultrasound surveillance did not require a cerclage and so avoided the potential perioperative complications of cerclage insertion. However, those that did require an ultrasound-indicated cerclage were at high risk of preterm birth so should be followed up closely to enable adequate preterm birth preparation. Further prospective studies comparing history indicated cerclage and US surveillance in women with one prior preterm event are necessary.

"I had given up on being a mother": a survey of 183 women's experience of transabdominal cerclage (TAC)

BACKGROUND

Transabdominal cerclage (TAC) is a relatively uncommon intervention for preventing preterm birth. This study aimed to investigate the experience of women who had undergone this procedure.

METHODS

The survey was designed in collaboration with a preterm birth studies public and patient involvement (PPI) group and ethical approval was granted by KCL BDM Research Ethics Panel (LRS-19/20-13205). Members of closed Facebook group, UK TAC Support, were invited to complete an online questionnaire about their experience of TAC, and pregnancies before and after having it placed. The survey was open between December 2019 and May 2020. Open and closed questions provided both qualitative and quantitative data for analysis, which was carried out using NVivo Pro 2020 v.1.4.1 qualitative data management software and SPSS Statistics 27 (IBM).

RESULTS

One hundred eighty-three participants completed the survey, having had TAC procedures carried out in 36 hospitals. Altogether, participants had experienced 287 preterm births (PTB) and late miscarriages (LM), equating to an average of 1.6 each (range 0-5), including 18 stillbirths. TAC was indicated in 123 (67%) for previous PTB and/or LM, 29 (16%) for cervical surgery and 31 (17%) for both. 151 (83%) TAC procedures were open, 32 (17%) laparoscopic. 86% (n = 157) were placed outside pregnancy. Of those placed in pregnancy, gestation at TAC ranged from 7 to 16 weeks. When comparing earliest pre- and post-TAC pregnancy gestation (excluding first trimester losses), median gestational weeks gained following TAC was 15.5 weeks (SD 6.89). Qualitative themes included: the struggle to get treatment; lack of TAC knowledge amongst clinicians; gratitude, hope and feeling protected; possible detrimental effects of TAC.

CONCLUSIONS

This very high-risk group found having a TAC gave great reassurance and hope, and were very grateful to have found the care they needed. However, they often struggled to get this support, frequently due to lack of clinician awareness. This may improve following roll-out of NHS England's Saving Babies Live Care Bundle and NHS commissioning guidelines for care of women at risk of PTB.

Longitudinal change in cervical length following vaginal or abdominal cervical cerclage: a randomized comparison

BACKGROUND

Cervical cerclage has been shown to reduce the risk of recurrent spontaneous preterm birth in a high-risk patient population; however, the mechanism is not well understood. Transabdominal cerclage is superior to low and high vaginal cerclage in reducing early spontaneous preterm birth and fetal loss in women with previous failed vaginal cerclage. Cervical length measurements are commonly used to monitor high-risk women and may explain the mechanism of success.

OBJECTIVE

This study aimed to evaluate the rate of change in longitudinal cervical length after randomized placement of low transvaginal, high transvaginal, or transabdominal cerclage in women with a previous failed vaginal cerclage.

STUDY DESIGN

This was a planned analysis of longitudinal transvaginal ultrasound cervical length measurements from patients enrolled in the Vaginal Randomised Intervention of Cerclage trial, a randomized controlled trial comparing transabdominal cerclage or high transvaginal cerclage with low transvaginal cerclage. Cervical length measurements at specific gestational ages were compared over time and between groups, using generalized estimating equations fitted using the maximum-likelihood random-effects estimator. In addition, cervical length measurements were compared in women with transabdominal cerclage placed before and during pregnancy. The diagnostic accuracy of cervical length as a predictor of spontaneous preterm birth at <32 weeks of gestation was explored.

RESULTS

This study included 78 women who underwent longitudinal cervical length assessment (70% of the analyzed cohort) with a history of failed cerclage, of whom 25 (32%) were randomized to low transvaginal cerclage, 26 (33%) to high transvaginal cerclage, and 27 (35%) to transabdominal cerclage. Abdominal cerclage was superior to low (P=.008) and high (P=.001) vaginal cerclage at maintaining cervical length over the surveillance period (14 to 26 weeks of gestation) (+0.08 mm/week, 95% confidence interval, -0.40 to 0.22; P=.580). On average, the cervical length was 1.8 mm longer by the end of the 12-week surveillance period in women with transabdominal cerclage (+1.8 mm; 95% confidence interval, -7.89 to 4.30; P=.564). High vaginal cerclage was no better than low cervical cerclage in the prevention of cervical shortening; the cervix shortened by 13.2 mm over 12 weeks in those with low vaginal cerclage (95% confidence interval, -21.7 to -4.7; P=.002) and by 20 mm over 12 weeks in those with high vaginal cerclage (95% confidence interval, -33.1 to -7.4; P=.002). Preconception transabdominal cerclage resulted in a longer cervix than those performed during pregnancy; this difference was significant after 22 weeks of gestation (48.5 mm vs 39.6 mm; P=.039). Overall, cervical length was an excellent predictor of spontaneous preterm birth at <32 weeks of gestation (receiver operating characteristic curve, 0.92; 95% confidence interval, 0.82-1.00).

CONCLUSION

In women with a previous failed cervical cerclage, in the next pregnancy, the cervical length in women treated with vaginal cerclage funneled and shortened over time, whereas there was preservation of cervical length in women who receive transabdominal cerclage. Cervical length remained longer in transabdominal procedures performed before pregnancy than in transabdominal procedures performed during pregnancy. Overall, cervical length was an excellent predictor of spontaneous preterm birth in our cohort. Our findings may explain the mechanism of benefit for transabdominal cerclage, with its high placement better maintaining the structural integrity of the cervix at the level of the internal os.

Second stage cesarean section and the risk of preterm birth in subsequent pregnancies

OBJECTIVE

To evaluate the risk of spontaneous preterm birth on subsequent pregnancies after second stage cesarean section.

METHODS

This is a retrospective cohort study. Women were included if they had their two consecutive births in Toulouse University Hospital in the study period. The first birth was a singleton livebirth at term (≥37 weeks of gestation), divided in three categories according to the mode of delivery: vaginal delivery (group A), cesarean section before the second stage of labor (group B), cesarean section during the second stage of labor (group C). The subsequent pregnancy was the first subsequent pregnancy, conducted after 16 weeks of gestation. The primary outcome was spontaneous preterm birth in the subsequent pregnancy, defined as delivery before 37 weeks of gestation. Secondary endpoints included preterm rupture of membranes in the subsequent pregnancy.

RESULTS

Between 2003 and 2018, 7776 women (84.7%) in group A, 1263 (13.8%) in group B and 143 (1.5%) in group C were included. The adjusted odds ratio of spontaneous preterm birth before 37 weeks of gestation after second stage cesarean section was 2.4 (group C vs group A + B, 95% confidence interval: 1.2-4.8), P = 0.01). The rate of preterm rupture of membranes was also significantly higher in group C (6% vs 2% in group A, P = 0.009, 6% vs 3% in group B, P= 0.05) with OR = 3.0 (group C vs group A + B, 95% CI: 1.55-6.16, P < 0.001).

CONCLUSION

History of term second stage of labor cesarean section is an independent risk factor for spontaneous preterm birth and for preterm rupture of membrane in the subsequent pregnancy.

Prior term delivery increases risk of subsequent recurrent preterm birth: An unexpected finding

Background

Women with a prior pregnancy at term are generally considered to be at reduced risk for subsequent spontaneous preterm birth (sPTB), whereas a previous sPTB is a major predictor for a future sPTB.

Aims

The objective of this study was to investigate the risk of recurrent sPTB in women with a prior term birth and a subsequent sPTB.

Materials and Methods

This is a retrospective cohort study conducted at St Thomas’ Hospital in London, UK. There were 430 women included: 230 with a term birth (caesarean section or vaginal delivery) preceding a sPTB (term + sPTB group) and 200 with a prior sPTB only (sPTB only group). The primary outcome was sPTB, <37 weeks gestation.

Results

Of the term + sPTB group, 38.7% (89/230) had a recurrent sPTB compared to 20% (40/200) in the sPTB only group (P < 0.0001), with a relative risk (RR) of 1.9. Of women who had a term caesarean section and a subsequent PTB, 50% (30/60) had a further sPTB (RR 2.5 compared to the sPTB only group), while 34.7% (59/170) of women who had a term vaginal birth and subsequent sPTB, had a further sPTB (RR 1.7 compared to the sPTB only group).

Conclusion

In women who have had a previous sPTB, the risk of a recurrence is much higher than in women with a prior term birth. The aetiology of PTB may be different in this subgroup of women and needs to be further elucidated to determine how best to identify and treat them.

Previous term emergency caesarean section is a risk factor for recurrent spontaneous preterm birth; a retrospective cohort study

OBJECTIVES

Emergency caesarean sections (EmCS), particularly those performed in the second stage of labour, have been associated with a risk of subsequent preterm birth. More worrying is that the risk of sPTB recurrence appears to be high in women who have had a second stage EmCS and a subsequent sPTB. However, there is a paucity of evidence regarding the risk of recurrence in women who have had a prior term EmCS at any stage of labour followed by a sPTB. This study aims to investigate the relationship between all term in labour EmCS and the risk of recurrent spontaneous preterm birth (sPTB).

STUDY DESIGN

This is an observational, retrospective cohort study conducted at St Thomas' Hospital, a tertiary-level maternity hospital in London, United Kingdom. 259 women were included; 59 women with a term in labour EmCS preceding a sPTB (EmCS group) and 200 women with a prior sPTB only (control group). The initial EmCS was further categorised into first stage (FS)-EmCS or second stage (SS)-EmCS. Primary outcome was sPTB in Pregnancy C < 37 weeks' gestation. Secondary outcomes included sPTB < 34 weeks' and < 24 weeks' gestation.

RESULTS

54% (32/59) of the EmCS group had a recurrent sPTB < 37 weeks compared to 20% (40/200) of the control women (p < 0.0001) with a relative risk of 2.71 [95%CI 1.87-3.87]). Of women who had a SS-EmCS and a subsequent PTB, 61.9% (13/21) had a further sPTB (RR 3.0 [95%CI, 1.8-4.5] compared to control women). In addition, there is nearly a 6-fold increased risk of a recurrent sPTB or midtrimester loss < 24 weeks' gestation in these women (RR 5.65 [95%CI2.6-12.0]).

CONCLUSIONS

In women who have had a previous sPTB in which a term in labour EmCS is a risk factor, the risk of a further sPTB is much higher than in those women where a prior sPTB is the sole risk factor. Furthermore, EmCS at both the first and second stage of labour are associated with a increased risk of recurrent sPTB. Further work should ascertain which women who have had a prior term EmCS are at risk of sPTB and recurrence, and how best to identify and treat them.

Duration of the second stage of labour and risk of subsequent spontaneous preterm birth

OBJECTIVES

To determine the risk of spontaneous preterm birth (sPTB) associated with the length of second stage of labour in the first term delivery.

DESIGN

Retrospective cohort study.

SETTING

University hospital.

POPULATION

Women with first two consecutive singleton births and the first birth at term. Those who did not reach the second stage of labour in the first delivery were excluded.

METHODS

Charts from 2007 to 2019 were reviewed.

MAIN OUTCOME MEASURES

Rate of sPTB (<37 weeks of gestation) in the second delivery.

RESULTS

Of 13 958 women who met study inclusion criteria, 1464 (10.5%) parturients had a prolonged second stage (≥180 min) in their first term delivery. The rate of sPTB in the second delivery was similar in those with and without a prolonged second stage in first delivery (2.8% versus 2.8%; adjusted odds ratio [aOR] 1.35, 95% CI 0.96-1.90). After adjustment for mode of delivery, prolonged second stage was also not associated with subsequent sPTB in those who delivered by spontaneous and operative vaginal delivery. Those delivered by second-stage caesarean section in the first delivery had a higher risk of sPTB in the second delivery (25/526, 4.8%; aOR 2.66, 95% CI 1.71-4.12; p < 0.001), with a more pronounced risk in those with second-stage caesarean following a prolonged second stage of labour (15/259, 5.8%; aOR 3.40, 95% CI 1.94-5.94; p < 0.001).

CONCLUSION

Second-stage duration in a first term vaginal delivery is not associated with subsequent sPTB. The risk of sPTB is increased following second-stage caesarean section, particularly if performed after a prolonged second stage.