Balshaw, who has 24 caps, made his last Leeds appearance against Powergen Cup opponents Llanelli Scarlets in October, and has not featured in England colours since the Six Nations victory over Scotland at Twickenham nine months ago.
He was also forced to pull out of the British & Irish Lions tour to New Zealand with a torn thigh muscle after being named in the initial party by Sir Clive Woodward.
Initially, Leeds hoped the abdominal problem would clear up with treatment but Tykes' medical staff decided surgery was the best option for a long-term cure and Balshaw had an operation.
"We are not putting any timescale on when he will return to action," said Leeds rugby director Phil Davies.
"Iain is still only 24 years of age and, on his day, is one of the most exciting players in world rugby.
"We are going to make sure he is 100 per cent before he returns to training and playing, and ensure that he will be able to have a long-term future at the club.
"I know it has been a frustrating time for Iain, and the injury has been a difficult one to pinpoint.
"But we are all confident we have taken the right course of action now, and 'Balsh' can begin to work towards a positive outcome."
Leeds will monitor Balshaw's progress over the coming months, and they have not given up hope on him playing again this season.