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Articles In This Section

• A to Z: Aortic Stenosis

  In aortic stenosis, the aortic valve is narrower than it's supposed to be and can't open all the way.

• A to Z: Annular Ligament Displacement

  Nursemaid's elbow is a partial dislocation of the elbow joint that happens when a ligament slips out of place near the elbow.

• A to Z: Alcohol Abuse

  Learn about alcohol abuse and consequences of excessive drinking.

• A to Z: Atrioventricular Septal Defect

  Learn about congenital heart defects and conditions that affect newborn babies.

• A to Z: Alpha Thalassemia

  Learn about genetic disorders and diseases and conditions that affect the blood.

• A to Z: Abscess, Dental

  See: Abscess, Periapical.

• A to Z: Anaphylaxis

  Anaphylaxis is a sudden, life-threatening reaction that is usually caused by an allergy.

• A to Z: Arthrogryposis

  Learn about congenital conditions and conditions that affect the muscles and joints in newborn babies.

• A to Z: Anal Fissure

  An anal fissure is a cut or tear in the lining of the anus.

• A to Z: Arrhythmia

  An arrhythmia is an abnormal heart rhythm usually caused by an electrical "short circuit" in the heart.

• A to Z: Acne, Infant

  Infant acne is common in babies, and usually goes away on its own without treatment or scarring.

• A to Z: Amenorrhea, Secondary

  Secondary amenorrhea is when a girl who had been getting her period stops menstruating for more than 6 months or for more than three of her usual cycles.

• A to Z: Amenorrhea, Primary

  Primary amenorrhea is when a girl does not start her period by age 15 or 3 years after she begins puberty.

• A to Z: Amenorrhea

  Amenorrhea is when a girl is not getting her period.

• A to Z: Asthma

  Asthma is a lung condition that causes difficulty breathing.

• A to Z: Achondroplasia

  Learn about genetic disorders and conditions that affect growth and development.

• A to Z: Attention Deficit Hyperactivity Disorder (ADHD)

  Learn about behavioral disorders and conditions that affect children's moods, activities, and interactions.

• A to Z: Autism

  Learn about developmental disorders and conditions that affect children's moods, activities, and interactions.

• A to Z: Atrial Septal Defect (ASD)

  Learn about congenital heart defects and conditions that affect the heart and circulatory system.

• A to Z: Arteritis

  Learn about conditions that affect the heart and blood vessels.

• A to Z: Anorexia Nervosa

  Learn about anorexia nervosa, a type of eating disorder.

• A to Z: Acute Febrile Mucocutaneous Lymph Node Syndrome (MCLS)

  See: Kawasaki Disease.

• A to Z: Atopic Dermatitis

  See: Eczema.

• A to Z: Alopecia Areata

  Alopecia areata is a condition that causes hair loss on the scalp and sometimes elsewhere on the body.

• A to Z: Ataxia, Cerebellar

  See: Cerebellar Ataxia.

• A to Z: Adrenal Insufficiency

  Adrenal insufficiency is a condition that happens when the adrenal glands do not work properly.

• A to Z: Adenovirus

  Adenoviruses are a group of viruses that can infect the membranes (tissue linings) of the respiratory tract, eyes, intestines, and urinary tract. They are common among infants and young children.

• A to Z: Adynamic Ileus

  Learn about intestinal blockages and conditions that affect the digestive tract.

• A to Z: Acute Lymphoblastic Leukemia (ALL)

  Learn about different types of leukemia and cancers that affect the blood and bone marrow.

• A to Z: Acute Myeloid Leukemia (AML)

  Learn about different types of leukemia and cancers that affect the blood and bone marrow.

• A to Z: Abscess, Periapical

  Learn about complications of infections and conditions that affect the teeth, gums, and mouth.

• A to Z: Abnormality of Gait (Gait Abnormality)

  Learn about abnormality of gait (or gait abnormality), an unusual walking pattern or style.

• A to Z: Abscess, Skin

  A skin abscess forms when bacteria get under the skin.

• A to Z: Atrial Flutter

  Atrial flutter is an abnormal heart rhythm that causes the heart to beat too fast.

• A to Z: Atresia, Aortic

  Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

• A to Z: Atresia, Pulmonary

  Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

• A to Z: Atresia, Tricuspid

  Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

• A to Z: Atresia, Esophageal

  Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

• A to Z: Atresia, Anal

  Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

• A to Z: Atresia, Choanal

  Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

• A to Z: Atresia, Biliary

  Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

• A to Z: Atresia

  Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

• A to Z: Apthous Ulcers (Canker Sores)

  Apthous ulcers, or canker sores, are non-contagious small ulcers that can occur inside the mouth, often causing discomfort during eating or talking.

• A to Z: Acanthosis Nigricans

  Acanthosis nigricans is a condition in which the skin thickens and darkens in places.

• A to Z: Arthropathy

  Learn about conditions that affect the joints, complications of diabetes, and complications of nervous system damage.

• A to Z: Anemia

  Learn about anemia, a common blood disorder that happens when the level of healthy red blood cells in the body becomes too low.

• A to Z: Abscess

  Learn about immune system responses, infections, and issues that affect the skin.

• A to Z: Appendicitis

  Appendicitis is an inflammation of the appendix, and requires surgery.

• A to Z: Anterior Cruciate Ligament (ACL) Injuries

  Learn more about ACL injuries and how they're treated.

• A to Z: Abrasion

  An abrasion is a minor scrape of the skin that can be treated easily with proper cleaning and care.

• A to Z: Asthma, Attack

  Learn more about asthma attacks, when asthma symptoms suddenly become severe.

• A to Z: Allergy

  With allergies, the immune system overreacts and tries to "fight" allergens, which are ordinary things that cause an allergic reaction.