What does uterine bleeding at 18 weeks' gestation with no products expelled and a closed cervical os indicate?

Uterine bleeding at 18 weeks' gestation, accompanied by no products of conception expelled and a closed cervical os, indicates a threatened abortion. In this scenario, the presence of vaginal bleeding signifies potential complications during early pregnancy, but the closed cervical os suggests that the pregnancy is still viable at this point.

Threatened abortion is characterized by spotting or bleeding during the first half of pregnancy, with the cervical os remaining closed and no tissue being expelled. This condition can sometimes resolve without any adverse outcomes for the pregnancy, and appropriate monitoring is often recommended.

In contrast, missed abortion would imply that the fetus has died but has not been expelled, generally associated with signs such as a closed os and no bleeding early on. Inevitable abortion would present with cervical dilation along with bleeding, suggesting that the process of miscarriage is progressing. A complete abortion would denote the complete expulsion of pregnancy tissue, resulting in a closed os and absence of bleeding following that event. Therefore, the symptoms and clinical findings align with a diagnosis of threatened abortion.