Guidance

Bowel Cancer Screening: Guidelines for Endoscopy

Updated 11 July 2025

Applies to England

These guidelines are to support screening services in being able to provide a high-quality endoscopy that is safe, effective and adheres to best practice. 

1. Colonoscopy in the NHS Bowel Cancer Screening Programme (BCSP)

Colonoscopy should be offered to people within the BCSP (or where appropriate following an index colonoscopy, a limited colonoscopy or flexible sigmoidoscopy):

  • following a BCSP FIT result requiring further investigation (index colonoscopy)
  • for assessment/polypectomy after abnormal computed tomography colonoscopy (CTC)
  • to check a polypectomy site of a BCSP patient post polypectomy
  • for surveillance of a BCSP patient post polypectomy
  • for surveillance of genetically confirmed lynch syndrome patients

All people requiring a colonoscopy should be assessed for fitness by a specialist screening practitioner (SSP) prior to their procedure being booked. A clinical decision should be made and recorded by the screening service for those individuals who may have had a recent endoscopy procedure assessing the suitability of the previous procedure and the appropriateness of offering a further procedure through the BCSP.

Lynch syndrome colonoscopy surveillance patients may also require a suitability assessment if they have had a more recent symptomatic colonoscopy or require their colonoscopy surveillance to be brought forward or postponed due to planned pregnancy, IVF round, cancer treatment or planned surgery. 

Bowel cancer screening patients should be assessed in a dedicated SSP clinic. NHS Bowel Cancer Screening Programme Service Specification No. 26 (available on Future NHS collaboration platform) indicates this consultation should take approximately 45 minutes per patient and fully prepare the individual for their procedure.  The screening service can offer this assessment (including the lynch syndrome surveillance suitability assessment) as a face to face or a virtual assessment (by telephone or video call) dependent on patient needs. 

2. Patients unfit for colonoscopy

For people with significant comorbidities the risks of colonoscopy may outweigh the benefits. In these situations, a clinical decision should be made by a BCSP accredited colonoscopist in conjunction with the patient, to discuss if any screening intervention is appropriate.

In cases where a patient is unfit for colonoscopy and the clinical condition will not improve, the patient can be ceased from screening following discussion with the patient.  This should be documented within the patient’s episode notes on the bowel cancer screening IT system (BCSS) (refer to Bowel Cancer Screening Consent and Ceasing Guidance).

Some patients who are currently unfit for colonoscopy may have a condition that is likely to clinically improve or be on medication such as anticoagulants that should not be stopped for a diagnostic procedure. In these situations, a clinical decision should be made referring to relevant guidance (e.g. ) as well as seeking external advice from specialist clinicians if appropriate (e.g. haematologist/cardiologists/alcohol liaison teams) to assess suitability for colonoscopy. Options should then be discussed with the patient on when and how to proceed.   All patients on anticoagulants alone with a history of prior coronary stents must either be switched to aspirin (provided there are no contraindications) or discussed with an interventional cardiology consultant first (refer to ).  

Alternative options may include:

  • a computed tomography colonoscopy (CTC) for those that meet the criteria for a colonoscopy but who are assessed as medically unfit for the procedure (refer to BCSP Guidelines for CTC Imaging).  This includes those with complex, severe co-morbidities, with medication or mobility needs making the risks or difficulties of colonoscopy unacceptable, those with significant neurological, cardiovascular or respiratory co-morbidities which might compromise the safety of the procedure and those that are deemed too frail to undergo standard laxative bowel preparation
  • a diagnostic colonoscopy
  • or to delay the colonoscopy

A subsequent plan for management of any pathology identified must be agreed with the patient.

These decisions must be documented and episode notes entered onto BCSS to ensure that all reports and alerts are acted upon to ensure timely progression and closure of a patient episode.

Under the Equality Act 2010, screening providers have a legal duty to make reasonable adjustments to make sure services are accessible to people with learning and physical disabilities . NHS bowel cancer screening: identifying and reducing inequalities - 51 (www.gov.uk) provides more information on identifying and reducing inequalities

The consent process should commence at the SSP clinic or during the telephone/video consultation. It is the responsibility of the SSP to ensure that the patient has understood enough information to be able to make an informed decision about whether to proceed with the investigation. The person may sign the consent form at the SSP appointment subject to local policy.

If the patient does not have the capacity to consent for the procedure, then a  should be arranged by the screening centre to decide how to proceed.

The consent process should follow the principles outlined in the British Society of Gastroenterology (BSG) . The process must include:

  • what the test involves
  • benefits of the test
  • risks of the test
  • risks of not having the test
  • risks of sedation
  • potential to miss pathology

Colonoscopists need to define the extent of consent before the procedure and consent should be taken for treatments that can reasonably be expected to occur during the procedure.  The scope of that consent should not be exceeded unless failure to intervene would cause immediate harm. 

The consent form must be signed or confirmed by the patient and the accredited colonoscopist on the day of the procedure, prior to the patient entering the examination room.  This will include consent for the removal of a large polyp if required during the index procedure as well as other complex procedures including endoscopic mucosal resections. If this consent is not obtained prior to the index procedure and any additional risks clearly discussed with the patient, they should be booked for another procedure and appropriate consent obtained. 

The BCSP accredited colonoscopist must ensure they reaffirm with the patient any medical conditions or medications that may have a bearing on the colonoscopy procedure.

The BCSP accredited colonoscopist must ensure they are aware of any travel plans that the patient may have in the next 2 weeks and must have a discussion with the patient that they may not be able to fly post polypectomy.  If polypectomy is not possible, then it is acceptable to perform a diagnostic examination with the patient’s consent and book another date when the patient can safely have their polypectomy procedure for those patients who are medially fit for a colonoscopy but do not wish to proceed, the screening service must allow the patient 2 weeks to make their decision.  If the patient remains undecided, they are then able to opt back into the pathway.

During the colonoscopy procedure the patient has the right to withdraw consent at any time and in this case the procedure must be stopped as soon as it is safe to do so. Some patients can continue with the procedure after a short pause, but consent to progress must be obtained from the patient.

Patients should receive verbal confirmation regarding the outcome of their procedure, given a copy of their written report and be made aware of any potential complications after the procedure, before being discharged from the endoscopy unit. They should also be given clear contact instructions for advice if it is required along with what to do in an emergency.

An arrangement should be made for an SSP to contact the patient the next working day of the colonoscopy to ensure no problems have occurred.  The screening service should minimise anxiety and avoid leaving messages on a Friday if there is no one to contact during the weekend.

4. Colonoscopy procedure

All BCSP colonoscopy procedures should be performed in a centre that has been awarded Joint Advisory Committee on Gastrointestinal Endoscopy (JAG) accreditation and approved by commissioners and the local screening quality assurance service (SQAS). A new screening site request form needs to be completed and submitted by the screening service to commissioners and SQAS for approval (This form can be obtained from your regional QA advisor).

If a site loses JAG accreditation there is no requirement to stop screening while working towards re-accreditation, but commissioners and SQAS must be informed and provided with a recovery action plan. 

Any screening centres that undergo a complete refurbishment must provide confirmation to the commissioners and SQAS that JAG has been approached to undertake an assessment of the upgraded facilities to retain JAG accreditation.

BCSP colonoscopy lists should be supported by nurses, who are competent to perform the roles that they are expected to undertake

An SSP or screening practitioner (SP) must be in attendance to support the patient, complete the required datasets and record the outcome of the examination agreed between the performing colonoscopist and SSP in real time on BCSS.

All colonoscopists, including those that are insourced (locum/bank staff), must be accredited by JAG to perform BCSP colonoscopy. The use of a non-accredited colonoscopist on a screening list must only be done in exceptional circumstances (i.e. when a colonoscopist is off sick and the patient has taken bowel preparation) and patients must be given a choice to be scoped or to be rebooked.  It is not to be used to address capacity issues.  If a non-accredited colonoscopist is used, the Clinical Director of the screening programme must immediately inform SQAS and commissioners and ensure that the non-accredited colonoscopist meets the required quality standards.

Information about the application process and education material become a BCSP accredited colonoscopist can be found on the .  A new screener request form needs to be completed and submitted by either the screening centre clinical director or the screening centre programme manager to the regional SQAS team for prior approval (This form can be accessed through the and should be sent to the regional QA advisor for approval and processing).

Screening services should also make sure that they follow other Joint Advisory Group (JAG) on Gastrointestinal Endoscopy guidance in particular:

  • checklist on the use of insourcing providers ().  This provides a more detailed and expanded list of actions to those identified below which should be undertaken by the service

  • guidance from JAG regarding breaks in service particularly those that exceed 12 months (). This identifies what action is required by a screening service if an endoscopist has had a break in service i.e. whether retraining/mentorship.  Agreement from the Screening Quality Assurance Service (SQAS) professional clinical advisor and service lead is required.  This will also be applicable to those colonoscopists that are insourced

Patients undergoing colonoscopy should be offered analgesia in line with guidance ().  

A small proportion of patients (e.g. lynch syndrome surveillance patients) may require intravenous propofol as deep sedation for colonoscopy and all centres should make a reasonable effort to provide this for appropriate patients. In cases where this is not possible then these colonoscopies can be performed by a BCSP accredited colonoscopist on a symptomatic or theatre list with an SSP present to be able to complete the datasets and record the outcome on the bowel cancer screening system. Alternatively, the patient may be transferred to another screening centre offering this service.

In the case of an incomplete colonoscopy, it is at the discretion of the BCSP accredited colonoscopist to request a repeat procedure, possibly by an alternative BCSP accredited colonoscopist or with an alternative bowel preparation, or to request a BCSP computed tomography colonoscopy (CTC).  If optimal views cannot be attained by washing, then a repeat colonoscopy should be arranged. For lynch syndrome surveillance patients, services should consider arranging a repeat procedure following an incomplete colonoscopy with an expert colonoscopist or a repeat procedure under deep sedation/general anaesthesia.  If this fails, CTC is an option although CTC should be avoided where possible due to the risk of radiation induced cancers and lack of validation of CTC in this population​.

Incidental findings (such as diverticular disease, hemorrhoids) are not part of the screening pathway.  However, screening services should ensure that there is a local policy in place on how to manage these incidental findings identified during colonoscopy. Screening services are responsible for ensuring that patients are either referred directly to the relevant department or via the GP. If the referral is made directly, the screening service must ensure that the GP and patient are informed of the referral.

5. Removal of polyps

The colonoscopist and all endoscopy staff must be familiar with all the endoscopic accessories, including the diathermy machine and its settings ensuring that equipment is in good working order with the correct settings prior to the procedure.

Polyps should be removed safely using standard techniques. Efforts should be made to ensure that there is a clear margin (ideally 2mm) between the head of the polyp and the diathermy excision margin

These include:

  • use of cold snare when appropriate
  • submucosal injection
  • endoscopic techniques to reduce bleeding risk following polypectomy (such as use of loops, clips or adrenaline injections) may be employed at the discretion of the colonoscopist

Hot biopsy should not be used.

In general, pedunculated polyps or sessile polyps less than 20mm in size should be removed at the index colonoscopy, unless they have high risk features (Kudo type V crypt pattern, Central depression, Surface ulceration, Non-lifting, Tethering or in-drawing of surrounding mucosal folds) or are in a high risk position (within 2mm of the appendix orifice, within 1mm of a diverticular opening, on an anastomotic suture line, on the ileo-caecal valve opening). For sessile polyps >20mm, or with high risk features or in a high risk position these would not be expected to be removed at an index colonoscopy. This is because removal may take additional time not available at the index procedure and removal carries additional risks which will need explaining to the patient as part of the consent process, usually over and above the standard colonoscopy consent information. 

Where an individual colonoscopist decides to remove a sessile colonic polyp >20mm or with high risk features or positioning they will be required to justify this decision subsequently, particularly in the event of a complication. 

No colonoscopist should resect a polyp they consider to be beyond their level of expertise. Patient safety is paramount and in these cases the procedure should be rescheduled to be performed by a colonoscopist with the necessary experience with an SSP in attendance to record outcomes on the BCSS.  The BCSP accredited colonoscopist is responsible for ensuring patents requiring further complex polypectomy procedures or endoscopy mucosal resections (EMRs) are appropriately brought back and specific consent is obtained

Lesions not removed at the index colonoscopy should be documented with several good quality photographs, have their position marked by tattoo (unless they are in the rectum or caecum or are very bulky and obvious where local policy may apply).  Biopsies should not be performed unless there are strong grounds to believe that subsequent endoscopic resection will not be possible or appropriate.

A decision will be made by the screening colonoscopist in discussion with the specialised screening practitioner on the day of the index colonoscopy and communicated directly to the patient which of the following 3 pathways to follow:

A. Repeat colonoscopy by any screening colonoscopist for EMR/polypectomy

B. Repeat colonoscopy by a local screening colonoscopist with more experience of EMR

C. Direct referral to complex polypectomy MDT

Repeat colonoscopy/EMR should be booked as a priority to prevent delays in the patient pathway (and a breach if cancer is eventually diagnosed) and consideration given whether a double slot is required to ensure adequate time.

Patients listed for repeat colonoscopy/EMR should be provided with the patient information leaflet to describe the planned procedure and risk of complications (see Section 12: Patient Information).

The BCSP accredited colonoscopist is responsible for ensuring patients requiring further complex polypectomy procedures or endoscopy mucosal resections (EMRs) are appropriately brought back and specific consent is obtained.

The management of large non-pedunculated colorectal polyps should be in line with BSG guidelines.

All screening centres should have one or more accredited colonoscopists with the experience required to perform advanced polypectomy. If the resection of a polyp is beyond the expertise of local colonoscopists, for example if it requires endoscopic submucosal dissection (ESD), then this may be referred to another screening centre with the appropriate expertise. In these situations, a clearly documented pathway should be in place to show clinical responsibilities and timescales and should be performed by an accredited colonoscopist with an SSP in attendance.  If there is a local expert, it is recommended that they become a BCSP accredited colonoscopist.

An alternative option is to have the ESD referred to a symptomatic list at a tertiary centre, the screening service should ensure there is a process in place that enables the outcome to be recorded accurately on BCSS.

Surgical resection for benign lesions should be avoided, if possible, but when considered necessary after multidisciplinary discussion involving expert therapeutic endoscopists (ideally in a complex polypectomy MDT), the outcome of surgery should be recorded and disseminated to facilitate learning.  In cases where resection for a benign lesion is undertaken outside of the standard BCSP pathway, the outcome must be entered onto the BCSS to ensure the correct post polypectomy pathway as the patient will be brought back into programme for surveillance.

A project is currently being rolled out to allow optical diagnosis with a resect and discard strategy for diminutive polyps (< 5mm) to be delivered by NHS BCSP.  Optical diagnosis involves a colonoscopist making an optical diagnosis of small polyp pathology with high confidence, recording photographic documentation of these polyps with white light and narrow band imaging (NBI) and then discarding the polyps rather than sending to histopathology.  This will be delivered by colonoscopists who have undertaken accreditation in optical diagnosis with a subsequent quality assurance process in place to monitor performance.  Training will be delivered by approved Optical Diagnosis champions and have access to appropriate equipment at each screening service. 

Optical Diagnosis with a resect and discard strategy () is not acceptable in the following circumstances:

  • accredited OD endoscopist has NOT been added to BCSS
  • unaccredited OD endoscopist as the testing clinician
  • patient has a Lynch Syndrome diagnosis recorded (even if they have withdrawn from Lynch syndrome surveillance)
  • an aspirant endoscopist who is in a procedure as the operator CANNOT undertake optical diagnosis (when an aspirant endoscopist is in a procedure as an observer AND the testing clinician is accredited, optical diagnosis can take place)
  • rectal polyps ≤5mm
  • polyps in anus

6. Post polypectomy

Patients within the BCSP should have surveillance procedures performed at an interval determined by the .

Patients undergoing surveillance colonoscopy should be reassessed by an SSP prior to the procedure to ensure there is no new relevant medical information. This can be a telephone/video consultation, but they should be offered the opportunity of a face-to-face clinic meeting to discuss the procedure if they wish.

7. Infection control

All colonoscopy performed within the BCSP should comply with current national guidance on infection control and should be signed off by the local Trust infection prevention and control team to ensure safe practice.

8. Quality standards

All BCSP accredited colonoscopists are required to make a significant commitment to the programme and should be able to demonstrate performing the minimum (or equivalent for annualised job plans) of one BCSP list a week (equating to over 120 colonoscopies per annum). Cases may include screening, surveillance, diagnostic, therapeutic colonoscopies, and lynch surveillance colonoscopies.  Sufficient procedures must be performed to allow quality standard analysis, maintaining skill sets of the colonoscopists and ensuring capacity within the screening service.

ճBSCP quality standardsԻ must be achieved by all practising colonoscopists including those that are insourced (locum/bank staff).

All screening centres should have a clinical director or lead colonoscopist who is responsible for monitoring the performance of all colonoscopists undertaking procedures within their programme (including locum consultants). If the clinical director is not an accredited colonoscopist, there needs to be a lead BCSP accredited colonoscopist responsible for monitoring performance.

In addition, all colonoscopists (including those insourced) should have an assigned principal clinical director from the screening programme (see Section 9 Governance and Risk Management below for further detail). This principal clinical director provides clear governance/oversight ensuring their assigned BCSP colonoscopists are accountable for delivering a high-quality screening service which is compliant with pathway standards, key performance indicators and national guidance.  Their assigned BCSP colonoscopists will know how to report any potential risks including instances of non-compliance which the clinical directors can raise through their host organisation’s governance and management structures.  All colonoscopists are responsible for collecting and recording activity, adverse events and key performance indicators and sharing this with their assigned principal clinical director and clinical director /lead colonoscopist (if different) along with details of all the screening centres where they undertake BCSP colonoscopies.  All colonoscopists should inform the clinical director/lead colonoscopist of the screening programme of the name of their assigned principal clinical director (if different).

All BCSP colonoscopists should have regular feedback on their performance at least on a six-monthly basis with the clinical director or lead colonoscopist of the screening service and on an annual basis with their principal clinical director (if different)This will include a review against all BCSP colonoscopy standards (including workload, caecal intubation rates with photographic evidence, polyp retrieval rates, adenoma detection rates and withdrawal times) and key performance indicators (including comfort, sedation, use of reversal drugs). Individual colonoscopists who work at multiple sites are required to collate and share their key performance indicators with the principal clinical director.  

SQAS will review both service level and collated data from all colonoscopists on a six-monthly basis.  SQAS will formally write and escalate to the principal clinical director any concerns relating to an individual colonoscopist (including those insourced) whose key performance indicators are not being met.  A copy of this letter will be sent to the clinical director at all other screening centres The individual colonoscopist should work with the principal clinical director and SQAS to generate an action plan for improvement and the principal clinical director should provide support during this process. 

All new colonoscopists (or insourced colonoscopists) should be appropriately inducted and familiar with the screening pathway.  They should have reviewed the standard bowel cancer screening programme procedures and processes including the escalation of incidents and adverse events.  They should be trained in the use of equipment and the checks that are required to assure a safe service.    

The principal clinical director should also ensure that all colonoscopists that they are responsible for:

  • are provided with appropriate training/mentorship
  • receive continued assessment of their professional development
  • review their attendance at network meetings/screening service meetings to ensure they are being kept up to date with national guidance, receiving any shared learning and new developments within the BCSP
  • review of their participation in screening service audit activities to ensure quality standards are being maintained

9. Governance and risk management

BCSP colonoscopies must be governed by the same processes as those undertaken in the endoscopy unit for symptomatic patients. Where there is a deviation from standard practice, or for common scenarios such as diabetic patients or those on anticoagulant or antiplatelet therapy, then there should be specific BCSP standard operating procedures in place.

If a bowel cancer screening service is provided by more than one Trust, then additional governance arrangements must be in place between the host Trust and other providers. Lessons learned from issues or incidents should be applied across the whole screening centre and not just on a particular site.

Governance arrangements for multi-site or provider screening centres can be complex, but all members of the team should be aware of the endoscopy and BCSP specific guidelines and operational policies.

There must also be appropriate governance/oversight arrangements in place for when screening services insource colonoscopists (locums/bank staff) or outsource to external agencies.  and checklist should be followed and SOPs developed. This should include:

  • written agreements for the provision of service which include national quality standards and key performance indicators for bowel cancer screening programme (BCSP), the type of activity and the volume that will be provided, the responsibilities for capturing and reporting incidents, adverse events and near misses in line with national guidance and alert screening teams of any patient concerns or operational issues
  • immediately informing SQAS and commissioners of the names and roles of the staff/organisations BCSP workload is being insourced/outsourced
  • ensuring that all colonoscopists (including those insourced and outsourced) have the appropriate professional qualifications (e.g. GMC/NMC/AHP number accurately recorded on BCSS) and are bowel cancer screening programme accredited by Joint Advisory Group (JAG) on gastro-intestinal endoscopy (evidence of a JAG certificate)
  • ensuring that all colonoscopists (including those insourced and outsourced) have a bowel cancer screening system (BCSS) account which correctly reflects the role being undertaken at the screening centre to ensure that datasets can be completed, and key performance indicators can be aggregated. SQAS will undertake regular validation checks on BCSS logins of colonoscopists (including those insourced)
  • all colonoscopists (including those insourced and outsourced) must have a named “principal clinical director” who is professionally responsible for the individual colonoscopist ensuring quality standards for the bowel cancer screening programme are being maintained.  For newly accredited colonoscopists, this would be the clinical director for the screening service that they have their initial 12-month contract with.  For all others, it would be with the clinical director of the principal screening service they are contracted to or of the colonoscopist is not assigned to a specific screening service, a nominated clinical director needs to be identified as their principal clinical director to provide that governance oversight.  This could be through a paid arrangement.  This will also include any colonoscopists contracted through an external agency.  SQAS will need to be provided with the details of the principal clinical director responsible
  • the clinical director at the insourced screening service (if different from the principal clinical director) would also have the responsibility in ensuring that the insourced colonoscopist meets the national bowel cancer screening standards, is fit to practice working within the scope of practice and feeds back any concerns to the principal clinical director.

There are inherent risks to performing colonoscopy. The screening centre is responsible for ensuring all measures are in place to minimise the risk.

All incidents and reportable events should be reported to SQAS along with it being reported on the Trust’s internal incident management process.

  • For screening safety incidents, screening services should follow the guidance for managing screening incidents

  • Screening services should in addition to reporting reportable events to SQAS (an occurrence that is inherent risk to the screening test e.g. perforation, bleed, post polypectomy syndrome/post procedure pain/cardio/ cerebrovascular events or a death within 30 days of procedure), the screening centre must also continue to record the relevant information on bowel cancer screening system (BCSS) under adverse events when screening system requests it

  • Screening services should also maintain non-conformance logs of any isolated minor events which have no associated harm, errors with little or no safety risk or there is minor variance in the usual pathway.  Non-conformance logs will be reviewed at programme boards or requested at forthcoming QA visits/pathway reviews

10. Audit

Bowel cancer screening centres must demonstrate adherence to the programme standardsԻ to other parameters of colonoscopy quality and safety not included in the BCSP standards. A rolling programme of audit should be in place to demonstrate this and these data will be available on the BCSS. 

11. Post investigation colorectal cancers

Screening centres should discuss any post colonoscopy or computed tomography colonoscopy (CTC) cancers that are identified within the screening centre at team meetings to incorporate any learning points from the discussions. Trust policies and processes for applying duty of candour must also be followed.

As recommended by the World Endoscopy Organisation (WEO), JAG now requires that endoscopy units audit their post colonoscopy colorectal cancers.  BCSP colonoscopists are expected to take part in this post colonoscopy colorectal cancer audit (PCCRC) Any BCSP cases identified as Unsatisfactory following a full review of colonoscopy episode and diagnostic case by 3 accredited colonoscopist within the screening centre should be reported using a screening incident assessment form (SIAF) and sent to regional QA teams.  Learning from any cases reviewed as Satisfactory – Learning Possible should be shared at screening centre and programme board meetings.

12. Patient information

Patient information leaflets on colonoscopy are available online. The leaflets are available in English and 10 other languages. ճEnglish version is in HTML format and an easy guide version is available.

Screening services should have an information leaflet available for screening patients who require an endoscopic mucosal resection (EMR) for a large/flat colonic polyp. (A sample of a patient leaflet is available and can be supplied on request to your regional QA Advisor).