Pitfalls in first-trimester bleeding.

The focus of this article is first-trimester bleeding. Vaginal bleeding during the first 3 months of pregnancy is a common event. It is important that the emergency physicians recognize patients with vaginal bleeding who may have an adverse outcome if misdiagnosed or not treated appropriately in the emergency department. Causes of first-trimester vaginal bleeding include implantation bleeding, spontaneous abortions, ectopic pregnancy, and lesions involving the female reproductive system and perineal area infections.