Author: Dr Henry Wei. Sources checked 15 October 2026.
Use FIT alongside the clinical assessment
I assess bleeding, iron deficiency, weight change, bowel symptoms and examination findings before interpreting FIT. Persistent or progressive symptoms need a documented review or investigation plan.
1. Establish why FIT is being used
Population screening, symptomatic assessment and surveillance are separate decisions. As at October 2026, NZ screening is two-yearly for ages 56–74 in eight districts, including all three Auckland districts, and 58–74 elsewhere.
New symptoms use the symptomatic pathway. FIT is currently accessed through secondary care, with direct primary-care access planned over 2027–2028.
2. Assess urgency before requesting the test
Document bleeding, bowel habit, duration, weight, family history and previous colonoscopy. Examine the abdomen and anorectum when indicated, and check FBC and iron studies.
Obstruction, significant acute bleeding or severe illness needs acute assessment. A mass or strong cancer suspicion warrants timely investigation without waiting for FIT.
3. Read the value and units
These are the 2026 NZ symptomatic bands in ng haemoglobin/mL of sample buffer. They are not numerically interchangeable with µg/g of stool.
In routine practice, the laboratory usually reports a binary positive or negative result. The triage service uses the quantitative level behind that report to prioritise follow-up.
The Health NZ pathway summary reports that results above 750, 50–750 and below 50 contained about 80%, 11% and fewer than 9% of colorectal cancers respectively. These are population-level distributions across the bands, not an individual patient's percentage risk.
In the published NZ symptomatic pilot, colorectal cancer prevalence was 3.1%; a result of at least 150 µg/g had 78.1% sensitivity and 95.9% specificity, while three of 32 cancers (about one in ten) were FIT-negative at the pilot's low detection threshold (<10 µg/g). The pilot thresholds and units differ from the current NZ pathway, so use these figures as performance context rather than interchangeable cut-offs.
| Result | Action |
|---|---|
| Below 50 | Usually reported as negative. No automatic colonoscopy or CTC; safety-net and arrange GP review if symptoms persist, recur or worsen at six weeks or beyond. |
| 50–750 | Usually reported as positive. Refer for non-urgent lower-GI investigation or review, generally targeted within about six weeks. |
| Above 750 | Usually reported as positive. Refer for urgent lower-GI investigation, usually colonoscopy, targeted within about two weeks. |
4. Complete the investigation or review
Track the returned sample, result and any referral. A negative FIT reduces colorectal cancer likelihood but does not replace an otherwise indicated investigation.
After a negative result, agree treatment and review. National guidance advises reassessment if symptoms persist, recur or worsen at six weeks or beyond; review sooner for concern or already-prolonged symptoms.
Persistent watery diarrhoea may need colon biopsies or assessment for coeliac disease and bile acid diarrhoea. FIT measures bleeding rather than these causes.
Clinical pearls
- New symptoms need assessment even when the patient is outside screening age or recently had a negative screening FIT.
- Many polyps and some cancers produce little or intermittent bleeding.
- A positive FIT needs assessment; repeating it to seek a negative result is unhelpful.
Information to share with your patient
Related clinician articles
References
- Health NZ: symptomatic lower bowel investigation guidance (2026)
- Health NZ: national symptomatic FIT rollout
- Saw et al: New Zealand FIT for symptomatic pilot (2025)
- Health NZ: National Bowel Screening Programme and current age rollout
- ACPGBI and BSG: symptomatic FIT guideline (2022), principles rather than UK referral cutoffs
- NCI: colorectal cancer screening tests and their limitations
- Health NZ: Check if you're eligible for bowel screening
- Australian Government: How bowel screening with the program works
- NHS: Bowel cancer screening
- USPSTF: Colorectal Cancer Screening final recommendation