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INTRODUCTION/OBJECTIVES: It is reported that fecal incontinence may present as a late complication of anal fissure (1) or other anorectal procedures, that rectal distensibility and volume thresholds for sensations decrease after stapled hemorrhoidopexy (2), and that noxious and non-noxious distensions stimulate different afferent nerve pathways (3). This study aimed to search anal sphincter and rectal factors that determine fecal incontinence after anorectal surgery (FIAS).
METHODS: Seventeen patients (50±15 years, 11 females) with fecal incontinence (10±15 CI: 3-17 incontinence episodes per week) after anorectal surgery (sphincterotomy =5, fistulotomy =5, rectal prolapse =4, hemorrhoidectomy =1, others =2; 2±1 CI:1.2-3.2 years after surgery) were studied [clinical assessment, rectosigmoidoscopy, anorectal manometry (MMS, Netherlands) and barostat (G&J, ON, CA)] and compared with healthy subjects (n=11, 22±2 years, 10 females for manometry and; n=10, 25±7 years, three females, for barostat studies). Rectal sensory thresholds, tone and compliance were evaluated with an electronic barostat using the ascending method of limits. Mean±SD, binominal 95% confidence interval, and nonpaired Student two-tailed t test with alpha=0.05.
RESULTS: (Table). Compared with healthy subjects, FIAS patients showed lesser rectal compliance (p= 0.0129) and rectal tone at lower volume (p= 0.0029). The thresholds for non-noxious stimuli of gas sensation (p= 0.0272) and urge-to-defecate sensation (p= 0.0245) were reported by FIAS patients at higher pressure than healthy subjects. The noxious stimulus of pain was reported by FIAS patients at similar pressure than healthy subjects (p= 0.9). Compared with healthy subjects FIAS patients showed greater anal squeeze pressure (p= 0.041). However, anal resting pressure and rectoanal inhibitory reflex parameters (RAIR) were similar.
CONCLUSION: FIAS patients preserve internal anal sphincter function but present with impaired rectal tone and compliance and hyposensitivity for non-noxious stimuli. The results also support the concept that noxious and non-noxious distensions stimulate different afferent nerve pathways and suggest that an impaired afferent nerve pathway and abnormal rectal structure and function are involved in the genesis of fecal incontinence after anorectal surgery.
REFERENCES: (1) Levin A et al. Int J Colorectal Dis 2011. (2) Corsetti M et al. J Gastrointest Surg 2009;13:2245-51. (3) Awad RA et al. Gastroenterology 2011;140:S744.

Table

Variable (mean±SD)	Fecal incontinence after surgery	Healthy subjects
Tone (ml)	43±42 CI: 23−63	103±51 CI: 71-135*
Compliance (v/p)	5±5 CI: 2-7	11±6 CI: 7-16*
First sensation (mmHg)	16±4 CI: 14-18	14±5 CI: 10-17
Gas sensation (mmHg)	23±5 CI: 20-25	17±6 CI: 14-21*
Urge to defecate (mmHg)	30±8 CI: 25-35	22±7 CI: 17-26*
Pain sensation (mmHg)	36±7 CI: 32-40	35±8 CI: 30-41
Anal resting pressure (mmHg)	46±25 CI: 34-58	34±22 CI: 21-48
Anal squeeze pressure (mmHg)	87±65 CI: 56-118	43±24 CI: 28-57*
RAIR duration (s)	20±7 CI: 17-24	19±5 CI: 16-23
RAIR relaxation (%)	59±17 CI: 51-67	74±31 CI: 55-93

*=p<0.05 compared with healthy subjects