Is what we clearly see really so obvious? Ultrasonography and transcervical embryo transfer--a review

To critically review the role of ultrasound-guided embryo transfer (ET) and its influence on the outcome of in vitro fertilization (IVF).

Medline review of published manuscripts.

Studies evaluating the role of ultrasound-assisted ET have had mixed results, and although meta-analysis of prospective trials suggests an improvement in outcome, limitations in study design may overstate the effect of ultrasonography. Other ET techniques may eliminate the advantages provided by ultrasonography, limiting its benefit to specific clinical scenarios. However, because no trial has demonstrated an adverse effect and because cases that may benefit from its use often cannot be predicted reliably, the routine application of ultrasonography can be justified.