Gastric bypass surgery is one of a range of bariatric or weight loss procedures used to combat morbid obesity.
It combines the creation of a small stomach pouch to restrict food intake and the construction of bypasses of the duodenum and other segments of the small intestines to decrease the ability to absorb calories and nutrients from food.
It is usually restricted to people with a Body Mass Index in excess of 40 or 35 in the cases of people who have accompanying serious weight-related problems, such as diabetes or high blood pressure.
Its success rate is high with patients who go through it claiming they have regained a quality of life they thought they would never see again. But as with any major surgery, it comes with risks that vary according to the patient's age and health.
This surgery is mainly carried out in two Irish hospitals; publicly at St Columcille's Hospital, Loughlinstown, where there is a waiting list of up to three years and privately at the Bons Secours Hospital in Cork where there is no current waiting list.
The cost of bypass surgery privately here is in the region of €15,000 with the three main health insurance companies covering all or part of that cost. Margaret Donnelly's entire procedure cost €9,650; €6,000 of which was paid by her insurance company, Quinn Healthcare.
But many Irish people are opting to go to the UK or elsewhere to have the operation and a number of agencies are based here that specialise in referrals abroad.
Consultant bariatric surgeon at the Bon Secours Hospital in Cork, Mr Colm O'Boyle has estimated there are upwards on 40,000 who'd benefit from some form of weight loss surgery but he has warned of the potential risks of travelling abroad.
"Ideally I would like to see a better recognition of the benefits of this surgery but it is crazy for people to have to go abroad, particularly if they have private health insurance.
"Any patient that comes here will have extensive follow-up care with a multi-disciplinary team," he said.