Colostomy Procedure for Low Rectal Cancer
For low rectal cancer, the definitive surgical procedure is abdominoperineal resection (APR) with total mesorectal excision (TME), which necessitates creation of a permanent end sigmoid colostomy. 1
Definitive Surgical Management
When APR with Permanent Colostomy is Required
APR with permanent end colostomy is indicated when:
- The tumor directly involves the anal sphincter or levator muscles 1
- A margin-negative resection would result in loss of anal sphincter function and incontinence 1
- The tumor is located in the lower third of the rectum and sphincter preservation is not technically feasible 1
The APR involves en bloc resection of the rectosigmoid, rectum, anus, surrounding mesentery, mesorectum (via TME technique), and perianal soft tissue, requiring creation of a permanent colostomy. 1
Alternative: Sphincter-Preserving Surgery
For select patients with low rectal cancer, intersphincteric resection (ISR) with coloanal anastomosis may avoid permanent colostomy while maintaining oncologic safety. 2, 3 This approach:
- Requires careful patient selection with favorable tumor characteristics 2
- Typically necessitates a temporary diverting ileostomy that can be reversed after healing 2
- Provides similar oncological outcomes to APR with shorter hospital stays and lower postoperative morbidity 3
- May result in decreased anal function compared to higher anastomoses, though most patients achieve satisfactory continence 2, 4
Preoperative chemoradiotherapy may enable sphincter preservation in cases where initial tumor bulk prevented consideration of sphincter-sparing surgery. 1
Emergency/Obstructive Presentation
Decompressive Stoma Strategy
If low rectal cancer presents with obstruction, create a transverse loop colostomy rather than performing emergency resection. 1, 5, 6 This approach:
- Allows proper staging workup and timely initiation of neoadjuvant chemoradiotherapy 5, 6
- Provides a long-term solution through the entire duration of neoadjuvant treatment 1, 5
- Can remain in place to protect a future anastomosis if sphincter preservation becomes possible 1
Transverse loop colostomy is preferred over sigmoid colostomy because:
- It is easier to fashion due to greater mobility of the transverse colon 1
- It avoids risk of damage to the marginal arcade 1
- It does not alter the left abdominal region if permanent end colostomy becomes necessary at definitive resection 1
When APR is Predictable
An end sigmoid colostomy may be created initially when APR is clearly predictable at the time of emergency presentation. 1
Critical Pitfall to Avoid
Self-expanding metallic stents (SEMS) are contraindicated for low rectal cancer obstruction because they cause chronic pain, tenesmus, and worsening quality of life, and radiation/chemotherapy can cause tumor necrosis leading to stent migration and perforation that compromise oncologic results. 1, 5, 6
Quality of Life Considerations
Patients undergoing APR report worse body image, worse micturition symptoms, and less sexual enjoyment compared to those with sphincter-sparing surgery. 1 However, long-term quality of life between patients with or without permanent colostomy appears fairly comparable. 1
The safe distal margin for rectal resection must be ≥2 cm from the lower tumor edge, and a minimum of 6-8 lymph nodes should be examined. 1