In a perfect world, nobody would ever get sick or injured or need medical care. In a near-perfect world, health care systems would always provide high-quality care and medical professionals would make unerring diagnoses and prescribe or perform exactly the right treatments.

But in our imperfect world, hospitals, doctors, and other health care professionals can and do make mistakes. A much-publicized 1999 study by the Institute of Medicine estimated that medical mistakes could kill as many as 98,000 people in U.S. hospitals every year. A more recent study by the health care ratings company HealthGrades estimated that the number of “patient safety incidents” in hospitals rose to 1.24 million between 2002 and 2004, up from 1.14 million over the previous three years.

But there is good news. “The media tends to focus on the sensationalistic stories, but there’s a lot of good that’s being done as well,” says Diane Pinakiewicz, president of the National Patient Safety Foundation, a nonprofit organization dedicated to reducing health care errors. “The health care industry is recognizing that errors do happen and finding proactive ways to correct the processes that lead to those mistakes. They’re also encouraging patients and their family members to take a proactive role in detecting and preventing errors.”

Following are five kinds of medical mistakes and problems that can lead to mistakes, what the health care industry is doing to prevent them, and what you can do to ensure that they don’t happen to you or a loved one.

1. Confusing medical directions or advice

Too often, patients leave the doctor’s office or hospital without a clear understanding of how they’re supposed to care for themselves. Consider asthma, a condition that affects thousands and needs daily management. A 2005 Global Asthma Physician and Patient survey of 6,000 doctors showed that 85 percent devote less than half of their time to communicating key facts about asthma management.

“People are often too afraid or intimidated to ask questions about their health care — if they don’t understand something, they just smile and nod,” says Dr. James Battles, a senior service fellow for patient safety at the U.S. Agency for Healthcare Research and Quality (AHRQ).

What’s being done: Doctors are recognizing the need to communicate more thoroughly and effectively, even if they’re limited in the time that they can spend with patients. National physician organizations like the American Academy of Family Physicians and the American College of Physicians have issued guidelines and created teaching modules to help physicians improve their communication skills, and most doctors have brochures and instruction sheets that explain conditions and treatments in detail.

What you can do: “If you don’t understand something, or if you need more information, you need to speak up and demand clear answers — that’s what you’re paying your doctors for,” says Battles.

Experts recommend taking a list of questions to every doctor’s visit and writing down or tape recording the answers so you can review them later. Also, consider asking a family member or friend to come with you to serve as another pair of ears and ask questions that might not occur to you.

2. Missed diagnoses

Doctors have an array of diagnostic tools and tests to get to the root of medical problems, but they don’t always follow up on test results. A 2005 study published in the Annals of Internal Medicine examined the medical records of more than 2,500 patients at Boston-area hospitals and found their doctors didn’t always know about test results that signaled a serious problem; in some cases, they didn’t even know that certain tests had been ordered.

What’s being done: Some hospitals are setting up computer systems that electronically alert doctors when a suspicious test result comes in. At the VA Ann Arbor (Mich.) Healthcare System, for example, radiologists code each medical image; a “Code 8” tag, for example, indicates an unexpected sign of cancer that requires immediate follow-up. Doctors are alerted to the Code 8 scans by a written report and a phone call, which prevents patients who could have cancer from falling through the cracks.

It’s also becoming easier to transmit images from X-ray, MRI, CT, and PET scans over the Internet, so doctors can access them right after a test is complete. This reduces chances that the results will be lost and helps ensure more immediate treatment.

What you can do: Never assume that no news is good news. Call the doctor or hospital and ask about test results. Also, if all the tests turn out negative but you still think something is wrong, don’t hesitate to pursue the problem by getting a second (or even third or fourth) opinion.

3. Wrong-site surgery

This is perhaps the most horrifying and dramatic kind of medical mistake: A patient wakes up after surgery to find that the wrong limb has been operated on or the wrong procedure has been performed. Wrong-site surgery encompasses all surgical procedures performed on the wrong patient, wrong body part, wrong side of the body, or at the wrong level of the correctly identified anatomic site. As of December 2005, 455 wrong-site surgeries had been reported to the Joint Commission on Accreditation of Healthcare Organizations, a nonprofit agency that evaluates and accredits health care facilities.

What’s being done: Studies show that most wrong-site surgeries occur in orthopedic cases, and orthopedic surgeons were the first group to formally tackle this issue. In 1998 the American Academy of Orthopedic Surgeons created the “Sign Your Site” campaign, reminding surgeons to mark the surgical site with their initials before making the first incision. In 2004, the Joint Commission made surgical site marking mandatory for all accredited hospitals and surgery centers.

What you can do: Ask your surgeon to mark the surgical site before you are sedated or anesthetized so you can ensure it’s in the correct place. Also, ask if the surgical team routinely takes a “time out” just before the surgery begins. During a time out, the team takes a few critical moments to assure themselves that they are performing the correct procedure at the correct site on the correct person.

4. Health care-associated infections

You might correlate the antiseptic smell of doctors’ offices or hospitals with cleanliness, but the truth is, health care facilities are breeding grounds for infectious diseases such as pneumonia, hepatitis, and tuberculosis, which can be passed between health care workers and patients. These infections, which are called health care-associated infections, affect approximately 2 million people and cause 90,000 deaths annually, according to the Centers for Disease Control (CDC).

What’s being done: The CDC has numerous guidelines for protecting patients from health care-associated infections, including specific instructions for managing surgical incisions, ventilators, catheters, and other procedures and devices that make patients vulnerable to infection.

What you can do: Many health care-associated infections are transmitted from patient to patient through a seemingly innocuous source: the hands of health care workers. Make sure that every medical professional who touches you cleans his or her hands first by washing them or using a hand-sanitizer gel.

5. Medication errors

According to the AHRQ, 7,000 people die each year from taking the wrong kind or dosage of medication or taking it in the wrong way. Adverse medication reactions are responsible for more than 4 million doctor visits every year, according to a 2005 AHRQ study. Many of these incidents could be prevented if patients knew more about the medicines they take and how and when to take them.

What’s being done: Many hospitals, doctors’ offices, and pharmacies now have computer systems in place that can detect and flag possible drug interactions. Pharmacists, who are experts in medications and medication management, also are providing more one-on-one consultations with patients to answer their medication questions.

What you can do: Experts recommend the following:
■ Tell your doctor about all the med­ications you’re taking, including prescription and over-the-counter medicines and dietary supplements such as vitamins and herbs.
■ Make sure your doctor knows about any medications you’re
allergic to and any adverse reactions you’ve had.
■ If your doctor handwrites your prescription, make sure you can read it, and when you pick up the medicine from the pharmacy, make sure the type and dosage are correct.
■ Make sure you understand everything about what the medicine is for, how to take it and for how long, and possible side effects — and what to do about them.
What’s the take-home message? Find medical professionals you trust, but trust your own judgment and instincts as well, and speak up if something doesn’t seem right. “By being vigilant, engaged, and informed, patients can work with health care providers to prevent mistakes from happening,” says Pinakiewicz. “They can and should become partners in their own health care.”