Impact of caesarean scar defects on the success of assisted human reproduction: the NICHE-ART prospective French cohort study protocol

Abstract

Background: The global increase in caesarean sections (CS), currently at 21.1% of all deliveries, has led to a rise in uterine scar defects, or 'niches', at the hysterotomy site. These niches, detectable in 13%-84% of cases via transvaginal ultrasound (TVS) and 42%-84% through sonohysterography (SHG), may contribute to gynaecological complications, including abnormal uterine bleeding, chronic pain and secondary infertility. Niche-associated risks for in vitro fertilisation (IVF) outcomes remain underexplored, and this study aims to evaluate their impact on clinical pregnancy rates.

Methods and analysis: This multicentre, prospective, non-interventional study will involve 250 women with a history of CS and secondary infertility undergoing IVF in 14 reproductive units of French Hospital. Participants will be assessed using SHG and TVS to determine niche presence (measurements of the length, depth and width of the niche, and residual myometrial thickness (RMT)). A niche is diagnosed by an indentation of at least 2 mm at the site of the caesarean scar, with a large niche defined as RMT <3 mm. The primary outcome is clinical pregnancy rate, with secondary outcomes including live birth rates, biochemical pregnancies and obstetric complications. Multivariate logistic regression will control for confounders. The duration of the inclusion period is estimated to be 42 months.

Ethics and dissemination: The study protocol was approved by the relevant French medical review board, 'Comité de Protection des Personnes Sud Méditerranée IV', on 10 November 2020 and recorded prospectively (before the inscription of the first participant) under the number ID-RCB: 2020-A02068-31. The study will be conducted according to the guidelines of the Declaration of Helsinki. Informed consent will be obtained from all participants. The findings will be published in peer-reviewed journals and presented at relevant meetings.

Trial registration number: ClinicalTrials.gov, ID: NCT04869007. Registered on 16 August 2020.

Keywords: Cesarean Section; Pregnancy; Reproductive medicine; Subfertility.

Figure 1. Schedule of the NICHE-assisted reproductive technology timeline, using the Standard Protocol Items: Recommendations for Interventional Trials figure. hCG, human chorionic gonadotropin.