Other namesDyssynergic defecation

Anismus or dyssynergic defecation is the failure of normal relaxation of pelvic floor muscles during attempted defecation. It can occur in both children and adults, and in both men and women (although it is more common in women). It can be caused by physical defects or it can occur for other reasons or unknown reasons. Anismus that has a behavioral cause could be viewed as having similarities with parcopresis, or psychogenic fecal retention.[citation needed]

Symptoms include tenesmus (the sensation of incomplete emptying of the rectum after defecation has occurred) and constipation. Retention of stool may result in fecal loading (retention of a mass of stool of any consistency) or fecal impaction (retention of a mass of hard stool). This mass may stretch the walls of the rectum and colon, causing megarectum and/or megacolon, respectively. Liquid stool may leak around a fecal impaction, possibly causing degrees of liquid fecal incontinence. This is usually termed encopresis or soiling in children, and fecal leakage, soiling or liquid fecal incontinence in adults.

Anismus is usually treated with dietary adjustments, such as dietary fiber supplementation. It can also be treated with a type of biofeedback therapy, during which a sensor probe is inserted into the person's anal canal in order to record the pressures exerted by the pelvic floor muscles. These pressures are visually fed back to the patient via a monitor who can regain the normal coordinated movement of the muscles after a few sessions.

Some researchers have suggested that anismus is an over-diagnosed condition, since the standard investigations or digital rectal examination and anorectal manometry were shown to cause paradoxical sphincter contraction in healthy controls, who did not have constipation or incontinence.[1] Due to the invasive and perhaps uncomfortable nature of these investigations, the pelvic floor musculature is thought to behave differently than under normal circumstances. These researchers went on to conclude that paradoxical pelvic floor contraction is a common finding in healthy people as well as in people with chronic constipation and stool incontinence, and it represents a non-specific finding or laboratory artifact related to untoward conditions during examination, and that true anismus is actually rare.

Signs and symptoms

Symptoms include:


Stylized diagram showing action of the puborectalis sling, and the formation of the anorectal angle. A-puborectalis, B-rectum, C-level of anorectal ring and anorectal angle, D-anal canal, E-anal verge, F-representation of internal and external anal sphincters, G-coccyx & sacrum, H-pubic symphysis, I-Ischium, J-pubic bone.

To understand the cause of anismus, an understanding of normal colorectal anatomy and physiology, including the normal defecation mechanism, is helpful. The relevant anatomy includes: the rectum, the anal canal and the muscles of the pelvic floor, especially puborectalis and the external anal sphincter.[citation needed]

The rectum is a section of bowel situated just above the anal canal and distal to the sigmoid colon of the large intestine. It is believed to act as a reservoir to store stool until it fills past a certain volume, at which time the defecation reflexes are stimulated.[4] In healthy individuals, defecation can be temporarily delayed until it is socially acceptable to defecate. In continent individuals, the rectum can expand to a degree to accommodate this function.[citation needed]

The anal canal is the short straight section of bowel between the rectum and the anus. It can be defined functionally as the distance between the anorectal ring and the end of the internal anal sphincter. The internal anal sphincter forms the walls of the anal canal. The internal anal sphincter is not under voluntary control, and in normal persons it is contracted at all times except when there is a need to defecate. This means that the internal anal sphincter contributes more to the resting tone of the anal canal than the external anal sphincter. The internal sphincter is responsible for creating a watertight seal, and therefore provides continence of liquid stool elements.[citation needed]

The puborectalis muscle is one of the pelvic floor muscles. It is skeletal muscle and is therefore under voluntary control. The puborectalis originates on the posterior aspect of the pubic bone, and runs backwards, looping around the bowel.

The point at which the rectum joins the anal canal is known as the anorectal ring, which is at the level that the puborectalis muscle loops around the bowel from in front. This arrangement means that when puborectalis is contracted, it pulls the junction of the rectum and the anal canal forwards, creating an angle in the bowel called the anorectal angle. This angle prevents the movement of stool stored in the rectum moving into the anal canal. It is thought to be responsible for gross continence of solid stool. Some believe the anorectal angle is one of the most important contributors to continence.[5]

Conversely, relaxation of the puborectalis reduces the pull on the junction of the rectum and the anal canal, causing the anorectal angle to straighten out. A squatting posture is also known to straighten the anorectal angle, meaning that less effort is required to defecate when in this position.[6]

Distension of the rectum normally causes the internal anal sphincter to relax (rectoanal inhibitory response, RAIR) and the external anal sphincter initially to contract (rectoanal excitatory reflex, RAER). The relaxation of the internal anal sphincter is an involuntary response. The external anal sphincter, by contrast, is made up of skeletal (or striated muscle) and is therefore under voluntary control. It can contract vigorously for a short time. Contraction of the external sphincter can defer defecation for a time by pushing stool from the anal canal back into the rectum. Once the voluntary signal to defecate is sent back from the brain, the abdominal muscles contract (straining) causing the intra-abdominal pressure to increase. The pelvic floor is lowered causing the anorectal angle to straighten out from ~90o to <15o and the external anal sphincter relaxes. The rectum now contracts and shortens in peristaltic waves, thus forcing fecal material out of the rectum, through the anal canal and out of the anus. The internal and external anal sphincters along with the puborectalis muscle allow the feces to be passed by pulling the anus up over the exiting feces in shortening and contracting actions.[citation needed]

In patients with anismus, the puborectalis and the external anal sphincter muscles fail to relax, with resultant failure of the anorectal angle to straighten out and facilitate evacuation of feces from the rectum. These muscles may even contract when they should relax (paradoxical contraction), and this not only fails to straighten out the anorectal angle, but causes it to become more acute and offer greater obstruction to evacuation.

As these muscles are under voluntary control, the failure of muscular relaxation or paradoxical contraction that is characteristic of anismus can be thought of as either maladaptive behavior or a loss of voluntary control of these muscles. Others claim that puborectalis can become hypertrophied (enlarged) or fibrosis (replacement of muscle tissue with a more fibrous tissue), which reduces voluntary control over the muscle.

Anismus could be thought of as the patient "forgetting" how to push correctly, i.e. straining against a contracted pelvic floor, instead of increasing abdominal cavity pressures and lowering pelvic cavity pressures. It may be that this scenario develops due to stress. For example, one study reported that anismus was strongly associated with sexual abuse in women.[7] One paper stated that events such as pregnancy, childbirth, gynaecological descent or neurogenic disturbances of the brain-bowel axis could lead to a "functional obstructed defecation syndrome" (including anismus).[8] Anismus may develop in persons with extrapyramidal motor disturbance due to Parkinson's disease.[9] This represents a type of focal dystonia.[10] Anismus may also occur with anorectal malformation, rectocele,[11] rectal prolapse[12] and rectal ulcer.[12]

In many cases however, the underlying pathophysiology in patients presenting with obstructed defecation cannot be determined.[13]

Some authors have commented that the "puborectalis paradox" and "spastic pelvic floor" concepts have no objective data to support their validity. They state that "new evidence showing that defecation is an integrated process of colonic and rectal emptying suggests that anismus may be much more complex than a simple disorder of the pelvic floor muscles."[13]


Persistent failure to fully evacuate stool may lead to retention of a mass of stool in the rectum (fecal loading), which can become hardened, forming a fecal impaction or even fecaliths.[citation needed]

Liquid stool elements may leak around the retained fecal mass, which may lead to paradoxical diarrhoea and/or fecal leakage (usually known as encopresis in children and fecal leakage in adults).[14][15][16][17]

When anismus occurs in the context of intractable encopresis (as it often does), resolution of anismus may be insufficient to resolve encopresis.[18] For this reason, and because biofeedback training is invasive, expensive, and labor-intensive, biofeedback training is not recommended for treatment of encopresis with anismus.

The walls of the rectum may become stretched, known as megarectum.[19]


In the Rome IV classification, diagnostic criteria for "functional defecation disorders" are as follows:[20]

2 subcategories exist within the functional defecation disorders category:

For all of these Rome-IV diagnoses, diagnostic criteria must have been fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis.[20] The subcategories F3a and F3b are defined by age- and gender-appropriate normal values for the technique.[20]

Previous Rome criteria recommended that anorectal testing is not usually indicated in patients with symptoms until patients have failed conservative treatment (e.g., increased dietary fiber and liquids; elimination of medications with constipating side effects whenever possible).[citation needed]


Several definitions have been offered:

Digital rectal examination

Main article: digital rectal examination

Physical examination can rule out anismus (by identifying another cause) but is not sufficient to diagnose anismus.

Anorectal manometry

The measurement of pressures within the rectum and anus with a manometer (pressure-sensing probe).

Evacuation proctography

defecating proctogram, and MRI defecography


Anismus can be subcategorized into 4 types based on the results of anorectal manometry testing:[22]

Anismus is classified as a functional defecation disorder. It is also a type of rectal outlet obstruction (a functional outlet obstruction). Where anismus causes constipation, it is an example of functional constipation. Many authors describe an "obstructed defecation syndrome", of which anismus is a cause.[24]

The Rome II classification functional defecation disorders were divided into 3 types,[25] however the symptoms the patient experiences are identical.[26]

It can be seen from the above classification that many of the terms that have been used interchangeably with anismus are inappropriately specific and neglect the concept of impaired propulsion. Similarly, some of the definitions that have been offered are also too restrictive.

Rectal cooling test

The rectal cooling test is suggested to differentiate between rectal inertia and impaired relaxation/paradoxical contraction [27]

Other techniques include manometry, balloon expulsion test, evacuation proctography (see defecating proctogram), and MRI defecography.[28] Diagnostic criteria are: fulfillment of criteria for functional constipation, manometric and/or EMG and/or radiological evidence (2 out of 3), evidence of adequate expulsion force, and evidence of incomplete evacuation.[28] Recent dynamic imaging studies have shown that in persons diagnosed with anismus the anorectal angle during attempted defecation is abnormal, and this is due to abnormal (paradoxical) movement of the puborectalis muscle.[29][30][31]


Initial steps to alleviate anismus include dietary adjustments and simple adjustments when attempting to defecate. Supplementation with a bulking agent such as psyllium 3500 17 mg per day will make stool more bulky, which decreases the effort required to evacuate.[23] Similarly, exercise and adequate hydration may help to optimise stool form. The anorectal angle has been shown to flatten out when in a squatting position, and is thus recommended for patients with functional outlet obstruction like anismus.[5] If the patient is unable to assume a squatting postures due to mobility issues, a low stool can be used to raise the feet when sitting, which effectively achieves a similar position.[citation needed]

Treatments for anismus include biofeedback retraining, botox injections, and surgical resection. Anismus sometimes occurs together with other conditions that limit (see contraindication) the choice of treatments. Thus, thorough evaluation is recommended prior to treatment.[32]

Biofeedback training for treatment of anismus is highly effective and considered the gold standard therapy by many.[18][33][34] Others however, reported that biofeedback had a limited therapeutic effect.[35]

Injections of botulin toxin type-A into the puborectalis muscle are very effective in the short term, and somewhat effective in the long term.[36] Injections may be helpful when used together with biofeedback training.[37][38]

Historically, the standard treatment was surgical resection of the puborectalis muscle, which sometimes resulted in fecal incontinence. Recently, partial resection (partial division) has been reported to be effective in some cases.[35][39]

Etymology and synonyms

Paradoxical anal contraction during attempted defecation in constipated patients was first described in a paper in 1985, when the term anismus was first used.[40] The researchers drew analogies to a condition called vaginismus, which involves paroxysmal (sudden and short lasting) contraction of pubococcygeus (another muscle of the pelvic floor). These researchers felt that this condition was a spastic dysfunction of the anus, analogous to 'vaginismus'. However, the term anismus implies a psychogenic etiology, which is not true although psychological dysfunction has been described in these patients. Hence:

Latin ani - "of the anus"
Latin spasmus - "spasm"

(Derived by extrapolation with the term vaginismus, which in turn is from the Latin vagina - "sheath" + spasmus - "spasm")

Many terms have been used synonymously to refer to this condition, some inappropriately. The term "anismus" has been criticised as it implies a psychogenic cause.[41] In the most widely accepted classification systems (ICD-11 and Rome-IV, the term "dyssynergic defecation" is preferred.[21][20] As stated in the Rome II criteria, the term "dyssynergic defecation" is preferred to "pelvic floor dyssynergia" because many patients with dyssynergic defecation do not report sexual or urinary symptoms,[25] meaning that only the defecation mechanism is affected.

Other synonyms include:

See also


  1. ^ Voderholzer, W A; Neuhaus, D A; Klauser, A G; Tzavella, K; Muller-Lissner, S A; Schindlbeck, N E (1 August 1997). "Paradoxical sphincter contraction is rarely indicative of anismus". Gut. 41 (2): 258–262. doi:10.1136/gut.41.2.258. PMC 1891465. PMID 9301508.
  2. ^ a b c d Phillips, [edited by] Steven D. Wexner, Andrew P. Zbar, Mario Pescatori; with a foreword by Robin (2005). Complex anorectal disorders investigation and management. London: Springer. ISBN 978-1852336905. ((cite book)): |first= has generic name (help)CS1 maint: multiple names: authors list (link)
  3. ^ a b c Wexner, edited by Andrew P. Zbar, Steven D. (2010). Coloproctology. New York: Springer. ISBN 978-1-84882-755-4. ((cite book)): |first= has generic name (help)CS1 maint: multiple names: authors list (link)
  4. ^ Shafik, A; Mostafa, RM; Shafik, I; Ei-Sibai, O; Shafik, AA (2006-07-28). "Functional activity of the rectum: A conduit organ or a storage organ or both?". World Journal of Gastroenterology. 12 (28): 4549–52. doi:10.3748/wjg.v12.i28.4549. PMC 4125645. PMID 16874870.
  5. ^ a b Altomare, DF; Rinaldi, M; Veglia, A; Guglielmi, A; Sallustio, PL; Tripoli, G (February 2001). "Contribution of posture to the maintenance of anal continence". International Journal of Colorectal Disease. 16 (1): 51–4. doi:10.1007/s003840000274. PMID 11317698. S2CID 19755817.
  6. ^ Sikirov, D (July 2003). "Comparison of straining during defecation in three positions: results and implications for human health". Digestive Diseases and Sciences. 48 (7): 1201–5. doi:10.1023/a:1024180319005. PMID 12870773. S2CID 7625852.
  7. ^ Leroi, AM; Berkelmans, I; Denis, P; Hémond, M; Devroede, G (July 1995). "Anismus as a marker of sexual abuse. Consequences of abuse on anorectal motility". Digestive Diseases and Sciences. 40 (7): 1411–6. doi:10.1007/bf02285184. PMID 7628260. S2CID 36324110.
  8. ^ a b Kairaluoma, MV (2009). "[Functional obstructed defecation syndrome]". Duodecim; Laaketieteellinen Aikakauskirja. 125 (2): 221–5. PMID 19341037.
  9. ^ Tolosa, E.; Compta, Y. (2006). "Dystonia in Parkinson's disease". Journal of Neurology. 253 (Suppl 7): VII7–VI13. doi:10.1007/s00415-006-7003-6. PMID 17131231. S2CID 21944227.
  10. ^ Mathers, S.; Kempster, P.; Swash, M.; Lees, A. (1988). "Constipation and paradoxical puborectalis contraction in anismus and Parkinson's disease: a dystonic phenomenon?". Journal of Neurology, Neurosurgery, and Psychiatry. 51 (12): 1503–1507. doi:10.1136/jnnp.51.12.1503. PMC 1032764. PMID 3221217.
  11. ^ Thompson, J.; Chen, A.; Pettit, P.; Bridges, M. (2002). "Incidence of occult rectal prolapse in patients with clinical rectoceles and defecatory dysfunction". American Journal of Obstetrics and Gynecology. 187 (6): 1494–1499, discussion 1499–500. doi:10.1067/mob.2002.129162. PMID 12501052.
  12. ^ a b Velasco, F.; López, R.; Pujol, J.; Sancho, F.; Llauradó, J.; Lluís, F.; Clavé, P. (1998). "The use of anorectal manometry and dynamic proctography in patients for diagnosis of solitary rectal ulcer syndrome". Revista Espanola de Enfermedades Digestivas. 90 (6): 454–458. PMID 9708010.
  13. ^ a b Lubowski, DZ; King, DW (February 1995). "Obstructed defecation: current status of pathophysiology and management". The Australian and New Zealand Journal of Surgery. 65 (2): 87–92. doi:10.1111/j.1445-2197.1995.tb07267.x. PMID 7857236.
  14. ^ Catto-Smith, AG; Nolan, TM; Coffey, CM (September 1998). "Clinical significance of anismus in encopresis". Journal of Gastroenterology and Hepatology. 13 (9): 955–60. doi:10.1111/j.1440-1746.1998.tb00768.x. PMID 9794197. S2CID 23110387.
  15. ^ Hoffmann, BA; Timmcke, AE; Gathright JB, Jr; Hicks, TC; Opelka, FG; Beck, DE (July 1995). "Fecal seepage and soiling: a problem of rectal sensation". Diseases of the Colon and Rectum. 38 (7): 746–8. doi:10.1007/bf02048034. PMID 7607037. S2CID 38351811.
  16. ^ Rao, SS; Ozturk, R; Stessman, M (November 2004). "Investigation of the pathophysiology of fecal seepage". The American Journal of Gastroenterology. 99 (11): 2204–9. doi:10.1111/j.1572-0241.2004.40387.x. PMID 15555003. S2CID 27454746.
  17. ^ van der Hagen, SJ; Soeters, PB; Baeten, CG; van Gemert, WG (September 2011). "Conservative treatment of patients with faecal soiling". Techniques in Coloproctology. 15 (3): 291–5. doi:10.1007/s10151-011-0709-1. PMC 3155048. PMID 21720889.
  18. ^ a b Nolan T, Catto-Smith T, Coffey C, Wells J (August 1998). "Randomised controlled trial of biofeedback training in persistent encopresis with anismus". Arch. Dis. Child. 79 (2): 131–5. doi:10.1136/adc.79.2.131. PMC 1717674. PMID 9797593.
  19. ^ Real Martínez, Y; Ibáñez Moya, M; Pérez Mota, A (June 2007). "[Megarectum and anismus: a cause of constipation]". Revista Española de Enfermedades Digestivas. 99 (6): 352–3. doi:10.4321/s1130-01082007000600009. PMID 17883300.
  20. ^ a b c d e f g h i j k "Appendix A: Rome IV Diagnostic Criteria for FGIDs". Rome Foundation.
  21. ^ a b "DD92.2 Functional defaecation disorders. ICD-11 for Mortality and Morbidity Statistics".
  22. ^ a b Bordeianou, Liliana G.; Carmichael, Joseph C.; Paquette, Ian M.; Wexner, Steven; Hull, Tracy L.; Bernstein, Mitchell; Keller, Deborah S.; Zutshi, Massarat; Varma, Madhulika G.; Gurland, Brooke H.; Steele, Scott R. (April 2018). "Consensus Statement of Definitions for Anorectal Physiology Testing and Pelvic Floor Terminology (Revised)". Diseases of the Colon & Rectum. 61 (4): 421–427. doi:10.1097/DCR.0000000000001070. PMID 29521821.
  23. ^ a b c d e f al., senior editors, Bruce G. Wolff ... et (2007). The ASCRS textbook of colon and rectal surgery. New York: Springer. ISBN 978-0-387-24846-2. ((cite book)): |first= has generic name (help)CS1 maint: multiple names: authors list (link)
  24. ^ a b Marzouk, Deya. "Obstructed Defaecation Web". Retrieved 20 August 2012.
  25. ^ a b Bharucha, AE; Wald, A; Enck, P; Rao, S (April 2006). "Functional anorectal disorders". Gastroenterology. 130 (5): 1510–8. doi:10.1053/j.gastro.2005.11.064. PMID 16678564.
  26. ^ Rao, SS; Mudipalli, RS; Stessman, M; Zimmerman, B (October 2004). "Investigation of the utility of colorectal function tests and Rome II criteria in dyssynergic defecation (Anismus)". Neurogastroenterology and Motility. 16 (5): 589–96. doi:10.1111/j.1365-2982.2004.00526.x. PMID 15500515. S2CID 26066949.
  27. ^ Shafik, A; Shafik, I; El Sibai, O; Shafik, AA (March 2007). "Rectal cooling test in the differentiation between constipation due to rectal inertia and anismus". Techniques in Coloproctology. 11 (1): 39–43. doi:10.1007/s10151-007-0323-4. PMID 17357865. S2CID 36172856.
  28. ^ a b Berman L, Aversa J, Abir F, Longo WE (July 2005). "Management of disorders of the posterior pelvic floor". Yale J Biol Med. 78 (4): 211–21. PMC 2259151. PMID 16720016.
  29. ^ Murad-Regadas, S.; Regadas, F.; Barreto, R.; Rodrigues, L.; De Souza, M. (2009). "A novel two-dimensional dynamic anal ultrasonography technique to assess anismus comparing with three-dimensional echodefecography". Colorectal Disease. 11 (8): 872–877. doi:10.1111/j.1463-1318.2009.02018.x. PMID 19681980. S2CID 1888530.
  30. ^ Chu, W.; Tam, Y.; Lam, W.; Ng, A.; Sit, F.; Yeung, C. (2007). "Dynamic MR assessment of the anorectal angle and puborectalis muscle in pediatric patients with anismus: technique and feasibility". Journal of Magnetic Resonance Imaging. 25 (5): 1067–1072. doi:10.1002/jmri.20914. PMID 17410575.
  31. ^ Murad-Regadas, S.; Regadas, F.; Rodrigues, L.; Souza, M.; Lima, D.; Silva, F.; Filho, F. (2007). "A novel procedure to assess anismus using three-dimensional dynamic anal ultrasonography". Colorectal Disease. 9 (2): 159–165. doi:10.1111/j.1463-1318.2006.01157.x. PMID 17223941. S2CID 30918501.
  32. ^ Kaye, D; Wenger, N; Agarwal, B (1978). "Pharmacology of intraperitoneal cefazolin in patients undergoing peritoneal dialysis". Antimicrobial Agents and Chemotherapy. 14 (3): 318–21. doi:10.1128/aac.14.3.318. PMC 352457. PMID 708010.
  33. ^ Chiarioni G, Salandini L, Whitehead WE (July 2005). "Biofeedback benefits only patients with outlet dysfunction, not patients with isolated slow transit constipation". Gastroenterology. 129 (1): 86–97. doi:10.1053/j.gastro.2005.05.015. PMID 16012938.
  34. ^ Rao SS, Seaton K, Miller M, et al. (March 2007). "Randomized controlled trial of biofeedback, sham feedback, and standard therapy for dyssynergic defecation". Clin. Gastroenterol. Hepatol. 5 (3): 331–8. doi:10.1016/j.cgh.2006.12.023. PMID 17368232.
  35. ^ a b Faried, M; El Nakeeb, A; Youssef, M; Omar, W; El Monem, HA (August 2010). "Comparative study between surgical and non-surgical treatment of anismus in patients with symptoms of obstructed defecation: a prospective randomized study". Journal of Gastrointestinal Surgery. 14 (8): 1235–43. doi:10.1007/s11605-010-1229-4. PMID 20499203. S2CID 28441828.
  36. ^ Farid, M.; Youssef, T.; Mahdy, T.; Omar, W.; Moneim, H.; El Nakeeb, A.; Youssef, M. (2009). "Comparative study between botulinum toxin injection and partial division of puborectalis for treating anismus". International Journal of Colorectal Disease. 24 (3): 327–334. doi:10.1007/s00384-008-0609-7. PMID 19039596. S2CID 16943528.; Farid, M.; El Monem, H.; Omar, W.; El Nakeeb, A.; Fikry, A.; Youssef, T.; Yousef, M.; Ghazy, H.; Fouda, E.; El Metwally, T.; Khafagy, W.; Ahmed, S.; El Awady, S.; Morshed, M.; El Lithy, R. (2009). "Comparative study between biofeedback retraining and botulinum neurotoxin in the treatment of anismus patients". International Journal of Colorectal Disease. 24 (1): 115–120. doi:10.1007/s00384-008-0567-0. PMID 18719924. S2CID 26068227.
  37. ^ Joo, J.; Agachan, F.; Wolff, B.; Nogueras, J.; Wexner, S. (1996). "Initial North American experience with botulinum toxin type a for treatment of anismus". Diseases of the Colon and Rectum. 39 (10): 1107–1111. doi:10.1007/BF02081409. PMID 8831524. S2CID 27642905.
  38. ^ Farid, M; El Monem, HA; Omar, W; El Nakeeb, A; Fikry, A; Youssef, T; Yousef, M; Ghazy, H; Fouda, E; El Metwally, T; Khafagy, W; Ahmed, S; El Awady, S; Morshed, M; El Lithy, R (January 2009). "Comparative study between biofeedback retraining and botulinum neurotoxin in the treatment of anismus patients". International Journal of Colorectal Disease. 24 (1): 115–20. doi:10.1007/s00384-008-0567-0. PMID 18719924. S2CID 26068227.
  39. ^ Farid, M.; Youssef, T.; Mahdy, T.; Omar, W.; Moneim, H.; El Nakeeb, A.; Youssef, M. (2009). "Comparative study between botulinum toxin injection and partial division of puborectalis for treating anismus". International Journal of Colorectal Disease. 24 (3): 327–334. doi:10.1007/s00384-008-0609-7. PMID 19039596. S2CID 16943528.
  40. ^ Preston, DM; Lennard-Jones, JE (May 1985). "Anismus in chronic constipation". Digestive Diseases and Sciences. 30 (5): 413–8. doi:10.1007/BF01318172. PMID 3987474. S2CID 20213990.
  41. ^ Rao, Satish S.C. (31 August 2008). "Dyssynergic Defecation and Biofeedback Therapy". Gastroenterology Clinics of North America. 37 (3): 569–586. doi:10.1016/j.gtc.2008.06.011. PMC 2575098. PMID 18793997.
  42. ^ Bleijenberg, G; Kuijpers, HC (February 1987). "Treatment of the spastic pelvic floor syndrome with biofeedback". Diseases of the Colon and Rectum. 30 (2): 108–11. doi:10.1007/BF02554946. PMID 3803114. S2CID 31492289.
  43. ^ Help for Constipation