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Because the miss rate of polyps in colonoscopy remains high, an appropriate approach for all polyps, even for lesions detected upon endoscope insertion, plays an important role in achieving high-quality colonoscopy.
During colonoscopy, although left-sided polyps detected upon endoscope insertion are often missed after withdrawal of the endoscope, they are commonly not removed instantly during insertion of the endoscope; rather, they are removed during the withdrawal phase (WP) after the cecum has been reached. Teramoto et al
reported that instant polypectomy upon endoscope insertion is associated with a shorter procedure time, but this strategy requires advanced insertion and polypectomy techniques. Here, we propose a novel marking technique termed “suction marking method” as an alternative to performing polypectomy during the insertion phase (IP) of colonoscopy. Suction marks can be easily created by artificially applying suction pressure onto the mucous membrane, and these red marks assist redetection of polyps upon withdrawal of the colonoscope.
We designed this prospective single-center study to investigate whether the application of suction marks near polyps detected during the IP improves their redetection rate upon withdrawal of the endoscope.
Methods
Patients
All patients aged ≥20 years referred for total colonoscopy at Sano Hospital between March and May 2019 were screened for eligibility for the study. Written informed consent was obtained from each patient before the study. The exclusion criteria were as follows: colonoscopy indication due to bleeding, history of colectomy (excluding appendectomy), inflammatory bowel disease, polyposis of the alimentary tract, use of anticoagulant agents, pregnancy, and failure to reach the cecum or severe discomfort in a previous colonoscopy.
The suction marking method was applied to patients, and the details of the examination were fully documented when at least 1 target polyp was detected during the IP. Target lesions in the left side of the colon were defined as follows: (1) adenomas or sessile serrated adenomas/polyps <10 mm and (2) hyperplastic polyps 6 to 10 mm in size. Patients with ≥6 polyps, poor bowel preparation, disinhibition/agitation due to sedation, and difficulty with endoscope insertion were excluded from the analysis.
The study was approved by the institutional review board of Sano Hospital, Kobe, Japan (No. 201902-02) and was registered in a clinical trial registry (UMIN000036030).
Procedures
Eight senior endoscopists with at least 5 years of experience who had performed over 300 colonoscopies per year participated in this study. Premedications included scopolamine butylbromide (10-20 mg), midazolam (2.5-5 mg), and meperidine (25-50 mg, additionally used when required). Colonic insufflation was performed with CO2 gas in all cases. We used the Olympus 260 and 290 series colonoscopes with EVIS Lucera Spectrum or EVIS Lucera Elite video processors (Olympus Corporation, Tokyo, Japan). Distal attachments or transparent caps were not used during this trial. Yox Dispo Ope (Koike Medical, Tokyo, Japan) was used to apply the suction marks, and its pressure setting was 60 kPa.
Upon endoscope insertion, 1 suction mark was created per lesion by aspiration of colonic mucosa for at least 10 seconds once a target lesion was detected (Figure 1, Figure 2, Figure 3, Figure 4). Each suction mark was made beside the lesion on either the oral or the distal side. The endoscopists chose the location where suction marking was technically easier to apply. This process was repeated when the suction mark was unclear. After a clear suction mark was confirmed, endoscope insertion was resumed, and all polyps were removed upon withdrawal of the endoscope by cold snare polypectomy. To measure the rate of successful redetection of polyps detected during the IP, we used 2 terms suggested by Teramoto et al:
(1) hiding polyp, a polyp detected during endoscope insertion, lost in the WP but eventually found after reinsertion of the colonoscope, and (2) missed polyp, a polyp detected during endoscope insertion but not found after a minimum of 2 minutes of reinspection.
The data capture sheet we used for this study included the following parameters: name of endoscopist, detection of target lesions (yes or no), quality of bowel preparation (excellent, good, or poor), use of analgesics and/or sedation, endoscope model used, number of target lesions detected during the IP, number of hiding and missed polyps, number of resected polyps during the WP, cecal intubation time, total procedure time, treatment time, time required to find each hiding polyp, time spent searching for missed polyps, endoscopic diagnosis, size, morphologic type, and location of polyps.
The primary endpoint of this study was the proportion of hiding and missed polyps. The secondary endpoint included the duration of suction applied per lesion.
Results
A total of 166 patients were recruited for the trial from March to May 2019, and 39 patients (23.5%) had at least 1 detectable target lesion during the IP. Thirty-nine target lesions from 33 patients were eligible for full assessment (Fig. 5).
The mean age of the study population was 63.6 ± 9.9 years, and 51.5% were men. Ninety-seven percent of patients received sedation, and the most common indication was surveillance colonoscopy after polypectomy (Table 1). Target lesions were mostly adenomas (34 [87.2%]) in the sigmoid colon (23 [59.0%]); their morphologic feature was type 0-IIa (34 [87.2%]), and their mean size was 4.3 ± 1.9 mm (Table 2). All target polyps were successfully redetected on endoscope withdrawal (Table 3). However, 1 hiding polyp (2.6%, 6 mm) in the sigmoid colon was reported. A mean suction duration of 30.2 ± 24.2 seconds was required to create a visible mark on the colonic mucosa. The mean withdrawal time was 7.5 ± 2.9 minutes. Adverse events were not reported during this trial.
Table 1Baseline characteristics of patients
Total number of patients (n)
33
Male:female
17:16
Age (mean ± SD)
63.6 ± 9.9
Sedation
Sedatives only
30
Sedatives + analgesics
2
No sedatives or analgesics
1
Bowel preparation
Excellent
14
Good
19
Indications
Surveillance after polypectomy
13
FIT positive
9
Symptomatic
6
Other
5
FIT, Fecal immunochemical testing; SD, standard deviation.
Our trial demonstrated the effectiveness of the suction marking method for successful redetection of polyps found during the IP. As presented in Video 1 (available online at www.VideoGIE.org), the suction marks were sufficiently prominent to assist redetection of polyps, and all marks were readily visible upon withdrawal. Notably, the proportion of hiding and missed polyps dropped significantly from 38% to 2.6% and 10% to 0%, respectively, in comparison with our previous randomized trial.
Our strategy is advantageous because it can reduce the rate of missed lesions without requiring specific devices or skills. Another advantage of suction marking is that it does not cause excessive gas insufflation because air is automatically aspirated during the marking procedure; therefore, theoretically it does not lead to difficult endoscope insertion.
The only disadvantage of our strategy is the 30-second interval needed to create a suction mark, which may be frustrating in comparison with the conventional strategy. To maintain the time efficiency of routine colonoscopy, our trial focused on left-sided and small/diminutive polyps and excluded multiple polyps. The main limitation of our study is that it was conducted in a single center with a small number of patients, and there was no control group.
In conclusion, the suction marking method is a novel technique to prevent missing polyps detected upon endoscope insertion. Although this technique requires a short interval during endoscope insertion, it is a simple, reliable, cost-free, and widely available method for achieving better quality of colonoscopy.
Disclosure
All authors disclosed no financial relationships relevant to this publication.
Acknowledgments
The authors thank Wataru Sano, Mikio Fujita, Santa Hattori, and Mineo Iwatate for providing technical support, and Stephen Landua for English narration.
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