Advances in diagnostic assessment of fecal incontinence and dyssynergic defecation

Abstract

Disorders of the anorectum and pelvic floor affect approximately 25% of the population. Their evaluation and treatment have been hindered by a lack of understanding of underlying mechanism(s) and a working knowledge of the diagnostic advances in this field. A meticulous evaluation of anorectal structure and its function can provide invaluable insights to the practicing gastroenterologist regarding the pathogenic mechanism(s) of these disorders. Also, significant new knowledge has emerged over the past decade that includes the development of newer diagnostic tools such as high-resolution manometry and magnetic resonance defecography as well as a better delineation of the clinical and pathophysiologic subtypes of constipation and incontinence. This article provides an up-to-date review on the role of diagnostic tests in the evaluation of fecal incontinence and constipation with dyssynergic defecation.

Fig 1

High Definition Manometry and pressure topography during rest and voluntary squeeze. In the healthy subject (left), normal resting and normal increase in sphincter pressure is seen whereas in the incontinent subject the sphincter is weak during squeeze.

Fig 2

Neurophysiological changes following translumbar magnetic stimulation. In healthy subject (left), normal motor evoked potential with a short latency (arrow) can be seen whereas in the incontinent subject (right), the MEP onset is prolonged onset and amplitude is decreased indicating neuropathy.

Fig 3

Assessment of colonic, regional and whole gut transit with a wireless motility capsule in a subject with chronic constipation and dyssynergic defecation. The time is represented on the horizontal axis. The blue line represents temperature changes, the green line the pH changes and the red line the pressure changes. GET+ Gastric emptying time; SBTT= Small bowel transit time; CTT= Colonic transit time. The colonic transit is delayed in this subject normal CTT <59 hours) emphasizing the overlap between dyssynergic defecation and slow colonic transit.

Fig 4

Manometric and pressure topographic changes in a healthy individual (left) and a patient with dyssynergic defecation (right). In healthy subject, normal relaxation of anal sphincters can be seen both with manometry and topography whereas in the dyssynergic subject there is increase in rectal pressure with paradoxical increase in anal sphincter pressure seen both with manometry and topography.