Impact of Isthmocele on Assisted Reproductive Treatment Outcomes: An Age-matched Retrospective Study

The impact of caesarean scar niche on fertility - a systematic review

BACKGROUND

The trend of increasing caesarean section (CS) rates brings up questions related to subfertility. Research regarding the influence of CS on assisted reproduction techniques (ART) is conflicting. A potential mechanism behind CS-induced subfertility is intra uterine fluid resulting from a caesarean scar defect or niche. The vaginal microbiome has been repeatedly connected to negative ART outcomes, but it is unknown if the microbiome is changed in relation to a niche.

METHODS

This systematic review describes literature investigating the effect of a niche on live birth rates after assisted reproduction. Furthermore, studies investigating a difference in microbial composition in subfertile persons with a niche compared to no niche are evaluated. Pubmed, Embase and Web of Science were searched on March 2023 for comparative studies on both study questions. Inclusion criteria were i.e., English language, human-only studies, availability of the full article and presence of comparative pregnancy data on a niche. The quality of the included studies and their risk of bias were assessed using the Newcastle-Ottawa scale for cohort studies. The results were graphically displayed in a forest plot.

RESULTS

Six retrospective cohort studies could be included on fertility outcomes, with a total of 1083 persons with a niche and 3987 without a niche. The overall direction of effect shows a negative impact of a niche on the live birth rate (pooled aOR 0.58, 95% CI 0.48-0.69) with low-grade evidence. Three studies comparing the microbiome between persons with and without a CS could be identified.

CONCLUSION

There is low-grade evidence to conclude that the presence of a niche reduces live birth rates when compared to persons without a niche. The theory that a caesarean has a negative impact on pregnancy outcomes because of dysbiosis promoted by the niche is interesting, but there is no sufficient literature about this.

Effect of previous caesarean section on reproductive and pregnancy outcomes after assisted reproductive technology: A systematic review and meta‑analysis

Pregnancies following previous caesarean section (CS) are associated with higher incidence of infections, postpartum haemorrhage and obstetric complications. The present study aimed to explore the effect of previous CS on reproductive, maternal and neonatal outcomes in women who underwent assisted reproductive techniques (ART). A systematic review and meta-analysis were conducted to assess reproductive and pregnancy outcomes following ART in women with and without a previous CS. Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines were followed. Eligible language articles written in English, published up to October 2023, were identified in Medline, Google Scholar and Science Direct databases. The quality of the included studies was assessed using the Newcastle Ottawa Scale. A total of 19 articles, reporting on 13 different outcomes met the inclusion criteria. It was revealed that women with previous CS had 9% lower clinical pregnancy rates, 13% lower live birth rates, 11% lower implantation rates and 28% lower multiple pregnancy rates compared with women who had prior natural vaginal deliveries. Additionally, previous CS was associated with an 8-fold higher risk of difficult embryo transfers. No significant differences were noted in ectopic pregnancy rates, miscarriage rates or biochemical pregnancy rates. The present systematic review and meta-analysis demonstrated that previous CS is associated with decreased prospects of clinical pregnancy, live birth and successful embryo implantation during ART. The findings of the present study underscored the need to counsel women with prior CS regarding its potential impact on ART outcomes.

Isthmocele and Infertility

Isthmocele is a gynecological condition characterized by a disruption in the uterine scar, often associated with prior cesarean sections. This anatomical anomaly can be attributed to inadequate or insufficient healing of the uterine wall following a cesarean incision. It appears that isthmocele may impact a woman's quality of life as well as her reproductive capacity. The incidence of isthmocele can range from 20% to 70% in women who have undergone a cesarean section. This review aims to sum up the current knowledge about the effect of isthmocele on fertility and the possible therapeutic strategies to achieve pregnancy. However, currently, there is not sufficiently robust evidence to indicate the need for surgical correction in all asymptomatic patients seeking fertility. In cases where surgical correction of isthmocele is deemed necessary, it is advisable to evaluate residual myometrial thickness (RMT). For patients with RMT >2.5-3 mm, hysteroscopy appears to be the technique of choice. In cases where the residual tissue is lower, recourse to laparotomic, laparoscopic, or vaginal approaches is warranted.

Impact of cesarean scar defect on reproductive outcomes after assisted reproductive technology

In the last twenty years, the cesarean section rate has been rising in China, leading to an increased prevalence of cesarean scar defect (CSD) and secondary infertility. CSD decreases receptivity of endometrium, induces adenomyosis and endometriosis, disrupts uterine micro-environment and causes difficulties in embryo transplant operation as well as has further pregnancy complications. For women undergoing assisted reproductive technology (ART), CSD significantly reduces live birth rate, clinical pregnancy rate and embryo implantation rate. CSD can be effectively treated by hysteroscopic surgery, laparoscopic surgery and transvaginal surgery to increase the pregnancy rate. This article reviews the research progress on the impact of CSD on the reproductive outcomes of ART, the potential factors and related treatments, and provides a reference for the management of CSD patients undergoing ART.

Isthmocele, not cesarean section per se, reduces in vitro fertilization success: a systematic review and meta-analysis of over 10,000 embryo transfer cycles

IMPORTANCE

Previous reviews have shown that a history of cesarean section (CS) is associated with a worse in vitro fertilization (IVF) prognosis. To date, whether the decline in the IVF chances of success should be attributed to the CS procedure itself or to the presence of isthmocele remains to be clarified.

OBJECTIVE

To summarize the available evidence regarding the impact of isthmocele on IVF outcomes.

DATA SOURCES

Electronic databases and clinical registers were searched until May 30, 2023.

STUDY SELECTION AND SYNTHESIS

Observational studies were included if they assessed the effect of isthmocele on IVF outcomes. Comparators were women with isthmocele and women without isthmocele with a previous CS or vaginal delivery. Study quality was assessed using the modified Newcastle-Ottawa Scale.

MAIN OUTCOMES

The primary outcome was the live birth rate (LBR). The effect measures were expressed as adjusted odds ratios (aORs) and unadjusted odds ratios (uORs) with 95% confidence intervals (95% CIs). The body of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation working group methodology.

RESULTS

Eight studies (n = 10,873 patients) were included in the analysis. Women with isthmocele showed a lower LBR than both women with a previous CS without isthmocele (aOR, 0.62; 95% CI, 0.53-0.72) and those with a history of vaginal delivery (aOR, 0.55; 95% CI, 0.42-0.71). The LBRs in women with a previous CS without isthmocele and those with a history of vaginal delivery were similar (aOR, 0.74; 95% CI, 0.47-1.15). Subgroup analysis suggested a negative effect of the intracavitary fluid (ICF) in women with isthmocele on the LBR (uOR, 0.36; 95% CI, 0.18-0.75), whereas the LBRs in women without ICF and those without isthmocele were similar (uOR, 0.94; 95% CI, 0.61-1.45).

CONCLUSION AND RELEVANCE

We found moderate quality of evidence (Grading of Recommendations Assessment, Development and Evaluation grade 3/4) supporting a negative impact of isthmocele, but not of CS per se, on the LBR in women undergoing IVF. The adverse effect of isthmocele on IVF outcomes appears to be worsened by ICF accumulation before embryo transfer.

CLINICAL TRIAL REGISTRATION NUMBER

CRD42023418266.

Prevalence and clinical effect of caesarean scar defects in women undergoing IVF

RESEARCH QUESTION

How common are caesarean scar defects (isthmocele) among patients who have had previous caesarean delivery undergoing IVF for secondary infertility? Does the presence of isthmocele affect the chances of success of IVF?

DESIGN

In this cohort study, women referred to an Italian public assisted reproduction centre between January 2016 and April 2021 were retrospectively reviewed. Women with a history of caesarean delivery and an indication for IVF were selected. On the basis of the local policy, all patients with a history of caesarean section underwent saline contrast sonography (SCS). Sonographic evaluation was standardized.

RESULTS

One hundred and forty-four women were eligible, of whom 22 declined SCS and eight decided to delay pregnancy seeking. Overall, 114 women were available for data analysis. Seventy-six women were diagnosed with caesarean scar defects, corresponding to a prevalence of 67% (95% CI 58 to 75%). Baseline characteristics of women with and without isthmocele were similar. Conversely, the clinical pregnancy rate (adjusted OR 0.31, 95% CI 0.13 to 0.72) and live birth rate (adjusted OR 038, 95% CI 0.17 to 0.86) were significantly lower among affected women. No associations between specific sonographic defect characteristics and IVF outcome could be identified.

CONCLUSIONS

Caesarean scar defects are common among women with a history of caesarean section requiring IVF. The presence of these lesions may reduce the chance of success of the procedure.

Diagnosis and management of isthmocele (Cesarean scar defect): a SWOT analysis

The purpose of this State-of-the-Art Review was to provide a strategic analysis, in terms of strengths, weaknesses, opportunities and threats (SWOT analysis), of the current evidence regarding the management of uterine isthmocele (Cesarean scar defect). Strengths include the fact that isthmocele can be diagnosed on two-dimensional transvaginal ultrasound, and that surgical repair may restore natural fertility potential and prevent secondary infertility, as well as reduce the risk of miscarriage and other obstetric complications. However, there is a lack of high-quality evidence regarding the best diagnostic method and criteria, as well as the potential benefits of surgical repair with respect to fertility. There is a need for experienced surgeons skilled in the various isthmocele repair techniques. Isthmocele repair does not prevent the need for Cesarean delivery in subsequent pregnancies. There is increasing awareness regarding the accuracy of transvaginal ultrasound in diagnosing isthmocele. This may lead to surgical correction and prevention of obstetric and perinatal complications in subsequent pregnancies, including Cesarean scar pregnancy. Regarding threats, the existence of different surgical techniques means that there is a risk of selecting an inadequate approach if the type of isthmocele and the patient's characteristics are not considered. There is a risk of overtreatment when asymptomatic defects are repaired surgically. Finally, there is an absence of cost-effectiveness analyses to justify routine repair. Thus, while there are many data suggesting that isthmocele has an adverse effect on both natural fertility and the outcome of assisted reproduction techniques, high-quality evidence to support surgical isthmocele repair in all asymptomatic patients desiring future fertility are lacking. There is increasing agreement to recommend hysteroscopic repair of isthmocele as a first-line approach as long as the residual myometrial thickness is at least 2.5-3.0 mm. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

The definition, diagnosis, and symptoms of the uterine niche - A systematic review

Of all neonates, 21% are delivered by cesarean section (CS). A long-term maternal complication of an SC is a uterine niche. The aim of this review is to provide an overview of the current literature on imaging techniques and niche-related symptomatology. We performed systematic searches on imaging and niche symptoms. For both searches, 87 new studies were included. Niche evaluation by transvaginal sonography (TVS) or contrast sonohysterography (SHG) proved superior over hysteroscopy or magnetic resonance imaging. Studies that used SHG in a random population identified a niche prevalence of 42%-84%. Niche prevalence differed based on niche definition, symptomatology, and imaging technique. Most studies reported an association with gynecological symptoms, poor reproductive outcomes, obstetrical complications, and reduced quality of life. In conclusion, non-invasive TVS and SHG are the superior imaging modalities to diagnose a niche. Niches are prevalent and strongly associated with gynecological symptoms and poor reproductive outcomes.

Reproductive and pregnancy outcomes following embryo transfer in women with previous cesarean section: A systematic review and meta-analysis

INTRODUCTION

Cesarean section affects subsequent spontaneous pregnancies because of implantation issues. However, its impact on post-embryo transfer pregnancies is still debated. This review aimed to evaluate the impact of a previous cesarean section on fertility and pregnancy outcomes of women undergoing fresh or frozen embryo transfer.

MATERIAL AND METHODS

MEDLINE, Scopus, ClinicalTrials.gov, Scielo, EMBASE, Cochrane Library at the CENTRAL, and LILACS were searched from inception to February 2021. Studies were included if they evaluated reproductive or pregnancy outcomes after fresh or frozen embryo transfer in infertile women with a previous cesarean section relative to women with a previous vaginal delivery. Random-effect meta-analyses to calculate risk ratio (RR) or mean differences with 95% confidence intervals (CI) followed by subgroup analysis for fresh and frozen embryo transfer were performed. Risk of bias and quality assessment were conducted using Newcastle-Ottawa scale and GRADE criteria. The review was registered in the International Prospective Register of Systematic Reviews (CRD42021226297).

RESULTS

Ten studies, with data provided for 13 696 participants, were eligible. For embryo transfers after cesarean section, compared with vaginal delivery, there was a significant reduction of the live birth rate (RR 0.88, 95% CI 0.79-0.99) and biochemical pregnancy rate (RR 0.89, 95% CI 0.82-0.96). No statistically significant differences were found for clinical pregnancy rate (RR 0.92, 95% CI 0.84-1.02), ectopic pregnancies (RR 1.00, 95% CI 0.68-1.46), pregnancy loss (RR 1.05, 95% CI 0.94-1.18), multiple pregnancies (RR 0.80, 95% CI 0.63-1.02), stillbirths (RR 0.86, 95% CI 0.27-2.69), birth defects (RR 1.71, 95% CI 0.49-5.96) or birthweight (mean difference 46.82, 95% CI -40.16 to 133.80). Subgroup analysis revealed an increased risk for preterm birth in post-cesarean section fresh embryo transfer pregnancies (RR 1.59, 95% CI 1.16-2.19).

CONCLUSIONS

Low-grade evidence shows that post-embryo transfer pregnancies in infertile women who had a previous cesarean delivery result in reduced biochemical pregnancy and live birth rates relative to women with a previous vaginal delivery. An increased risk for preterm birth is notable in post-fresh embryo transfer pregnancies.