A very large yolk sac may exist in normal pregnancy. When embryonic heartbeats exist, the poor quality and early regression of a yolk sac are more specific than the large size of a yolk sac in predicting pregnancy loss. When an embryo is undetectable, a relatively large yolk sac, even of normal shape, may be an indicator of miscarriage.

This prospective study was undertaken to evaluate the prognostic value of uterine perfusion on the day of human chorionic gonadotropin administration in patients who were undergoing intrauterine insemination. Uterine perfusion was evaluated by measuring the pulsatility index of the ascending branch of the uterine arteries on the day of administration of human chorionic gonadotropin. No pregnancy occurred when the pulsatility index of the ascending branch of the uterine arteries was more than 3. The fecundity rate was 18% when the pulsatility index was less than 2 and was 19.8% when the pulsatility index was between 2 and 3 (not significant). The continuing pregnancy rate was 18% when the pulsatility index was less than 2, compared with 12.1% when the pulsatility index was between 2 and 3 (P < 0.05). Our data suggest that the measurement of uterine perfusion on the day of human chorionic gonadotropin administration may have predictive value regarding fecundity and the continuation of pregnancy in intrauterine insemination.

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