Patients with certain types of conditions
- Pregnancy – causes pressure in the veins in the pelvis and legs, causing blood flow to move more slowly. After the delivery, a woman is still at risk for developing a blood clot for a few weeks.
- Oral contraceptive use and estrogen therapy
- Inflammatory bowel disease (e.g., Crohn’s disease or ulcerative colitis)
- Conditions that make the blood clot too much, such as the antiphospholipid antibody syndrome