First-Trimester sonogram can predict odds of early fetal loss. (Following Bleeding or Pain).

BOSTON -- Advances in ultrasound technology have made it possible to glean a host of clinically important sonographic information very early in the first trimester, Dr. Peter M. Doubilet said at an ultrasound meeting sponsored by Harvard Medical School and Brigham and Women's Hospital.

It is now possible to predict the odds that a fetus will survive into the second trimester and to determine the odds of pregnancy loss following bleeding or pain in the first 7 weeks after conception, said Dr. Doubilet, professor of radiology at the hospital.

Many women experience pain and bleeding during the early first trimester. In most cases, this implantation bleeding" has no negative prognostic significance, but bleeding can also signal ectopic pregnancy or impending pregnancy failure. Ultrasound examination is critical in identifying when the bleeding means trouble.

"You need to answer three questions: Is there a gestational sac? Are the sac contents normal in appearance? Are the adnexa normal in appearance?" he said.

If there is no gestational sac, look very carefully at the adnexa for extraovarian complexes or solid masses. In these cases, the odds of an ectopic pregnancy are high. Presence of a tubal ring or an embryonic pulse cinches the diagnosis.

If there are no extraovarian masses, look within the ovaries. It is essential, however, to distingnish between cystic masses suggestive of ectopic pregnancy and normal intraovarian luteal cysts. The giveaway is in the echogenicity of the cyst. Ectopic cysts will be highly echogenic, while corpus luteum will have an echogenicity equivalent to or slightly less than the ovary itself.

If there is no gestational sac, it may be that the pregnancy is still in its earliest stages. However, by 5 weeks the sac should be present. Serum [beta]HCG milestones can come in handy in these cases. Using the International Reference Preparation standards, if the HCG level is at least 1,000 mIU/mL, the gestational sac should be identifiable. If HCG is at least 7,200 mIU/mL, the yolk sac should be present. If it exceeds 10,800 mIU/mL, the embryo should be identifiable.