All 13 adult hospitals in the District of Columbia were too crowded for one hour Wednesday night to accept any more patients brought in by ambulance.

The crunch -- probably the first time in city history that no beds were available -- was but the latest and most extreme symptom of the acute overcrowding that has occureed in most hospitals in the Washington and Baltimore areas since the first of the year.

As was the case earlier, the overcrowding is not occurring in the emergency rooms so much as it is inside the hospitals. The emergency room staffs simply have no empty beds elsewhere in the hospitals for new patients.

On any given night, several hospitals tell fire departments ambulance dispatchers that they are overcrowded and the ambulances bypass those hospitals. With all the hospitals jammed from 6 p.m. to 7 p.m. Wednesday, patients were simply taken by ambulance to the nearest emergency rooms and hospital staffs were forced to cope.

Hospital adminstrators say they have no idea what is causing the influx of patients.

"Nothing really explains what's going on in the District of Columbia," said Dr. Dennis O'Leary, medical director of George Washington University Hospital.

Among the more unusual recent manifestations of the continuing crisis are:

George Washington University Hospital was forced to put some male patients in gynecology wards.

Georgetown University Hospital admitted adults to pediatric wards.

A pregnant woman at the Washington Hospital Center found herself in a bed in a unit normally reserved for recovering burn patients.

Several times in the last month all major Baltimore hospitals have simultaneously gone on what they call "red alert," meaning they do not have a single bed in the hospital with equipement to monitor the condition of acutely ill patients.

Fairfax Hospital has been putting adults in pediatric beds," although we haven't had to put men in [obstetrical] beds yet," a spokeswoman said.

At George Washington, as many as four surgery patients at a time have spent the night in the recovery room, waiting for available beds in the hosptial's intensive care unit.

Some nurses in George Washington Hospital have complained that such an arrangement, coupled with a shortage of nurses, compromises the quality of patient care.

But Dr. O'Leary, the medical director, said the patients receive the same care in the recovery room they would receive in the intensive care unit.

O'Leary did say the overcrowding is being badly aggravated by a general nursing shortage in the city.

"Without question we've been very strapped . . . both in terms of training and getting the numbers. I can't invent nurses out of thin air," O'leary said.

Some observers have suggested that the problem in the District was caused by the closing last fall of Doctors Hospital. But according to O'Leary, the loss of the 156 beds being used by Doctors has not had a major impact on the city's hospitals, and certainly doesn't account for the problems in the suburbs and Baltimore.

"Everybody's willing to speculate," he said "to guess whether there's some epidemic or disease category, but we can't find anything."

Officials of hospitals here and in Baltimore generally agree that the patients being admitted to their hospitals now are a sicker group than they are used to seeing, with several problems rather than a single disease.

Some physicians speculate that one of two things may be occurring:

The aging of the American population may be catching up with its health care system; or, hospitals are saving patients today whom they might not have saved a few years ago -- therefore, the patients who might have died are now occupying hospital beds.

District health planners, who have predicted that the city would have an excess of 1,100 hospital beds by 1985, are watching the current crisis with intense interest.

Planners are not saying there are 1,100 excess beds now, said Sheila Joroff, chief of the health planning and resource development branch of the city's health planning system.

"What we're saying is that with the advent of a number of things, including a lot of nursing home beds we have licensed and if the census projections are correct, and the suburbs continue to send patients to the city at the same rate by 1985 we will have 1,100 excess beds."

The current crunch, Joroff said does not yet disprove those projections.