Inclusion Criteria - healthy women:

• Healthy volunteers aged 18-80 years.
• Able to provide written informed consent before participating in the study.
• Able to communicate adequately with the investigator and to comply with the requirements for the entire study.

Inclusion Criteria - female patients, aged 18-80 years:

• Defecatory disorders.Women with (a) symptoms of chronic constipation for 1 year with any 2 or more of the following symptoms for 3 months or longer, i.e. <3 bowel motions/week, straining ≥ 25% of time, hard or lumpy stools ≥ 25% of time, incomplete evacuation ≥ 25% of time, feeling of anorectal blockage ≥ 25% of time; (b) diagnostic tests indicative of difficult defecation; (c) scheduled to undergo pelvic floor retraining by biofeedback therapy.
• Able to provide written informed consent before participating in the study.
• Able to communicate adequately with the investigator and to comply with the requirements for the entire study.

Exclusion Criteria - healthy women:

Items indicated with an asterisk (*) are also exclusion criteria for patients

• Clinical evidence of significant cardiovascular, respiratory, renal, hepatic, gastrointestinal, hematological, neurological, psychiatric or other disease that may interfere with the objectives of the study and/or pose safety concerns.*
• Current symptoms of a functional gastrointestinal disorder assessed by questionnaire 32, 33.
• Putative risk factors for pelvic floor trauma, i.e. six or more vaginal deliveries, birthweight >4500gms (macrosomia), or known 4th degree perineal tear.
• Medications that are likely to alter gastrointestinal motility, e.g., opiates, anticholinergic medications, alpha adrenergic agonists, calcium channel or b blockers; stable dose of thyroxine will be permitted.
• Active rectal inflammation, cancer; perianal sepsis; history of pelvic radiation, rectosigmoid surgery or inflammatory bowel disease.*
• Anxiety or depression as assessed by the Hospital Anxiety and Depression Questionnaire 34.
• BMI greater than 32 kg/m2.*