Grading of obstetric anal sphincter injury: endoanal or transperineal ultrasound?

Tess Nagy; Stefaan Pacquee; Carolyn Pieri; Kate Moore; Emmanuel Karantanis

doi:10.1071/CJ25201

RESEARCH ARTICLE (Open Access)

Previous Next Contents Vol 31(2)

Grading of obstetric anal sphincter injury: endoanal or transperineal ultrasound?

Tess Nagy ^A ^* , Stefaan Pacquee ^A , Carolyn Pieri ^A , Kate Moore ^A ^B and Emmanuel Karantanis ^A ^B

+ Author Affiliations

- Author Affiliations

^A St George Hospital – Pelvic Floor Unit, 28A Gray Street, Kogarah, NSW 2217, Australia.

^B University of New South Wales – Obstetrics and Urogynaecology, St George Hospital, Level 1 WR Pitney Clinical Sciences Building, Gray Street, Kogarah, NSW 2217, Australia.

^* Correspondence to: tess.carruthers@health.nsw.gov.au

Australian and New Zealand Continence Journal 31, CJ25201 https://doi.org/10.1071/CJ25201

Submitted: 6 February 2025 Accepted: 19 May 2025 Published: 19 June 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of Continence Health Australia (CHA). This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Background

Obstetric Anal Sphincter Injury (OASI) occurs in up to 5% of vaginal deliveries and is associated with significant maternal morbidity. 3D endoanal ultrasound (EAUS) is considered the gold standard for imaging anal sphincter pathology. 3D/4D transperineal ultrasound (TPUS) is a less invasive alternative that is more widely available.

Aims

To evaluate agreement between EAUS and TPUS in detecting anal sphincter defects after primary repair of OASI and to assess the correlation between the degree of anal sphincter defect on ultrasound and anal incontinence symptom severity.

Methods

Twenty-seven primiparous women, after primary OASI repair, underwent clinical examination, EAUS, and TPUS at a median of 6 months post-delivery. Agreement between clinical grading, EAUS, and TPUS was assessed using weighted kappa statistics. Anal incontinence symptoms were evaluated using the St. Mark’s Incontinence Score (SMIS).

Results

Moderate agreement was found between clinical grading and both EAUS (κ = 0.713) and TPUS (κ = 0.594). Agreement between EAUS and TPUS grading was also moderate (κ = 0.593). No significant association was found between ultrasound findings and anal incontinence symptoms at 6-month follow-up.

Conclusion

TPUS demonstrates promise as an alternative to EAUS for evaluating anal sphincter injuries after OASI repair, showing moderate agreement. Further research is needed to refine diagnostic criteria and establish the relationship between imaging findings and long-term functional outcomes.

Keywords: anal incontinence, endoanal ultrasound, faecal incontinence, OASI, obstetric anal sphincter injury, perineal trauma, translabial ultrasound, transperineal ultrasound.

References

1 Australian Institute of Health and Welfare. National core maternity indicators 2021. Canberra: AIHW; 2021.

2 Williams A, Lavender T, Richmond DH, Tincello DG. Women’s experiences after a third-degree obstetric anal sphincter tear: a qualitative study. Birth 2005; 32(2): 129-136.
| Crossref | Google Scholar | PubMed |

3 Bols EMJ, Hendriks EJM, Berghmans BCM, et al. A systematic review of etiological factors for postpartum fecal incontinence. Acta Obstet Gynecol Scand 2010; 89(3): 302-314.
| Crossref | Google Scholar | PubMed |

4 Tucker J, Clifton V, Wilson A. Teetering near the edge; women’s experiences of anal incontinence following obstetric anal sphincter injury: an interpretive phenomenological research study. Aust N Z J Obstet Gynaecol 2014; 54(4): 377-381.
| Crossref | Google Scholar | PubMed |

5 Fernando RJ, Sultan AH, Radley S, et al. Management of obstetric anal sphincter injury: a systematic review & national practice survey. BMC Health Serv Res 2002; 2(1): 9.
| Crossref | Google Scholar | PubMed |

6 Kumar A, Scholefield JH. Endosonography of the anal canal and rectum. World J Surg 2000; 24(2): 208-215.
| Crossref | Google Scholar | PubMed |

7 Santoro GA. Imaging the pelvic floor. Tech Coloproctol 2017; 21(7): 497-499.
| Crossref | Google Scholar | PubMed |

8 Sultan AH, Kamm MA, Talbot IC, et al. Anal endosonography for identifying external sphincter defects confirmed histologically. Br J Surg 1994; 81(3): 463-465.
| Crossref | Google Scholar | PubMed |

9 Sultan AH, Kamm MA, Nicholls RJ, Bartram CI. Prospective study of the extent of internal anal sphincter division during lateral sphincterotomy. Dis Colon Rectum 1994; 37(10): 1031-1033.
| Crossref | Google Scholar | PubMed |

10 Taithongchai A, Thakar R, Sultan AH. Management of subsequent pregnancies following fourth-degree obstetric anal sphincter injuries (OASIS). Eur J Obstet Gynecol Reprod Biol 2020; 250: 80-85.
| Crossref | Google Scholar | PubMed |

11 Dietz HP. Exoanal imaging of the anal sphincters. J Ultrasound Med 2018; 37(1): 263-280.
| Crossref | Google Scholar | PubMed |

12 Roos A-M, Abdool Z, Sultan AH, Thakar R. The diagnostic accuracy of endovaginal and transperineal ultrasound for detecting anal sphincter defects: the PREDICT study. Clin Radiol 2011; 66(7): 597-604.
| Crossref | Google Scholar | PubMed |

13 Okeahialam NA, Thakar R, Sultan AH. Comparison of diagnostic criteria for significant anal sphincter defects between endoanal and transperineal ultrasound. Ultrasound Obstet Gynecol 2022; 60(6): 793-799.
| Crossref | Google Scholar | PubMed |

14 Dietz HP. Ultrasound imaging of maternal birth trauma. Int Urogynecol J 2021; 32(7): 1953-1962.
| Crossref | Google Scholar | PubMed |

15 Wong KW, Thakar R, Sultan AH, Andrews V. Can transperineal ultrasound improve the diagnosis of obstetric anal sphincter injuries? Int Urogynecol J 2022; 33(10): 2809-2814.
| Crossref | Google Scholar | PubMed |

16 Sultan AH. Editorial: obstetrical perineal injury and anal incontinence. Clin Risk 1999; 5(6): 193-196.
| Crossref | Google Scholar |

17 Maeda Y, Vaizey CJ, Parés D, Norton C, Vaizey C, Kamm MA. Does the St. Mark’s incontinence score reflect patients’ perceptions? A review of 390 patients. Dis Colon Rectum 2008; 51(4): 436-442.
| Crossref | Google Scholar | PubMed |

18 Gillor M, Shek KL, Dietz HP. How comparable is clinical grading of obstetric anal sphincter injury with that determined by four-dimensional translabial ultrasound? Ultrasound Obstet Gynecol 2020; 56(4): 618-623.
| Crossref | Google Scholar | PubMed |

19 Guzmán Rojas RA, Kamisan Atan I, Shek KL, Dietz HP. Anal sphincter trauma and anal incontinence in urogynecological patients. Ultrasound Obstet Gynecol 2015; 46(3): 363-366.
| Crossref | Google Scholar | PubMed |

20 Roos A-M, Thakar R, Sultan AH. Outcome of primary repair of obstetric anal sphincter injuries (OASIS): does the grade of tear matter? Ultrasound Obstet Gynecol 2010; 36(3): 368-374.
| Crossref | Google Scholar | PubMed |

21 Starck M, Bohe M, Valentin L. The extent of endosonographic anal sphincter defects after primary repair of obstetric sphincter tears increases over time and is related to anal incontinence. Ultrasound Obstet Gynecol 2006; 27(2): 188-197.
| Crossref | Google Scholar | PubMed |

22 Patton V, Kumar S, Parkin K, et al. The relationship between residual sphincter damage after primary repair, faecal incontinence, and anal sphincter function in primiparous women with an obstetric anal sphincter injury. Neurourol Urodyn 2019; 38(1): 193-199.
| Crossref | Google Scholar | PubMed |

23 Andrews V, Sultan AH, Thakar R, Jones PW. Occult anal sphincter injuries – myth or reality? BJOG 2006; 113(2): 195-200.
| Crossref | Google Scholar | PubMed |

24 Roper JC, Thakar R, Sultan AH. Under-classified obstetric anal sphincter injuries. Int Urogynecol J 2022; 33(6): 1473-1479.
| Crossref | Google Scholar | PubMed |

25 Taithongchai A, Van Gruting IMA, Volløyhaug I, et al. Comparing the diagnostic accuracy of 3 ultrasound modalities for diagnosing obstetric anal sphincter injuries. Am J Obstet Gynecol 2019; 221(2): 134.e1-134.e9.
| Crossref | Google Scholar |