Two of the region's leading medical centers have racked up the city's highest number of "diversions" - periods when ambulances are advised to steer clear because the emergency room is so full.

The Hospital of the University of Pennsylvania and Thomas Jefferson University Hospital are working to reduce such diversions as the number of emergency rooms in the city has continued to fall. This year, Penn has reduced the disruptions by 22 percent and Jefferson by 28 percent.

As they seek solutions, the hospitals are examining their own practices, reflecting a national shift in efforts to address the perennial crisis of ER overcrowding.

Consider Jefferson. This year it reduced diversion hours even though the number of ER patients, the severity of their medical needs, and staffing stayed about the same. Jefferson relieved overcrowding by finding ways to move patients in and out of the ER - and the whole hospital - faster.

"That's where I'm focused, on improving efficiencies," said Rex Mathew, hired by Jefferson two years ago for the new job of vice president of emergency medicine clinical operations.

This is not to suggest that the nation's emergency medical-care system has been slacking. From 1992 to 2002, the number of annual emergency-room visits increased 23 percent, while the number of ERs decreased 15 percent, studies show.

In the Philadelphia region, the contraction has been more dramatic - from 62 ERs in 1993 to 38 now, a 39 percent decrease. The most recent loss was this year's closing of Northeastern Hospital, which had 45,000 emergency visits annually. The impact has been felt at Aria Health-Frankford Campus, where Joaquin Rivera died in the ER while waiting for care on Nov. 28.

While there is no evidence that overcrowding played a role in his death, Frankford had nearly as many diversions in November - 121 hours - as all of last year.

Emergency departments are beset by growing numbers of the uninsured, the chronically ill, and the aged.

Nonetheless, experts say it's time for hospitals to stop blaming ER overcrowding on economic, social, and demographic factors that are beyond their control, and start looking inward. A recent Government Accountability Office report found that even in life-and-death cases, large percentages of ER patients do not see doctors within recommended times.

"Many hospitals have done little to address the patient-flow obstacles that lead to overcrowded" emergency rooms, says a report by Urgent Matters, an ER improvement initiative funded by the Robert Wood Johnson Foundation.

Jefferson and Hahnemann University Hospital are among six U.S. hospitals using grants from Urgent Matters to develop practical strategies for reducing ER crowding. These will be shared nationally through newsletters, the Web, and conferences.

Some of the strategies seem embarrassingly obvious.

Under the standard triage system, for example, patients are ranked according to medical urgency. The least urgent - sprained ankles, sore throats, cuts that need a few stitches - typically spend hours waiting to be seen by an ER doctor.

Jefferson's solution has been to assign nurse-practitioners to nonurgent cases, aiming to get those patients in and out within 90 minutes. Hahnemann, too, has improved its triage system, resulting in lower rates of "left-without-being-seen" - patients who get fed up and leave.

Comparing last year with this year through November, diversion hours dropped from 1,141 to 785 at Jefferson, and from 942 to just 4 at Hahnemann, according to data from the Philadelphia Fire Department, which oversees city ambulances.

Most fixes, however, are neither easy nor obvious. Sick patients may lie on gurneys for hours in ERs, uncomfortable and taking up precious space, while they wait for a hospital bed to become available.

"I think for a long time people thought the ER can solve this problem, but it can't," said Bruce Siegel, director of Urgent Matters and of George Washington University's Center for Health Care Quality. "What we've found is that someone keeping track of capacity in the whole hospital is critical. Someone who says, 'Tomorrow we'll be full, so we need physicians to discharge patients earlier.' If a doctor is tied up in the morning, maybe get a nurse-practitioner to do it."

Identifying the reasons a hospital is "full" is both crucial and complex. Maybe it means janitors are slow to clean empty rooms, or several nurses called in sick.

"The problem is not just physical space but effective space," said Robert McNamara, chair of emergency medicine at Temple University Hospital. "With hospital margins tight, there may be beds, but no staff to cover them. And hospitals try to keep staffing tight to keep costs down."

Temple has the city's busiest ER, with 74,000 adult and 20,000 pediatric patients this year - 24 percent of whom were admitted to the hospital, McNamara said. Anticipating a surge in demand following Northeastern's closure, Temple added ER staff and made a concerted effort to speed up testing and discharge procedures, he said.

This year, through November, Temple had 118 hours when ambulances were diverted.

The Hospital of the University of Pennsylvania, with about 60,000 ER patients and a 26 percent admission rate, was by far the city's leading diverter - more than 1,000 hours through November.

Diversions are only advisories. If nearby ERs are equally crowded, or if a patient would be endangered by going further, ambulance personnel can override the advice.

In any case, diversions are a sign of patient flow problems.

To address this, Penn this year began phasing in a "transition unit" - 17 small rooms where ER patients waiting for hospital admission can have privacy and sleep in a real bed, said Stephanie Abbuhl, vice chair of Penn's department of emergency medicine.

Abbuhl thinks the new unit is a big reason Penn's diversion hours are down over last year.

But the crowding conundrum continues to evolve. One question is whether health-care reform - which now seems imminent - may increase ER volume rather than reducing it, as millions more Americans become insured.

"Historically, a lot of people thought of the emergency department as a safety net for the uninsured," said Mathew at Jefferson. "Now, it's much more about people with insurance getting quick, efficient care" rather than waiting months to see a primary-care doctor.

Contact staff writer Marie McCullough at 215-854-2720 or mmccullough@phillynews.com.