An abscessed tooth is a pus-filled pocket that can form in any part of a tooth. It can be classified into different types depending on the cause and location where it develops.

The heart is perhaps the most critical internal organ. It purifies deoxygenated blood and supplies it to different body parts through a large blood vessel called the aorta. Aortic dissection is a health condition that occurs when there is a tear in the inner layers of the aorta.

Acute Respiratory Distress Syndrome (ARDS) is a serious health disorder that damages the lungs and can prove to be fatal. This condition requires immediate attention as it collects fluid in the lungs, causing depleted airflow to other organs.

Angiomyolipoma is a tumor comprising blood vessels, muscle, and fat commonly diagnosed in the kidneys. Although benign (noncancerous), it can cause discomfort and other issues. A health expert may remove the tumor if it grows large enough and cause bleeding.

Anthrax primarily affects livestock and wild animals; however, humans can contract this infection from sick animals through direct or indirect contact. Bacillus anthracis, a spore-forming bacteria, causes this rare infection.

Aphasia is a condition that affects the manner in which a person communicates. It can be observed in their speech and how they write and comprehend written and spoken words.

Appendicitis is a condition brought on by an inflamed and infected appendix—a small pouch-like organ attached to the large intestine. The condition can affect people of all ages; however, it is common among those between 10 and 30.

Anal cancer is rare cancer that occurs in the anal canal or the skin around the anus. However, the incidence among people has gradually increased in the past few years, especially in older people and those with a history of HPV infections.