Doctors, nurses, dentists and other healthcare professionals live by the Hippocratic oath: Do No Harm. But sometimes things go wrong, patients are injured and doctors are sued for malpractice. In those situations, medical professional liability insurance steps in to protect the healthcare professional from liability associated with wrongful practices that may result in bodily injury, medical expenses and property damage, as well as the cost of defending lawsuits related to such claims, as the National Association of Insurance Commissioners (NAIC) explains it. Generally, a medical professional liability insurance policy covers bodily injury or property damage as well as liability for personal injury such as mental anguish. NAIC says that "The complexity involved in discovering negligence results in a higher percentage of premium dollars going toward defense and cost containment expenses. Medical liability insurers spend substantial funds investigating and defending claims where there is an adverse patient outcome not resulting from negligence." Policy price is a major factor in choosing medical malpractice carriers, but it's not the only one. Medical professionals should also consider company history, peer referrals, and value-added services as online training, risk analysis and policy review. Here is a look at the 15 medical malpractice carriers that rose to the top of that market in 2018, based on data from the NAIC. Related: Medical malpractice settlement awards $140M to 255 patients of doctor convicted of fraud Top 15 medical malpractice insurance carriers in 2017, as ranked by the NAIC Delayed Diagnosis Case Yields $3.1 Million Verdict in Passaic Top 10 financial & professional lines risks in 2019, according to Marsh