What is the most likely diagnosis for a pregnant patient experiencing vaginal bleeding, mild cramping, and a dilated cervical os at 11 weeks of gestation?

The symptoms and clinical findings presented in this scenario suggest that the most likely diagnosis is an inevitable abortion. At 11 weeks of gestation, vaginal bleeding and mild cramping are common signs that pregnancy may be at risk. The key detail here is the presence of a dilated cervical os, which indicates that the cervix is starting to open in the context of a pregnancy loss.

In the case of an inevitable abortion, there is already a progression towards loss of the pregnancy, and the opening of the cervical os supports this diagnosis. This situation implies that the process of miscarriage is underway and that the pregnancy cannot continue, given that dilation of the cervix typically precedes the passage of pregnancy tissue.

Threatened abortion, in contrast, would be characterized by vaginal bleeding and cramping without cervical dilation. Complete abortion would suggest that all pregnancy tissue has been expelled, while incomplete abortion pertains to some pregnancy tissue remaining in the uterus. Both of these options would typically show a closed cervical os or have already completed the process if the abortion is complete. Thus, the clinical presentation aligns most closely with inevitable abortion due to the combination of symptoms and the open cervical os.