The aim of this monocentric, prospective, non randomised study with 25 healthy volunteers is to assess anorectal function ( i.e rectal compliance and sensory thresholds) in health with a short protocol barostat versus conventional procedures (i.e. standard barostat protocol and high resolution anorectal manometry). Anorectal dysfunction is a key mechanism in the development of fecal incontinence and symptoms of obstructive defecation.

In this study volunteers will be examined - after explanation, physical examination and verification of in- and exclusion criteria - by anorectal barostat with short and standard protocol as well as by proctoscopy and endoanal ultrasound.

For a coordinated anorectal function in addition to the anal sphincter the perception of rectal distension (visceral perception) and elasticity / compliance of the anorectum and stool consistency is important. A disturbed anorectal function may lead to functional defecation disorders or incontinence.

The currently available methods for measuring physiological assessment of anorectal function mostly focus on measurement of sphincter pressures, but generally provide no complete explanation for the underlying pathophysiology of defecation disorders. By voluntary contraction of the striated muscles of the external anal sphincter and puborectalis muscle defecation can be further delayed. In addition, however, other continence mechanisms play an important role.

The Group for the Study of functional gastrointestinal disorders at the Clinic for Gastroenterology at the University Hospital of Zurich has a great expertise in the establishment of new research methods such as the already in routine clinical practice used high-resolution anorectal manometry and has conducted numerous studies with anorectal Barostat. To use the results of Barostat also in everyday clinical practice in patients with defecation disorders this technique means significant simplification of the instrumental methodology and shortening of the work described in the literature. Before the simplified barostat can be used with the shortened protocol in different patient groups and clinical practice, it generally requires the validation of the technique in healthy subjects to define the range of normal values.

Inclusion criteria:

• Healthy men and women between 18 and 65 years of age without gastrointestinal disease needing medical or surgical treatment.
• No medication (with the exception of occasional intake of paracetamol)
• Availability of all investigations (high resolution anorectal manometry, anorectal barostat with short and standard protocol, proctoscopy and endoanal ultrasound to assess sphincter morphology)
• Good communication with study doctor and meeting of all study requirements.
• Written consent after detailed explanation of study.

Exclusion criteria:

• Gastrointestinal symptoms especially fecal incontinence and obstructed defecation
• Structural or functional changes of upper and lower GI Tract (i.e gastric ulcer, malignancy , symptoms of IBS)
• Symptomatic or manometrically diagnosed motility disorders of the upper and lower GI tract for example anismus
• Surgery or interventions in the lower and upper GI tract (appendectomy and hernia excluded) included congenital malformations
• Pelvic radiation therapy
• Fecal incontinence, defined as involuntary loss of liquid or hard stool
• Functional defecation disorders as defined by the ROME III criteria.
• Pregnancy with history of vaginal delivery.
• Acute or chronic disease ( for example IBD)
• Malignancy
• Intake of medication one week prior to study begin. Anticoagulants and medication influencing GI motility like prokinetics, calcium channel blockers and antibiotics
• Drug or alcohol use
• Pregnancy and lactation
• Women at reproductive age will receive pregnancy testing before inclusion into study.
• Physical, mental , neurological or psychiatric conditions limiting ability to meet inclusion criteria