O-056 Dysmorphic uterus: lateral angle might associate with euploid blastocyst implantation
Authors: Romito A , Cimadomo D , Golino D , Pittana E , Exacoustos C , De Angelis C , Guido M , Romito I , Rienzi L , Ubaldi F M , Vaiarelli A 
Published: June 2023

Abstract

Study question
Are there a morphological features measured in coronal plane obtained by tridimensional transvaginal sonography (3D-TVS), associated with euploid blastocyst implantation?

Summary answer
Mean laeral angle (mLA) below 143 degrees was associated with lower clinical pregnancy rate among 47 euploid blastocyst transfers.

What is known already
The ESHRE/ESGE 2013 consensus on uterine malformation clustered in Class U1 (namely Dysmorphic uterus): T-shaped uterus (class U1a), uterus infantilis (Class U1b) and Class U1c including other minor abnormalities. Diagnostic criteria are still under major debate, however a few studies report an association between dysmorphic uterus and impaired fertility outcomes. In the literature, no evidence has been published on a selected population of euploid blastocyst transfers. Moreover, sonographic predictors of successful transfer in patients with dysmorphic uterus undergoing ART are not available.

Study design, size, duration
Cohort study involving 122 infertile couples undergoing ICSI with NGS-based PGT-A on trophectoderm biopsies between July-2022 and December-2023. A 3D-TVS was acquired in the luteal phase before starting ovarian stimulation. The primary outcome was to assess whether uterine morphological features associate with clinical pregnancy rate, defined as an ultrasonographic evidence of a gestational sac with fetal heartbeat per transfer. To date, 47 patients underwent vitrified-warmed single euploid blastocyst transfer.

Participants/materials, setting, methods
Uterine morphology was assessed in a coronal plane. Following measurements, we registered: (1) the distance between the two internal tubal ostia, (2) the width of the uterine cavity at corpus-isthmic level, (3) the lateral angle between the corpus-isthmic cavity, (4) the lateral indentation. The optimal cut-off values of mLA was evaluated with ROC curve; p &lt; 0.05 was considered statistically significant. SPSS version 25.0 was used for statistics.

Main results and the role of chance
Median age was 38 (IR:26-43). The main cause of infertility was tubal/ovulatory in 22 cases (46%), severe male factor in 18 (39%) and idiopathic in 18 (39%). Thirteen women (28%) experienced a previous miscarriage, and half of them were submitted to a uterine cavity revision. The mLA ranged from 126 to 180 degrees (median:156 degrees), whereas mean indentation ranged from 0 to 7.2 mm (median: 3.0 mm). The patients were categorized in 2 groups by the optimal cutoff value of mLA calculated based on ROC curve analysis. Dysmorphic uterus was defined in case of mLA (mean between right and left lateral angle) below 143 degrees (sensitivity 90%, specificity 54%; AUC=0.67). mLA levels were higher than this threshold in 37 women (80%). Relative risk to have a clinical pregnancy was 0.35 (95%CI 0.15-0.83) in dysmorphic uterus. Two women (25%) got pregnant in dysmorphic uterus group compared to 18 (72%) in normal uterus (p:0.026). After adjusting blastocyst quality and day of transfer, mLA association with a clinical pregnancy remained significant (RR 7.38, 95%CI 1.09-50.18 p = 0.04, Post hoc power: 65.3%).

Limitations, reasons for caution
Preliminary results. A larger sample is required to confirm these data.

Wider implications of the findings
The strength of the study is the definition of the impact of a dysmorphic uterus in IVF cycles with PGT-A. If confirmed in larger multicenter datasets, these data may select patients who could benefit from hysteroscopic metroplasty.

Trial registration number
not applicable