Background: Trans-abdominal ultrasound (TAUS) and transvaginal ultrasound (TVUS) are used for embryo transfer. However, few studies were conducted to compare the methods and assess their effect on pregnancy outcomes.
Methods: A retrospective cohort study was conducted at Mahdieh Hospital in Tehran, analyzing 506 ICSI cycles with fresh embryo transfer. The study period was from April 2019 to March 2022. Following the evaluation of patients’ profile, they were divided into two groups of TAUS (n=250) and TVUS (n=256). The pregnancy outcomes included positive test of β-HCG, history of miscarriage, ectopic pregnancy (EP), clinical pregnancy, and the duration of the embryo transfer were compared between two groups. Mann-Whitney U test, Pearson Chi-Square test, Fisher's exact test, and logistic regression were used for data analysis.
Results: The rate of chemical and clinical pregnancy in the TAUS group was higher compared to the TVUS group, which was statistically significant (p<0.05). The rate of live term birth and live preterm birth was higher in the TAUS group compared to the TVUS group, though the difference was insignificant. Moreover, EP and abortion rates were higher in TVUS group compared to the TAUS group, but the differences were not statistically significant. The odds ratio of achieving pregnancy was higher with TAUS compared to TVUS, but this was only statistically significant for the age variable.
Conclusion: The use of TAUS method appears to be associated with improved pregnancy outcome, including higher rates of chemical and clinical pregnancy, compared to TVUS. Yet, further research is needed to confirm these findings and elucidate underlying mechanisms.