Ultrasound-guided embryo transfer and the accuracy of trial embryo transfer.

BACKGROUND: Studies have suggested that ultrasound-guided embryo transfer (UG-ET) may improve the outcome in IVF; however, several factors may account for the improvement in pregnancy rate. This study examines the use of ultrasound to determine the accuracy of trial transfer (TT) in preparation for ET. METHODS: Sixty-seven consecutive patients prospectively underwent UG-ET over a 2 month period. Total cavity length by US was compared with the length noted by TT. A difference of greater than or equal to1 cm was considered significant. All embryos were placed within 1-2 cm of the fundus by US. RESULTS: Twenty patients (29.9%) had a difference of greater than or equal to1 cm and 13 patients (19.4%) had a difference of less than or equal to1.5 cm. Patients with a difference of greater than or equal to1 or greater than or equal to1.5 cm had a significantly greater depth at transfer (P<0.001) and uterine cavity length (P<0.001) when compared with patients without a difference. Clinical pregnancy, implantation, delivery and overall miscarriage rates did not differ between patients with a difference of greater than or equal to1 or greater than or equal to1.5 cm versus no difference. There were no ectopic pregnancies. CONCLUSIONS: Nineteen percent of patients had a discrepancy of greater than or equal to1.5 cm and similar to30% had a difference of greater than or equal to1 cm from TT at UG-ET, suggesting a benefit to UG-ET. A large prospective randomized trial comparing UG-ET with blind transfer is required to assess further if UG-ET should be used in all cases of ET.