The Impact of Cesarean Scar Defects on the Success of Assisted Human Reproduction

The prevalence of Caesarean sections continues to increase around the world. In France, the proportion of Caesarean sections has doubled from 11% in 1981 to 20,2% in 2016, bringing with it an increase in the risk of obstetrical complications. Uterine defects, or Isthomcele, first defined by Morris in 1995 as a scarring abnormality with a dehiscence of the hysterotomy following a caesarean section. This purely iatrogenic pathology can cause inter-menstrual bleeding or pelvic pain. Several definitions of isthmosceles exist in scientific literature with variations according to the nature of the reference examination chosen and the measurements made. However, for the majority of authors, isthmoceles are characterized by a residual myometrial thickness of less than 3 millimetres in the sagittal plane. The prevalence of isthmoceles amoung patients with a unicicatricial uterus is about 61%. Currently, the main diagnostic technique for isthmoceles are 2D or 3D ultrasound and hysterosonography. Small, non-controlled studies have found that surgical treatment of the isthmocele is effective in reducing metrorrhagia. In these studies, the authors noted that patients with metrorrhagia were also more frequently affected by secondary infertility. A small number of non-comparative studies with a low level of evidence have looked into the efficacy of surgical treatment of isthmoceles on related symptoms: metrorraghia, pelvic pain and/or secondary infertility. Their results show an idiopathic secondary infertility rate in the presence of isthmoceles prior to surgical treatment of approximately 66%. Significantly higher pregnancy rates after treatment suggest that the surgical management of isthmoceles is worthwhile. However, these data suffer from not negligible selection bias. The initial findings concerning fertility after surgical repair seem promising and some teams propose systematic surgical management of the isthmocele before a technique of assisted reproduction (ART) although without any evidence in literature. Isthmocele surgery can result in uterine perforations, adhesions and intrauterine synechia known to be detrimental to future fertility. The efficacy of surgical management of surgey must therefore be demonstrated prior to any attempts at treatment. This will require large prospective studies based on a consensual definition of isthmocele. The diagnosis using Hysterosonography is currently considered as the "gold standard" examination. The main hypothesis of our study is that a significant isthmocele, defined by a residual myometrial thickness of less than 3mm, measured in the sagittal plane by hysterosonography, could alter the results of ART.