Procedures · Chest, abdomen and GI3 min read5-question check
Ribs and sternum positioning
Above the diaphragm: erect, inspiration. Below: recumbent, expiration. Rotate the spine away from the injury.
Above or below
Rib exams are split by the diaphragm. For ribs above the diaphragm, the patient is erect if possible and holds a full inspiration, which drops the diaphragm and shows the upper ribs against air-filled lungs. A lower, chest-like kVp keeps bone contrast. For ribs below the diaphragm, the patient is recumbent and holds a full expiration, which raises the diaphragm so the lower ribs sit over the abdomen. They need a higher, abdomen-like kVp. Upper ribs: CR to T7, top of the IR about 1.5 inches above the shoulders. Lower ribs: bottom of the IR at the iliac crest.
AP or PA
Place the injured area closest to the IR. Posterior pain calls for an AP. Anterior pain calls for a PA. Many departments also take a PA chest, because a pneumothorax or hemothorax can matter more than the fracture.
Picking the oblique
A 45-degree oblique frees the axillary ribs from superimposition. The rule is to turn the spine away from the injury. For an anterior injury, use a PA oblique, RAO or LAO, with the injured side away from the IR. For a posterior injury, use an AP oblique, RPO or LPO, with the injured side toward the IR. Worked example: right anterior pain gets a PA and an LAO. Left posterior pain gets an AP and an LPO. In both, the spine moves away from the injured ribs.
Sternum
A straight PA hides the thin sternum over the spine. A 15 to 20 degree RAO shifts it just left of the spine, over the heart shadow, which gives an even background. A thin chest needs more rotation and a deep chest needs less. Center about 1 inch left of the spinous processes, midway between the jugular notch and xiphoid. A breathing technique, low mA with a 2 to 3 second exposure during shallow breathing, blurs ribs and lung markings. If the patient cannot cooperate, suspend on expiration. The lateral is erect at 72 inches, shoulders drawn back, on full inspiration.
Clinical Example
A patient fell against a counter and points to the right lower anterior ribs. You take a PA with the patient recumbent on expiration, then an LAO, which turns the right side away from the IR and clears the axillary ribs from the spine. A PA chest rules out a pneumothorax.
Common Mistakes
- Using inspiration for ribs below the diaphragm, which drops the diaphragm so the lower ribs straddle lung and abdomen densities.
- Choosing an RAO for right anterior pain, which puts the spine over the injured ribs.
- Rotating the sternum 45 degrees instead of 15 to 20 degrees.
- Suspending respiration on the RAO sternum when the patient could do a breathing technique.
Why It Matters
The registry tests breathing by diaphragm level, the oblique that matches an injury site, and why the sternum is shot RAO with a breathing technique.
Key Relationships
- Above the diaphragm → erect, full inspiration, lower kVp
- Below the diaphragm → recumbent, full expiration, higher kVp
- Anterior injury → PA oblique, injured side away from IR
- Posterior injury → AP oblique, injured side toward IR
- Sternum → 15 to 20 degree RAO over the heart shadow