Typically implantation bleeding does not contain clots and consists only of very light spotting, according to About.com Miscarriage and Pregnancy Loss. Clots are more commonly present during a regular menstrual cycle. They can also be an early indication of pregnancy loss. Implantation bleeding refers to light bleeding that takes place in some women as the fertilized eggs attach to the uterine wall in the very early stages of pregnancy.
When implantation bleeding occurs, it is typically within eight to 10 days after ovulation as the uterus begins to adjust to the pregnancy, according to About.com. Implantation bleeding is commonly mistaken for a light period in some women; in others it is simply overlooked due to being so light. While light spotting near the time of an expected period may indicate implantation bleeding initially, if the flow of blood becomes heavier, is a bright or dark red or begins to have clots, it is probably not implantation bleeding. Implantation bleeding is most often brown or a lighter colored discharge and lasts anywhere from a few hours to a few days. A woman who suspects she is pregnant should visit a doctor to have an early blood or urine test to rule out or confirm pregnancy.