Computed Tomography Colonography (CTC): Is It Really the Non-Invasive Option We Think It Is? A Patient Experience Study.

Aims: Computed tomography colonography (CTC) is seen as a more tolerable alternative to colonoscopy, but patients struggle with the steps required for optimal diagnostic imaging. This prospective study aims to understand the experience of patients undergoing CTC.
Methods: A survey was completed by a convenience sample of patients before and after CTC over 7 months. The 13-item questionnaire covered pre-test information, overall and specific experience of the test. The responses were tabulated and analyzed using descriptive statistics. Qualitative free-text responses were coded for content and thematic analysis.
Results: At a response rate of 51%, surveys were received from 41 patients. Overall, most patients (54%) found the investigation better than expected. However, 18% stated they were not informed of potential side effects. Side effects were experienced by 49% of patients, including diarrhea (34%) and abdominal pain (24%). About 59% experienced discomfort with gas insufflation, and 86% found turning during the investigation difficult.
Conclusion: A significant proportion of patients undergoing CTC experience side effects and difficulties completing the investigation. Patient information is important to improve patient experience of CTC.

With the introduction of straight-to-test CTC and an aging population worldwide, the volume of frail patients being referred direct from primary care will increase. Our study has highlighted the various components of CTC to consider when referring for this test that some patients find difficult.

Introduction

Colorectal cancer is the third most common cancer for both men and women in England (1) and is the second most common cause of cancer-related deaths in the United Kingdom (2). Colonoscopy is the gold-standard investigation for suspected colorectal cancer (3), but computed tomography colonography (CTC), developed in 1994 (4), has now superseded barium enema as the investigation of choice when colonoscopy is unsuccessful or deemed inappropriate (5).

CTC is a radiological investigation used to identify neoplastic lesions in the colon and rectum. The procedure involves the use of abdominal and pelvic computed tomography (CT), enhanced by the use intra-luminal contrast and gaseous distension. Patients are required to perform repositioning maneuvers in the confined space of a CT scanner in order to obtain optimal prone and supine diagnostic images (6).

Frailty describes an important multifaceted medical syndrome in which individuals experience increased vulnerability to dependency and death due to reduced physiological and physical reserve (7). There are several validated models used to screen for frailty, of which the Clinical Frailty Scale, developed by Rockwood et al, provides a simple and rapid assessment tool and is commonly used in the United Kingdom (8). On a scale of 1 (very fit) to 9 (terminally ill), patients who score 5 or higher are considered frail.

CTC has a relative sensitivity to colonoscopy of up to 96% (9) but requires less cathartic preparation (10) and is therefore frequently recommended in frailty, with 25% of patients undergoing CTC being assessed as mild to severely frail (11). It is increasingly recognized that many frail patients struggle with the preparation, gas insufflation, and mobilization required for optimal CTC images.

The demand for CTC investigations has been rising in recent years (12) and direct referral from primary care has been introduced in certain regions of the United Kingdom (13). In addition to this, the COVID-19 pandemic has added pressure to the growing waiting lists of endoscopic and radiological investigations. Appropriate referrals will be vital to help ensure services can address the backlog.

This study aims to better understand the experience and tolerability of patients undergoing CTC in order to better prepare prospective patients and aid clinical decision-making in the investigation of potential colorectal cancer.

Methods

The authors undertook a single-centered, observational cohort study at a large volume tertiary colorectal center. We hypothesized that various aspects of the CTC protocol, aimed at enhancing diagnostic imaging, may have a significant impact on a patient's experience of the investigation.

Survey Tool

A patient experience survey was designed by the authors from the colorectal surgery department, and through collaboration with the trust's patient survey team, was refined to maximize content validity and optimize layout. Following approval for use by the Questionnaire, Interview & Survey Group (QIS), the survey was piloted on 5 patients, and subsequently adapted in consultation with the department of radiology to improve useability. The 13-item survey consisted of 2 Likert scales, 10 discreet questions and the option to expand in 4 free-text boxes and was accompanied by a cover letter. It was designed to investigate various aspects of the patient's experience, including the quality of the pre-test information, overall and specific experience of the test including side effects, discomfort from gas insufflation and difficulty performing the required maneuvers. The full survey is available in Figure 1.

Figure 1.

Patient experience survey.

Patient Sampling and Data Collection

All patients who underwent a CTC at the radiology department were eligible to participate in this study. This cohort included patients referred from the outpatient departments, inpatient admissions and direct referrals from primary care. Indications for the investigation included: clinical suspicion of colorectal malignancy where patients were deemed unsuitable for colonoscopy, failed colonoscopy and surveillance imaging of previously identified colorectal pathology. A convenience sample of 41 patients was obtained over a 7-month period. There was an interruption of 12 weeks due to the COVID-19 pandemic, where scanning and data collection was suspended, before the radiology department restarted at a reduced operating capacity.

Patients were invited to participate in the study upon checking into the department. They were then provided with an information leaflet and verbally consented by the radiographer for their anonymous participation in the study. Responses were completed before and after the procedure and collected in a designated box.

CTC Protocol

At 2 days before the scan, patients were instructed to eat a low-fiber diet up until and including lunch time. After this, they were permitted a soft food diet. On the day of the scan, patients could drink clear fluids only. Patients were asked to drink 2 50 mL doses of Gastrograffin® (Bracco Diagnostics Inc.) in the 2 evenings prior to the scan. Intravenous hyoscine butylbromide was administered prior to gas insufflation. An automated carbon dioxide insuflator was used to achieve maximal pressures tolerated by patients. Two positions were used in the scanning protocol: prone and supine, and images were captured on inspiration.

Statistical Analysis

The frequency of responses per question was tabulated and analyzed using descriptive statistics. Questions were analyzed individually, using a denominator equivalent to the total number of fully completed responses. Some results were grouped to aid interpretation of scaled responses. Qualitative free-text responses were coded for content and thematic analysis (14).

Results

There was a response rate of 51%. There were no major complications or unplanned admissions following CTC. Full results are shown in Table 1.

Table 1.

Questionnaire Results.

	Total	%	n =
Were you told why you needed the procedure?
Yes completely	30	77	39
Yes to some extent	8	21	39
No	0	0	39
Can't remember	1	3	39
Did you receive written information?
Yes	36	92	39
No	3	8	39
Can't remember	0	0	39
Did you find this written information helpful?
Yes definitely	35	95	37
Yes to some extent	2	5	37
No	0	0	37
Can't remember	0	0	37
Explanation of procedure?
Yes completely	29	76	38
Yes to some extent	4	11	38
No	3	8	38
Can't remember	2	5	38
Explanation of risks/benefits?
Yes completely	25	66	38
Yes to some extent	8	21	38
No	4	11	38
Can't remember	1	3	38
Explanation of how to take contrast?
Yes completely	29	83	35
Yes to some extent	2	6	35
No	3	9	35
Can't remember	1	3	35
Explanation of dye side effects?
Yes completely	21	64	33
Yes to some extent	4	12	33
No	6	18	33
Can't remember	2	6	33
Did you have all the information needed?
Yes	37	95	39
No	1	3	39
Not sure	1	3	39
Side effects experienced?
Yes	19	51	37
No	18	49	37
Side effects:
Mild diarrhea	9	24	37
Bad taste	5	14	37
Nausea	6	16	37
Severe diarrhea	5	14	37
Stomach pain	10	27	37
Other:	4	11	37
Any amount of diarrhea	14	38	37
	Total	%	n =
Experience:
Better than expected	21	54	39
About same as expected	17	44	39
Worse than expected	0	0	39
Not sure	1	3	39
Discomfort inserting tube
No discomfort	20	57	35
Discomfort 2/5	8	23	35
Discomfort 3/5	7	20	35
Discomfort 4/5	0	0	35
Extreme discomfort 5/5	0	0	35
Any degree of discomfort	15	43	35
Discomfort with gas insufflation
No discomfort	14	41	34
Discomfort 2/5	7	21	34
Discomfort 3/5	10	29	34
Discomfort 4/5	3	9	34
Extreme discomfort 5/5	0	0	34
Any degree of discomfort	20	59	34
Discomfort removing tube
No discomfort	22	63	35
Discomfort 2/5	8	23	35
Discomfort 3/5	5	14	35
Discomfort 4/5	0	0	35
Extreme discomfort 5/5	0	0	35
Any degree of discomfort	13	37	35
Turning difficulty
Yes	22	59	37
Yes to some extent	10	27	37
No difficulty	5	14	37
Any degree of difficulty	32	86	37
Was your dignity maintained?
Yes definitely	34	92	37
Yes to some extent	3	8	37
No	0	0	37
Communication of results?
Yes	24	69	35
No	11	31	35

Quantitative

Overall, the majority of patients (54%) found the investigation better than expected and 100% felt their dignity was maintained. However, 51% reported some form of side effect. Over a third (38%) of these experienced diarrhea from the contrast drink, of which 5 (14%) was severe. Abdominal pain (27%), followed by nausea (16%), were the next most common side effects associated with the scan (Figure 2).

Figure 2.

Side effects.

Around half of patients found the tube insertion uncomfortable (43%), and 59% experienced discomfort from the gas insufflation itself. None rated this discomfort extreme, but 50% rated it at a level 2 to 3 out of 5, and 9% 4 out of 5 in severity. Removing the tube was felt to be uncomfortable in only 37% of cases (Figure 3). Regarding mobility issues, 86% had any degree of difficulty performing the turning maneuvers in the scanner, of whom 59% had significant difficulty.

Figure 3.

Patient discomfort.

About 97% understood the indication for this test and 95% found their written information helpful. Despite this, 8% felt they were not told what would happen during the procedure, 11% felt they were not informed of the risks and benefits, 9% did not know how to take the contrast dye and 18% were not aware of its potential side effects. Regarding follow-up, 31% were unsure how and when their results would be communicated to them.

Free Text Responses

The majority of free-text responses were shared in the final comments section. The 4 main themes identified reflect the relative importance of aspects identified from the quantitative results.

Information giving. The degree to which patients felt informed had an influence on their overall experience, with some feeling empowered: “they explained everything,” while others felt they were “given vague instructions.”

Feeling at ease. Reflecting the high reporting of dignity maintenance, patients valued the “considerate and friendly team,” who were “helpful and caring” and allowed patients to feel “able to relax.”

Physical difficulties. Some of those who struggled in the procedure chose to elaborate further, providing reasoning for their difficulties: “being a bigger lady” and describing their “difficulty turning due to back problems.” Some chose to offer suggestions, including “maybe some grab handles.”

Very good service. Some felt they “need not have worried,” finding the overall experience positive. Practical elements including having their “appointment on time” was highly valued.

Discussion and Conclusions

CTC’s use in Frail Populations

In a review completed in our center (9), 25% of patients with a documented Rockwood frailty score undergoing CTC were mild-severely frail. CTC provided a definitive diagnosis in 79% of cases, however 31% of the 306 patients required further investigation with endoscopy to either confirm or rule out a suspicion on the CTC. About 18% of those requiring further investigation had a Rockwood score of 5 or over.

With the introduction of straight-to-test CTC (13) and an aging population worldwide (15), the volume of frail patients being referred direct from primary care will increase. Previous studies have shown good overall tolerability of CTC (16), but our study has highlighted the various components of the test that some patients find difficult which is important for clinicians to consider when referring for CTC.

Whilst protocols for CTCs differ between units, our study has illustrated issues related to different aspects of the preparation and procedure.

Preparation

Fecal tagging is a fundamental stage in all CTC protocols and although supplemental cathartic bowel preparation is no longer used in many centers, the gastrointestinal effects of agents such as Gastrograffin® are often neglected. Our study has found that Gastrograffin® produced a number of frequently reported side effects including abdominal pain and diarrhea. Previous studies have not shown any significant biochemical abnormality (17) caused by fecal tagging agents, however clinicians may need to be aware of the potential risk dehydration may cause to those with reduced renal functions or significant comorbidities.

Emphasis should be placed by the clinical team during the consenting process on the potential effects of fecal tagging agents. Frailty may affect the patient's ability to mobilize to the toilet or administer analgesia when required and practical preparations may need to be made in their home in the period prior to the test, for example extra support or a commode. Whilst minimal preparation CTC protocols have been developed which provide an overall more tolerable investigation (18), it does not entirely prevent potentially significant patient distress.

Scanning Protocol

Adequate colonic distension is important in achieving good quality diagnostic imaging, with one study finding a reduction in false positive rates from 15% to 5% (19) and reduced scanning time (20). Other methods of achieving colonic distension, used in varying combinations, include turning maneuvers and the use of antispasmodic agents, although evidence for the use of the latter is weak (20), and many minimally invasive CTC protocols do not recommend their use.

A significant proportion of our patient population experienced discomfort with the overall use of gas, however the majority of these found the discomfort moderate. We are also unable to draw any direct conclusions regarding the impact of this discomfort on the patients’ overall experience and tolerability.

A significant proportion of our patient population struggled manoeuvering during the investigation, with patients reporting increased body habitus and pre-existing back pain as contributing factors.

Patients with restricted mobility, not otherwise deemed frail, referred for CTC following a failed colonoscopy due to this reason, should be assessed for their ability to complete the required turning maneuvers in the CT scanner. Using a combination of 2 scanning positions has been shown to increase the quality of colonographic imaging (21), although, for those less mobile, it has been suggested this could be using a combination of supine-left decubitus as an alternative to supine-prone, while still achieving adequate test sensitivity.

The issues raised in this study, combined with the fact CTCs are time consuming to perform and report, means other imaging strategies may need to be considered, particularly in the context of rising demand. Alternatives include: For patients deemed unsuitable for surgical or oncological intervention but where diagnostic information will be aid in advanced and supportive care planning, intravenous contrast-enhanced CT (IVCT) without specialist colonographic protocols can be considered. IVCT has been demonstrated to have a sensitivity of 72.4% for the detection of invasive colorectal cancers but a low sensitivity for polyp detection (10.1%) (22). The inferiority of IVCT should be considered in the context of the patient and that progression from adenoma to adenocarcinoma may take 5 to 8 years (23). If IVCT is used to exclude malignancy, the negative predictive value for invasive colorectal malignancy of 78.9% to 100% (22,24). IVCT can be performed without the need for oral contrast, gas insufflation or patient turning and the scan itself requires less time in the scanner and radiologist reporting time.

1. Non-Colonography CT

CTC is clearly the superior investigation to IVCT in the identification of polyps and colorectal malignancy however for patients in whom invasive investigation or treatment would be intolerable, IVCT could provide adequate prognostic information regarding significant or extensive disease or metastasis. As such, evaluation of the clinical significance of test characteristics in relation to patient-specific needs and involving patients in these discussions will aid in clinical decision-making (25). The number of minimally invasive imaging technique protocols has increased globally in recent years (26). Further evaluation of how frailty affects the tolerance of each aspect of CTC is required in order to develop individualized patient tailored CTC protocols. This could allow us to balance patient experience with adequate diagnostic outcomes.

2. Patient Tailored CTC Protocols

The data collected in this study contributes to a growing pool of information that referring clinicians can use to prepare and select patients for our current CTC protocols.

Limitations

The study was carried out at a single center and has a relatively small sample size. It should be considered, therefore, that this study may not have captured all experiences of patients undergoing CTC. The volume of patients recruited into the study was restricted, in part, due to the disruption caused by the COVID-19 pandemic that came into effect halfway through data collection. It is also important to consider that the restrictions imposed and anxiety around the virus transmission may have changed the demographics of patients seen in clinic and attending for outpatient investigations. Due to the relatively greater risk of the virus to older populations, our study group may have under-represented those considered more frail. Supplementation with results from a larger study will help to validate the findings presented in this paper. The requirement for personal protective equipment and non-touch interactions with reception staff may also have influenced patient experience but did not disrupt the CTC protocol used in the center.