The timing of bowel preparation before colonoscopy determines the quality of cleansing, and is a significant factor contributing to the detection of flat lesions: A randomized study

Table 1 Basal features of patients in the four preparation groups

	Group 1	Group 2	Group 3	Group 4	P
Patients (n)	43	45	45	44
Gender ratio (M/F)	21:22	24:21	19:26	21:23	NS
Age (yr) (mean ± SD)	58.0 ± 15.9	52.4 ± 16.7	53.6 ± 15.2	54.0 ± 16.5	NS
Chronic constipation (%)	17.1	26.3	24.4	27.2	NS
Polyp surveillance (%)	23.3	12.5	6.6	13.6	NS

Table 2 Comparison of rate of patients with cleansing quality ≥ 4, between different treatment groups (mean ± SD, %)

Group	Global	Cecum	Ascending	Transverse	Descending-sigmoid	Rectum
1	78.6 ± 0.2	72.1 ± 0.2	79.1 ± 0.2	81.0 ± 0.1	76.7 ± 0.2	79.1 ± 0.2
2	80.0 ± 0.2	84.4 ± 0.1	77.8 ± 0.2	82.2 ± 0.1	86.7 ± 0.1	86.7 ± 0.1
3	26.7 ± 0.2b	38.6 ± 0.2b	22.2 ± 0.2b	35.6 ± 0.2b	60.0 ± 0.2d	57.8 ± 0.2d
4	6.8 ± 0.1 b	14.6 ± 0.1b	9.8 ± 0.1b	32.6 ± 0.2b	45.5 ± 0.2b	50.0 ± 0.2b

^bP < 0.01 vs Group 1, 2. (Bonferroni´s correction);

^dP < 0.01 vs Group 2.

Table 3 Distribution by size and shape of all polyps detected in the patients who received bowel preparation the same day and the day before

Lesion	Preparationsame day(group 1, 2)	Preparationday before(group 3, 4)	P
Polyp size (mean ± SD)	5.6 ± 3.8	5.3 ± 5.1	NS
Polyp size ≤ 5 mm (n = 121)	59	62	NS
Flat lesions (n = 37)	28	9	< 0.01
Flat lesions size (mean ± SD)	4.8 ± 3.7	9.0 ± 12.0	NS
Protruding polyps (n = 146)	69	77	NS
Protruding polyps size (mean ± SD)	5.9 ± 3.8	4.9 ± 3.6	NS
Total polyps (flat + protruding) (n = 183)	97	86	NS

Bonferroni's correction.

Table 4 Polyp status in patients who received bowel preparation the same day or the day before (group 3, 4), n (%)

	Preparationsame day(group 1, 2)	Preparationday Before(group 3, 4)	P
Patients (n)	(88)	(89)
Any polyp	46 (52.3)	40 (44.9)	NS
Flat lesions1	19 (21.6)	8 (9.0)	< 0.05
Protruding polyps2	35 (39.7)	37 (41.6)	NS
Multiple (≥ 3) polyps	16 (18.1)	14 (15.7)	NS
Small ( ≤ 5 mm) polyps	39 (44.3)	33 (37.0)	NS

¹Irrespective of the existence of protruding polyps;

²Irrespective of the existence of flat polyps.

Table 5 Comparison of the tolerance variables in the four groups n (%)

Side effect	Group 1	Group 2	Group 3	Group 4	P
Nausea	17 (39.5)	24 (53.3)	24 (53.3)	15 (34.1)	NS
Vomiting	4 (9.3)	10 (22.2)	10 (22.2)	8 (18.2)	NS
Disgusting1	10 (23.3)	12 (26.7)	12 (26.7)	12 (27.3)	NS
Thirst1	6 (13.9)	9 (20.0)	9 (20)	12 (27.2)	NS
Abdominal pain1	4 (9.3)	4 (8.9)	3 (6.6)	5 (11.4)	NS
Anal pain1	1 (2.3)	4 (8.9)	1 (2.2)	2 (4.5)	NS

¹As moderate or severe.