Differential Diagnosis for Spotting Blood in the First Trimester
- Single most likely diagnosis
- Threatened abortion: This is the most common cause of spotting in the first trimester, often due to implantation of the embryo, hormonal changes, or a cervical polyp. It is characterized by vaginal bleeding with the cervix closed and the fetus still viable.
- Other Likely diagnoses
- Implantation bleeding: This occurs when the embryo attaches to the uterine lining, causing light bleeding or spotting. It is a normal part of early pregnancy and usually happens around 6-12 days after fertilization.
- Cervical polyp or cervicitis: These conditions can cause spotting due to inflammation or a growth on the cervix. They are relatively common and can be diagnosed with a pelvic exam.
- Miscarriage: While not as common as threatened abortion, miscarriage is a possible cause of spotting in the first trimester, especially if the bleeding is heavy or accompanied by cramping.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Ectopic pregnancy: Although rare, an ectopic pregnancy can cause spotting and is a life-threatening condition if not promptly diagnosed and treated. It occurs when the embryo implants outside the uterus, often in the fallopian tube.
- Molar pregnancy: A molar pregnancy is a rare condition where the placenta grows abnormally, potentially causing spotting, and can lead to serious complications if not treated.
- Placenta previa: This condition, where the placenta covers the cervix, can cause spotting and is a significant risk factor for severe bleeding during pregnancy and delivery.
- Rare diagnoses
- Uterine rupture: Although extremely rare in the first trimester, uterine rupture can cause spotting and is a life-threatening emergency.
- Uterine arteriovenous malformation (AVM): A rare condition where there is an abnormal connection between arteries and veins in the uterus, potentially causing spotting due to bleeding.
- Gestational trophoblastic disease (GTD): A group of rare conditions where the placenta grows abnormally, potentially causing spotting and other complications during pregnancy.