Related Experiment Video
Updated: Aug 18, 2026

Quantification of Levator Ani Hiatus Enlargement by Magnetic Resonance Imaging in Males and Females with Pelvic Organ Prolapse
Published on: April 17, 2019
Sonographic, manometric, and myographic evaluation of the anal sphincters morphology and function
1Department of Gastroenterology, Heirich Heine University Hospitals, Düsseldorf, Germany.
Purpose:
A direct comparison of anal sphincter physiology (muscle performance and anatomy-muscle thickness) has not yet been undertaken but may be of importance in patients with defecation disorders.
Methods:
We evaluated 15 healthy volunteers by means of anorectal manometry to determine pressure functions of the internal and external and sphincter. Transcutaneous electromyography was recorded to assess the electrical activity of the external anal sphincter. Thickness of the anal sphincter muscles was measured sonographically from within the anal canal with dorsal projection using a 7.5-MHz 360 degrees rectal panorama scanner.
Results:
It was shown that neither is the muscle thickness of the external anal sphincter during rest (6.26 +/- 1.02 mm) or during squeezing (7.40 +/- 1.39 mm) correlated to its squeeze pressure (138.8 +/- 15.2 mmHg), nor is the diameter of the internal anal sphincter (2.09 +/- 0.58 mm) correlated to its resting pressure (61.1 +/- 15.2 mmHg). Finally, the thicker the internal and sphincter muscle, the lower the electrical activity of the external anal sphincter during squeezing (r = 0.74, P < 0.001).
Conclusion:
It is concluded that both manometry to assess sphincter function and sonography to determine sphincter morphology are important measures in the evaluation of continence function.
Related Concept Videos
Muscles of the Pelvic Floor and Perineum
Perineal Layer
The perineum is a diamond-shaped area below the pelvic diaphragm, divided into an anterior urogenital triangle that contains the external genitals and a posterior anal triangle housing the anus. The urogenital...
Assessment of the Rectum and Anus
Rectal Inspection
Begin by inspecting the perianal and anal areas for color, texture, rashes,...
Imaging Studies III: Gastrointestinal Motility Studies and Virtual Colonoscopy
Radionuclide Testing
Radionuclide testing is a sophisticated medical technique for assessing gastrointestinal motility. It focuses on gastric emptying and colonic transit time. Radioactive markers track the movement of food through the digestive system, providing insights into gastrointestinal disorders.
In gastric emptying studies, a meal's liquid and solid...
Anatomy of the Genitourinary System II: Bladder and Urethra
Urodynamic Studies: Uroflowmetry

