If your doctor did not test specifically for pregnancy then you will need to go back. The doctor can order a chemistry panel to be done and this is to check for electrolytes, glucose, bun, and CO2 levels. It provides information about metabolism in the body. A more inclusive test is a chem. 20 which has cholesterol levels, electrolytes and other information. A doctor can also do a CBC with is a blood count. A pregnancy test will check the hcg in the blood stream and is very accurate. If the blood work was just done you could try and call and ask if they can include a pregnancy test.