Marci Lavine Bloch was a little anxious one night last year when the pharmacy couldn't locate the prescription for an antibiotic that her pediatrician's office had phoned in for her young son's ear infection.

Although Bloch knew that it was too late to reach her doctor if she called the practice's Silver Spring office, she made the call anyway. She knew her call would be automatically hooked up with a nurse triage program that took care of most of the practice's nighttime and weekend phone calls from parents.

These triage lines work by having after-hours calls transferred to a hospital, where specially trained nurses answer the phones. The nurses talk with parents and tell them how to treat the child or determine that a doctor should be consulted.

Most of these services use a software program that prompts the nurses with questions to assess symptoms. The nurses can then urge parents to rush to an emergency room, phone the patient's doctor at home or dispense advice recommended by the software program--such as the correct dose of acetaminophen to bring down a fever. A report of each call is faxed to the child's doctor before office hours begin in the morning.

About 50 children's hospitals across the United States host triage lines for pediatricians, and another 300 community hospitals and medical centers have nurses on staff who handle after-hours calls for internists and pediatricians, says Barton Schmitt, director of the After Hours Call Center at the Children's Hospital in Denver, which was among the first pediatric nurse triage programs in this country. Schmitt is also the author of the software used by many nurse triage lines.

In the Washington area, about 30 pediatric practices contracted for such services with Children's After Hours, a nurse triage program at Children's National Medical Center. Children's closed its three-year-old program last month as a cost-cutting measure, but Suburban Hospital in Bethesda opened a similar program on Dec. 28. Suburban's service is limited, at least for now, to pediatricians in Montgomery County and Northwest Washington.

The Inova Health System in Northern Virginia also has a nurse triage line. It's used by about 100 doctors who are part of the health system or have visiting privileges at Inova's five hospitals.

It's easy to see why doctors like the service. Schmitt says that at busy practices--where each pediatrician has more than 1,000 patients--doctors on call can get 20 to 30 calls before they go to bed each night and three to five after they've gone to sleep. Stephen Harrison, part of a six-pediatrician practice in Reston, says that during the winter--when viruses and the flu ratchet up the number of sick children--as many as 100 parents from his practice phoned Children's After Hours on a weekend.

According to Maureen Leahy, administrator of Children's nurse triage program, 60 percent of the calls to the program were for information easily dispensed by a well trained nurse. They most commonly involved colds, fever, earache, vomiting and coughs. About 15 percent of calls required immediate attention from a doctor or a visit to an emergency room, and 25 percent required an office visit the next day, which is in line with the national averages, according to Schmitt.

Children's received few complaints about its After Hours program from parents, says Leahy. The chief complaint was the time it could take for a nurse to return a call. If all the nurses are on the phone, parents calling most triage lines will reach a receptionist or a voice mail system that instructs them to call 911 if there is a life-threatening emergency. In nonemergency situations, they're instructed to leave their name, phone number and the child's symptoms. Nonemergency calls are generally returned within an hour, program administrators say.

Parents who have used triage lines have also complained that they are asked too many questions during the assessment. And some parents want their own pediatrician to be called immediately, without having to describe the child's symptoms to the nurse. (Each practice sets its own criteria for being contacted by nurses.)

Rikki Reifer, a Silver Spring mother of three daughters 7 and under, was frustrated one night when she called to speak with her doctor about an insect bite that was swelling up on her then-3-year-old daughter and gave up while going through a lengthy set of questions with the nurse. "I knew about cold compresses," she says. "I just wanted to talk to the doctor." She called her doctor the next morning to talk with him, and her daughter was fine.

For the most part, though, national studies show that both parents and doctors like the nurse triage programs. Allison Kempe, a physician at the Children's Hospital in Denver, says a study done at the hospital--to be published next year in the Archives of Pediatric and Adolescent Medicine--found that doctors thought nurses had made appropriate referrals to the emergency room more than 90 percent of the time. Kempe also surveyed parents who used nurse lines at five hospitals across the country, and she found parent satisfaction to be very high at all five.

In fact, some parents say they prefer calling the nurses to reaching their pediatrician, knowing that they won't be waking the doctor for what may turn out to be an insignificant question. Other parents point to instances where the nurse has gone farther to help them than they thought their own doctor might.

Errin Smith, whose four daughters are aged 2 to 7, says being able to talk with the nurse at Children's for as long as she needed was what she liked best about the service. Several weeks ago her 2-year-old daughter, Chandler, had a fever of 104 in the middle of the night, and two other daughters were also sick. Smith, a nurse at Washington Adventist Hospital, called her doctor's office and was connected to Children's, where she received instructions for bringing the temperature down. "An hour later the nurse called back to make sure Chandler was okay, and it was nice just to have another grown-up to talk to," Smith says.

Robert McDowell, part of a four-doctor practice in Chevy Chase, says his partners view the service as part of their patient education program. "By patiently answering their questions, the nurses are teaching parents how to deal with minor illnesses, leaving the doctors free to handle more urgent medical problems," McDowell says.

But some doctors question whether such education really needs to take place at 1 in the morning. Blair Eig, part of a three-doctor practice in Silver Spring, says his practice doesn't get a lot of nonurgent questions at night. "We try to teach them what they need to know during well-child visits," Eig says.

Eig says cost is another reason for not signing up with the program. Children's charged doctors $6 per call, although its costs for operating the phone service were more than double that, according to Leahy. For now, few doctors pass on the cost of the nurse triage lines to patients, according to the American Academy of Pediatrics.

While costs are a consideration, physicians expect to see more use of nurses for after-hours care, either through hospitals or with practices banding together and hiring their own.

"Physicians are people, too," says Art Guarinello, a Maryland pediatrician. "This gives them a break so they're fresh when they need to be."