The potential of colonoscopy can only be realised if the procedure is completed safely with good visualisation of the mucosa. This multicentre study is the first large scale prospective evaluation of colonoscopy practice in a cross section of teaching hospitals, DGHs, private hospitals, and paediatric units.
Over the past 15 years, there has been an increasing demand for colonoscopy in the UK. In 1987, it was recommended that 160 colonoscopies should be provided annually for a population of 100 000.6
In 1990, the BSG recommended that approximately 200 colonoscopies per annum would be required to provide a service for a population of 100 000.19
In 2001, the BSG working party suggested that the average DGH should plan for an annual workload of 800–1000 lower gastrointestinal procedures per 100 000 population.20
This represents a fivefold increase in expectation over 15 years.
In this study, 39 DGHs performed a mean of 149 colonoscopies over the four month period (equating to 447 per annum). The 10 teaching hospitals performed a mean of 213 procedures (equating to 639 per annum). Many hospitals participating in the study serve populations well over 100 000, indicating that there is serious under provision of colonoscopy in most hospitals.
Approximately two thirds of colonic disease is within reach of a 60 cm flexible sigmoidoscope and many diagnoses are within range of a rigid sigmoidoscope. In this study, only half of the patients found to have a malignant looking tumour at colonoscopy had previously undergone rigid or flexible sigmoidoscopy.
Excellent bowel preparation is a prerequisite for good quality colonoscopy. Poor bowel preparation is associated with prolonged intubation time.21
Bowel preparations usually include sodium phosphate (for example, Fleet), magnesium salts (for example, Picolax), or polyethylene glycol (for example, Klean prep). A meta-analysis of sodium phosphate and polyethylene glycol showed that sodium phosphate yielded a better preparation and was better tolerated by patients than polyethylene glycol.22
Two studies comparing magnesium salt with sodium picosulphate (Picolax) and polyethylene glycol showed sodium picosulphate to be better tolerated by patients.23,24
Sodium picosulphate also gave better bowel preparation.24
Two studies comparing sodium phosphate with sodium picosulphate showed better preparation with sodium phosphate in one study and a similar outcome from both preparations in the other.25,26
Despite these publications, sodium phosphate was the least used preparation in our study. Sodium picosulphate was the most commonly used cleansing agent followed by polyethylene glycol. It is of interest that the caecal intubation rate was higher for sodium phosphate than for sodium picosulphate (82% and 73%, respectively) and that the polyethylene glycol preparation was similar to sodium phosphate.
Endoscopy guidelines recommend the routine placement of an intravenous plastic cannula prior to the procedure.27
Use of a “butterfly” needle is considered unsafe.28
Prior to colonoscopy, 87% of patients were cannulated with a plastic cannula and in 11% a “butterfly” needle was used for venous access. Continuous intravenous access was not established in 2.2% of high risk patients.
Supplemental oxygen is recommended when patients are sedated. Oxygen was administered to 72% of patients who received sedation but 11.4% of high risk patients did not receive supplemental oxygen.
Prior to colonoscopy, most patients receive a combination of intravenous sedation and analgesia. Midazolam is generally the sedative of choice for short term sedation.29
Midazolam plus pethidine is the most frequently used regimen (57.8% of colonoscopies). The recommended dose of midazolam for sedation is usually 70 μg/kg (that is, 5 mg for a 70 kg patient) and diazepam 10–20 mg.30
This study indicates that a significant number of patients receive more than the recommended sedative dose of benzodiazepine; 25% of patients receiving midazolam had greater than 5.0 mg and 8% of patients receiving diazemuls had greater than 20 mg (36% received more than 10 mg).
When combined sedation and analgesia is administered, pethidine should be injected before the benzodiazepine as this allows safer titration of the sedative drug.31
In this study, 28% of patients were given the benzodiazepine prior to pethidine. Single agent sedation was used in approximately 13% of patients and unsedated colonoscopy in 4%.
Despite evidence that patient administered nitrous oxide/oxygen inhalation provides analgesia equivalent to opiates and results in less desaturation and quicker recovery times, only 1% of colonoscopists use this approach to conscious sedation.32–34
One controlled trial has indicated that the antispasmodic hyoscine butylbromide (Buscopan) increases the speed of colonoscope insertion.35
Teaching hospitals and DGHs used hyoscine butylbromide in 17.7% and 15.7% of procedures, respectively, while its use was reported in 52.7% of procedures in private hospitals. Caecal intubation rates were similar for procedures with and without hyoscine butylbromide.
The aim of colonoscopy is to inspect the entire colon and competent colonoscopists intubate the caecum in at least 90% of patients.18
The caecum can only be positively recognised by visualising the ileocaecal valve.36
Other signs, including transillumination, identification of the tri-radiate fold, appendix orifice, and finger indentation over the right iliac fossa, may provide misleading information.
In this study, the definition of a colonoscopy did not include examinations where the express purpose was to perform a limited left sided examination. Caecal intubation was reported in 76.9% of procedures. However, when identification of the ileocaecal valve or intubation of the terminal ileum were the only criteria used for successful colonoscopy, just 56.9% of procedures could be considered complete. This indicates that completion rates are unacceptably low.
The colonoscopist judged caecal intubation and there was no independent verification. Caecal intubation based on landmarks other than visualisation of the ileocaecal valve or terminal ileal intubation almost certainly overestimate completion rates. Restricting a complete colonoscopy to only those reports that positively identified the ileocaecal valve or intubated the terminal ileum provides an objective measure of completion and the adjusted intubation rate is considerable cause for concern. The difference between the overall and adjusted caecal intubation rate may reflect subjective optimism by the endoscopist who fails to recognise the importance of ileocaecal valve identification.
There was an inverse relationship between caecal intubation rate and increasing patient morbidity and age. Older and ill patients are more likely to require two investigations for complete assessment and therefore in some units, barium enema or computed tomography pneumocolon might be considered as an alternative first line investigation for these patients.
Completion rates were markedly reduced in the presence of a benign or malignant stricture (37% and 20%, respectively). However, in patients with a tumour but no stricture, the caecal intubation rate was only 54%; therefore half will require a further colonoscopy to examine the proximal colon for synchronous lesions.
Previous studies have identified colonoscopy as more difficult in females.14,21
This is reflected in our study where caecal intubation rates for men and women were 81% and 73%, respectively.
Using their own criteria for caecal intubation, colonoscopists reported failure to reach the caecum in 21% of cases. The commonest reasons for incomplete colonoscopy were patient discomfort (35.3%), looping (30.3%), and poor bowel preparation (19.8%). There was considerable scope for addressing each of these complications. Patient discomfort and looping often reflect poor technique. Scrupulous attention to preparation should also reduce the number of failed procedures.
Eighty three per cent of colonoscopists reported that close supervision was not provided in the early learning period and 61% had never attended a formal training course. The caecal intubation rate was higher when colonoscopy was performed by consultant gastroenterologists, physicians and paediatricians (84%), and medical trainees (81%). Lower completion rates were recorded for consultant coloproctologists and general surgeons (71.5%) and surgical trainees (69.2%). The caecal intubation rate for staff grade endoscopists, associate specialists, and general practitioners was 74%. The different completion rates for medical and surgical endoscopists might reflect differences in training and case mix. Medical endoscopists received more supervision and course work than surgeons, and this may account for some of the difference. There is considerable scope to formalise training with a view to accreditation, and all colonoscopists should be encouraged to develop a plan for improving practice.
Polyps and diverticulosis accounted for the most common diagnoses. An abnormality was discovered in 54% of procedures. When inflammatory bowel disease assessment, rectal bleeding, or clarification of barium enema were prime indications for colonoscopy, pathology was discovered in more than half of the patients. When change of bowel habit or abdominal pain was the sole indication, more than 60% of colonoscopies were reported as normal.
Polyps were discovered in 22.5% of patients and polypectomy was attempted in the majority. Incomplete polypectomy was reported in one in five colonoscopies. Failure to deal effectively with polyps leaves diagnostic uncertainty and the need to repeat the procedure. The high rate of incomplete polypectomy requires further analysis but may relate to issues of skills training.
The most serious complications of colonoscopy are perforation, bleeding, and death. For comparison, summaries of previous studies reporting complications of colonoscopy are summarised in table 3. In this study, significant bleeding requiring admission to hospital occurred in six patients (1:1537), and rarely required intervention. Twelve patients experienced myocardial infarction and/or cerebrovascular accidents. Perforation was recorded in 1:769 patients. In “non interventional” colonoscopies, eight perforations were recorded (0.1%) and in “interventional” colonoscopies, four perforations were recorded (0.2%).
Summary of previous studies of colonoscopy complications
Of the 10 deaths occurring within 30 days of the procedure, four were considered to be due to severe comorbid disease rather than the procedure itself. It is likely that these patients were extremely ill at the time of colonoscopy. The procedure related mortality was 1:1537. Overall, the bleeding and perforation rates were within the expected range but the mortality rate was higher than previously quoted.37
The increased mortality rate might be attributed to the design of the study as no other study has specified a 30 day follow up period.
The patient questionnaire indicates that most had received some form of written instruction and/or explanation prior to the procedure but the majority of patients were unaware of the major risks associated with colonoscopy. Despite recommendations that consent is sought before the patient arrives for the procedure, most patients are asked to provide consent immediately prior to the procedure and often in the endoscopy room.38
It should be possible for the consent procedure to be reassessed and changed in those units not compliant with best practice.
In summary, this cross sectional study of colonoscopic practice indicates that there is currently under provision of colonoscopy in the NHS. Screening of high risk individuals is already recommended in the UK and it has been estimated that this will require 1.25 colonoscopy sessions per week for a DGH (assuming six colonoscopies per session and a population of 250 000).39,40
It has been estimated that introduction of a faecal occult blood screening programme would require at least one extra colonoscopy session per week in a DGH.40
Unless there is a dramatic increase in manpower and resources available for lower gastrointestinal investigations, the introduction of a national screening programme would rapidly overburden already inadequate facilities.
A national agenda is necessary to address the shortfalls in current colonoscopic practice. The unacceptably low caecal intubation rate and inadequate polyp removal rate can be improved with better training. Accessible and ongoing training should be made available to both trainees and more experienced endoscopists. Teaching colonoscopy requires considerable skill and the recent establishment of “training the trainers” courses is a critical innovation which should ultimately improve performance.
In conclusion, this study of colonoscopic practice indicates that while there are centres where practice is of the highest quality, considerable effort is required to raise the overall quality of colonoscopy. High calibre early training, regular refresher courses, peer review, and continuous audit of standards at local and national levels must emerge from this study as a priority for all endoscopists performing colonoscopy.