Doctors identify the cause of testicular swelling by asking questions about symptoms and performing a physical exam, according to Dr. Anuja P. Shah for the Merck Manual Consumer Version. Physicians also assess the patient's medical history to determine if existing disorders are causing the swelling.
Physicians unsure of the diagnosis commonly perform an ultrasonography to reveal the source of any fluid in the testicles, explains Dr. Shah. Testing for testicular cancer that includes blood tests or a CT scan of the chest, pelvis and abdomen may also be necessary to determine the cause of testicular swelling.
The physical exam involves feeling the spermatic cord, epididymis and testis to evaluate the location of the swelling and source of the pain, notes Dr. Shah. A physician may also shine a light behind the scrotum to determine if a lump or collection of fluid exists in the testicles. Questions during the physical exam revolve around any changes in the swelling or variations when the patient lies down, coughs or strains, or stands up.
Common causes of testicular swelling include a hernia in the groin, widening of the veins where blood is transported from the testis or fluid collection in the scrotum, states Dr. Shah. Less common causes include cancer of a testis, blood collection in the scrotum, excess fluid in the body or a cyst in the epididymis.