Doctors usually make a diagnosis of cellulitis by carefully examining the symptoms of the patient. In most cases, further testing is not required and the doctor may start treatment with antibiotics. In some cases however, doctors may recommend Doppler ultrasounds, CT scans, or MRI’s to rule out the possibility of other complications. If the initial treatments do not produce positive results, the doctor may call for further skin and blood testing. Some of the common tests for cellulitis diagnosis include: