What is the protocol for an abdominal (ABD) X-ray?

Abdominal X-Ray Protocol

Standard Protocol for Abdominal X-Ray

For suspected anorectal foreign body, obtain lateral and anteroposterior plain X-ray films of the chest, abdomen, and pelvis to identify the foreign body position, determine its shape, size, and location, and detect possible pneumoperitoneum 1.

Standard Views Required

• Anteroposterior (AP) view of the abdomen and pelvis 1
• Lateral view of the chest, abdomen, and pelvis 1
• Upright chest X-ray when perforation is suspected to detect free air 1

Patient Positioning for Optimal Detection

• Have the patient stand or lie in left lateral decubitus position for 10-15 minutes before obtaining X-rays when free air is suspected, as this allows even 1 cc of free peritoneal air to become visible 2
• For suspected bowel obstruction or perforation, erect or lateral decubitus chest radiographs can be performed if CT is unavailable 1

Clinical Context Determines Appropriateness

When Abdominal X-Ray IS Appropriate

• Suspected anorectal foreign body - X-ray should be obtained BEFORE digital rectal examination to prevent accidental injury to the examiner from sharp objects 1, 3
• Suspected bowel perforation in resource-limited settings where CT is unavailable 1
• Suspected bowel obstruction as a screening tool, though CT is superior 1
• Detection of radiopaque foreign bodies or urinary calculi 4

When Abdominal X-Ray Should NOT Be Used

• Nonlocalized abdominal pain - CT abdomen/pelvis with IV contrast is the preferred initial imaging, changing diagnosis in 49% and management in 42% of patients 4
• Suspected diverticulitis - CT has >95% sensitivity versus limited utility of plain films 4
• Suspected appendicitis - CT has 95% sensitivity and 94% specificity 4
• Routine screening in emergency departments - plain films have limited diagnostic yield and rarely change management 5, 6, 7

Critical Limitations to Recognize

Poor Sensitivity for Most Acute Conditions

• Only 74-84% sensitivity for confirming large bowel obstruction, compared to 93-96% for CT 1
• 30-50% of bowel perforations show no free air on X-ray, especially in elderly patients 2
• Cannot detect non-radiopaque foreign bodies - CT or contrast-enhanced imaging is required 1
• Cannot visualize abscesses, extramural complications, or soft tissue pathology 1

When to Escalate to CT Immediately

• If X-ray shows suspected free air but findings are inconclusive, proceed directly to CT scan, which is the gold standard 2
• In hemodynamically stable patients with suspected perforation, obtain contrast-enhanced CT rather than relying on plain films 1
• When clinical suspicion remains high despite negative or equivocal X-ray findings 4, 6

Common Pitfalls to Avoid

• Do not perform digital rectal examination before obtaining X-ray when foreign body is suspected, as sharp objects can injure the examiner 1, 3
• Do not rely on abdominal X-ray as a routine screening tool - it has limited diagnostic yield and exposes patients to unnecessary radiation 5, 6, 7
• Do not assume negative X-ray rules out perforation - 30-50% of perforations show no free air, particularly in elderly patients 2
• Do not use X-ray to diagnose constipation - sensitivity is only 73.8% with specificity of 26.8%, leading to overdiagnosis 8
• Do not delay CT imaging in clinically deteriorating patients while pursuing non-diagnostic plain films 4

Radiation Exposure Considerations

• Abdominal X-rays expose patients to significant radiation without commensurate diagnostic benefit in most emergency presentations 6, 7
• Consider ultrasound as first-line imaging for right upper quadrant pain, pregnant patients, or children where radiation exposure is a concern 4
• CT abdomen exposes patients to approximately 10 mSv (compared to 3 mSv annual background radiation), but provides vastly superior diagnostic information 4