Hypotheses: High definition manometry (HDM) is safe and feasible in humans; HDM accurately characterizes anorectal anatomy and function in healthy humans; HDM provides comparable information regarding the structure and function of the anorectal region, to that obtained from ano-rectal manometry and anal ultrasonography (AUS), in patients with fecal incontinence or constipation.

Methods: 20 healthy volunteers, 20 patients with fecal incontinence, 20 patients with constipation will be recruited. Because anorectal disorders are more common in women, the investigators will recruit approximately 8 men and 12 women in each group. Each subject will undergo anorectal manometry, anal ultrasound and high definition manometry.

Data Analysis: Spearman correlational analysis will be performed to compare the parameters listed above. Also, the diagnostic yield of anal ultrasonography vs HDM in identifying anatomic sphincter defects will be assessed.

Inclusion Criteria:

For patients:

1. Either fecal incontinence (the occurrence of at least one episode of involuntary discharge of stool matter per week) or constipation (Rome III criteria) (16,17)
2. Adults between the ages of 18-80 yrs.

For healthy volunteers:

1. Adults between the ages of 18-80 yrs
2. No gastrointestinal symptoms

Exclusion Criteria:

1. Rectal prolapse or anal fissure on physical examination
2. Recent pelvic or recto-anal surgery (< 6 months ago)
3. History of pelvic irradiation.

We will recruit 20 healthy volunteers, 20 patients with fecal incontinence, 20 patients with constipation. Because anorectal disorders are more common in women, we will recruit approximately 8 men and 12 women in each group. Because it is possible subjects may sign consent but not participate in the study, or drop out of the study before completion, we will recruit a total of 80 subjects.