Original scientific paper
FECAL INCONTINENCE A novel concept: The role of the internal anal sphincter (IAS) in defecation and fecal incontinence
Abdel Karim M. El Hemaly
orcid.org/0000-0002-5576-8987
; Faculty of Medicine, Department of Obstetrics and Gynecology & Urogynaecology,Al Azhar University,3 emad el din kamel street, Nasr City, Cairo, Egypt
Laila A. Mousa
; Faculty of Medicine, Department of Obstetrics and Gynecology & Urogynaecology,Al Azhar University,3 emad el din kamel street, Nasr City, Cairo, Egypt
Ibrahim M. Kandil
; Faculty of Medicine, Department of Obstetrics and Gynecology & Urogynaecology,Al Azhar University,3 emad el din kamel street, Nasr City, Cairo, Egypt
Fatma S. El Sokkary
; Faculty of Medicine, Department of Obstetrics and Gynecology & Urogynaecology,Al Azhar University,3 emad el din kamel street, Nasr City, Cairo, Egypt
Ahmad G. Serour
; Faculty of Medicine, Department of Obstetrics and Gynecology & Urogynaecology,Al Azhar University,3 emad el din kamel street, Nasr City, Cairo, Egypt
Hossam Hussein
; Faculty of Medicine, Department of Obstetrics and Gynecology & Urogynaecology,Al Azhar University,3 emad el din kamel street, Nasr City, Cairo, Egypt
Abstract
Introduction. Fecal incontinence is involuntary escape of stool, mucus and/or flatus.Its causes are: anal sphincter damage (childbirth trauma, surgical trauma.); constipation; diarrhea; rectocele; rectal prolapse and rarely congenital causes. Fecal material entering the rectum is evacuated by defecation during which: 1. The smooth muscles of the distal colon and rectum contract, propelling the feces into the anal canal; 2.The anal sphincter relaxes allowing defecation to occur. We put forward a recent concept on the patho-physiology of defecation.The mechanism of defecation has two stages: first stage: (in early childhood) before training; second stage is after training. The mother starts to teach her child how to control himself. This is gained by maintaining high alpha sympathetic tone at the internal anal sphincter (IAS) keeping it closed all the time till appropriate place and time are available. Wherever appropriate place is available and there is a desire, six neuromuscular actions will occur: 1) the person will lower the acquired high alpha sympathetic tone at the IAS relaxing it opening the anal canal; 2) through the voluntary nervous system (NS) he will widen the ano-rectal angle to bring the anal canal and the rectum on one axis. This is done through the pelvic floor muscles; 3) through, voluntary NS he will also relax the external anal sphincter (EAS); then synergistic actions between the voluntary and autonomic nervous system occur; 4) the abdominal and diaphragmatic muscles contract, increasing the intra- abdominal pressure and forcing the feces through the anal canal (via the voluntary NS); 5) the smooth muscles of the distal colon and rectum contract, propelling the feces into the anal canal (through the autonomic NS); 6) followed by sequential contractions of the three parts of the EAS (deep then superficial and then the subcutaneous parts) that will squeeze the anal canal propelling any residual contents.
Objectives. Imaging of the anal canal by 3-dimension ultrasound (3DUS) in normal women and women suffering from fecal incontinence and from rectocele, to compare the state of the IAS and EAS. Methods. 40 patients with FI were assessed clinically and by imaging using 3DUS, and also 10 normal women not suffering from fecal incontinence (FI) as a control. Results. The anal canal is closed in normal women, with intact IAS. In women suffering from FI the anal canal is wide and open with torn IAS. Conclusion. The internal anal sphincter (IAS) is a collageno-muscular tissue cylinder that surrounds the anal canal innervated by alpha-sympathetic nerve supply from the hypogastric nerves. It is surrounded in its lower part by the EAS which is a striated muscle innervated by the pudendal nerve. Its damage during childbirth causes fecal incontinence, and mending its torn wall restores fecal continence.
Keywords
fecal incontinence; internal anal sphincter; external anal sphincter; central nervous system; alpha sympathetic nervous system
Hrčak ID:
68421
URI
Publication date:
1.6.2010.
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