A regulation requiring D.C. physicians to perform 49 common surgical procedures without keeping the patient overnight has significanly cut hospital admissions for surgery and substantially reduced health care costs, a medical review group said yesterday.

The National Capital Medical Foundation said that its rule -- which governs certain procedures on 195,000 Medicare and Medicaid patients in the District of Columbia -- caused a 55 percent reduction in hospitalizations for the 13 most frequent operations on the list. More than $600,000 a year in government payments to hospitals was saved because of the reduced hospitalization, the foundation said.

Those results were based on a foundation study of surgical cases at 13 District hospitals before and after Dec. 1, 1979, when the rule became mandatory.

"This shows we are saving money without hurting patients," said Dr. Robert L. Hackney Jr., one of the foundation trustees.

Among the 13 operations studied were abortion, circumcision, tubal ligation and biopsy of breast. Except for abortion, those procedures are covered by Medicare and Medicaid. In the District of Columbia, the Department of Human Services will fund abortions for Medicare and Medicaid recipients.

The foundation's findings represent the latest action in the national movement toward "ambulatory surgery," which encourages a patient to leave the operating facility and go home after surgery rather than spend several days in the hospital. Ambulatory surgery has been gaining in popularity for more than a decade because it can save money, keep hospital beds free for the more seriously ill and allow patients to return to their jobs more quickly.

Even private insurers agree that ambulatory surgery is the vanguard of the future. "Absolutely," said Barry Wilson, vice president of public affairs for Blue Cross, which insures 1.4 million people in the metropolitan Washington area.

Wilson said that the local Blue Cross adopted an ambulatory surgery program last year to educate physicians and patients. That program is voluntary, however. Blue Cross has no immediate plans to require ambulatory surgery, Wilson said.

The foundation rule permits hospitalization of a patient undergoing surgery when the physician believes that it is necessary. But specific reasons for hospital admission must be documented, the rule says.

In the study released yesterday, the National Capital Medical Foundation compared hospitalization of patients for the 13 selected operations during the first six months of 1979, before the ambulatory surgery rule was adopted, to the first six months of 1980, after it had been implemented.

At one hospital, the number of cases in which there were stays of three days or less fell from 1,169 before the rule to 525 after the rule -- a 55 percent drop.

To compute the savings that resulted from that decline, the foundation estimated the cost of having one of the 13 surgical procedures performed on a walk-in basis at $276, including anethesia. The same procedure done with anesthesia was $756.85, the foundation said.

The $480.85 difference translates into a savings of $619,334 over a period of one year for all 13 procedures, the study said.

The National Capital Medical Foundation, which consists of 2,400 physician members, is one of 187 medical review organizations established by federal law to review medical expenses and practices related to Medicare and Medicaid programs.

Last year, the review groups came under attack by budget-cutters who questioned whether the organizations were costing the government more money than they were saving.

Trustees said yesterday that the ambulatory surgery concept has encountered some resistance.

Three cited by foundation president Dr. William R. Felts included:

Insurance company rules that pay benefits only when the procedure is performed in a hospital where the person has been admitted as a regular patient. Dr. Felts said those restrictions have begun to change, however, as companies recognize the savings that can be achieved when the person goes homes immediately.

Concern in the medical profession about the safety of surgery performed at some place other than a hospital, such as a walk-in clinic or doctor's office, where the patient wouldn't stay overnight. Since complications are most likely to occur during the first 24 hours after surgery, doctors traditionally have preferred that the patient stay at least one night in the hospital after surgery. But more recently medical groups have endorsed ambulatory surgery.

Convenience of the hospital for physicians scheduling their time and for patients needing surgery. Dr. Felts said that hospitals are beginning to respond to this problem by making their rules and schedules more flexible.

One other kind of resistance was aslo cited by the trustees. "There has been some emotional feeling that something is being taken away from them [Medicare and Medicaid patients]," said Dr. Paul Schlein, a past president of the foundation.