II. Epidemiology
- Represents 25% of Perirectal Abscess
III. Pathophysiology
-
Perirectal Abscess involving ischiorectal space or fossa
- Space contains primarily adipose tissue
- Anatomic boundaries
- Horseshoe Abscess
- Abscess between the anal canal and the Sacrum extends anteriorly and bilaterally into the ischiorectal space
IV. Signs: Low Abscess
- See Perirectal Abscess
- Infection of fatty tissue below Rectum
- Perianal tenderness and swelling 2-3 cm from anal verge
V. Differential Diagnosis
- High Abscess
- Low Abscess
- Perianal Abscess (immediately adjacent to anal verge)
VI. Imaging
- CT Pelvis
- Intrarectal Ultrasound
- Evaluation of complex or suspected high abscess
VII. Management
- See Perirectal Abscess
- Ischiorectal Abscess incision should be made as close to anal verge as possible
- Minimizes length of potential fistula formation
- Local Incision and Drainage indications
- Low abscess without signs of higher spread
- Non-toxic appearance
- Surgical Consultation for drainage indications
- Signs of fasciitis and deep ischiorectal spread
- Horseshoe abscess drainage is complex
- Posterior incision placed between Coccyx and anus
VIII. Complications: Deep spread of infection
- Posterior rectal space infection (horseshoe abscess)
- High Ischiorectal Abscess
IX. References
- Marx (2002) Rosen's Emergency Medicine, p. 1952
- Roberts (1998) Procedures, Saunders, p. 649-51
- Sherman, Bahga and Vietvuong (2022) Crit Dec Emerg Med 36(7): 23-9