Management of Prominent Mesorectal Vessels in Sigmoid Colon on CT
Prominent mesorectal vessels in the sigmoid colon on CT are typically a normal anatomical variant or represent vascular engorgement from underlying pathology (such as obstruction, volvulus, or inflammation) rather than a primary pathologic finding requiring specific intervention—the key is to identify and treat any underlying cause rather than the vessels themselves.
Clinical Context and Differential Diagnosis
The finding of prominent mesorectal vessels should prompt evaluation for underlying pathology:
- Sigmoid volvulus presents with dilated colon, air/fluid levels, and the characteristic "whirl sign" representing twisted colon and mesentery on CT, which would explain prominent vessels 1
- Large bowel obstruction from any cause (tumor, stricture) can lead to vascular engorgement and prominent mesenteric vessels 2
- Anatomical variants including persistent descending mesocolon (PDM) can present with distinctive anatomy of colonic vessels, with shortened mesocolon and altered vascular branching patterns 3
Diagnostic Approach
When prominent mesorectal vessels are identified on CT:
- Review the entire CT systematically for signs of obstruction (dilated bowel loops >2.5 cm proximal to collapsed loops), volvulus (whirl sign), or mass lesions 2, 1
- Assess bowel wall integrity looking for pneumatosis, which can identify coexistent ischemia and/or infarction with sensitivity of 75-100% 2
- Evaluate vascular anatomy including the origin of the inferior mesenteric artery (IMA) relative to the duodenum, as nearly one-third of patients have the IMA originating at or above the duodenum 4
- Look for anatomical variants such as PDM, which occurs when the descending colon fails to fix to the lateral abdominal wall and is associated with altered vascular anatomy 3
Management Algorithm
If No Underlying Pathology Identified:
- No specific intervention is required for prominent vessels alone—this represents a normal variant or incidental finding
- Clinical correlation with symptoms is essential; asymptomatic patients require no treatment
If Sigmoid Volvulus is Present:
- For uncomplicated cases, endoscopic decompression is first-line treatment with 70-91% success rate 1
- After successful decompression, definitive sigmoid resection should be performed during the same hospital admission, as recurrence rates without resection are 45-71% 1
- For patients with septic shock, bowel ischemia, or perforation, immediate surgical intervention is mandatory with resection (Hartmann's procedure or sigmoid resection with primary anastomosis) 1
If Obstruction from Tumor is Present:
- Emergency surgical exploration via laparotomy is indicated for peritonitis or perforation 5
- Colonoscopy with biopsy should be performed in suspected malignancy when emergency surgery is not indicated 2
- Hartmann procedure is appropriate for hemodynamically unstable patients or those with significant comorbidities 1, 5
Special Surgical Considerations
When surgery is required in patients with prominent mesorectal vessels:
- For benign conditions like volvulus, full oncological high ligation is not typically needed—the main consideration is ensuring adequate vascular supply to the remnant colon 1
- In cases with PDM, special attention is required during vessel dissection to maintain blood flow to the intestine, with awareness of the positional relationship between the left colic artery and marginal artery 3
- Preoperative axial CT scans provide crucial information about central vascular anatomy, including IMA origin and branching patterns 4
Critical Pitfalls to Avoid
- Do not assume prominent vessels alone indicate pathology—they may represent normal anatomical variation or physiologic response to underlying conditions
- Do not miss underlying sigmoid volvulus, as mortality for emergency surgery is 12-20% compared to 5.9% for elective resection 1
- Do not overlook anatomical variants like PDM during surgical planning, as these require modified dissection techniques to preserve vascular supply 3
- Do not delay surgical intervention when signs of ischemia, perforation, or peritonitis are present, as these require immediate operative management 1, 5