Determining normal anorectal physiology values in healthy females.

All eligible volunteers will be invited for a one hour, single visit, anorectal physiology testing. No follow up is planned. . After obtaining informed consent, patients will perform anorectal manometry (ARM) and balloon expulsion testing (BET) according to a standard protocol. Briefly, after rectal examination, a 7-lumen water-perfused manometry catheter with 0.5 cm spaced sideholes and a compliant balloon attached to the end is used (Dentsleeve International, Canada). The catheter is connected to calibrated pressure transducers and data from the pressure transducers is displayed in digital form on a computer using data conversion software (Neomedix, Sydney Australia). Each individual study comprises assessments of the following parameters: (i) resting anal sphincter pressure, (ii) maximum anal sphincter squeeze pressure, cough pressure and duration of maximum anal squeeze and (iii) rectal pressure on strain and concomitant anal relaxation or paradoxical contraction. Neurophysiology testing using surface EMG is used to asses for squeeze and anal relaxation on strain. This takes approximately 15 minutes. Sensation thresholds will be tested using two different techniques: 1- Using a 50ml syringe air continuously injected at a rate of 100ml/minute into a balloon at the end of an anorectal catheter, as is standard in the Unit 2- Using an infinitely compliant balloon continuously injected in a rapid barostat protocol, as recently been suggested to be a more reliable measure of sensation All patients will perform both techniques. In both techniques: a. The patient is told to report when they first feel the sensation of the balloon inside the rectum, which is recorded as the rectal sensitivity threshold. b. Continuing to fill the balloon with air the patient then reports when they have the urge to defecate. c. Still continuing to fill the balloon with air the patient then reports when they cannot tolerate the inflation of the balloon any more, which is recorded as the maximum tolerated volume. The balloon is quickly deflated (manually or automatically) at the time of reported maximal tolerated volume or at a maximum volume of 300 ml, whatever is reached sooner. Sensation testing will takes approximately 25 minutes. Dyssynergic defecation using the balloon expulsion test will be tested using three different techniques: 1- Using a 50 ml water filled party balloon tied to a catheter, as is standard protocol in the Unit 2- Using a 16F Foley catheter filled with 50 ml water as has been recently suggested 3- Using a commercially available non-latex rectal balloon. All patients will perform these techniques, while the order of performance will be equally distributed. In both techniques: a. The patients try to push the balloon out while sitting over a private toilet. b. The time it takes to expel the balloon is noted. If the patient is unable to expel balloon after 3 minutes the balloon is deflated and removed. This will take approximately 10 minutes. Anorectal ultrasound will be performed as standard to ensure no major breaks in the internal or external sphincter that may undermine the normal exam. This involves 10 minutes of testing.