Right biopsy protocol for microscopic colitis: Reduced workload and carbon footprint while maintaining diagnostic accuracy

Table 1 Demographic characteristics and bowel symptoms of index colonoscopies, comparing lymphocytic and collagenous subtypes, n (%)

	Microscopic colitis	Lymphocytic colitis	Collagenous colitis
Total number	228	145	83
Age at diagnosis (yr)	60 (IQR: 48-72)	60 (IQR: 47-71)	60 (IQR: 50-74)
Male	66 (29)	47 (32)	19 (23)
Female	162 (71)	98 (68)	64 (77)
Bowel symptoms available	196 (86)	122 (84)	74 (89)
Diarrhea (n = 196)	192 (98)	119 (98)	73 (99)
Alternating motions (n = 196)	3 (1.5)	2 (1.6)	1 (1.4)
No diarrhea (n = 196)	1 (0.5)	1 (0.8)	0 (0)

IQR: Interquartile range.

Table 2 Biopsy sampling patterns observed among 228 index colonoscopies

Biopsy sampling pattern	n (%)
Biopsy container labelled “random colon” present	60 (26)
Only a container labelled “random colon” present	46 (20)
Full serial biopsies from all colonic segments	8 (4)
A container labelled “right colon” and one labelled “left colon”	84 (37)
Other combinations of containers	76 (33)
At least one container identified as originating from the right colon	150 (66)
At least one container identified as originating from the left colon (excluding the rectum)	158 (69)
At least one container identified from both right and left colon (excluding the rectum)	136 (60)
At least one container labelled “rectal”	117 (51)

Table 3 Diagnostic yield by location, calculated per set of biopsies from each site among colonoscopies with at least one container identified from that site

Location of biopsy set	Diagnostic yield
Right colon (n = 150)	150/150 (100%, 95%CI: 98-100)
Left colon (n = 158)	145/158 (92%, 95%CI: 86-95)
Rectum (n = 117)	88/117 (75%, 95%CI: 67-82)

CI: Confidence interval.

Table 4 Diagnostic yield by location, calculated per individual biopsy container

Location of containers	Diagnostic yield
Right colon (n = 209)	205/209 (98%, 95%CI: 95-99)
Left colon (n = 199)	182/199 (91%, 95%CI: 87-95)

CI: Confidence interval.

Table 5 Diagnostic yield by location, calculated per set of biopsies from each site, among colonoscopies with at least one container identified from the right colon and one container identified from the left colon (excluding the rectum) (n = 136)

Location of biopsy set	Diagnostic yield
Right colon	136/136 (100% 95%CI: 97-100)
Left colon	123/136 (90% 95%CI: 84-94)

CI: Confidence interval.