Patients classified as being in urgent need of diagnostic tests to determine if they have ailments such as cancer of the colon or stomach have to wait six months to be seen at Letterkenny General Hospital.
People classified as needing "routine" screening have to wait even longer. The waiting time for colonoscopy and gastroscopy is 18 months, according to figures released by the North Western Health Board.
The chief executive of the board, Mr Pat Harvey, has admitted he is concerned at the waiting lists and times for these diagnostic procedures and promised to carry out a comprehensive review of the situation.
He said the board planned to engage an additional consultant next month to reduce the waiting time. "This arrangement will commence on November 14th with an initial two sessions per week. This will equate to approximately 40 additional patients being treated per week," he said.
The waiting time at Sligo General Hospital, meanwhile, is much shorter. Here, urgent cases are dealt with within four to six weeks, and 18 weeks for routine cases.
Mr Harvey stressed that "very urgent" cases are discussed with consultants and seen within days. The figures were released following a request from health board member and Donegal GP Dr Paul Stewart.
Dr Stewart told The Irish Times he raised the issue after a surgeon at Letterkenny Hospital expressed particular concern to him about the waiting time for these patients.
"Obviously if you have a waiting-list of six months to a year for routine cases it's of grave concern because, with the best will in the world, some of these routines will have malignancies and if it takes a year to see them, it's a bit late in the day," he said.
He added that patients would be classed as urgent if they showed weight loss or bleeding, for example, while routine cases would include persons who had, for example, an altered bowel habit, with diarrhoea one day and constipation the next. "It's an indication they need an investigation because some of those people would turn out to have bowel cancer," he said.
"For patients to wait six months is unacceptable, but to have to wait a year is even more unacceptable," Dr Stewart added.
There are over 600 patients on both the colonscopy and gastroscopy waiting-lists at Letterkenny hospital compared to less than 200 on both lists at the hospital in Sligo.
Colonoscopy is a diagnostic and/or therapeutic procedure used to help in the diagnosis of colon cancer, inflammatory bowel diseases, haemorrhoids and other problems related to the colon. During the procedure the entire colon is examined using a lighted flexible tube and the physician may take biopsies.
A gastroscopy is an examination of the lining of the oesophagus, stomach and duodenum (first part of the upper bowel) using a flexible instrument called an endoscope, which is passed through your mouth. Biopsies may also be taken.