OTTAWA — After more than a year of political turmoil punctuated by his admission of crack cocaine use and drunken escapades, Mayor Rob Ford of Toronto was admitted to a hospital on Wednesday after learning that he had an abdominal tumor.

The mayor’s hospitalization will have little effect on the operation of Toronto, Canada’s largest city. Last fall, the City Council stripped Mr. Ford of all but ceremonial powers after he admitted to smoking crack, a confession preceded by months of denial. Yet like his two-month stay in a drug and alcohol rehabilitation program earlier this year, Mr. Ford’s admission to a hospital has prevented him from actively campaigning for re-election in a vote to be held next month.

Dr. Rueben Devlin, the chief executive of the Humber River Hospital, told reporters during a brief news conference on Wednesday night that a biopsy and other tests would be needed to identify the tumor, which is in the lower left quadrant of Mr. Ford’s abdomen, a process likely to take until the end of this week.

He added that a CT scan revealed that “it wasn’t a small tumor, but the size isn’t as relevant as what it is.”