Bruises that do not result from the application of force (blunt trauma) may be a symptom for other conditions: People with such bruises often have a problem with their blood. Platelet or coagulation disorders often lead to the increased bruising. Unexplained bruising may be a warning sign of child abuse, domestic abuse, or serious medical problems such as leukemia or meningoccocal infection. Unexplained bruising can also indicate internal bleeding or certain types of cancer.