1. ©2014 MFMER | slide-1 Fat Herniation Through the Canal of Schwalbe A Site of Lateral Perineal Hernias Alper Cesmebasi, M.D. 1,2, Nicole Abel 2, R. Shane Tubbs, PhD 2,3, Marios Loukas, MD, PhD 2 1 Department of Neurologic Surgery, Mayo Clinic, Rochester, MN 2 Department of Anatomical Sciences, St George’s University School of Medicine, Grenada, West Indies. 3 Division of Pediatric Neurosurgery, Children’s Hospital, Birmingham, AL Minnesota Surgical Society 2014 Fall Meeting 10 October 2014

2. ©2014 MFMER | slide-2 Cadaveric Study Routine anatomical abdominopelvic dissection of a 68 yo F cadaver yielded an incidental finding of perineal fat herniation On further examination, the herniation was noted to be between the levator ani muscle and the obturator internus fascia and omental in nature Posterior lateral herniation thru canal of Schwalbe No other anatomical findings on dissection and prior history were unremarkable

3. ©2014 MFMER | slide-3

4. ©2014 MFMER | slide-4 Perineal Hernias Perineal hernias are rare herniations of intra-abdominal contents through a weakness in the perineal floor Female Perineum, showing the sites of perineal hernias with relation to the superficial transverse perineal muscle. *Figure from: Carter JE. In Howard FM, Perry CP, Carter JE, et al., eds. Pelvic Pain: Diagnosis and Management. Philadelphia: Lippincott Williams& Wilkins, 200: 385-413.

5. ©2014 MFMER | slide-5 Canal of Schwalbe Hiatus occurring along the arcus tendineus of the levator ani muscle from the obturator internus fascia Acts as a site of lateral pelvic herniations for omentum, preperineal fat, small bowel, and sigmoid into the ischiorectal fossae

6. ©2014 MFMER | slide-6 Posterior Lateral Perineal Hernias Predispositions Extensive abdominoperineal resections, perineal prostatectomies, or atrophic pelvic floor Manifestations Soft protuberance between the gluteal muscles making sitting painful and difficult Reduces upon recumbency Weakness on the adductor muscles of thigh Obturator nerve impingement Rarely associated with constipation or sensation of incomplete defecation. Severe: strangulation (if the hiatus is large)

7. ©2014 MFMER | slide-7 Treatment Surgical treatment may utilize laparoscopic transabdominal approach Hernial sac should be reduced and a preperitoneal dissection should be done to define the borders of the hiatal ring Smaller defects closed with a primary repair utilizing nonabsorbable sutures Larger defects and atrophic floors require a tension-free repair with overlay mesh

8. ©2014 MFMER | slide-8 Conclusions Herniations through the hiatus of Schwalbe present as rare posterior lateral perineal herniations Resultant from a weakened pelvic floor postoperatively Asymptomatic, but presents as a soft protuberance between the gluteal muscles Incarceration and strangulation of bowel occurs with larger herniations Surgical treatment may be primary repair (small) or with mesh (larger defects)

9. ©2014 MFMER | slide-9 Acknowledgements R Shane Tubbs, PhD Marios Loukas, MD, PhD St George’s University School of Medicine The authors gratefully thank the individual who donated their body to the Department of Anatomy. This report was made possible by the selfless gift from donor cadaver patient.

10. ©2014 MFMER | slide-10 References Wang JK, Wolff BG. Posterior perineal hernia. Sem Colon Rectal Surg 2009;20:150-154. Carter JE. 2002. Sciatic, Obturator, and Perineal Hernias: A View from the Gynecologist. In:Fitzgibbons RJ, Greenberg AG. Nyhus and Condon’s Hernia. 5 th ed. Lippincott Williams& Wilkins, Philadelphia, pp 539-549 Flament JB, Avisse C, Delattre JF. (2001) Anatomy of the Abdominal Wall. In:Bendavid, R., Abrahamson, J., Arregui, M.E. Abdominal Wall Hernias. Springer-Verlag, New York, pp. 63. Malangoni MA, Rosen MJ. (2012) Chapter 46: Hernias. In: Townsend CM, Beauchamp RD, Evers BM, Mattox KL, eds. Sabiston Textbook of Surgery, 19 th edn. Saunders, Philadelphia, pp. 1137 Rayhanabad J, Sassani P, Abbas MA. (2009) Laparoscopic repair of perineal hernia, JSLS, 13: 237- 241. Singh K, Reid WMN, Berger LA. (2001) Translevator Gluteal Hernia, Int Urogynecol J, 12: 407-409. Skandalakis JE, Gray SW, Akins JT. (1974). The Surgical Anatomy of Hernial Rings. Surg Clin North Am, 54:1227-1246. Thorek P. (1985) Pelvic Diaphragms. In: Thorek P. Anatomy in Surgery, 3 rd ed. Springer-Verlag, Berlin, pp 572-577. Zimmerman LM, Anson BJ. (1967) Anatomy and Surgery of Hernia. William and Wilkins Co., Baltimore, pp. 353, 358-360. Zinner MJ, Ashley SW. (2007) Maingot’s Abdominal Operations. McGraw-Hill Professional, New York, pp. 129.