Dynamic anal manometry in the assessment of patients with obstructed defecation

Patients with obstructed defecation show no consistent abnormalities when assessed by standard anorectal physiologic methods. With a recently developed technique for dynamic anal manometry, we studied 13 female patients with obstructed defecation and 20 healthy volunteers. Seven parameters of anal function were measured. There were no differences between the median values for the two groups. Seven patients (54 percent; 95 percent confidence limits, 25–81 percent) had anal compliance below the normal range, either during opening or closing of the sphincter at rest (five patients), during squeeze (one patient), or both (one patient). Opening and closing pressures of the sphincer at rest, maximal closing pressure during squeeze, and anal hysteresis were normal. Standard anal manometry did not show any differences between patients and controls. Rectal compliance was lower in patients with obstructed defecation, median difference 5 ml/cm H₂O (95 percent confidence limits, 1–9 ml/cm H₂O). In conclusion, the more detailed method of dynamic anal manometry shows that some patients with obstructed defecation have a less compliant anal sphincter and a less compliant rectum, but in many patients no abnormal findings can be made.