CT Imaging Protocol for Suspected Gastric Outlet Obstruction
For suspected gastric outlet obstruction, obtain a CT abdomen and pelvis with IV contrast and neutral oral contrast (water or dilute barium suspension). 1
Recommended Protocol Specifications
Essential Components
IV Contrast: Mandatory to assess for:
- Nodular or irregular wall thickening
- Soft tissue attenuation of wall thickening (distinguishing malignancy from edema)
- Mucosal enhancement patterns
- Lymphadenopathy and distant metastases 1
Neutral Oral Contrast: Use water or dilute barium suspension to:
- Delineate the intraluminal space
- Avoid obscuring mucosal enhancement (positive oral contrast impedes this assessment)
- Allow detection of intraluminal bleeding if present 1
Coverage Area
CT abdomen and pelvis is preferred over CT abdomen alone because:
- Allows assessment for distant metastases in the pelvis
- Malignancy is now the most common cause of GOO in adults (peptic ulcer disease incidence has decreased with widespread H2 blocker use) 1
- Provides comprehensive anatomic evaluation when symptoms are nonspecific 1
What CT Can Detect in GOO
The scan will identify multiple findings even when a gastric mass is not well-visualized due to underdistension:
- Nodular or irregular wall thickening/enhancement
- Soft tissue attenuation of wall thickening (suggests malignancy rather than edema)
- Perforation with ulcerated mass
- Lymphadenopathy
- Distant metastases
- Gastric outlet obstruction from edema or chronic inflammatory changes near antrum/pylorus 1
Protocols to Avoid
Do NOT order:
- CT without IV contrast - significantly less sensitive for diagnosis 1
- CT without and with IV contrast (dual-phase non-contrast + contrast) - limited added value for this indication 1
- Multiphase CT - not routinely performed unless acute GI bleeding is specifically suspected 1
Clinical Context
Malignancy has replaced peptic ulcer disease as the leading cause of GOO in adults 1. The initial imaging evaluation with CT and oral contrast will demonstrate both the obstruction and possible etiologies 2. While endoscopy remains the reference standard for definitive diagnosis and tissue sampling, CT provides critical anatomic information for surgical planning and staging 1, 3.
Common Pitfall
Avoid positive oral contrast agents - they impede assessment of mucosal enhancement and preclude evaluation of intraluminal bleeding, both of which are critical for distinguishing benign from malignant causes 1.