While heart failure can often be diagnosed by assessing a patient and using diagnostic tools, it can still be confused with other conditions. Patient assessments for heart failure are often done to determine if edema (swelling), shortness of breath, or difficulty in breathing are present. However, these signs and symptoms can be present in a wide variety of other ailments including allergic reactions and kidney failure. Echocardiography can also be used to determine if there are any abnormalities of the heart, but these scans may be inconclusive or affected by factors such as technician experience and skill and equipment performance. The BNP lab test is used in conjunction with these tools to determine if heart failure is present.