The embryo versus endometrium controversy revisited as it relates to predicting pregnancy outcome in in-vitro fertilization-embryo transfer cycles

To evaluate embryonic and endometrial factors for their value in predictingpregnancy outcome in in-vitro fertilization (IVF) and embryo transfer, aretrospective data collection and prospective uterine artery colour Dopplerimaging study was performed in a university-based IVF-embryo transferprogramme setting. A total of 210 patients were included and grouped asfollows: (I) IVF with controlled ovarian stimulation (214 cycles); (II)frozen-thaw cycle of autologous embryos (30 cycles); (III) oocyte donation,no cryopreservation (12 cycles); (IV) frozen-thaw cycle with embryos fromdonated oocytes (10 cycles). Embryo quality was significantly better inpregnant than non-pregnant cycles (group I, P = 0.0104; groups II-IV, P =0.0418). The endometrial echo was significantly thicker in pregnant versusnon-pregnant patients in group I (P = 0.0059), but not in groups II-IV (P =0.741). Past uterine surgery or abnormalities had no effect on pregnancyoutcome. There were no significant differences in mean uterine arteryresistance index or peak systolic velocity in pregnant versus non-pregnantpatients in groups II-IV. Thus, embryo quality is the most reliablepredictor of pregnancy outcome. Endometrial measurements were significantlythicker in subsequently pregnant patients only in group I, where theendometrium reflects the hormonal environment. Doppler parameters were notuseful in predicting pregnancy outcome.