Search Pattern - XR Abdomen
Reading an abdominal radiograph can be fast, but only if you're considering the study completely. Radiologists do this in a blink of an eye after years of practice, but that kind of wiring isn't accessible if you're just getting started. Here's how to do that efficiently as a beginner.
1. Do you have the right study open?
- Are you looking at the right patient? Always confirm patient identity with two constant identifiers (name, MRN, DOB).
- Never use room number for patient identity.
- Are you looking at the most current exam? Confirm the date and time of exam that you're viewing.
2. Is the study technique adequate?
- Indication - is abdominal radiography a realistic choice based on what the provided history indicates you're trying to diagnose?
- Reasonable indications for abdominal radiography include initial screening for constipation, free air (not perfect - only 80% sensitivity), small bowel obstruction (SBO), cecal volvulus, sigmoid volvulus, necrotizing enterocolitis (NEC), retained surgical material (sponges, needles), percutaneous gastrostomy tube placement (after injecting gastrografin in the tube), double-J ureteral stent placement confirmation.
- Escalate to CT for detecting appendicitis, acute cholecystitis, pancreatitis, diverticulitis, obstructing ureteral stone, small volume perforations/free air, and most other conditions.
- Field of view - does the study adequately cover these parts: lung bases, abdomen and pelvis, and proximal femurs
- Patient positioning - is the selected patient positioning helpful for the disease you're trying to detect?
- supine - on the back. Fine as an initial assessment for anything. In patients with suspected free air, don't expect to see air clearly layering under the diaphragms. In patients with small bowel obstruction (SBO), don't expect to see air-fluid levels.
- upright - sitting or standing. Helps detect free air (perforation), because air gathers and layers under the diaphragm. Helps detect SBO because air-fluid levels will show up.
- lateral decubitus - laying on the side. Left lateral decubitus means left side down (touching the table); right lateral decubitus means right side down. Good for additional views to search for free air, rising to the non-dependent side (side not touching the table). Used with infants.
3. Is there any pathology?
Draw your attention to A-B-B-D: air, bowel, bones, devices.
A. Air
Lung bases, free air
- Lung bases - check for infiltrate, mass, subpulmonic pneumothorax
- Free air - intraperitoneal or retroperitoneal. Look for air under the diaphragm (practical, reasonable to detect), and Rigler sign (hard to see). On lateral decubitus, look for air next to the side of the abdominal wall that's opposite the side that's touching the table, called the "non-dependent" side.
B. Bowel
Small bowel, large bowel
- Small bowel - small bowel is more centrally located. Use the valvulae conniventes (narrowly spaced rings in the small bowel) to confirm you're looking at small bowel. Is the small bowel distended? Where are the loops that are distended? Do you see air-fluid levels?
- Large bowel - large bowel is more peripherally located. Use the haustra (widely spaced rings in the large bowel) to confirm you're looking at large bowel. Is the large bowel distended? Do you see air-fluid levels?
- Distribution of air distention -
- Ileus or early SBO - small + large bowel distention
- later SBO - small bowel distention, but not large bowel
- Cecal volvulus - large bowel distention, paradoxically in the left upper quadrant. Possibly also extensive small bowel distention (backing up from this proximal large bowel obstruction).
- Sigmoid volvulus - large bowel distention, centered on the mid-to-lower pelvis. Possibly also extensive small and large bowel distention (backing up from this distal large bowel obstruction).
C. Bones
Check for lytic or sclerotic lesions that might be concerning for metastatic disease. Don't worry about cataloging degenerative change. That's not the emphasis of this study.
D. Devices
Check for tubes, lines, stimulators, sponges and other retained surgical instruments.