An ovarian cystectomy is a surgery that removes a cyst from your ovaries. It's usually done only if the cyst is large or painful.

Atrial flutter is a type of arrhythmia. It causes the heart to beat faster than normal. Atrial flutter can increase the risk for certain serious problems, such as stroke.

Atrial fibrillation, or A-fib, is a common type of heart arrhythmia. It causes fast, chaotic electrical signals in the atria.

An anal stricture is a narrowing of the end of the tube (anal canal) that takes stool out of the body. This can cause pain and other problems with passing stool.

Alopecia areata is a condition that causes your hair to fall out. It causes bald patches on the scalp, but it can also cause hair loss on other parts of the body.

Actinic keratosis is a skin growth caused by sun damage. Many people get these growths, especially as they age. This is because of regular exposure to the sun over years.

Acanthosis Nigricans is a skin condition that causes dark, thick patches on the skin. It is more common in people who have diabetes or are at risk of developing diabetes.

Zika is a virus spread through the bite of a mosquito. It may also be passed on through sexual contact and blood transfusions.

Yersiniosis is a foodborne illness. It causes inflammation in the small intestine and colon. It is more common in children.

Tinea unguium is a type of fungal infection. The fungus infects the fingernails and, more commonly, the toenails. It's more common in men, older adults, and people who have diabetes or peripheral vascular disease.