Initial Management of Partially Obstructing Rectal Cancer
For a partially obstructing rectal cancer, create a diverting stoma (preferably transverse loop colostomy) rather than resecting the tumor, as this allows proper staging and neoadjuvant chemoradiotherapy to be administered before definitive oncologic surgery. 1, 2
Immediate Resuscitation and Diagnostic Steps
- Obtain CT scan immediately as it is the best imaging technique to evaluate large bowel obstruction and assess the extent of disease 1
- Initiate fluid resuscitation with crystalloids to correct dehydration and electrolyte imbalances from the obstruction 1
- Start broad-spectrum antibiotics targeting gram-negative and anaerobic bacteria immediately, as bacterial translocation occurs across the obstructed bowel wall 2
- Discontinue antibiotics after 24 hours to minimize development of multidrug-resistant organisms 2
- Check complete blood count, serum creatinine, and inflammatory markers to assess physiologic status and degree of systemic compromise 2
Why Stoma Creation is Superior to Emergency Resection
The evidence strongly supports avoiding emergency tumor resection for several critical reasons:
- Obstructing rectal cancer invariably represents locally advanced disease requiring neoadjuvant chemoradiotherapy for optimal oncologic outcomes 1
- Emergency resection eliminates the opportunity for proper staging workup and neoadjuvant therapy, compromising long-term survival 2
- The surgical goal is obstruction relief, not definitive cancer treatment at this stage 1
Optimal Stoma Type and Location
Create a transverse loop colostomy as the procedure of choice for the following reasons:
- Transverse colostomy is recommended as it provides long-term decompression throughout the entire neoadjuvant treatment period 1, 2
- Plan the stoma location anticipating the future definitive surgery (either low anterior resection with diverting ileostomy or abdominoperineal resection) 1
- Alternative stoma options (loop ileostomy or end colostomy) can be considered based on the planned definitive procedure 1
Why Self-Expanding Metal Stents (SEMS) Are Contraindicated
Do not use SEMS for obstructing rectal cancer despite its utility in left colon obstruction:
- SEMS causes chronic pain and tenesmus in low rectal cancers, significantly worsening quality of life 1, 2
- Radiation and chemotherapy cause tumor necrosis which increases risk of stent migration and perforation, potentially compromising oncologic outcomes 1
- A stoma will be required anyway at the time of definitive resection (either permanent with APR or temporary with low anterior resection) 1
Post-Operative Oncologic Pathway
After stoma creation and recovery:
- Complete staging with full colonoscopy, chest/abdomen/pelvis CT, and MRI pelvis 2
- Initiate neoadjuvant chemoradiotherapy as the standard treatment for locally advanced rectal cancer 1, 2
- Perform definitive surgical resection after restaging following neoadjuvant therapy, likely low anterior resection with temporary diverting ileostomy versus abdominoperineal resection 2
Management of Hemodynamically Unstable Patients
If the patient develops signs of instability during presentation or surgery:
- Consider the patient unstable if any of the following are present: pH < 7.2, core temperature < 35°C, base excess < -8, coagulopathy, or signs of sepsis/septic shock requiring vasopressors 1
- Apply damage control principles with the simplest procedure to achieve decompression 1
- Hartmann's procedure (resection with end colostomy, no anastomosis) becomes the damage control operation if resection is necessary 2
Critical Pitfalls to Avoid
- Never perform emergency resection of obstructing rectal cancer in stable patients, as this prevents optimal oncologic treatment 1, 2
- Avoid SEMS placement despite its advantages in left colon obstruction, as rectal cancer has unique anatomic and treatment considerations 1, 2
- Do not delay stoma creation attempting prolonged medical management, as this delays definitive staging and treatment 1