Shlomo Mor-Yosef, director of Hadassah Hospital, said that while the surgery went well, Sharon's main problem remained his continuing state of unconsciousness and "the dramatic event this morning will not help him recover and is not a good sign".
Medical experts hold little hope for the 77-year-old leader's recovery after a massive brain haemorrhage on 4 January. He has been in a coma since the stroke.
"The condition of Prime Minister Sharon is stable but critical," Mor-Yosef told reporters after the four-hour operation. "In the morning, there was really immediate danger to his life, but now ... (there is) no immediate danger."
Reduced blood flow
Sharon was rushed to the operating theatre after a CT scan revealed intestinal damage stemming from reduced blood flow that caused tissue to die.
"We removed 50 cm from his bowel, or 20 inches," Mor-Yosef said.
A Sharon aide said his condition "was not as bad as thought in the beginning".
Earlier, a hospital source said doctors did not expect Sharon to survive the day and a hospital spokeswoman described
his condition as the most critical since admission.
Sharon's death would almost certainly leave Ehud Olmert, named interim prime minister after the 77-year-old leader's
brain haemorrhage last month, in charge until elections in six weeks.
A CT scan of his brain earlier this week showed that he was in serious but stable condition.
On 1 February, Sharon had a feeding tube inserted in his stomach, an indication that his doctors are thinking in terms of long-term care for the 77-year-old Sharon.
Sharon is being kept at the
Hadassah Ein-Kerim hospital
The CT scans have been used to assess bleeding and swelling in Sharon's brain.
According to past hospital statements, there have been no changes in the results of the scan in recent weeks, but Sharon has failed to regain consciousness.
Sharon suffered a stroke with what was described as "significant" bleeding in his brain a day before he was to check into Hadassah Hospital for a procedure to correct a tiny defect in his heart that was said to have contributed to a mild stroke he suffered two weeks earlier.
Doctors have come under fire from critics who questioned whether Sharon should have been treated with massive doses of anticoagulants after his first stroke, which was caused by a small blood clot in a cranial artery.
Doctors admitted that the anticoagulants made it more difficult for them to stop the bleeding from the later haemorrhagic stroke.
The extensive bleeding and the lengthy operations Sharon underwent to stop it have led experts to conclude that he must have suffered severe brain damage and was unlikely to regain consciousness.