"I've gotten called off the bandstand, raced into town, delivered a baby, raced back and finished the last set," chuckles George Ryan, the anecdote neatly indicating the two hats he has worn for nearly three decades as cornet player and obstetrician. For 26 years he was at Harvard Medical School, first as a student and then as faculty member. In 1977 he accepted a position as professor of obstetrics and gynecology at the University of Tennessee. This Saturday Ryan will bring his Hot Cotton Jazz Band to the Ramada Inn, Bethesda, for a concert-dance sponsored by the Potomac River Jazz Club (for information call the PRJC's hot line, a 24-hour weekly update of area traditional jazz activities, at 532-8723).

"I was born in 1929," the Mississippi- and Louisiana-raised Ryan says, "and some of my earliest recollections are of music of the 1930s." His jazz-loving parents -- who are now in their late seventies and will accompany the band to the Sacramento Jazz Festival later this month -- were taking him to New Orleans to hear bands at an early age, "in the days when Tony Almerico had the Parisian Room, and the band out on the little balcony to attract people in was the Junior Dixie Band," which later became the Dukes of Dixieland.

Ryan took up trumpet at the age of 10, and in college in the 1940s "was trying to play like Dizzy Gillespie." In the Army in the early '50s, stationed in La Rochelle, France, he was asked to sub one night for an ailing trumpet player at the officers' club. "They played a lot of Dixie, and when I returned to Boston I found a great group of collaborators." Those Harvard runs saw Ryan teaming up with countless traditional jazz musicians, many of whom routinely rehearsed in the basement of his Brookline home, and eventually he founded and led two bands, the East Bay City Jazz Band and the Steamboat Stompers.

Naturally, upon arriving in Memphis eight years ago, one of his top priorities was forming another jazz band, but election to the presidency of the American College of Obstetrics and Gynecology compelled postponement of that objective until 1982, when Ryan stepped down from the post. "I was traveling all over the country," he recalls, adding that this schedule gave him the opportunity to sit in with bands from Hawaii to the District, including Turk Murphy's in San Francisco and the Federal Jazz Commission here.

The Hot Cotton Jazz Band came into being three years ago, when Ryan helped organize a jazz festival for Memphis and a home-town band was needed. He rounded up six other musicians, taught them seven traditional jazz standards, "and we played our one set on opening night as the host band." Since then the HCJB has played a regular schedule of Sunday afternoons at local hotels and performed frequently at jazz festivals here and abroad, including those of Scotland and The Netherlands.

"Repertoire is all-important," Ryan points out. "You have to find fairly esoteric stuff, like Wilbur De Paris' 'Wrought Iron Rag,' and 'Sweet Man,' which I found on an old Ethel Waters record. I tape them and make seven copies, and everybody in the band listens to it in their car going to work until they are sick and tired of it -- but they get quite excited when they produce it.

"We make a point of trying, in almost every piece, to do either a break or a tight harmony or a complex ending. We like the tightly arranged stuff, but we also want to stretch out, and we like some interplay between instruments. Our belief is that audiences like the ensemble type of band -- they marvel at a good solo, but they join in with the ensemble and there's no question to us that that's the happy sound that people come for."

Is he ever made to feel uncomfortable up there on the bandstand? "The thing you run into is all the jokes," he says. "You're playing, and out in front of you dancing is a couple that knows you, and the guy has to make the remark 'I didn't know that times were getting that hard for doctors.' And some of the wives giggle. But most of them come up afterwards and say, 'It's so wonderful -- it tells me you're a human being.' I never heard anyone say, 'My God, I don't want my doctor doing that.' "