Expert transvaginal ultrasound is determinant for diagnosing pelvic conditions after recurrent implantation failure in IVF.

Objective: Recurrent implantation failure (RIF) is a clinical phenomenon characterized by a lack of implantation after several embryo-transfers. The aim of this study was to evaluate missing pelvic pathologies in patients with RIF, following at least two embryo-transfers of good-quality blastocyst, using a dedicated transvaginal ultrasound (TVS) performed by experienced specialists. Methods: This retrospective study included patients with RIF who were admitted to the Gynecological Ultrasound Unit of the University of Rome 'Tor Vergata' between 2020 and 2024 for a second-opinion ultrasound. Only patients with transfers of euploid blastocysts and/or blastocysts from oocytes donation were included. All patients underwent 2D, 3D and Power-Doppler transvaginal examination to evaluate all possible pelvic pathologies. Results: The study included 152 patients who met the inclusion criteria. Pathological pelvic findings were identified in 45 of 152 women during the initial TVS scans performed at the IVF centres before ET, whereas expert TVS evaluation at our center after RIF diagnosed pelvic pathology in 129 of 152 cases (p < 0.0001). Significant differences were observed for all pathological ultrasound findings between the initial IVF center scan and the expert TVS, except for isthmocele. In particular, the lowest overall agreement (OA), Cohen's Kappa (K) and positive percent agreement (PPA) was described regarding the diagnosis of adenomyosis, uterine malformations, hydrosalpinx and deep infiltrated endometriosis. Conclusion: Our study revealed a significant discrepancy in the diagnosis of ultrasound-detectable pelvic pathologies between IVF centres and our expert gynecological ultrasound unit. This difference highlights the potential underdiagnosis of critical pelvic conditions when ultrasound is performed by not expert sonographers in IVF centres.