The value and the future of CT colonography, the emerge of highly competitive diagnostic modality

Introduction

Colorectal cancer is one of the most common cancers in the western hemisphere, ranking third after lung and breast cancer worldwide with an increased incidence with age; median age at diagnosis is about 70 (1,2).

Increasing awareness of colorectal cancer and developing rapid access service to investigate symptoms, has mounted the demand on colonoscopy as a first line investigation. Consequently, there has been an increase in pressure on colonoscopy units, schedulers and on endoscopists to achieve the targeted high completion rate of 90% and above (3-5).

Through observation of our practice the colonoscopy request form has all information related to: risk of infection, renal function, anti-coagulants and other safety precautions. However, there is no reference to the risk factors of a challenging colonoscopy or predictive factors of incomplete colonoscopy, such as abdominal surgery, pelvic surgery and hysterectomy (6-9).

As it is essential to achieve over 90% success rate for completion of colonoscopy and to reduce the pressure on waiting lists, it is equally vital for endoscopists to maintain these figures in order to maintain their competency. However, this maintenance of competency and success rate will be challenged by difficult colonoscopies. This conflict of interest on completion may have adverse effects on patient’s safety, and patient’s satisfaction. In addition, failure of colonoscopy may add more financial pressure and strain to the system by further delays and requirements for repeat conventional colonoscopy, colonoscopy under general anesthesia or even a request for CTC.

On the other hand, availability of CTC—a minimally invasive imaging technique—in investigating colorectal cancer may be considered as an alternative modality in a high-risk group, due to its growing success in screening, surveillance, detecting polyps and extra-colonic findings (10-15).

Furthermore, CT colonography has been proven to be a safe and minimally invasive imaging technique, a valuable diagnostic tool for examining the entire colon and a good alternative compared to other colorectal cancer screening tests. Devir et al. (16) compared CT colonography and conventional colonoscopy in detecting colorectal lesions, and found high sensitivity values in colorectal lesions over 1 cm. CTC showed 83% sensitivity and 95% specificity, with a positive predictive value of 95% and a negative predictive value of 83% for the detection of colorectal polyps and masses.

Therefore, our aims in this study are to assess the value of CTC against the conventional colonoscopy in a group of patients who had incomplete colonoscopy, to determine the potential of considering CTC as an alternative to colonoscopy in this group.

We present the following article in accordance with the STARD reporting checklist (available at http://dx.doi.org/10.21037/dmr-20-22).

Methods

A retrospective study was carried out, collecting radiological data of 469 patients who underwent CTC between January 2015 and December 2015. All data was retrieved from the radiology department at Diana Princess of Wales Hospital through computer-based records. This is including colonoscopy reports for comparison. All reports of CTC, colonoscopy including the referral forms were reviewed and analysed accordingly. The data was analyzed and revealed 469 had CTC: for 259, the primary request to investigate bowel symptoms was CTC; 158 had CTC due to a failed colonoscopy and the remaining 52 had CTC and colonoscopy requested, but no sufficient data to suggest why patients had both tests and therefore excluded.

One hundred and fifty-eight patient endoscopy reports were reviewed: 56 patients were excluded from the study as colonoscopy was abandoned due to poor bowel preparation, and had flexible sigmoidoscopy on the primary request. CTC imaging reports of 102 patients were extracted and colonoscopy reports of these patients were assessed. Measured data included: age, sex, indication, types of sedation, history of hysterectomy, abdominal surgery and abdominal pain. CTC reports were analyzed against the incomplete colonoscopy to determine any risk factors or pathological causes attributed to incomplete colonoscopy. The study was conducted in accordance with the declaration Helsinki (as revised in 2013).

Statistical analysis

Descriptive statistics were used in this study through SPSS in analysing quantitative categorical data.

Results

In the studied group of 102 patients, the main indication for colonoscopy was changing bowel habit followed by positive fecal occult blood and anaemia (Figure 1). Thirty-four percent of patients had Entonox and 66% had awake sedation of mixed fentanyl and Midazolam.

Figure 1 Indications for colonoscopy.

The number of females was considerably higher than that of males: 82.3% female [84] compared to just 17.6% male [18] with P value <0.001. Female median age was 65.5 (range, 25–94) compared to male median age which was 66 (range, 32–83) with no statistical difference P value 0.29 (Table 1).

The procedure had to be stopped for 81 patients (79.4%) due to pain, 16 (15.6%) due to looping, 4 (3.9%) due to acute bend and one patient had persistent bradycardia therefore procedure abandoned (Figure 2).

Figure 2 Causes of incomplete colonoscopy.

Sigmoid colon was the most common site for failure 65 (63.7%) followed by the splenic flexure 16 (15.7%), transverse colon 10 (10%), hepatic flexure 9 (9%) and 2 (2%) failed to intubate the cecum (Figure 3).

Figure 3 Failed sites.

All patients who had incomplete colonoscopy had CTC completed.

In 58 (57%) CTC was normal, 36 (35%) diverticulosis, 6 (6%) polyps, 2 in rectum size 4 and 5 mm; 3 in sigmoid size 4, 6, 6 mm and 1 in cecum of 4 m. There were 2 strictures in sigmoid colon deemed impassable (Figure 4).

Figure 4 CT colonography (CTC): intra-colonic findings.

CTC showed incidentally 10 pathology, 4 (4%) of clinical significance required further investigation and this included lymphoma, benign adrenal tumour, indeterminate lesion in the lung required follow up scan and benign pancreatic cyst (Figure 5).

Figure 5 CT colonography (CTC): extra-colonic findings.

In 79 patients, 77.4% risks factors for incompletion were identified. Twenty-six had hysterectomy, and 2 had bulky pelvic uterus, 22 (21.5%) abdominal pain/IBS, 12 (11.8%) patients had open abdominal surgery with midline incision, 11 (10.8%) had severe diverticula disease, 4 (3.9%) laparoscopic surgery and 2 (1.9%) patients deemed frail to have colonoscopy (Table 2). In all failed patients CTC was completed and offered diagnosis at no risk.

Discussion

Colonoscopy is widely used in investigating and screening colorectal cancer: one of the most common cancer affecting male and female worldwide (17-21).

It has the diagnostic and therapeutic advantage ranking colonoscopy as one of the most popular tools in its current era with an estimated 14.2 million colonoscopies performed in 2002 (22).

However, the risk of perforation, which could range between 0.019% to 0.8% of diagnostic and 0.10% to 3% of therapeutic, has always been of an interest to many researchers in spite of the remarkable success of colonoscopy (23). This interest is mainly triggered by the associated risk of mortality and morbidity as a third of patients may require stomas (24).

Dedicated research over the last decade disclosed risk factors leading to adverse events in colonoscopy (25-28).

Perforation continued to be a great concern in colonoscopy with its impact on patients and the health system. Therefore, understanding of the mechanisms and disclosure of the risk factors of perforation in colonoscopy may prevent serious consequences. This was highlighted in Rai et al. (29) 2018 published paper, appreciating the value of colonoscopy in reducing the number of colorectal cancer whilst declaring colonic perforation as a serious complication with high morbidity and mortality. The incidence of perforation will only continue to rise as the number of colonoscopies performed increases.

Without a universal and agreed protocol on a selective colonoscopy in a high-risk group, colonoscopy will continue to be a challenging procedure to patients and endoscopists.

In our study, 79 (77.4%) of those who failed colonoscopy had associated risk factors for incompletion. Two patients (aged 93 and 83) were deemed unsuitable for colonoscopy due to frailty and poor mobility on the day of the procedure. CTC was arranged as an alternative and diverticular disease was confirmed in both patients as the cause of symptoms.

Ageing is of a concern when it comes to colonoscopy. Several studies investigated risk factors for iatrogenic perforations during colonoscopy. In a retrospective analysis of risk factors using the clinical outcomes Research Initiative National Endoscopic Database, Bielawska et al. (30) found age greater than 75 years, is one of the risk factors significantly associated with increased risk of early perforation.

Regardless of the associated co morbidity, elderly patients have limited physiological and physical reserves to undergo a procedure that sometimes could be very challenging. Most importantly, their ability to stand complications is low. On the other hand, full cooperation and following commands during the procedure proved to be another major challenge to elderly patients and endoscopists.

Although the median range of patient’s age in our study was 65, aging has always been of concern in particular with the increasing demand on colonoscopy and the increasing number of elderly patients attending for colonoscopy. This was demonstrated in Kim et al. (31) in this recently published article in 2019, there has been a concern regarding the increased morbidity and mortality related colonoscopy by increasing number of elderly patients attending for the test.

Furthermore, in Day et al. (32) a systematic review and meta-analysis of adverse events in older patients undergoing colonoscopy showed adverse events and complications will not be tolerated in this group, in particular with limited physical and functional reserves to cope with complications, hence morbidity is high.

Nevertheless, predicting incomplete colonoscopy and displaying risk factors contributing to incomplete colonoscopy were disclosed and linked to the presence of abdominal surgery and complicated diverticular disease. In Cirocco et al. (33), a 1995 study on 1,047 patients concluded women, especially those with a history of abdominal hysterectomy, had a significantly lower caecal intubation rate, usually because of failure to pass through the sigmoid colon.

In our study, 31% of females [26] had hysterectomy and 1.9% [2] had large uterus. In 18 patients with hysterectomy (69%) the failure was in the sigmoid and similarly colonoscopy was abandoned in the sigmoid in the 2 patients with a bulky uterus. This may reflect a fact that changes in pelvic anatomy predispose endoscopists to a challenging procedure, due to the close anatomical relations between the most difficult part to navigate through (sigmoid) and the surroundings in the pelvis.

Binding the fact of a challenging sigmoid in this group and a higher rate of perforation in sigmoid (34), there is no safeguard protocol to consider an alternative as a first-choice modality in this group.

The argument therefore, is that many patients with hysterectomy and pelvic surgery had colonoscopy completed, but at a higher probability of mortality and morbidity, with pain, higher sedative dose, longer procedure time and poor experience.

The challenge in colonoscopy is not restricted to one risk factor and it is evident that patients with abdominal surgery are also at risk during colonoscopy. In Shah et al. (35), factors associated with incomplete colonoscopy were: elderly, female, past abdominal surgery and pelvic surgery. These findings are observed in our group of 102, where 16 patients had abdominal surgery, 12 (11.8%) with midline incision and 4 (3.9%) had laparoscopic surgery. These findings encouraged the authors to support that alterations in abdominal anatomy contributes to failed colonoscopies and unsatisfactory experience for both patients and endoscopists. Such observations may favor CTC as a first line option in this group, unless colonoscopy is recommended for highly suspected pathology or requested for polypectomy.

In Hanson et al. (36), the study looked into anatomical variation of the colon and its impact on incomplete colonoscopy. One hundred patients had CTC after incomplete colonoscopy compared with a control group who had complete colonoscopy after CTC. The study showed significant statistical difference between the complete and incomplete colonoscopy groups in terms of history of abdominal surgery (26.0% vs. 48.0%; P<0.01), advanced diverticular disease (22.0% vs. 34.0%; P<0.05) and the length of colon. Total colorectal length in the incomplete group was longer than the complete group (mean, 167.0 vs. 210.8 cm; P<0.0001), and the difference was noted in the different segment of the colon; in the sigmoid, colon length was longer in the incomplete group than the complete group (mean, 48.7 vs. 66.8 cm; P<0.0001), transverse colon length (mean, 49.2 vs. 66.3 cm; P<0.0001), number of flexures (mean, 9.6 vs. 11.9; P<0.0001).

In Dafnis et al. (37), the study demonstrated, presence of diverticulosis had an impact on failed colonoscopy.

In our study, 11 (10.8%) had severe diverticular disease; the procedure had to stop in the sigmoid and this repeatedly demonstrates that variations in sigmoid anatomy and presence of different pathology are strong indicators of ability to complete colonoscopy. Prior knowledge of such variation may prove to be necessary to consider alternative options. Nevertheless, this group underwent uneventful CTC as an alternative at no risk.

In summary, our study disclosed the risk factors for incomplete colonoscopy and its implications on patients, services and endoscopist. Colonoscopy in the identified high-risk group could be extremely challenging to endoscopists, and may expose patients to a higher rate of morbidity and mortality as compared to its rival CTC.

CTC, in our study, proved to be an alternative diagnostic procedure to colonoscopy in this group. Therefore, a universal safeguard protocol considering CTC as an alternative first line investigation may need to be addressed in the future, to avoid colonoscopy in the high-risk group for incomplete colonoscopy and its unwanted consequences.

Conclusions

Colonoscopy is a challenging procedure in high-risk patients for incomplete colonoscopy in the presence of CTC a successful and a safe diagnostic imaging alternative. This study sheds the light on the future of CTC as a first line modality in this group.

Acknowledgments

Presented at the Association of Surgeons of Great Britain and Ireland, Liverpool 9-11 May 2018. Presented at International Healthcare Summit, Dubai 18-19 Dec 2017.

Funding: None.

Footnote

Reporting Checklist: The authors have completed the STARD reporting checklist. Available at http://dx.doi.org/10.21037/dmr-20-22

Data Sharing Statement: Available at http://dx.doi.org/10.21037/dmr-20-22

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/dmr-20-22). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. No procedures performed in our studies involving patients. Informed consent was not required. The data was collected for internal audit for improvement and quality assurance. No statement from patients are required or consent.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Brenner H, Kloor M, Pox CP. Colorectal cancer. Lancet 2014;383:1490-502. [Crossref] [PubMed]
2. Ferlay J, Shin HR, Bray F, et al. Estimates of worldwide burden of cancer in 2008: GLOBOCAN 2008. Int J Cancer 2010;127:2893-917. [Crossref] [PubMed]
3. Cardin F, Minicuci N, Andreotti A, et al. Maximizing the general success of cecal intubation during propofol sedation in a multi-endoscopist academic centre. BMC Gastroenterol. 2010;10:123. [Crossref] [PubMed]
4. Rex DK, Bond JH, Winawer S, et al. U.S. Multi-Society Task Force on Colorectal Cancer. Quality in the technical performance of colonoscopy and the continuous quality improvement process for colonoscopy: recommendations of the U.S. Multi-Society Task Force on Colorectal Cancer. Am J Gastroenterol 2002;97:1296-308. [Crossref] [PubMed]
5. Mitchell RM, McCallion K, Gardiner KR, et al. Successful colonoscopy; completion rates and reasons for incompletion. Ulster Med J 2002;71:34-7. [PubMed]
6. Koido S, Ohkusa T, Nakae K, et al. Factors associated with incomplete colonoscopy at a Japanese academic hospital. World J Gastroenterol 2014;20:6961-7. [Crossref] [PubMed]
7. Shah HA, Paszat LF, Saskin R, et al. Factors associated with incomplete colonoscopy: a population-based study. Gastroenterology 2007;132:2297-303. [Crossref] [PubMed]
8. Neerincx M. Colonic work-up after incomplete colonoscopy: significant new findings during follow-up. Endoscopy 2010;42:730-5. [Crossref] [PubMed]
9. Anderson JC, Messina CR, Cohn W, et al. Factors predictive of difficult colonoscopy. Gastrointest Endosc 2001;54:558-62. [Crossref] [PubMed]
10. Pickhardt PJ. Imaging and Screening for Colorectal Cancer with CT Colonography. Radiol Clin North Am 2017;55:1183-96. [Crossref] [PubMed]
11. Furlow B. Computed tomography colonography. Radiol Technol. 2013;84:493-511. [PubMed]
12. Yoshida H, Dachman AH. Computer-aided diagnosis for CT colonography. Semin Ultrasound CT MR 2004;25:419-31. [Crossref] [PubMed]
13. Halligan S, Altman DG, Taylor SA, et al. CT colonography in the detection of colorectal polyps and cancer: systematic review, meta-analysis, and proposed minimum data set for study level reporting. Radiology 2005;237:893-904. [Crossref] [PubMed]
14. Gluecker TM, Johnson CD, Wilson LA, et al. Extracolonic findings at CT colonography: evaluation of prevalence and cost in a screening population. Gastroenterology 2003;124:911-6. [Crossref] [PubMed]
15. Hara AK, Johnson CD, MacCarty RL, et al. Incidental extracolonic findings at CT colonography. Radiology 2000;215:353-7. [Crossref] [PubMed]
16. Devir C, Kebapci M, Temel T, et al. Comparison of 64-Detector CT Colonography and Conventional Colonoscopy in the Detection of Colorectal Lesions. Iran J Radiol 2016;13:e19518. [Crossref] [PubMed]
17. Waldmann E, Regula J, Ferlitsch M. How can screening colonoscopy be optimized? Dig Dis 2015;33:19-27. [Crossref] [PubMed]
18. Brenner H. Risk of progression of advanced adenomas to colorectal cancer by age and sex: estimates based on 840,149 screening colonoscopies. Gut 2007;56:1585-9. [Crossref] [PubMed]
19. Brenner H, Altenhofen L, Stock C, et al. Prevention, early detection, and overdiagnosis of colorectal cancer within 10 years of screening colonoscopy in Germany. Clin Gastroenterol Hepatol 2015;13:717-23. [Crossref] [PubMed]
20. Brenner H, Altenhofen L, Stock C, et al. Natural history of colorectal adenomas: Birth cohort analysis among 36. million participants of screening colonoscopy. Cancer Epidemiol Biomarkers Prev 2013;22:1043-51. [Crossref] [PubMed]
21. Brenner H, Altenhofen L, Stock C, et al. Expected long-term impact of the German screening colonoscopy program on colorectal cancer prevention: analyses based on 4,407,971 screening colonoscopies. Eur J Cancer 2015;51:1346-53. [Crossref] [PubMed]
22. Seeff LC, Richards TB, Shapiro JA, et al. How many endoscopies are performed for colorectal cancer screening? Results from CDC's survey of endoscopic capacity. Gastroenterology 2004;127:1670-7. [Crossref] [PubMed]
23. Cai SL, Chen T, Yao LQ, et al. Management of iatrogenic colorectal perforation: from surgery to endoscopy. World J Gastrointest Endosc 2015;7:819-23. [Crossref] [PubMed]
24. Iqbal CW, Cullinane DC, Schiller HJ, et al. Surgical management and outcomes of 165 colonoscopic perforations from a single institution. Arch Surg 2008;143:701-6. [Crossref] [PubMed]
25. Herman LL, Kurtz RC, McKee KJ, et al. Risk factors associated with vasovagal reactions during colonoscopy. Gastrointest Endosc 1993;39:388-91. [Crossref] [PubMed]
26. Reumkens A, Rondagh EJ, Bakker CM, et al. Post-Colonoscopy Complications: A Systematic Review, Time Trends, and Meta-Analysis of Population-Based Studies. Am J Gastroenterol 2016;111:1092-101. [Crossref] [PubMed]
27. Church J. Complications of colonoscopy. Gastroenterol Clin North Am 2013;42:639-57. [Crossref] [PubMed]
28. Kothari ST, Huang RJ, Shaukat A, et al. ASGE review of adverse events in colonoscopy. Gastrointest Endosc 2019;90:863-76.e33. [Crossref] [PubMed]
29. Rai V, Mishra N. Colonoscopic Perforations. Clin Colon Rectal Surg 2018;31:41-6. [Crossref] [PubMed]
30. Bielawska B, Day AG, Lieberman DA, et al. Risk factors for early colonoscopic perforation include non-gastroenterologist endoscopists: a multivariable analysis. Clin Gastroenterol Hepatol 2014;12:85-92. [Crossref] [PubMed]
31. Kim SY, Kim HS, Park HJ. Adverse events related to colonoscopy: Global trends and future challenges. World J Gastroenterol 2019;25:190-204. [Crossref] [PubMed]
32. Day LW, Kwon A, Inadomi JM, et al. Adverse events in older patients undergoing colonoscopy: a systematic review and meta-analysis. Gastrointest Endosc 2011;74:885-96. [Crossref] [PubMed]
33. Cirocco WC, Rusin LC. Factors that predict incomplete colonoscopy. Dis Colon Rectum 1995;38:964-8. [Crossref] [PubMed]
34. Iqbal CW, Chun YS, Farley DR. Colonoscopic perforations: a retrospective review J Gastrointest Surg 2005;9:1229-35. [Crossref] [PubMed]
35. Shah HA, Paszat LF, Saskin R, et al. Factors Associated With Incomplete Colonoscopy: A Population-Based Study. Gastroenterology 2007;132:2297-303. [Crossref] [PubMed]
36. Hanson ME, Pickhardt PJ, Kim DH, et al. Anatomic Factors Predictive of Incomplete Colonoscopy Based on Findings at CT Colonography. AJR Am J Roentgenol 2007;189:774-9. [Crossref] [PubMed]
37. Dafnis G, Granath F, Påhlman L, et al. Patient factors influencing the completion rate in colonoscopy. Dig Liver Dis 2005;37:113-8. [Crossref] [PubMed]