Health New Zealand has corrected information previously provided about Canterbury colonoscopy waiting lists after identifying inconsistencies in its original data.

Figures released to Chris Lynch Media on Thursday, under the Official Information Act show 4,174 people were waiting for a colonoscopy across the Canterbury district at the end of May.

That included 3,225 surveillance patients whose procedures were due, 928 patients classified as non urgent and 21 urgent patients.

The figures exclude surveillance patients whose procedures were not yet due, patients referred through the National Bowel Screening Programme and specialist paediatric gastroenterology patients.

Health NZ said its original response, issued on 9 July, included everyone enrolled in the surveillance programme, whether they were currently waiting for a procedure or not.

“We have since validated the information against national diagnostics data and are providing corrected figures,” Health NZ said.

Surveillance colonoscopies are scheduled at defined intervals for people at increased risk of bowel cancer or those with previous findings such as polyps or inflammatory bowel disease.

At Christchurch Hospital, surveillance patients currently waiting for a colonoscopy were an average of 2.7 months beyond the date their procedure was due as of 31 May.

For surveillance cases completed between 1 June 2025 and 31 May 2026, the average delay beyond the due date was 4.8 months.

The response also showed Christchurch Hospital’s gastroenterology department declined 2,358 referrals during the same 12 month period.

However, 2,353 of those were referrals for CT colonography that Health NZ classified as not required or not appropriate. Health NZ said it was unable to isolate how many declined referrals related specifically to surveillance procedures.

A total of 10,642 endoscopy procedures were performed at Christchurch and Ashburton hospitals during the 12 months to the end of May.

Christchurch Hospital completed 10,066 procedures, while Ashburton Hospital completed 576. The figures included colonoscopies, gastroscopies, combined procedures and other forms of endoscopy.

Health NZ expects about 3,300 colonoscopies to have been completed through private providers during the 2025 and 2026 financial year, although final figures have not been confirmed.

It said up to 22 percent of referrals sent to private providers were returned following clinical review. Reasons included patients being considered too high risk for a private setting, providers needing more information and capacity constraints.

The Christchurch Hospital Endoscopy Expansion Project remains scheduled to begin operating in November.

As of 15 July, Christchurch Hospital employed 16 gastroenterologists, representing 13.15 full time equivalent positions against a budgeted 13.93 positions. Health NZ said it was recruiting for the remaining 0.78 position.

Health NZ said the figures were provisional and could change because they had not completed the full quality assurance process used for published data.