Clinical Characteristics and Pathophysiology of Fecal Incontinence Mixed With Constipation: An Underrecognized Problem.

INTRODUCTION

Fecal incontinence (FI) and chronic constipation (CC) are diagnosed as distinct problems, although many suffer with both problems. The phenotypical features and underlying mechanisms of FI mixed with CC (FI-MC) is unclear. We investigated the clinical and pathophysiological characteristics of FI-MC and compared with FI alone and healthy controls.

METHODS

In a retrospective study, patients with FI were categorized as having FI-MC or FI alone. For comparison, we recruited healthy controls. All subjects completed bowel symptom questionnaire, anorectal manometry, balloon expulsion, neurophysiology, and anal ultrasound tests. Data were compared between the 3 groups.

RESULTS

We evaluated 165 patients with FI-MC, 184 with FI, and 31 controls. The prevalence of excessive straining, incomplete evacuation, pain, bloating, use of digital maneuvers, and enemas were higher ( P < 0.001) in the FI-MC than FI group. Anal resting pressure was lower ( P < 0.001) in FI than FI-MC group and controls. Anal squeeze and sustained squeeze pressures were lower ( P < 0.001), and lumbar and sacral plexus nerve conduction was prolonged ( P < 0.001) in the FI-MC and FI groups compared with controls, but similar between patient groups. Dyssynergic defecation was more ( P < 0.01) prevalent in FI-MC than FI or controls. Rectal sensory thresholds were lower in the FI-MC group than controls ( P < 0.05), but not between patient groups. The FI group had higher ( P < 0.01) prevalence of anal sphincter defects than FI-MC.

DISCUSSION: Patients with FI can be categorized into 2 phenotypes as FI alone and FI-MC. Each group demonstrates distinct clinical characteristics and pathophysiology. Recognizing each phenotype may improve management of patients with FI.