Inova Fairfax Hospital celebrated the completion of its renovated, expanded emergency department this week as it works to accommodate the region's population growth.

The $23.6 million upgrade, which took three years to complete, addresses a growing need for emergency care that can result in long waits. The emergency department has doubled in size to just under 45,000 square feet, enough to handle about 85,000 patient visits a year.

"We just looked at growth and demand, and it was growing on all fronts," Robert J. Cates, chairman of the Department of Emergency Medicine, said Monday. "This wasn't just a remodel. It was a major expansion and renovation."

Inova Fairfax is home to Northern Virginia's only Level 1 trauma unit, which means it can treat any type of injury, no matter how serious.

The expansion brings the number of spaces where patients are treated to 58, up from 33 now. The number of emergency treatment rooms, with beds, increased to 43 from 24, and hallway space was added that, if needed, could accommodate 22 more rooms, officials said.

Another 12 emergency treatment rooms have been added exclusively for pediatric patients, a first for Inova Fairfax. Those rooms will be available in January. The pediatric emergency department, which will have a staff of 13 doctors, will include child-friendly waiting areas and equipment, such as cribs and smaller blood pressure cuffs, officials said.

Trauma services also have expanded, with new space and improved radiology testing that includes a new on-site suite for CT scans, allowing patients to stay in the ER rather than be moved for diagnostic testing. Construction of a new lobby, the last piece of the expansion, has not yet begun.

Outside the ER, the hospital created a new ambulance bay beneath a landing pad for two helicopters.

About 30 percent of the hospital's emergency room patients end up being admitted to Inova Fairfax, about half of the hospital's total admissions. The expansion should allow the hospital to treat more than 90,000 patients a year in the emergency department, an increase of about 10,000, officials said.

Many of the hospital's emergency room patients are immigrants who speak limited English. To help them, Inova contracts with a company that provides phone interpreters in multiple languages in all rooms of the hospital.

The emergency room expansion follows other major projects, including construction of a 900-space parking garage and the opening of the new Heart Institute. In August, the first class of medical students from Virginia Commonwealth University's medical school began studying at Inova's new teaching campus at its Fairfax hospital. The campus, a joint venture between Inova and VCU in Richmond, eventually will house 48 third- and fourth-year students training in pediatrics, neurology, psychiatry and other specialties.

Inova officials are also conscious of the need for mass casualty planning as the hospital expands. The new ambulance bay area includes several decontamination showers for use by personnel or patients in a biological attack.

"It's part of the unfortunate new era we live in," Cates said. "We hope it's wasted money."

Registered nurse Stephanie Thompson updates a patient's chart. Almost one-third of emergency room patients are admitted to the hospital. Tara Hodges, right, and Tifanee Underwood work with a new CT scanner.