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The anatomy of the perineal membrane: its relationship to injury in childbirth and episiotomy
Author(s) -
Hudson Christopher N,
Sohaib Syed A,
Shulver Helen M,
Reznek Rodney H
Publication year - 2002
Publication title -
australian and new zealand journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.734
H-Index - 65
eISSN - 1479-828X
pISSN - 0004-8666
DOI - 10.1111/j.0004-8666.2002.00193.x
Subject(s) - perineum , anatomy , medicine , external anal sphincter , levator ani , episiotomy , anal canal , vagina , dissection (medical) , sphincter , pelvic floor , anus , surgery , rectum , pregnancy , biology , genetics
Background Episiotomy during childbirth, intended to protect the anal sphincter, may fail to do so. Furthermore damage to the anal sphincter complex may occur without complete perineal tear.We hypothesise that these particular injuries may occur due to posterior displacement of the anus leading to distraction of the anal sphincter complex from an anterior attachment to the perineal membrane. However, the anatomical basis for this has not been well defined. Objective To investigate the relationship between the anal sphincter and the perineal membrane. Materials and methods High‐resolution MRI scans of a female cadaver perineum were performed. The imaging findings were correlated with the anatomical structure identified on dissection and histological examination. Results The perineal membrane was easily identified on MR imaging. Fibres from the perineal membrane could be seen to attach to the anal sphincter complex at the apex of the perineal body. This was confirmed on histological examination and was a deeper layer than that of the decussation of the superficial transverse perineal muscle with the superficial part of the external anal sphincter. Conclusion The upper ano‐rectal canal and apex of the perineal body have demonstrable attachment to the free margin of the perineal membrane postero‐lateral to the lower vagina. This attachment would resist posterior displacement of the anal canal.