His family had a history in politics (Kelly's father's great grandfather, Michael Hillegas, was the first Treasurer of the United States), business, real estate and civil service.

[5] There, he created the "Kelly stitch", a procedure to treat Stress incontinence,[10][11] and performed the first successful C-section in Philadelphia.

[12] Then, in Prague in 1888, Czech physician Parel Pawlik showed him how to catheterize ureters using a speculum and how to conduct an air cystoscopy.

Because ureters tend to adhere to the peritoneum instead of maintaining its normal position along the psoas muscle during operations, it can be hard to find.

To reduce bleeding for cervical and endometrial cancers, he ligated the internal iliac artery, a technique that would come to be used in postpartum hemorrhages.

[13] He used radium to treat uterine hemorrhages and fibroid tumors and published these techniques in the Journal of the American Medical Association in 1914.

[19] Newspaper articles published in 1914,[20][21] detail Kelly's personal visit to zircon mines and prospects in Zirconia, North Carolina.

Kelly purportedly "expressed himself as highly pleased with the prospects for radium and took with him a number of specimens of zircon for assaying purposes".

[20] Additionally, in 1917, his own clinic had about 5.5 grams of radium and was one of the country's leading centers for radiation therapy for cancer treatment at the time.

[15] While Kelly was writing his book Operative Gynecology, he collaborated with the father of medical illustration, Max Broedel.

[13] Kelly encouraged Broedel to investigate the topic by himself and often extended deadlines for his illustrations to allow him time for independent research.

Having felt constrained by his own residency, he encouraged his interns to try many things, and to go abroad and observe, and also subsidized some of his assistants to publish their work.

[5][23] By the time he reached the end of his career, Kelly had written over 550 articles and books that covered subjects such as appendectomy, the use of radium, electrosurgery, urogynecology, and ureteral catheterization.

[25][26] Later on in his career, Kelly received the title of Honorary Curator by The Division of Reptiles and Amphibians at the University of Michigan.

[25] In 1924, with the help of Louis Krieger, he published a catalog of his mycological library, illustrations, and specimens, which had over 400,000 entries, an archive of artworks, 7000 titles on mushrooms, and replicas of fungi.

[13] He also had a log cabin on the Ahmic Lake with its own library, microscopes, and field glasses; there was a seating area on roof and he had a telescope to observe the stars.

As a teenager, Kelly would read the original Greek and Hebrew texts of the Bible and even passed out New Testament scripture to his fellow peers, exhibiting his early attempts at evangelism.

[25] In accordance with his faith, Kelly was a prohibitionist, opposed the use of birth control devices, and endeavored to eliminate prostitution.

He wanted to prevent people from being punished for sin and so even provided housing for former prostitutes who needed temporary lodging when they quit their practices and professed Christian beliefs.

Mencken satirized Kelly's religious devotion: "Before cock-crow in the morning he has got out of bed, held a song and praise service, read two or three chapters in his Greek Old Testament, sung a couple of hymns, cut off six or eight legs, pulled out a pint of tonsils and eyeballs, relieved a dozen patients of their appendices, filled the gallstone keg in the corner, pronounced the benediction, washed up, filled his pockets with tracts, got into a high-speed automobile,...and started off at 50 miles an hour to raid a gambling house and close the red-light district in Emory Grove, Maryland.