Update on Colonoscopy Preparation, Premedication and Sedation

Jeffrey R Lewis; Lawrence B Cohen

Expert Rev Gastroenterol Hepatol. 2013;7(1):77-87.

Timing of Preparation

Reducing the 'runway time' between the last ingestion of bowel preparation agent and colonoscopy improves visualization of the bowel, especially the proximal colon, and enhances the detection of polyps.^[10,11] A meta-analysis of five randomized controlled trials performed between 2005 and 2010 involving PEG-based preparations found that split dosing resulted in improved colon cleansing and patient satisfaction when compared with a preparation taken the day prior to examination.^[12] Several studies published during the past year further support this view and have even examined same-day preparation.

A study by Seo et al. examined the influence of time between last dose of PEG ingestion and start of colonoscopy on bowel preparation quality in 366 subjects.^[13] Subjects consumed a low-residue diet for 3 days; 2-l doses of PEG were administered the evening prior to the colonoscopy and another 2-l PEG 2–8 h prior to colonoscopy. The primary outcome was bowel cleanliness using the Ottawa Scale. The best preparation scores, both overall and within each segment, were observed in subjects who consumed their second dose of preparation 3–5 h prior to colonoscopy (Figure 1). Additionally, the study found that the volume of PEG ingested and patient compliance with instructions also correlated with the preparation outcome. While the limitations of this observational single-center study are evident, it serves to reinforce the concepts that split dosing and patient education play important roles in maximizing the quality of bowel cleansing and consequently the quality of colonoscopy.

(Enlarge Image)

Figure 1.

The relationship between preparation-to-colonoscopy interval and mean total Ottawa score.
*p < 0.05.
Ottawa: Ottawa Bowel Preparation Scale; PC: Preparation-to-colonoscopy.Reprinted with permission from [13].

Similar findings were reported by another group of Korean investigators who prospectively studied the quality of bowel preparation in 300 subjects undergoing colonoscopy.^[14] All subjects were prepared using a 4-l PEG solution. Subjects were requested to record when they began and completed the preparation as well as the procedure start time. They found that a better quality bowel preparation was present in subjects who began their preparation less than 7 h, and completed their preparation less than 4 h, prior to colonoscopy. The authors conclude that the timing of the bowel preparation relative to the time of examination is more important in determining the quality of bowel preparation than the time of examination. The authors conclude that the ideal 'window of opportunity' for achieving the optimal bowel preparation was 4–7 h prior to start of the examination. Comparable studies in western patients are eagerly awaited.

Same-day bowel cleansing for colonoscopy has been practiced in parts of Asia, particularly Japan, for many years. Until recently, this practice was inconceivable to endoscopists in the western world. The trend toward split-dosing has changed this attitude, however, and we are now seeing an increased number of reports describing same-day preparation. Researchers from Mayo Clinic Scottsdale (AZ, USA) retrospectively reviewed the colonoscopy records of 1345 subjects who underwent afternoon colonoscopy.^[15] All subjects were instructed to consume a low-fiber diet for 2 days prior to colonoscopy and were given the option of consuming a PEG-based preparation using one of the following dosing schemas: 4 l PEG the evening before, 4 l PEG the morning of, 2 l PEG plus bisacodyl (20 mg) the morning of or 2 l PEG taken the evening before and repeated the morning of colonoscopy. The primary outcome was bowel preparation quality according to the Aronchick score. Multivariate analysis indicated that preparations completed on the same day were more likely to result in a good or excellent preparation compared with the 4 l evening regimen (odds ratio: 7.03; 95% CI: 2.57–19.22; p < 0.001). The secondary outcomes of colonoscopy completion rates and ADR were similar for these three preparations. They concluded that a same-day PEG bowel preparation yields significantly improved colonic preparation for afternoon colonoscopy compared with preparations completed the evening prior to examination.

A study by Longcroft-Wheaten and Bhandari in the UK aimed to compare the efficacy and tolerability of sodium picosulfate in 227 subjects undergoing afternoon colonoscopy who received either two doses the day before and one dose at 8 AM the morning of colonoscopy or two doses on the day of examination (at 7 and 10 AM).^[16] The group that received the same-day preparation had better bowel cleansing than the split-dose group with average and excellent preparations observed in 98.4 and 89.5%, respectively (p = 0.0046). Furthermore, patient tolerance was superior with same-day preparation compared with the split-dose regimen. ADRs were similar in both groups.

The optimal regimen for optimizing bowel cleansing, regardless of the purgative agent selected, requires that at least part of the dose be administered within 4–7 h of the examination. This method of split-dosing preparation maximizes bowel cleansing, especially within the proximal colon where flat adenomas and subtle serrated lesions are easily missed if the bowel wall is not well cleansed. It is time for all endoscopists, regardless of what agent(s) they prefer for purgation, to adopt a split-dose regimen for colonoscopy preparation.

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Table 1. Ottawa Bowel Preparation Scale.
Quality of preparation	Score
Assessment of right, mid-colon and left colon
No liquid	0
Minimal liquid, no suctioning required	1
Small particles, suctioning required	2
Semi-solid, wash and suction	3
Solid stool, not all washable	4
Overall colon assessment
Amount of fluid present	0–2

The scale rates three sections of the colon, right (cecum and ascending colon), mid-colon (transverse and descending) and rectosigmoid, on a five-point scale (0–4).
Total score (0–14) is obtained by adding the scores for individual evaluation of right, mid-colon and left colon with the score of overall fluid.
Modified from [3].

Table 2. Approach to antiplatelet therapy in the periendoscopic period.
Thrombotic risk	Endoscopy with low bleeding risk	Endoscopy with high bleeding risk
*Low^†*
Coronary DES placed >12 months previously	Continue APA therapy	Stop ASA 5 days prior to EUS-FNA of cysts, EMR and ESD, ampullary resection and endoscopic sphincterotomy with large-balloon papillary dilation for biliary stone extraction
Bare-metal coronary stent placed >6 weeks previously without risk factors^‡		In patients taking a thienopyridine alone, it is recommended to substitute aspirin^§
Stroke without cardiac failure >6 weeks previously
*High^†*
Coronary DES placed ≤12 months previously	Continue dual APA therapy
Bare-metal coronary stent placed ≤6 weeks previously or >6 weeks with associated risk factors^‡		Delay endoscopy and/or consult a cardiologist to discuss temporary cessation of thienopyridine:Clopidogrel, 5 daysPrasugrel, 7 days
Stroke ≤6 weeks previously		ASA should be continued in all cases

^†Patients with a low thrombotic risk receive a single antiplatelet agent; those with a high thrombotic risk receive two antiplatelet agents.
^‡Risk factors: diabetes, renal failure, cancer, chronic heart failure, complex coronary artery stenosis or history of coronary stent thrombosis.
^§Thienopyridines should be stopped (clopidogrel for 5 days and prasugrel for 7 days) prior to procedure and aspirin substituted. Thienopyridines will be resumed shortly after the procedure if aspirin is inadequate for long-term prevention.
APA: Antiplatelet agent; DES: Drug-eluting stent; EMR: Endoscopic mucosal resection; ESD: Endoscopic submucosal dissection; EUS-FNA: Endoscopic ultrasonography-guided fine.needle aspiration.
Reprinted with permission from [26].

Table 3. Bleeding risk associated with endoscopic procedures.
Bleeding risk	Procedure	Continue aspirin	Continue thienopyridine
Low	EGD and colonoscopy ± biopsy	Yes	Yes
	EUS without FNA	Yes	Yes
	Colonic polypectomy <1 cm	Yes	No^†
	Dilation of digestive stenosis	Yes	No
	EUS-FNA of solid masses	Yes	No
	Digestive stenting	Yes	No
	ERCP with stent placement or papillary balloon dilation without endoscopic sphincterotomy	Yes	Yes
	Argon plasma coagulation	Yes	No^‡
High	EMR, ESD and ampullary resection	No	No
	Endoscopic sphincterotomy	Yes	No
	Endoscopic sphincterotomy + large balloon papillary dilation	No	No
	Colonic polypectomy >1 cm	Yes	No^†
	EUS-FNA of cystic lesions	No	No
	Percutaneous endoscopic gastrostomy	Yes	NA
	Esophageal variceal band ligation	Yes	No

^†Bleeding may be prevented by placing a detachable loop ligating device or utilizing submucosal injection. The resection of small polyps (<1 cm) is probably safe in patients taking clopidogrel (not prasugrel) with such preventive measures. Insufficient data are available regarding prophylactic endoclip placement.
^‡Argon plasma coagulation can be safely used to treat angiodysplasias without holding thienopyridines. EGD: Esophagogastroduodenoscopy; EMR: Endoscopic mucosal resection; ERCP: Endoscopic retrograde cholangiopancreatography; ESD: Endoscopic submucosal dissection; EUS-FNA: Endoscopic ultrasonography-guided fine needle aspiration; NA: Not applicable.
Reprinted with permission from [26].