Since the dawn of e-mail, patients have been pleading for more doctors to offer medical advice online. No traffic jams, no long waits, no germ-infested offices. There was always one major roadblock: Many health insurers wouldn’t pay for it. In recent weeks, Aetna Inc., the nation’s largest insurer, and Cigna Corp. have agreed to reimburse doctors for online visits. Other large insurers are expected to follow, experts say. These new online services, which typically cost the same as a regular office visit, are aimed primarily at those who already have a doctor. The virtual visits are considered best for follow-up consultations and treatment for minor ailments such as colds and sore throats. But some specialists, including cardiologists and gynecologists, also see these e-mail visits as ideal for periodic checkups that don’t require in-person presence. “People can wait a long time to get in to see their primary-care doctor and longer for a specialist. … To have immediate access is huge,” said Dr. Melissa Welch, Aetna’s medical director for northern California. As more doctors move online, others are looking ahead and adding webcams, even if the video quality remains spotty. Although visits to the doctor’s office certainly won’t disappear, the recent moves are evidence that long-delayed efforts to bring American medicine into the digital age may be gaining momentum. “Paying doctors to do more patient care over the Internet is a small but important step in a good direction,” said David Cutler, a Harvard University health care economist. “It increases patient access and could significantly improve their satisfaction.” If so, it comes at an auspicious time. Doctor visits in the United States have surged 20 percent in the last five years to more than 1.2 billion visits annually, according to the U.S. Centers for Disease Control and Prevention. Even as the population ages, the number of doctors is falling across the country, and experts predict that office wait times will increase in the coming years. Critics, including many doctors, contend that online medical care carries risks. Some worry that mistakes are bound to happen and that the practice raises several hard-to-answer ethical questions. Many of the new online consultations are far more structured than a simple e-mail. If insurance companies are expected to pay the bill, physicians need documentation of the event, including diagnosis and time spent. As a result, service companies have emerged to help doctors handle this. They typically arrange the online visits, maintain records and handle insurance reimbursements, patient co-payments and other payments. Doctors are encouraged to respond to patients within a day; they receive an e-mail reminder if they haven’t, with a phone call on the second day. Prices vary from $25 to $125, which patients pay with a credit card at the end of the session.