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Obesity means having so much body fat that your health is in danger. It's usually measured by body mass index (BMI), which is based on your weight compared to your height. In adults, obesity is a BMI of 30 or above.

Being obese can lead to type 2 diabetes, heart disease, high blood pressure, arthritis, sleep apnea, and stroke.

Last Revised: October 9, 2012

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Rhonda O'Brien, MS, RD, CDE - Certified Diabetes Educator

Obstetricians (also called OBs) are medical doctors who specialize in the care of pregnant women, from the time of conception through delivery and the period following delivery (postpartum). Most obstetricians are also gynecologists who diagnose and treat diseases of the female reproductive system and provide care for women when they are not pregnant.

An obstetrician can further specialize in perinatology (maternal-fetal medicine), which focuses on high-risk pregnancies, testing, and fetal development. Or an obstetrician may specialize in reproductive endocrinology and infertility (care of women who have hormonal or fertility problems).

Obstetricians can be board-certified through the Board of Obstetrics and Gynecology, which is recognized by the American Board of Medical Specialties.

Last Revised: August 17, 2012

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine

Occupational therapists are health and rehabilitation professionals who help people regain, develop, and build skills that are important for independent functioning, health, well-being, security, and happiness.

Occupational therapists work with people of all ages who, because of illness, injury, developmental delays, or psychological problems, need assistance in learning skills to help them lead independent, productive, and satisfying lives.

An occupational therapists (OT) can be licensed at the professional level after completing a degree in his or her field. OTs must also complete a supervised fieldwork program and pass a national certification exam.

Occupational therapy assistants (OTAs) typically have completed an associate degree program.

Last Revised: August 17, 2012

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine

Ophthalmologists are medical doctors who specialize in the diagnosis and treatment of eye problems, diseases, and injuries.

Ophthalmologists can diagnose and treat eye diseases, such as diabetic retinopathy and glaucoma; prescribe eyeglasses and contact lenses; treat eye injuries; and perform eye surgeries, such as cataract removal, glaucoma correction, or LASIK surgery. Ophthalmologists may further specialize in care of the retina (retina specialist) or in the care of children with eye problems (pediatric ophthalmologist).

Ophthalmologists can be board-certified by the Board of Ophthalmology, which is recognized by the American Board of Medical Specialties.

Last Revised: August 17, 2012

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine

The optic nerve is the nerve at the back of the eye that carries visual information from the eye to the brain.

Last Revised: July 22, 2011

Author: Healthwise Staff

Medical Review: Adam Husney, MD, MD - Family Medicine & Christopher J. Rudnisky, MD, MPH, FRCSC - Ophthalmology

Optometrists are health professionals who diagnose and treat vision problems and diseases of the eye. An optometrist is not a medical doctor, but rather a doctor of optometry (OD).

Optometrists can perform routine vision testing, prescribe eyeglasses and contact lenses, diagnose vision problems and eye disease, prescribe medicines to treat some diseases of the eye, and provide care before and after eye surgery.

After undergraduate study, optometrists must complete optometry school. They must take a national licensing examination and are licensed by the state in which they practice.

Last Revised: August 17, 2012

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine

Oral cancer is the growth of abnormal cells in any part of the mouth or lips. Most oral cancers start in the lining of the lips or mouth in the thin, flat cells called squamous cells.

Symptoms for oral cancer include sores or lumps that appear on the lips or in the mouth. Sometimes white patches that cannot be rubbed off may form in the lining of the mouth.

Treatment for oral cancer may include surgery and radiation.

Last Revised: December 21, 2012

Author: Healthwise Staff

Medical Review: Adam Husney, MD - Family Medicine & Arden Christen, DDS, MSD, MA, FACD - Dentistry

Orthopedic surgeons are medical doctors who specialize in bone, muscle, and joint surgery. This includes corrective procedures, such as removing torn cartilage or replacing a joint.

Some orthopedic surgeons specialize in specific areas such as shoulder surgery, hand surgery, or joint replacement.

Orthopedic surgeons can be board-certified through the Board of Orthopaedic Surgery, which is recognized by the American Board of Medical Specialties.

Last Revised: August 17, 2012

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine

Osteoarthritis is the type of arthritis that many people get as they age. It happens when the cartilage that cushions your joints—like your knees and hips—gradually breaks down. Then the bones rub against each other. This causes damage and pain. There are many treatments that can help with the pain and make it easier to move.

Last Revised: October 9, 2012

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & Stanford M. Shoor, MD - Rheumatology

Osteogenesis imperfecta is a group of rare disorders in which the bones are extremely fragile and break or fracture easily, often without apparent cause. The effects of the condition vary from case to case.

Treatment for osteogenesis imperfecta focuses on prevention of breaks and development of bone mass and strong muscles. Care may include assistive devices such as braces and wheelchairs.

Last Revised: November 6, 2012

Author: Healthwise Staff

Medical Review: Kathleen Romito, MD - Family Medicine & Carla J. Herman, MD, MPH - Geriatric Medicine

Osteomyelitis is an infection of the bone, often developing after an open fracture in which the bone pokes through the skin. It may also develop after an illness or injury that damaged the skin near or over a bone.

Symptoms may include:

  • A general feeling of illness (malaise).
  • Fever, chills, and sweating.
  • Deep bone pain.
  • Pain that is worse when pressing on the infected area or when standing.
  • Swollen and red skin (sometimes) over the affected bone.
  • Drainage of pus from the wound.

Antibiotic treatment is necessary to prevent destruction of bone tissue. If the osteomyelitis is severe, surgery may be required.

Last Revised: August 5, 2011

Author: Healthwise Staff

Medical Review: William H. Blahd, Jr., MD, FACEP - Emergency Medicine & David Messenger, MD

Osteoporosis is a disease that makes your bones thin, brittle, and easy to break. It's related to the loss of bone mass that happens as a natural part of aging. It's most common in women who have gone through menopause, but it can also occur in men.

As osteoporosis gets worse, it can lead to broken bones in the hip, spine, and wrist. Treatment can slow bone loss and increase bone thickness.

Last Revised: November 6, 2012

Author: Healthwise Staff

Medical Review: Kathleen Romito, MD - Family Medicine & Carla J. Herman, MD, MPH - Geriatric Medicine

Outpatient services are medical procedures, surgeries, therapies, classes, or tests that are done in a qualified medical center without the need for an overnight stay.

In general, outpatient centers focus on services for wellness and prevention, diagnosis, treatment, and rehabilitation. In these centers, a person may obtain childbirth education, diabetes education, counseling, imaging tests, lab tests, minor surgery, physical or occupational therapy, and drug rehabilitation. Government and health agencies rate and report on outpatient facilities and can help a person find a local, high-quality outpatient service center.

Last Revised: October 27, 2011

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & Michel M. Murr, MD - General Surgery, Bariatric Surgery

Medicines you can buy without a prescription are called nonprescription or over-the-counter (OTC) medicines. They may be taken to treat minor health problems at home.

Examples of over-the-counter medicines are acetaminophen, aspirin, antacids, decongestants, antihistamines, and laxatives.

It’s important to talk to your doctor about what medicines may not be safe to give children.

Last Revised: March 9, 2012

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Theresa O'Young, PharmD - Clinical Pharmacy

Oximetry is a medical test that uses a device called an oximeter to measure the amount of oxygen in the blood (oxygen saturation). A special sensor in a cuff or clip is placed on the end of a person's finger or toe or on the person's earlobe, and it measures the amount of oxygen in the blood flowing in the tiny blood vessels.

Last Revised: March 17, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & R. Steven Tharratt, MD, MPVM, FACP, FCCP - Pulmonology, Critical Care Medicine, Medical Toxicology

Oxygen therapy means using an oxygen tank or a machine to breathe in air that contains more oxygen than normal.

Oxygen therapy increases the amount of oxygen in the lungs and the bloodstream. A person with a health problem such as chronic obstructive pulmonary disease (COPD) may need oxygen therapy if there are signs that the cells of the body are not getting enough oxygen.

Oxygen therapy may be given by different methods, including a:

  • Tube placed under a person's nose (nasal cannula).
  • Plastic cup placed over a person's mouth and nose (oxygen face mask).
  • Tube (endotracheal tube) placed into the mouth and down the windpipe of a person who cannot breathe independently. The tube is attached to a machine (ventilator) that breathes for the person.

Last Revised: November 29, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Ken Y. Yoneda, MD - Pulmonology

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