Obstructive defecation: a failure of rectoanal coordination.
OBJECTIVE
The pathophysiology of obstructive defecation is unclear. We investigated whether impaired rectoanal coordination causes obstructive defecation and if this dysfunction can be corrected by biofeedback therapy.


METHODS
We prospectively studied 25 healthy subjects and 35 consecutive patients with constipation (>1 year) with anorectal manometry and balloon expulsion test. Symptoms were assessed from diary cards. Patients found to have obstructive defecation were offered biofeedback therapy. After treatment, their defecation dynamics and symptoms were reassessed.


RESULTS
Eighteen patients had obstructive defecation and 17 had normal defecation dynamics (nonobstructive). Five normals (20%) exhibited obstructive pattern but only one failed to expel balloon. In the obstructive group, during straining, the intrarectal pressure and defecation index were lower (p < 0.05), and anal residual pressure was higher (p < 0.01) when compared with the nonobstructive group or normals. After biofeedback therapy, the intrarectal pressure and defecation index increased (p < 0.02) and anal residual pressure decreased (p < 0.001); stool frequency, degree of straining, and bowel satisfaction scores improved (p < 0.05); 67% stopped laxatives and 11 patients discontinued stooling with digitation.


CONCLUSIONS
Patients with obstructive defecation showed impaired rectal contraction, paradoxical anal contraction, or inadequate anal relaxation. These features suggest that rectoanal coordination was impaired. Biofeedback therapy rectified these pathophysiological disturbances and improved constipation.
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, USA.
S S
SS
Rao
K D
KD
Welcher
J S
JS
Leistikow
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001003:Anal Canal / Q000503:physiopathology*; D001676:Biofeedback, Psychology / Q000502:physiology; D002400:Cathartics / Q000008:administration & dosage; D002404:Catheterization; D002908:Chronic Disease; D003106:Colon / Q000503:physiopathology; D003248:Constipation / Q000188:drug therapy / Q000503:physiopathology* / Q000628:therapy; D003672:Defecation / Q000502:physiology*; D019841:Defecography; D005260:Female; D005500:Follow-Up Studies; D005772:Gastrointestinal Transit / Q000502:physiology; D006801:Humans; D008297:Male; D008365:Manometry; D008499:Medical Records; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D009126:Muscle Relaxation / Q000502:physiology; D017060:Patient Satisfaction; D011312:Pressure; D011446:Prospective Studies; D012007:Rectum / Q000503:physiopathology*; D012677:Sensation / Q000502:physiology
D002400:Cathartics