What are the next steps in diagnosis and treatment for a patient with duodenal thickening found on computed tomography (CT) scan?

Duodenal Thickening on CT: Diagnostic Approach

When duodenal wall thickening is identified on CT, proceed directly to upper endoscopy with biopsy for tissue diagnosis, as CT findings are nonspecific and cannot reliably distinguish between inflammatory, infectious, and neoplastic etiologies. 1, 2

Immediate Assessment for Life-Threatening Complications

Before pursuing endoscopy, the CT must be scrutinized for complications requiring urgent surgical intervention:

• Perforation: Look for extraluminal gas (present in 97% of perforations), focal wall defect/ulcer (84% of cases), and combined wall defect plus thickening (95% sensitivity, 93% specificity for perforation localization) 2
• Fluid or fat stranding along the gastroduodenal region occurs in 89% of perforation cases 1
• Duodenal obstruction: Assess for luminal narrowing from edema or chronic inflammation, particularly near the pylorus 1
• Active bleeding: Identify hyperdense blood products or contrast extravasation 1

If any of these complications are present, immediate surgical consultation is mandatory rather than endoscopy. 3

Primary Differential Diagnoses to Consider

Malignant Causes

• Adenocarcinoma: Presents with nodular or irregular wall thickening, soft tissue attenuation, and potentially ulcerated masses 1
• Pancreatic cancer with duodenal invasion: Tumors in the pancreatic head can grow locally into the proximal duodenum, causing wall thickening and potential obstruction 4
• Lymphadenopathy or distant metastases suggesting malignancy should be assessed on the CT 1

Inflammatory/Infectious Causes

• Peptic ulcer disease: Wall thickening from submucosal edema with mucosal hyperenhancement, focal outpouching representing ulcer craters, and focal interruption of mucosal enhancement 1, 2
• Duodenitis: Produces nonspecific wall thickening similar to gastritis 5
• Crohn's disease: Can involve the duodenum with thickened bowel showing mural stratification and surrounding inflammatory stranding 4
• Infectious colitis: Though more commonly colonic, can extend to involve the duodenum 6

Traumatic Causes

• Duodenal hematoma: Shows wall thickening and fluid in the right anterior pararenal space without extraluminal gas or contrast extravasation 3

Critical CT Technical Requirements for Accurate Assessment

The quality of the CT scan directly impacts diagnostic accuracy:

• IV contrast is essential to assess mucosal hyperenhancement, interrupted mucosal enhancement, and distinguish inflammatory from neoplastic processes 1, 2
• Neutral oral contrast (water or dilute barium) should be used rather than positive contrast to avoid obscuring mucosal enhancement 1, 2
• Adequate gastric and duodenal distension requires 600-800 mL of water or neutral oral contrast with gas-producing agents 1

If the CT was performed without these technical specifications, interpretation is limited and findings may be unreliable. 1

Pattern Recognition on CT

Focal vs. Diffuse Thickening

• Focal, irregular, and asymmetrical thickening (<5 cm) strongly suggests malignancy 7
• Segmental or diffuse thickening (>5 cm) is usually caused by benign conditions such as ischemic, inflammatory, or infectious diseases 7

Associated Findings

• Perienteric fat stranding disproportionately more severe than the degree of wall thickening suggests an inflammatory condition rather than neoplasm 7
• Duodenal mural thickening or mucosal irregularity on CT has 100% positive predictive value for actual duodenal involvement in the context of adjacent malignancy 8

Definitive Diagnostic Algorithm

1. Review CT for complications requiring immediate surgery (perforation, obstruction, active bleeding) 1, 2

2. If no complications present, proceed to upper endoscopy with biopsy as the reference standard for diagnosis 1, 2, 5

   • Endoscopy provides both tissue diagnosis and therapeutic intervention 2
   • 76% of patients with nonspecific bowel wall thickening on CT have identifiable pathology on endoscopy 6

3. If duodenal mucosal infiltration is seen on endoscopy in the context of adjacent pancreatic or gallbladder malignancy, this confirms invasion and significantly impacts resectability 8

4. If endoscopy is normal but clinical suspicion remains high, consider:

   • CT or MR enterography with specialized protocols for small bowel evaluation 4
   • Repeat endoscopy if symptoms persist or worsen 6

Common Pitfalls to Avoid

• Do not rely on CT alone for definitive diagnosis of uncomplicated peptic ulcer disease or duodenitis—these produce nonspecific wall thickening requiring endoscopic correlation 5
• Do not assume benign etiology based solely on symmetric, regular thickening—well-differentiated adenocarcinoma and lymphoma can present this way 7
• Do not delay endoscopy in symptomatic patients with duodenal thickening, as only 24% will have normal findings and the majority have significant gastroenterologic disease 6
• Do not perform CT enterography in acutely ill patients who cannot tolerate large volumes of oral contrast—standard CT is adequate for detecting complications 4