Sigmoidocele may be internal if it is only detectable on defecography, or external if it detectable without imaging and associated with a rectocele or rectal prolapse.[2] It is a type of posterior compartment prolapse.[4]
Sigmoidocele may be classified according to size relative to the pubococcygeal line.[2][note 1]
Small: less than 3 cm between pubococcygeal line and the most inferior (lowest) point of the hernial sac.[2]
Moderate: 3–6 cm pubococcygeal line and the most inferior point of the sac.[2]
Large: more than 6 cm pubococcygeal line and the most inferior point of the sac.[2]
The severity of sigmoidocele can be described with reference to the position of the lowest loop of the sigmoid relative to lines drawn on defecography:
First-degree sigmoidocele: above the pubococcygeal line.[2]
Second-degree sigmoidocele: below the pubococcygeal line but above the ischiococcygeal line.[2][note 2]
Third-degree sigmoidocele: below the ischiococcygeal line.[2]
Obstructed defecation syndrome.[3] It has been suggested that a sigmoidocele does not cause obstruction, but rather is a compensatory mechanism which increases rectal pressure and helps evacuation in the presence of excessive perineal descent.[6]
The phenomenon is caused by a weak section of fascial supports of the vagina (the uterosacral cardinal ligament complex and rectal vaginal septum), which allows a section of peritoneum containing the sigmoid colon to prolapse out of normal position and descend between the rectum and the vagina.[1]
The mesentery of the sigmoid colon (the structure which attaches the colon to the abdominal wall) is termed the mesosigmoid. This structure is very flexible, which means that the sigmoid colon is very mobile and may change position. During defecation it may be pushed down, eventually causing sigmoidocele.[7]
Surgery is considered if there is a significant hernia combined with symptoms of obstructed defecation.[9]
Laparoscopic ventral mesh rectopexy has been used to correct sigmoidocele.[7] This procedure involves inserting a mesh between the rectum and the vagina. The mesh is suspended from the sacral promontory without tension. This acts to support the recto-vaginal septum and elevate a deep pouch of Douglas.[7] If there is prolapse of the middle compartment, sacrocolpopexy may be carried out to surgically correct all pelvic prolapse problems in the same procedure.[9]
Sigmoidocele normally occurs in females, and is uncommon.[1] Sigmoidocele is detected about 4-5% of the time when defecography is carried out.[3][1]
Notes
^The "pubococcygeal line" (PCL) is a reference line which may be drawn on defecography. It extends from the inferior (lower) border of the pubic symphysis to the last coccygeal joint. See Bordeianou et al. 2018.
^The "ischiococcygeal line" is a reference line which may be drawn on defecography. It extends from the inferior (lower) border of the ischium to the last coccygeal joint. See Bordeianou et al. 2018.
References
^ abcdefgZbar, AP; Wexner, SD, eds. (18 March 2010). Coloproctology. Springer London. pp. 140–143. ISBN978-1-84882-755-4.
^ abcRatto C, Parrello A, Dionisi L, Litta F (2014). Coloproctology: Colon, Rectum and Anus: Anatomic, Physiologic and Diagnostic Bases for Disease Management. Cham, Switzerland: Springer International Publishing. pp. 229, 280. ISBN978-3-319-10154-5.
^Steele SR, Maykel JA, Wexner SD (11 August 2020). Clinical Decision Making in Colorectal Surgery (2nd ed.). Cham: Springer International Publishing. pp. 22, 23. ISBN978-3-319-65941-1.
^Brown, SR; Hartley, JE; Hill, J; Scott, N; Williams, G, eds. (2012). Contemporary Coloproctology. London Heidelberg: Springer. p. 391. ISBN978-1-4471-5856-1.
^ abcdHerold A, Lehur PA, Matzel KE, O'Connell PR (2017). European Manual of Medicine: Coloproctology (Second ed.). Berlin, Germany. pp. 9, 129. ISBN978-3-662-53210-2.{{cite book}}: CS1 maint: location missing publisher (link)
^Schwandner, O; Poschenrieder, F; Gehl, HB; Bruch, HP (September 2004). "[Differential diagnosis in descending perineum syndrome]". Der Chirurg; Zeitschrift fur alle Gebiete der operativen Medizen. 75 (9): 850–60. doi:10.1007/s00104-004-0922-9. PMID15258747.
^ abSteele SR, Hull TL, Hyman N, Maykel JA, Read TE, Whitlow CB (20 November 2021). The ASCRS Textbook of Colon and Rectal Surgery (4th ed.). Cham, Switzerland: Springer Nature. p. 1014. ISBN978-3-030-66049-9.