Uterine niche is associated with adverse in vitro fertilization and intracytoplasmic sperm injection outcomes: a retrospective cohort study

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.

Reproductive outcomes after in vitro fertilization in women with cesarean section scar diverticulum: A retrospective study

PURPOSE

Some studies have suggested that cesarean section diverticulum may affect the pregnancy outcomes of assisted reproductive technology through a variety of mechanisms. This study aims to explore whether previous cesarean section and uterine scar diverticulum affect pregnancy outcomes after in vitro fertilization.

METHODS

This retrospective study included 954 infertile women with only one previous delivery who had in vitro fertilization treatment and underwent fresh embryo transplantation for the first time at our center between 2015 and 2019. We first divided the women into two groups by previous vaginal delivery (n = 557) or cesarean section delivery (n = 397), and the latter group included 88 women with cesarean diverticulum and 309 women without cesarean diverticulum. Baseline characteristics were compared and analyzed, and logistic regression analyses were performed to explore the different pregnancy outcomes among the above groups.

RESULTS

Although the live birth rate, clinical pregnancy rate, and mean embryo implantation rate after in vitro fertilization were significantly reduced in patients with previous cesarean section (live birth rate: 26.45% vs. 43.99%, adjusted OR: 0.602, CI: 0.447-0.810; clinical pregnancy rate: 35.26% vs. 49.91%, adjusted OR: 0.724, CI: 0.544-0.962; mean embryo implantation rate: 0.227 ± 0.378 vs. 0.243 ± 0.397, adjusted OR: 0.860, CI: 0.514-1.439), there were no significant differences in pregnancy outcomes between the women with cesarean diverticulum and without cesarean diverticulum (p > 0.05) or between the two groups at different ages. The live birth and clinical pregnancy rates in the women with residual muscle thickness ≤2.2 mm or prolonged menstruation were reduced, but the difference was not statistically significant (p > 0.05).

CONCLUSION

This study showed reduced pregnancy and live birth rates after in vitro fertilization in patients with previous cesarean section, while uterine scarring did not adversely affect pregnancy and delivery outcomes after in vitro fertiliazation.

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.

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.

Comparison of clinical effectiveness and subsequent fertility between hysteroscopic resection and vaginal repair in patients with cesarean scar defect: a prospective observational study

OBJECTIVE

To evaluate the clinical effectiveness and pregnancy rate after hysteroscopic resection (HR) and/or vaginal repair (VR) in patients with cesarean scar defect (CSD).

METHODS

This prospective observational study enrolled 191 patients who received CSD surgery in the First affiliated hospital of Sun Yat-sen University between September 2019 to February 2022 (96 in HR and 95 in VR, respectively). Patient follow-up were performed three months after surgery in both groups by transvaginal ultrasound to confirm the presence of fluid in the niche, along with the resolution of prolonged menses at the same time. The primary outcome was the clinical effectiveness between HR and VR, identified by the resolution of prolonged menses.

RESULTS

The rates of niche-fluid disappearance (70.1% vs 60.2%, P = 0.176) and prolonged menses resolution (74.8% vs 80.0%, P = 0.341) were comparable for HR and VR. A subgroup analysis for niche size revealed that HR provides patients with small niche a more favorable rate of menstrual resolution compared to VR (size of niche ≤ 15 mm2, aOR = 3.423, 95% confidence interval [CI] 1.073-10.918), but patients with large niche experience a lower rate of resolution compared to VR (size of niche > 25 mm2, aOR = 0.286, 95% CI 0.087- 0.938). During follow-up, 41 patients who wanted to conceive became pregnant. Kaplan-Meier estimates of the cumulative probability of pregnancy at 12 months and 24 months were 47.1% (95% CI: 34.5%, 58.8%) and 63.8% (95% CI: 52.5%, 72.9%), respectively. The median pregnancy time was 22 months (95% CI: 14.2, 29.8) after VR and 12 months (95% CI: 8.3, 15.7, Gehan-Breslow-Wilcoxon P = 0.021) after HR. Among patients with subsequent infertility, 31.6% achieved pregnancy by unassisted mode and 29.8% by IVF/ICSI. Moreover, among patients with previously failed IVF/ICSI treatment, 60% (12/20) obtained pregnancy, including 71.4% (10/14) after HR and 33.3% (2/6) after VR.

CONCLUSIONS

Hysteroscopic resection is as effective as vaginal repair at relieving symptoms of CSD-associated prolonged menses. Hysteroscopic resection is the modality of choice with an improvement in prolonged menses for small niche, while vaginal might be considered for a large niche. Furthermore, surgical intervention could improve the clinical pregnancy rate of CSD patients. All of these provide evidence for the individualized management of CSD.

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.