What causes feculent vomiting after anterior resection?

Causes of Feculent Vomiting After Anterior Resection

Feculent vomiting after anterior resection indicates mechanical bowel obstruction until proven otherwise and requires urgent surgical evaluation. 1

Life-Threatening Causes Requiring Immediate Assessment

Small bowel obstruction (SBO) is the most critical cause of feculent vomiting post-anterior resection and demands emergency surgical consultation. 1

• Internal hernia is a common cause of late SBO after colorectal surgery with anastomosis, presenting with acute onset crampy/colicky abdominal pain and bilious or feculent vomiting 1
• Anastomotic stricture can develop at the colorectal anastomosis site, causing progressive obstruction with eventual feculent vomiting 1
• Adhesive disease develops after any abdominal surgery and represents a frequent cause of mechanical obstruction 1
• Signs of complete intestinal obstruction and severe abdominal pain require emergency surgical assessment to rule out bowel ischemia or perforation 1

Non-Mechanical Causes of Vomiting

While less likely to cause true feculent vomiting, these conditions can present with severe vomiting after anterior resection:

Small Intestinal Bacterial Overgrowth (SIBO)

• SIBO occurs more commonly after bowel resection and can cause bloating, diarrhea, nausea, vomiting, weight loss, or malnutrition 1
• SIBO is more common with blind loops, dysmotility, diverticula, or strictures 1
• Other conditions that worsen symptoms after anterior resection should be excluded, particularly bile acid diarrhea (BAD), pancreatic exocrine insufficiency (PEI), and SIBO 1

Anastomotic Complications

• Anastomotic leak can present with fever, tachycardia, and vomiting in the early postoperative period 1
• For anastomotic stricture, endoscopic dilatation is the preferred treatment, with triamcinolone or needle knife stricturoplasty reserved for recurrent strictures 1

Diagnostic Approach

Contrast-enhanced CT is the imaging examination of choice when mechanical obstruction is suspected, as it can detect bowel obstruction, assess for internal hernia, and identify complications like perforation or ischemia 1

• In hemodynamically stable patients with suspected internal hernia, early explorative laparoscopy is mandatory to avoid late diagnosis, intestinal vascular compromise, and bowel resection 1
• Urgent neuroimaging or cross-sectional imaging is necessary if vomiting is associated with worsening symptoms, altered mental status, or new deficits 1

Critical Pitfalls to Avoid

• Do not attribute persistent vomiting to functional causes until comprehensive investigation has excluded organic causes, particularly mechanical obstruction 1
• Extensive investigation of symptoms within 3 months of surgery may be unnecessary for minor symptoms, as they often settle over time, but feculent vomiting is never a minor symptom 1
• Bilious or feculent vomiting indicates the obstruction is distal to the ligament of Treitz and requires different management than gastric outlet obstruction 1

Management Priorities

• Nasogastric tube placement for gastric decompression should be considered in patients presenting with symptoms of obstruction 1
• A multidisciplinary approach is required, including input from gastroenterology, surgery, pain management, and nutrition teams 1
• If symptoms persist beyond 3 months and conservative interventions have failed, referral to specialist services should be made 1