Advertisement

Pediatric Radiology

, Volume 44, Issue 7, pp 831–838 | Cite as

MRI anatomy of anteriorly displaced anus: what obstructs defecation?

  • Amr Abdelhamid AbouZeidEmail author
  • Shaimaa Abdelsattar Mohammad
  • Khaled Talaat Khairy
Original Article

Abstract

Background

Anteriorly displaced anus is an anomaly that is debated with regard to its nomenclature, diagnosis and management.

Objective

To describe MRI anatomy of the anal canal in children with anteriorly displaced anus and its impact on the process of defecation.

Materials and methods

We prospectively examined ten children (7 girls, 3 boys; age range 7 months to 8 years, mean 3 years) with anteriorly displaced anus between August 2009 and April 2012. Noncontrast MRI examinations were performed on a 1.5-T magnet. T1- and T2-weighted turbo spin-echo images were acquired in axial, sagittal and coronal planes of the pelvis. The anorectal angle and the relative hiatal distance were measured in mid-sagittal images, and compared with those of a control group using the Mann–Whitney test.

Results

In children with anteriorly displaced anus, no anatomical abnormality was depicted at the level of the proximal anal canal. However, the distal anal canal was displaced anteriorly, running out its external muscle cuff, which remained un-displaced at the usual site of the anus. This changes the orientation of the central axis of the anal canal by passing across instead of along the fibers of the longitudinal muscle coat. Children with anteriorly displaced anus had a more obtuse anorectal angle (mean 112.1°), which was significantly greater than that of the control group (mean 86.2°).

Conclusion

MRI is a valuable tool in studying the anatomy of the anal canal in children with anteriorly displaced anus. The abnormal orientation of the longitudinal muscle across the anal canal can explain the obstructed defecation in these children. Based on this study, it might be of interest to use MRI in studying equivocal cases and children with unexplained constipation.

Keywords

MRI Anorectal anomalies Ectopic anus Constipation Recto-perineal fistula Children 

Notes

Conflicts of interest

None

References

  1. 1.
    Kashyap P, Bates N (2004) Magnetic resonance imaging anatomy of the anal canal. Australas Radiol 48:443–449PubMedCrossRefGoogle Scholar
  2. 2.
    Tang ST, Cao GQ, Mao YZ et al (2009) Clinical value of pelvic 3-dimensional magnetic resonance image reconstruction in anorectal malformations. J Pediatr Surg 44:2369–2374PubMedCrossRefGoogle Scholar
  3. 3.
    Eltomey MA, Donnelly LF, Emery KH et al (2008) Postoperative pelvic MRI of anorectal malformations. Am J Roentgenol 191:1469–1476CrossRefGoogle Scholar
  4. 4.
    Hendren WH (1978) Constipation caused by anterior location of the anus and its surgical correction. J Pediatr Surg 13:505–512PubMedCrossRefGoogle Scholar
  5. 5.
    Leape LL, Ramenofsky ML (1978) Anterior ectopic anus: a common cause of constipation in children. J Pediatr Surg 13:627–630PubMedCrossRefGoogle Scholar
  6. 6.
    Schuster T, Joppich I, Schneider K et al (2000) A computerised vector manometry study of the so-called ectopic anus. Pediatr Surg Int 16:8–14PubMedCrossRefGoogle Scholar
  7. 7.
    Pakarinen MP, Rintala RJ (2010) Management and outcome of low anorectal malformations. Pediatr Surg Int 26:1057–1063PubMedCrossRefGoogle Scholar
  8. 8.
    Taccone A, Martucciello G, Dodero P et al (1992) New concepts in preoperative imaging of anorectal malformation. Pediatr Radiol 22:196–199PubMedCrossRefGoogle Scholar
  9. 9.
    Nievelstein RAJ, Vos A, Valk J (1998) MR imaging of anorectal malformations and associated anomalies. Eur Radiol 8:573–581PubMedCrossRefGoogle Scholar
  10. 10.
    Thambidorai CR, Raghu R, Zulfiqar A (2008) Magnetic resonance imaging in anterior ectopic anus. Pediatr Surg Int 24:161–165PubMedCrossRefGoogle Scholar
  11. 11.
    Alves JC, Sidler D, Lotz JW et al (2013) Comparison of MR and fluoroscopic mucous fistulography in the pre-operative evaluation of infants with anorectal malformation: a pilot study. Pediatr Radiol 43:958–963PubMedCrossRefGoogle Scholar
  12. 12.
    Holschneider A, Hutson J, Pena A et al (2005) Preliminary report on the international conference for the development of standards for the treatment of anorectal malformations. J Pediatr Surg 40:1521–1526PubMedCrossRefGoogle Scholar
  13. 13.
    Boechat MI (1992) Magnetic resonance imaging of the pediatric pelvis. Radiol Clin North Am 30:807–816PubMedGoogle Scholar
  14. 14.
    Van Beers BE, Kartheuser A, Delos MA et al (1996) MRI of the anal canal: correlation with histological examination. Magn Reson Imaging 14:151–156PubMedCrossRefGoogle Scholar
  15. 15.
    McHugh K (1998) The role of radiology in children with anorectal anomalies; with particular emphasis on MRI. Eur J Radiol 26:194–199PubMedCrossRefGoogle Scholar
  16. 16.
    Piloni V, Fioravanti P, Spazzafumo L et al (1999) Measurement of the anorectal angle by defecography for the diagnosis of fecal incontinence. Int J Colorectal 14:131–135CrossRefGoogle Scholar
  17. 17.
    Mohammad SA, AbouZeid AA (2013) MRI of persistent cloaca: can it substitute conventional imaging? Eur J Radiol 82:241–251PubMedCrossRefGoogle Scholar
  18. 18.
    Fielding JR (2002) Practical MR imaging of female pelvic floor weakness. Radiographics 22:295–304PubMedCrossRefGoogle Scholar
  19. 19.
    Tang S, Tong Q, Mao Y et al (2006) Magnetic resonance imaging of the anorectal striated muscle complex in normal children. J Pediatr Surg 41:1549–1555PubMedCrossRefGoogle Scholar
  20. 20.
    Pena A (2004) Comment on anterior ectopic anus. Pediatr Surg Int 20:902PubMedCrossRefGoogle Scholar
  21. 21.
    Reisner SH, Sivan Y, Nitzan M et al (1984) Determination of anterior displacement of the anus in newborn infants and children. Pediatrics 73:216–217PubMedGoogle Scholar
  22. 22.
    Herek O, Polat A (2004) Incidence of anterior displacement of the anus and its relationship to constipation in children. Surg Today 34:190–192PubMedCrossRefGoogle Scholar
  23. 23.
    Penninckx F, Debruyne C, Lestar B et al (1990) Observer variation in the radiological measurement of the anorectal angle. Int J Colorect Dis 5:94–97CrossRefGoogle Scholar
  24. 24.
    Penninckx F, Debruyne C, Lestar B et al (1991) Intraobserver variation in the radiological measurement of the anorectal angle. Gastrointest Radiol 16:73–76PubMedCrossRefGoogle Scholar
  25. 25.
    Upadhyaya P (1984) Mid-anal sphincteric malformation, cause of constipation in anterior perineal anus. J Pediatr Surg 18:183–186CrossRefGoogle Scholar
  26. 26.
    Lunniss PJ, Phillips RK (1992) Anatomy and function of the anal longitudinal muscle. Br J Surg 79:882–884PubMedCrossRefGoogle Scholar
  27. 27.
    Shafik A (1976) A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation III. The longitudinal anal muscle: anatomy and role in sphincter mechanism. Invest Urol 13:271–277PubMedGoogle Scholar
  28. 28.
    Petros P, Swash M, Bush M et al (2012) Defecation 1: testing a hypothesis for pelvic striated muscle action to open the anorectum. Tech Coloproctol 16:437–443PubMedCrossRefGoogle Scholar
  29. 29.
    Deutekom M, Dobben AC, Terra MP et al (2007) Clinical presentation of fecal incontinence and anorectal function: what is the relationship? Am J Gastroenterol 102:351–361PubMedCrossRefGoogle Scholar
  30. 30.
    Boyadzhyan L, Raman SS, Raz S (2008) Role of static and dynamic MR imaging in surgical pelvic floor dysfunction. Radiographics 28:949–967PubMedCrossRefGoogle Scholar
  31. 31.
    Campbell AM, Murphy J, Charlesworth PB et al (2013) Dynamic MRI (dMRI) as a guide to therapy in children and adolescents with persistent full thickness rectal prolapse: a single centre review. J Pediatr Surg 48:607–613PubMedCrossRefGoogle Scholar
  32. 32.
    Yong C, Ruo-yi W, Yuan Z et al (2013) MRI findings in patients with defecatory dysfunction after surgical correction of anorectal malformation. Pediatr Radiol 43:964–970PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Amr Abdelhamid AbouZeid
    • 1
    Email author
  • Shaimaa Abdelsattar Mohammad
    • 2
  • Khaled Talaat Khairy
    • 2
  1. 1.Department of Pediatric SurgeryAin-Shams UniversityCairoEgypt
  2. 2.Department of RadiodiagnosisAin-Shams UniversityCairoEgypt

Personalised recommendations