St. John’s Medical Center posted nearly $1 million in net gains for December, despite treating fewer patients for the first time in 10 months.

A busy month in the surgery department made up for the disparity, according to a monthly financial report released by Chief Financial Officer John Kren.

With another strong month on the books, the hospital has an extra $4.36 million to manage operations during the second half of the fiscal year, which began in July. Last year’s overall operating surplus was $3.7 million, the highest in at least a decade.

December’s totals tack another strong month on to a prolonged period of financial success for the hospital.

Officials credit much of the windfall to stable expenses and more Jackson residents opting to have joint replacement surgery done in town, rather than traveling to Salt Lake City or Idaho Falls.

Kren said the recovery of Jackson Hole’s economy is another reason for the hospital’s gains.

Last month, patients spent 49 fewer days than expected in the primary care and intensive care units. But they logged more time under the scalpel. Inpatient and outpatient surgical minutes and procedures were well ahead of budget in December.

“There were more people having surgery, but the case mix was less complex, resulting in less needed days to be spent in the hospital,” Kren said.

The number of babies born at St. John’s was also up.

Eighty-eight mothers delivered in the hospital’s obstetrics department in December, compared with 72 last year and the 68 births projected in the budget.

But hospital officials warn that the positive trends may not last.

“We’re really happy with our results now, but we want to make sure nobody believes this trend will continue over the next six months,” Chief Executive Lou Hochheiser said at a board meeting last week.

That would be “highly unique,” he said.

“We still have that gray cloud that’s moving across the country called health care reform,” he said.

St. John’s officials have said changes in reimbursements from Medicare could impact the hospital’s bottom line, a phenomenon that could affect health care providers across the country.