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Anal Physiology: The Physiology of Continence and Defecation

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The ASCRS Textbook of Colon and Rectal Surgery

Abstract

The physiology of the anus and its surrounding structures is the physiology of continence and controlled defecation. This is a physiology of balance and continuous feedback and complex reflexes. Continence requires balance between the pressure inside the rectum and the combined tone of the internal and external sphincters. This chapter provides an overview of the anatomy, specifically the innervation of the anal complex with regard to how it affects normal and pathologic defecation. The neuro-sensory-motor aspects of the sequences of events of defecation are reviewed. Conditions that result in disordered defecation, pelvic pain, and complications outside the GI system are discussed.

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Abbreviations

RAIR:

Rectoanal inhibitory reflex

SNS:

Sacral nerve stimulation

FI:

Fecal incontinence

MR:

Magnetic resonance

References

  1. Jorge JMN, Habr-Gama A. Anatomy and embryology of the colon rectum and anus. In: Wolff BG, Fleshman JW, Beck DE, Pemberton JH, Wexner SD, editors. The ASCRS textbook of colon and rectal surgery. New York, NY: Springer; 2007. p. 1–11.

    Google Scholar 

  2. Bollard RC, Gardiner A, Lindow S, Phillips K, Duthie GS. Normal female anal sphincter: difficulties in interpretation explained. Dis Colon Rectum. 2002;45:171–5.

    CAS  PubMed  Google Scholar 

  3. Gordon PH. Anatomy and physiology of the anorectum. In: Fazio VW, Church JM, Delaney CP, editors. Current therapy in colon and rectal surgery. 2nd ed. Philadelphia, PA: Elsevier Mosby; 2005. p. 1–4.

    Google Scholar 

  4. Milligan ETC, Morgan CN, Jones LE, Officer R. Surgical anatomy of the anal canal and the operative treatment of haemorrhoids. Dis Colon Rectum. 1985;28:620–8.

    Google Scholar 

  5. Morgan CN. The surgical anatomy of the anal canal and rectum. Postgrad Med J. 1936;12:287–314.

    CAS  PubMed  PubMed Central  Google Scholar 

  6. Taylor I, Duthie HL, Amallwwod R, et al. Large bowel myoelectrical activity in man. Gut. 1975;16:808–14.

    CAS  PubMed  PubMed Central  Google Scholar 

  7. Gordon PH. Anorectal anatomy and physiology. Gastroenterol Clin North Am. 2001;30:1–13.

    CAS  PubMed  Google Scholar 

  8. Gowers WR. The automatic action of the sphincter ani. Proc R Soc Lond. 1877;26:77–84.

    Google Scholar 

  9. Cornes H, Bartolo DCC, Stirra T. Changes in anal canal sensation after childbirth. Br J Surg. 1991;78:74–7.

    CAS  PubMed  Google Scholar 

  10. Miller R, Bartolo DCC, Cervero F, Mortenson NJ. Differences in anal sensation in continent and incontinent patients with perineal descent. Int J Colorectal Dis. 1989;4:45–9.

    CAS  PubMed  Google Scholar 

  11. Keighley MRB. Abdominal mucosectomy reduces the incidence of soiling and sphincter damage after restorative proctocolectomy and J-pouch. Dis Colon Rectum. 1987;39:386–90.

    Google Scholar 

  12. Stelzner F. The morphological principles of anorectal continence. In: Rickham PP, Hecker WSH, Prevot J, editors. Anorectal malformations and associated diseases, Progress in pediatric surgery series, vol. 9. Munich: Urban & Schwarzberg; 1976. p. 1–6.

    Google Scholar 

  13. Kaiser AM, Ortega AE. Anorectal anatomy. Surg Clin North Am. 2002;82:1125–38.

    PubMed  Google Scholar 

  14. Duthie HL, Gairns FW. Sensory nerve-endings and sensation in the anal region of man. Br J Surg. 1960;206:585–95.

    Google Scholar 

  15. Sangwan YP, Solla JA. Internal anal sphincter: advances and insights. Dis Colon Rectum. 1998;41:1297–311.

    CAS  PubMed  Google Scholar 

  16. Palit S, Lunniss PJ, Scott SM. The physiology of human defecation. Dig Dis Sci. 2012;57:1445–64.

    PubMed  Google Scholar 

  17. Bajwa A, Emmanuel A. The physiology of continence and evacuation. Best Pract Res Clin Gastroenterol. 2009;23:477–85.

    PubMed  Google Scholar 

  18. Brookes SJ, Dinning PG, Gladman MA. Neuroanatomy and physiology of colorectal function and defaecation: from basic science to human clinical studies. Neurogastroenterol Motil. 2009;21 Suppl 2:9–19.

    PubMed  Google Scholar 

  19. Gurjar SV, Jones OM. Physiology: evacuation, pelvic floor and continence mechanisms. Surgery. 2011;29(8):358–61.

    Google Scholar 

  20. Lubowski DZ, Meagher AP, Smart AC, et al. Scintographic assessment of colonic function during defecation. Int J Colorectal Dis. 1995;10:91–3.

    CAS  PubMed  Google Scholar 

  21. Brading AF, Ramalingam T. Mechanisms controlling normal defecation and the potential effects of spinal cord injury. In: Weaver LC, Polosa C, editors. Progress in brain research 2006; vol 152:p. 345-358 (Chapter 23).

    Google Scholar 

  22. Broens PMA, Penninckx FM, Ochoa JB. Fecal continence revisited: the anal external sphincter continence reflex. Dis Colon Rectum. 2013;56:1273–81.

    PubMed  Google Scholar 

  23. Lynn PA, Olsson C, Zagorodnyuk V, et al. Rectal intraganglionic laminar endings are transduction sites of extrinsic mechanoreceptors in the guinea pig rectum. Gastroenterology. 2003;125:589–601.

    Google Scholar 

  24. Lynn PA, Blackshaw LA. In vitro recordings of afferent fibres with receptive fields in the serosa, muscle and mucosa of rat colon. J Physiol. 1999;518(Pt 1):271–82.

    CAS  PubMed  PubMed Central  Google Scholar 

  25. Tanagho EA, Schmidt RA. Electrical stimulation in the clinical management of the neurogenic bladder. J Urol. 1988;140:1331–9.

    CAS  PubMed  Google Scholar 

  26. Ganio E, Luc AR, Clerico G, Trompetto M. Sacral nerve stimulation for treatment of fecal incontinence: a novel approach for intractable fecal incontinence. Dis Colon Rectum. 2001;44:619–29.

    CAS  PubMed  Google Scholar 

  27. Malouf AJ, Wiesel PH, Nicholls T, Nicholls RJ, Kamm MA. Sacral nerve stimulation for idiopathic slow transit constipation. Gastroenterol Clin North Am. 2001;118:4448–9.

    Google Scholar 

  28. Carrington EV et al. A systematic review of sacral nerve stimulation mechanisms in the treatment of fecal incontinence and constipation. Neurogastroenterol Motil. 2014;26(9):1222–37.

    CAS  PubMed  Google Scholar 

  29. Thumas TO, Dudding TC, et al. A systemic review of posterior tibial nerve stimulation for faecal incontinence. Colorectal Dis. 2012;15:519–26.

    Google Scholar 

  30. Ebert E. Gastrointestinal involvement in spinal cord injury: a clinical perspective. J Gastrointestin Liver Dis. 2012;21(1):75–82.

    PubMed  Google Scholar 

  31. Lynch AC, Frizelle FA. Colorectal motility and defecation after spinal cord injury in humans. In: Weaver LC, Polosa C, editors. Progress in brain research 2006;vol 152:193–203 (Chapter 23).

    Google Scholar 

  32. Nout YS, Leedy GM, Beattie MS, Bresnahan JS. Alterations in eliminative and sexual reflexes after spinal cord injury: defecatory function and development of spasticity in pelvic floor musculature. In: Weaver LC, Polosa C, editors. Progress in brain research 2006;vol 152:359–273 (Chapter 23).

    Google Scholar 

  33. Preziosi G, Raptis DA, Raeburn A, Panicker J, Emmanuel A. Autonomic rectal dysfunction in patients with multiple sclerosis and bowel symptoms is secondary to spinal cord disease. Dis Colon Rectum. 2014;57:514–21.

    PubMed  Google Scholar 

  34. Valle’s M, Mearin F. Pathophysiology of bowel dysfunction in patients with motor incomplete spinal cord injury: comparison with patients with motor complete spinal cord injury. Dis Colon Rectum. 2009;52:1589–97.

    Google Scholar 

  35. Bharucha AE, Rao SSC. An update on anorectal disorders for gastroenterologists. Gastroenterology. 2014;146:37–45.

    PubMed  Google Scholar 

  36. Bharucha AE, Wald A, Enck P, Rao S. Functional anorectal disorders. Gastroenterology. 2006;130:1510–8.

    PubMed  Google Scholar 

  37. van Ginkel R, Reitsma JB, Buller HA, et al. Childhood constipation: longitudinal follow-up beyond puberty. Gastroenterology. 2003;125:67–72.

    Google Scholar 

  38. Rao SSC, Tuteja AK, Vellema T, et al. Dyssynergic defecation: demographics, symptoms, stool patterns and quality of life. J Clin Gastroenterol. 2004;38:680–5.

    PubMed  Google Scholar 

  39. Rao SS, Welcher KD, Leistikow JS. Obstructive defecation: a failure of rectoanal coordination. Am J Gastroenterol. 1998;93:1042–50.

    CAS  PubMed  Google Scholar 

  40. Andromanakos N, Skandalakis P, Troupis T, Filippou D. Constipation of anorectal outlet obstruction: pathophysiology, evaluation and management. J Gastroenterol Hepatol. 2006;21:638–46.

    PubMed  Google Scholar 

  41. Felt-Bersma RJ, Tiersma ES, Cuesta MA. Rectal prolapse, rectal intussusception, rectocele, solitary rectal ulcer syndrome, and enterocele. Gastroenterol Clin North Am. 2008;37:645–68.

    PubMed  Google Scholar 

  42. Atkin GK, Suliman A, Vaizey CJ. Patient characteristics and treatment outcome in functional anorectal pain. Dis Colon Rectum. 2011;54:870–5.

    PubMed  Google Scholar 

  43. Hull M, Cort MM. Evaluation of the levator ani and pelvic wall muscles in levator ani syndrome. Urol Nus. 2009;29(4):225.

    Google Scholar 

  44. Eckardt VF, Dodt O, Kanzler G, Bernhard G. Anorectal function and morphology in patients with sporadic proctalgia fugax. Dis Colon Rectum. 2004;39:755–62.

    Google Scholar 

  45. Shin GH, Toto EL, Schey R. Pregnancy and postpartum bowel changes: constipation and fecal incontinence. Am J Gastroenterol. 2015;110:521–9.

    Google Scholar 

  46. Chiloiro M, Darconza G, Piccioli E, et al. Gastric emptying and orocecal transit time in pregnancy. J Gastroenterol. 2001;36:538–43.

    CAS  PubMed  Google Scholar 

  47. Oettling G, Franz HB. Mapping of androgen, estrogen and progesterone receptors in the anal continence organ. Eur J Obstet Gynecol Reprod Biol. 1998;77:785–95.

    Google Scholar 

  48. Shultz SJ, Wideman L, Montgomery MM, et al. Changes in serum collagen markers, IGF-I, and knee joint laxity across the menstrual cycle. J Orthop Res. 2012;30:1405–12.

    CAS  PubMed  PubMed Central  Google Scholar 

  49. Parks AG, Swash M. Denervation of the anal sphincter causing idiopathic anorectal incontinence. J R Coll Surg Edinb. 1979;24:94–6.

    CAS  PubMed  Google Scholar 

  50. Bharucha AE, Fletcher JG, Melton III LJ, et al. Obstetric trauma, pelvic floor injury and fecal incontinence: a population-based case–control study. Am J Gastroenterol. 2012;107:902–11.

    PubMed  PubMed Central  Google Scholar 

  51. Dudding TC, Vaizey CJ, Kamm MJ. Obstetric anal sphincter injury incidence, risk factors, and management. Ann Surg. 2008;247(2):224–37.

    PubMed  Google Scholar 

  52. Pretlove SJ, Thompson PJ, Toozs-Hobson PM, et al. Does the mode of delivery predispose women to anal incontinence in the first year postpartum? A comparative systematic review. BJOG. 2008;115:421–34.

    CAS  PubMed  Google Scholar 

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Author information

Authors and Affiliations

  1. Dept of Surgery, Division of Colon and Rectal Surgery etc, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Stoneman 9, Boston, MA, 02115, USA

    Vitaliy Poylin M.D., F.A.C.S., F.A.S.C.R.S.

  2. Dept of Surgery, Division of Colon and Rectal Surgery etc, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Stoneman 9, Boston, MA, 02115, USA

    Thomas E. Cataldo M.D., F.A.S.C., F.A.S.C.R.S.

Authors
  1. Vitaliy Poylin M.D., F.A.C.S., F.A.S.C.R.S.
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  2. Thomas E. Cataldo M.D., F.A.S.C., F.A.S.C.R.S.
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Corresponding author

Correspondence to Thomas E. Cataldo M.D., F.A.S.C., F.A.S.C.R.S. .

Editor information

Editors and Affiliations

  1. Division of Colorectal Surgery, University Hospitals Case Medical Center Case Western Reserve University, Cleveland, OH, USA

    Scott R. Steele

  2. Cleveland Clinic, Cleveland, OH, USA

    Tracy L. Hull

  3. Tufts University School of Medicine, Lahey Hospital & Medical Center, Burlington, MA, USA

    Thomas E. Read

  4. Ambrose and Gladys Bowyer, Loyola University, Chicago, IL, USA

    Theodore J. Saclarides

  5. University of Texas Medical Branch at Galveston, Galveston, TX, USA

    Anthony J. Senagore

  6. Ochsner Medical Center, New Orleans, LA, USA

    Charles B. Whitlow

Electronic Supplementary Material

Below is the link to the electronic supplementary material.

Normal defecography (Courtesy of Shauna Lorenzo-Rivero, MD, FACS, FASCRS) (WMV 1122 kb)

Defeocography of a patient with a rectocele (Shauna Lorenzo-Rivero, MD, FACS, FASCRS) (WMV 723 kb)

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© 2016 ASCRS (American Society of Colon and Rectal Surgeons)

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Poylin, V., Cataldo, T.E. (2016). Anal Physiology: The Physiology of Continence and Defecation. In: Steele, S.R., Hull, T.L., Read, T.E., Saclarides, T.J., Senagore, A.J., Whitlow, C.B. (eds) The ASCRS Textbook of Colon and Rectal Surgery. Springer, Cham. https://doi.org/10.1007/978-3-319-25970-3_3

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  • DOI: https://doi.org/10.1007/978-3-319-25970-3_3

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  • Publisher Name: Springer, Cham

  • Print ISBN: 978-3-319-25968-0

  • Online ISBN: 978-3-319-25970-3

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