Pregnancy and Perinatal Outcomes of Patients With Prior Cesarean Section After a Single Embryo Transfer in IVF/ICSI: A Retrospective Cohort 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.

Hysteroscopic Management of Symptomatic Cesarean Scar Diverticulum in Patients Undergoing Frozen-Thawed Embryo Transfer: Impact on Clinical Pregnancy Rates and Pregnancy Complications

This retrospective cohort study aimed to compare the clinical outcomes of patients with cesarean scar defect (CSD) undergoing frozen embryo transfer (FET) with or without hysteroscopic repair surgery. The study included 82 patients, with 48 patients in surgical group A (undergoing CSD repair) and 34 patients in surgical group B (undergoing hysteroscopic treatment for other uterine lesions). The results showed that patients in group A had a larger CSD volume and a different shape compared to group B. However, there was no significant difference in clinical pregnancy rates between the two groups. Additionally, there were no differences in miscarriage, live birth, or preterm birth rates, and no complications such as scar pregnancy or placental abnormalities were observed in either group. These findings suggest that hysteroscopic treatment of CSD in symptomatic patients undergoing FET does not increase the risk of pregnancy complications and can lead to comparable clinical pregnancy rates with asymptomatic patients. Further studies with larger sample sizes are needed to confirm these results and evaluate long-term reproductive outcomes following CSD repair.

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.

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

In 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, causes difficulty of embryo transplant operation and further pregnancy complications. For women undergoing assisted reproductive technology (ART), CSD significantly reduces embryo implantation rate, clinical pregnancy rate and live birth 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 treatment, to provide reference for CSD management in ART patients.

Changes in the characteristics and outcomes of high-risk pregnant women who delivered prior to and after China's universal two-child policy: a real-world retrospective study, 2010-2021

BACKGROUND

In 2016, the "universal two-child" policy, allowing each couple to have two children, was introduced in China. The characteristic change of the long-term period after the implementation of the universal two-child policy was unclear. We studied trends in the obstetric characteristics and their potential impact on the rates of cesarean section and preterm birth in the era of China's universal two-child policy.

METHODS

A tertiary center-based study (2010-2021) retrospectively focused single high-risk pregnancies who delivered from the one-child policy period (OCP, 2010-2015) to the universal two-child policy period (TCP, 2016-2021). A total of 39, 016 pregnancies were enrolled. Maternal demographics, complications, delivery mode and obstetric outcomes were analyzed. Furthermore, logistic regression analysis was used to explore the association between the cesarean section rate, preterm birth and implementation of the universal two-child policy, adjusting maternal age, parity, and fetal distress.

RESULTS

Ultimately a total of 39,016 pregnant women met the criteria and were included in this analysis. The proportion of women with advanced maternal age (AMA) increased from 14.6% in the OCP to 31.6% in the TCP. The number of multiparous women increased 2-fold in the TCP. In addition, the overall rate of cesarean section significantly decreased over the policy change, regardless of maternal age, whereas the risk of preterm birth significantly increased in the TCP. Adjusting for maternal age, parity and fetal distress, the universal two-child policy showed a significantly favorable impact on the cesarean section rate (RR 0.745, 95%CI (0.714-0.777), P < 0.001). Compared to the OCP group, a higher increase in fetal distress and premature rupture of membranes (PROM) were observed in the TCP group. In pregnancies with AMA, there was no increase in the risk of postpartum hemorrhage, whereas more women who younger than 35 years old suffered from postpartum hemorrhage in TCP. The logistic regression model showed that the universal two-child policy was positively associated with the risk of postpartum hemorrhage (RR: 1.135, 95%CI: 1.025-1.257, P = 0.015).

CONCLUSIONS

After the implementation of the universal two-child policy in China, the rate of the cesarean section significantly decreased, especially for women under 35 years old. However, the overall risk of postpartum hemorrhage increased in women under 35 years old, while there was no change in women with AMA. Under the new population policy, the prevention of postpartum hemorrhage in the young women should not be neglected.

Reproductive outcomes after laparoscopic resection of symptomatic niches in uterine cesarean scars: Long-term follow-up on the prospective LAPNICHE study

INTRODUCTION

After incomplete healing of the uterine cesarean section scar, a niche can be observed; 24% of the women develop large niches with a residual myometrial thickness <3 mm. In these cases a laparoscopic resection is possible. The effect of this new treatment on fertility outcome is not known yet. This paper describes reproductive outcomes 2 years after a laparoscopic niche resection and compares women with or without secondary infertility at baseline.

MATERIAL AND METHODS

A prospective cohort study was performed, with consecutive inclusion of women between 2011 and 2019. Women with a niche in the uterine cesarean scar, with a residual myometrial thickness of <3 mm and with a desire to become pregnant, were scheduled to undergo a laparoscopic niche resection because of one or more of the following problems (1) postmenstrual spotting; (2) midcycle intrauterine fluid accumulation diagnosed during the fertility workup or (3) difficulties with a previous embryo transfer and preferring a surgical therapy. The study is registered in the ISRCTN register (ref. no. ISRCTN02271575) on April 23, 2013.

RESULTS

There were 133 (62%) women included with a desire to become pregnant, 88 with secondary infertility. In all, 83 had an ongoing pregnancy at the 2-year follow-up. The ongoing pregnancy rate in patients with previous fertility problems was 60.2% compared with 66.7% in patients without infertility (odds ratio [OR] 0.68, 95% confidence interval [CI] 0.32-1.7). The OR for live births was 0.57 (95% CI 0.02-1.2). Overall, 8.3% of the pregnancies resulted in miscarriages by the 2-year follow-up.

CONCLUSIONS

The reproductive outcomes in women with and without previous fertility problems undergoing resection of a large niche are very promising and quite comparable in both groups. These results suggest, but do not prove, a beneficial effect of this therapy for these indications. The results support the design of future randomized controlled trials to evaluate the effect of niche resection vs expectant management to assess its additional value in women with or without fertility problems who desire pregnancy.

Effectiveness of laparoscopic niche resection versus expectant management in patients with unexplained infertility and a large uterine caesarean scar defect (uterine niche): protocol for a randomised controlled trial (the LAPRES study)

INTRODUCTION

A uterine niche is a defect at the site of the uterine caesarean scar that is associated with gynaecological symptoms and infertility. Promising results are reported in cohort studies after a laparoscopic niche resection concerning reduction of gynaecological symptoms in relation to baseline and concerning pregnancy outcomes. However, randomised controlled trials to study the effect of a laparoscopic niche resection on reproductive outcomes in infertile women are lacking. This study will answer the question if laparoscopic niche resection in comparison to expectant management improves reproductive outcomes in infertile women with a large uterine niche.

METHODS AND ANALYSIS

The LAPRES study is a randomised, non-blinded, controlled trial, including 200 infertile women with a total follow-up of 2 years. Women with the presence of a large niche in the uterine caesarean scar and unexplained infertility of at least 1 year or failed IVF will be randomly allocated to a laparoscopic niche resection within 6 weeks or to expectant management for at least 9 months. A large niche is defined as a niche with a depth of >50% of the myometrial thickness and a residual myometrium of ≤3 mm on transvaginal ultrasound. Those receiving expectant management will be allowed to receive fertility therapies, including assisted reproductive techniques, if indicated. The primary outcome is time to ongoing pregnancy, defined as a viable intrauterine pregnancy at 12 weeks' gestation. Secondary outcome measures are time to conception leading to a live birth, other pregnancy outcomes, received fertility therapies after randomisation, menstruation characteristics, patient satisfaction, quality of life, additional interventions, and surgical and ultrasound outcomes (intervention group). Questionnaires will be filled out at baseline, 6, 12 and 24 months after randomisation. Ultrasound evaluation will be performed at baseline and at 3 months after surgery.

ETHICS AND DISSEMINATION

The study protocol was approved by the medical ethics committee of the Amsterdam University Medical Centre. (Ref. No. 2017.030). Participants will sign a written informed consent before participation. The results of this study will be submitted to a peer-reviewed journal for publication. TRIAL REGISTRATION NUMBER DUTCH TRIAL REGISTER REF NO NL6350 : http://www.trialregister.nl.

Definition and Criteria for Diagnosing Cesarean Scar Disorder

Importance

Approximately 60% of women develop a uterine niche after a cesarean delivery (CD). A niche is associated with various gynecological symptoms including abnormal uterine bleeding, pain, and infertility, but there is little consensus in the literature on the distinction between the sonographic finding of a niche and the constellation of associated symptoms.

Objective

To achieve consensus on defining the clinical condition that constitutes a symptomatic uterine niche and agree upon diagnostic criteria and uniform nomenclature for this condition.

Design, Setting, and Participants

A consensus based modified electronic Delphi (eDelphi) study, with a predefined Rate of Agreement (RoA) of 70% or higher. Experts were selected according to their expertise with niche-related consultations, publications, and participation in expert groups and received online questionnaires between November 2021 and May 2022.

Main Outcomes and Measures

Definition, nomenclature, symptoms, conditions to exclude, and diagnostic criteria of an illness caused by a symptomatic uterine niche.

Results

In total, 31 of the 60 invited experts (51.7%) participated, of whom the majority worked in university-affiliated hospitals (28 of 31 [90.3%]), specialized in benign gynecology (20 of 31 [64.5%]), and worked in Europe (24 of 31 [77.4%]). Three rounds were required to achieve consensus on all items. All participants underlined the relevance of a new term for a condition caused by a symptomatic niche and its differentiation from a sonographic finding only. Experts agreed to name this condition cesarean scar disorder, defined as a uterine niche in combination with at least 1 primary or 2 secondary symptoms (RoA, 77.8%). Defined primary symptoms were postmenstrual spotting, pain during uterine bleeding, technical issues with catheter insertion during embryo transfer, and secondary unexplained infertility combined with intrauterine fluid. Secondary symptoms were dyspareunia, abnormal vaginal discharge, chronic pelvic pain, avoiding sexual intercourse, odor associated with abnormal blood loss, secondary unexplained infertility, secondary infertility despite assisted reproductive technology, negative self-image, and discomfort during participation in leisure activities. Consensus was also achieved on certain criteria that should be met and conditions that should be excluded before making the diagnosis.

Conclusions and Relevance

In this modified Delphi study, a panel of 31 international niche experts reached consensus for the constellation of symptoms secondary to a uterine niche and named it cesarean scar disorder.

Previous caesarean delivery and the presence of caesarean scar defects could affect pregnancy outcomes after in vitro fertilization frozen-thawed embryo transfer: a retrospective cohort study

BACKGROUND

Due to various iatrogenic and social factors, the global caesarean delivery (CD) rate has risen sharply in the past 30 years. It is more complicated and dangerous for women with a scarred uterus to experience pregnancy again than for women with a previous vaginal delivery (VD). In this study we investigated the impact of previous caesarean delivery (CD) and caesarean scar defects (CSDs) on pregnancy outcomes after in vitro fertilization frozen-thawed embryo transfer (IVF-FET).

METHODS

We conducted a retrospective cohort study that included 1122 women aged < 40 years who had a history of only one parturition (after 28 weeks of pregnancy) and who underwent their first FET cycle between January 2014 and January 2020. Patients were divided into the CD group, VD group, and CSD group. Thereafter, according to the number of transferred embryos, the CD, VD, and CSD groups were divided into the single embryo transfer (SET) group and the double embryo transfer (DET) group. Outcome measures in this study were live birth, clinical pregnancy, multiple pregnancy, ectopic pregnancy, pregnancy loss, pregnancy complications, preterm birth, and neonatal birth weight. Multivariate logistic regression was performed to evaluate the relationship between pregnancy outcomes and CD.

RESULTS

In SET patients, the clinical pregnancy and live birth rates were decreased in the CSD group compared with the VD and CD groups. In DET patients, the clinical pregnancy and live birth rates were significantly lower in theCSD group than in the CD and VD groups. After adjustment for confounders, previous CD and CSD were associated with a significantly lower clinical pregnancy rate and live birth rate than previous VD in the total sample. This effect was observed in DET patients, but not in SET patients. Additionally, DET patients with previous CD had a significantly higher multiple pregnancy rate (AOR = 0.47, 95% CI = 0.29, 0.75, P = 0.002) than those with previous VD, but no significant associations were observed in CSD and multiple pregnancies (AOR = 0.55, 95% CI = 0.23, 1.34, P = 0.192) between DET patients with CD and those with VD after adjusting for potential confounders.

CONCLUSIONS

Our study showed that during an FET cycle, previous CD and the presence of a CSD could negatively affect pregnancy outcomes especially in DET patients.