Fecoflowmetry: a new parameter assessing rectal function in normal and constipated subjects.

Abstract

Fecoflowmetry is a new technique by which the fecal flow rate is studied through recorded curves representing the changes that occur in the flow against time. Fecal flow rate is the product of rectal detrusor action against outlet resistance. The technique was performed on 36 normal volunteers and 88 chronically constipated patients. Simultaneous recording of the fecal flow rate and intra-abdominal and rectal neck pressures were performed. A water or paste enema was given to the individual. Upon feeling the desire to defecate, he or she was placed on a fecoflowmeter commode and was asked to defecate. Evaluation of the obtained defecation flow curve comprises the reporting on the defecated volume, flow time, mean and maximum flow rates, time to maximum flow, and shape of the curve. In the 88 constipated patients, two fecoflowmetric patterns were recognized: nonobstructive (inertia) and obstructive. They differ from each other in parameters and curve configuration. The defecated volume as well as mean and maximum flow rates were lower in outlet obstruction than in the inertia type, whereas flow time and time to maximum flow were longer. The ascending limb in the obstructive-type curve rose less steeply than in inertia; the curve had a long plateau, and the descending limb sloped more gradually. To conclude, fecoflowmetric studies could differentiate between defecation of normal and constipated subjects, and in the latter between the obstructive and inertia types of constipation. The technique was developed to simulate natural defecation. It provides quantitative and qualitative data concerning the defecation act. The technique is simple, easy, noninvasive, and nonradiologic. It can be used as a screening tool in defecation disorders.