A brain aneurysm, also called a cerebral aneurysm, is a bulge in a weak area of an artery in or around your brain. The constant pressure of blood flow pushes the weakened section outward, creating a blister-like bump. When blood rushes into this bulge, the aneurysm stretches even farther. It’s similar to how a balloon gets thinner and is more likely to pop …

Anterior vaginal prolapse, also known as a cystocele (SIS-toe-seel) or a prolapsed bladder, is when the bladder drops from its usual position in the pelvis and pushes on the wall of the vagina. The organs of the pelvis — including the bladder, uterus and intestines — are typically held in place by the muscles and connective tissues of the pelvic …

A popliteal aneurysm is a ballooned-out part of your popliteal artery, which is behind your knee. Half of the people with popliteal aneurysms will have them in both legs. Popliteal aneurysms can cause issues if they burst (rupture), send a clot down your leg (embolize) or block artery flow (thrombose). Some people can lose their legs or even their lives when this condition takes a …

Anthrax (pronounced “AN-thraks”) is an infectious disease caused by exposure to Bacillus anthracis bacteria. The bacteria are dormant, or inactive, in soil. Disease from anthrax mostly affects animals that graze on land that has the bacteria and is extremely rare in the United States. People can become infected through inhaled bacteria spores, contaminated food or water, or skin wounds. Antibiotics are the first line …

A thoracic aortic aneurysm is a bulge that develops in the part of your aorta that extends through your chest (thorax). You might hear it described as an expansion, ballooning or widening of your aorta. All of these words describe how an aneurysm disrupts the aorta’s normal, tube-like shape. A widened portion of your aorta qualifies as an aneurysm if it’s at least 50% …

Pseudomembranous colitis (PMC) is a severe form of colitis. In this condition, something attacks and injures your colon lining (mucosa). It might be bacteria, toxins or another illness. Your colon mucosa develops thickened, scab-like plaques over the wounds. Your healthcare provider might call these “pseudomembranes.” What are pseudomembranes? Pseudomembranes develop on mucous membranes, like your colon lining, when cells die. Your …

An aneurysm is a weak or expanded part of an artery, like a bulge in a balloon. Your arteries are large blood vessels that carry oxygenated blood from your heart to other parts of your body. If an area in an artery wall weakens, the force of blood pumping through can result in a bulge or aneurysm. Aneurysms usually aren’t painful. You …

Antibiotic-associated diarrhea refers to passing loose, watery stools three or more times a day after taking medications used to treat bacterial infections (antibiotics). About 1 in 5 people who take antibiotics develop antibiotic-associated diarrhea. Most often, antibiotic-associated diarrhea is mild and requires no treatment. The diarrhea typically clears up within a few days after you stop taking the antibiotic. More-serious …

Angelman syndrome is a rare, complex neurodevelopmental condition that primarily affects your nervous system. It’s caused by issues with a specific gene called UBE3A. Your nervous system is your body’s command center. Originating from your brain, it controls your movements, thoughts, behaviors and automatic responses to the world around you. Characteristic features of Angelman syndrome include: Developmental delay that’s often noticeable by six …

Antiphospholipid syndrome (APS) is a condition that makes your body much more likely than usual to form blood clots. Healthcare providers sometimes call it antiphospholipid antibody syndrome. The blood clots from APS can cause severe, life-threatening complications like strokes. They can also make pregnant people much more likely to experience miscarriages and other pregnancy complications. APS is an autoimmune disease. Autoimmune diseases happen when your immune …