One in 10 patients dies within 30 days of undergoing urgent, unplanned laparotomy and some of these deaths could be avoided, the authors say.
The National Emergency Laparotomy Audit team found the care for these high-risk patients was lacking at some hospitals.
Expert supervision and best treatment was not always immediately on hand.
The audit, commissioned by the Healthcare Quality Improvement Partnership and funded by the government, looked at data from more than 20,000 patients from 192 of 195 eligible NHS hospitals.
It found:
More than 30,000 patients have this emergency surgery each year in NHS hospitals within England and Wales.
The procedure, done under general anaesthetic, involves making an incision to operate inside the abdomen to treat life-threatening conditions such as bowel obstruction, perforation or a bleed.
Miss Clare Marx, president of the Royal College of Surgeons, is concerned the mortality rate for the procedure remains too high.
"This audit demonstrates patients are still not accessing a consistently high standard of care from initial assessment through to post-operative care," she said.
She said improving the outcomes for these patients should be made a top priority.
Iain Anderson, the lead surgeon involved in the audit, said many clinical teams had already reviewed and improved the way they delivered care. He urged other hospitals to follow suit.
"This audit is an essential step in helping all involved measure and continue that development and in indicating particularly to weaker teams how they might improve services and save lives," he said.
Prof Mike Grocott, chairman of the audit, said even a modest improvement could have a substantial benefit.
He said the audit team would be following up with the best and worst hospitals to understand what was being done well, sharing best practice to improve performance where necessary.
It may be necessary to accept more delays for routine surgery so these emergency cases can be given a higher priority, say the report authors.
The Office for National Statistics will soon be releasing new hospital-level data on emergency laparoscopy death rates.
Too many patients are dying following emergency bowel surgery, experts who have done a comprehensive audit of care across England and Wales warn.