Is uterine depth measurement by trans-vaginal ultrasound alone as accurate as measurement carried out by trans-abdominal ultrasound-guided trial transfer?

OBJECTIVES: To assess the reliability of trans-vaginal-scan (TVS) in measuring the uterine depth (UD) in comparison with ultrasound-guided trial-transfer (UTT). METHODS: This prospective study was conducted in 66 consecutive patients undergoing in-vitro fertilization and embryo transfer (IVF-ET). The study took place in a private IVF center in Jeddah, Saudi Arabia between November 2013 and January 2014. The patients underwent UD measurements using TVS and UTT, sequentially. All scans were performed by a single sonographer, and all UTT were carried out by a single physician who was blinded to the TVS measurement. RESULTS: The median (95% confidence interval) UD measurement using the TVS method was 6.9 cm (5.0-12.5) and UTT was 7.1 cm (5.9-13.5), (p<0.0001). Fifteen patients (22.7%) had a difference of >1 cm between the 2 measurement modalities (group-B). When measured by UTT, 93.3% of patients in group-B had UD ≥8cm, compared with 9.8% of patients in group-A, (p<0.0001). Group-B had a significantly longer uterine cavity when measured by UTT (p<0.0001), and a trend towards significance when measured by TVS (p=0.055). The TVS measurements generally underestimated UD when compared with UTT. CONCLUSION: Trans-vaginal-scan is less reliable than UTT and should not be used as a substitute. Larger sample-size studies involving different personnel, and equipment is needed.