When pinworm infection is suspected, the health professional will obtain a medical history and do a physical examination. During the physical exam, your doctor will examine the skin around the anus for redness and irritation. In addition, your doctor may ask you to collect a sample by using a piece of transparent adhesive tape. This test, sometimes called a cellophane or Scotch tape test, involves pressing a piece of transparent adhesive tape on the skin around the anus in the morning before you get up or bathe. This piece of tape is then viewed under a microscope to look for pinworms and their eggs. Using this test for 3 days in a row will successfully diagnose pinworms 90% of the time.³

Other tests may be done if the physical exam and cellophane test have not shown pinworms and an infection is still suspected.

• Stool sample. Although collecting a stool sample may be useful, it is usually not the best way to diagnose pinworms since female pinworms do not lay many eggs in the rectum.
• Examination of the lower intestine (colonoscopy). This test is done in only very rare cases of pinworms that have not cleared up with treatment or in cases where the diagnosis is unclear.

If a complication of pinworm infection is suspected, additional tests may be done. The specific tests that are needed will depend on the person's symptoms and the part of the body that is affected.