A hematoma on the lower leg can result in a localized infection, or cellulitis, if the area is swollen or there is even a tiny break in the skin, Mayo Clinic says. The infection can spread to the bloodstream, causing sepsis. The terms "sepsis" and "septicemia" are interchangeable, notes MedicineNet.
Cellulitis is most common in the lower extremities, and people with compromised immune systems, such as those with diabetes, HIV/AIDS, chronic leukemia, and liver or kidney disease, are at greatest risk. Signs of cellulitis include redness, pain, swelling and warmth in the area of the injury and possibly a fever, according to Mayo Clinic. Sometimes small red spots or blisters appear around the injured area as well.
When cellulitis spreads to the bloodstream, the bacteria can set off an inflammatory response in the entire body, and the characteristic signs and symptoms of sepsis ensue, Mayo Clinic says. These include an elevated heart and breathing rate, fever greater than 100.4 degrees Fahrenheit, and an abnormal white blood cell count, according to MedicineNet. If sepsis is severe, a decrease in urine output, changes in mental status, difficulty breathing and abdominal pain occur. If sepsis progresses to septic shock, the person's blood pressure drops, causing multiple organs to fail. The mortality rate from septic shock is around 50 percent, according to Mayo Clinic.