Staying healthy
Learning Center
Small cell, large cell cancer: What this means
Cancer cells are classified by how they look under a microscope. Learn common terms used to describe cancer cells.
Sitting risks: How harmful is too much sitting?
Sitting for long periods — such as in front of the TV or at a desk — appears to increase risk of death from cardiovascular disease and cancer.
Sentinel node biopsy
Learn what to expect during this procedure to remove lymph nodes for testing. The results can show whether cancer has spread.
Senior sex: Tips for older men
Sex isn't just for the young. Get tips for staying active, creative and satisfied as you age.
Sed rate (erythrocyte sedimentation rate)
Sed rate is a blood test that can reveal inflammatory activity in your body. It's often used to help diagnose conditions affecting your joints or muscles.
Scrotal masses
Lumps in the scrotum have various causes. Even painless lumps should be checked promptly by a health care professional.
STD testing: What's right for you?
Find out how your risk factors affect the types of tests you'll need for sexually transmitted infections (STIs).
Rheumatoid factor
Rheumatoid factor — This blood test can help diagnose autoimmune disorders such as rheumatoid arthritis, Sjogren syndrome and lupus.
Retrograde ejaculation
Learn about the symptoms and treatment options for this condition that can cause male infertility.
Retractile testicle
Find out about this condition that allows the testicle to move between the scrotum and groin.