A Few Radiology Tricks That Can Make a Big Difference
A wooden spoon, a change in positioning, or ordinary air can help answer questions that routine radiographs leave unresolved.
By Steve Mehler, DVM, DACVS
When abdominal radiographs are equivocal, the next step isn’t always a more complicated test. Sometimes a different view or simple technique can reduce superimposition and make the area of interest easier to interpret. These methods won’t replace ultrasound or other advanced imaging, but they can provide useful information when used to answer a focused clinical question.
Start by changing the view
A standard abdominal study generally includes lateral and ventrodorsal projections. When gastrointestinal disease is suspected, adding the opposite lateral view can be useful because gas shifts with the patient’s position. On a left lateral view, gas often moves into the pylorus; on a right lateral view, it tends to outline the fundus. That shift may reveal a lesion or foreign material hidden on the first image. www.vin.com
Before adding a contrast agent, consider whether repositioning alone could answer the question.
The wooden-spoon technique
A radiolucent wooden spoon or paddle can gently compress the abdomen and move bowel loops away from a region of interest. This may help separate overlapping intestinal loops, assess whether a suspicious loop stays fixed, or improve visibility of a structure such as the urinary bladder or kidney.
Here’s a practical approach:
Obtain survey views first. Identify the region of concern and decide whether compression could answer a specific question.
Use a radiolucent paddle. Place a wooden or plastic spoon with a long handle over the target area from the nondependent side.
Apply gentle, targeted pressure. The goal is to displace overlapping bowel—not flatten the abdomen. Expose while maintaining compression, then compare the image with the survey view.
Look for what moves and what stays. Mobile bowel may shift away from the target. Plicated bowel or a fixed lesion may remain in position, making its shape or contents easier to assess.
Use radiation-safety precautions, including appropriate shielding and keeping hands out of the primary beam. Avoid compression when it could worsen the suspected problem; diaphragmatic hernia, for example, is a recognized contraindication.
Use air as negative contrast
Air appears radiolucent on radiographs. When introduced into the stomach or colon, it creates contrast between the gas-filled lumen and surrounding soft tissue. Start with survey images, use these studies to answer a focused question, and obtain follow-up images promptly. Insufflation should be gradual and appropriate for the patient; avoid forceful catheter placement or overdistension.
Pneumocolonogram
Consider a pneumocolonogram when an object or gas-distended loop is visible but its location—colon versus small intestine—remains uncertain. Once the colon is outlined, the object’s position relative to it can help localize the finding.
A typical approach uses a lubricated, soft red-rubber catheter passed gently through the rectum, ideally far enough to reach the descending colon. Room air is introduced with a syringe in measured increments. One published clinical guide describes approximately 3–5 mL/kg, with additional air if the colon remains inadequately outlined; the appropriate amount depends on the patient and study goal. Stop if resistance or discomfort suggests the catheter or air is not advancing safely.
Repeat the relevant projections and trace the colon’s course. On a lateral view, identify the descending colon in the dorsal abdomen, ventral to the kidneys, and follow it caudally into the pelvic canal. If the colon is not clearly outlined, the study may not answer the localization question.
Pneumogastrogram
A pneumogastrogram uses air as negative contrast to outline the stomach’s lumen and contents. It may help when survey radiographs do not clearly show a suspected gastric foreign body, pyloric lesion, or mural abnormality.
Orogastric-tube technique: After obtaining survey images, pass a lubricated orogastric tube into the stomach using an appropriately measured tube and standard patient-safety precautions. Introduce room air gradually, aiming for enough distension to create a clear gas–soft-tissue interface—not maximal distension. One published technique describes approximately 20 mL/kg, stopping once the stomach is adequately distended or the patient shows discomfort. That amount is a published protocol, not a universal target.
Remove the tube while minimizing loss of air, then obtain images promptly. A left lateral view places gas in the pyloric region; a ventrodorsal view provides complementary information. Other projections can be selected to match the area of interest.
Nasogastric-tube access: If a nasogastric tube is used, confirm its position in the stomach radiographically before insufflating. Bedside checks alone can misidentify tube placement. Published descriptions of pneumogastrography primarily use an orogastric or stomach tube, so nasogastric access should be considered a practical adaptation rather than a well-studied standard technique.
Before insufflation, consider patient stability and the possibility of gastric perforation. If the study remains inconclusive or the clinical picture suggests an emergency, move to the next appropriate diagnostic or treatment step rather than relying on the pneumogastrogram alone.
Consider a horizontal-beam view for suspected free abdominal gas
If pneumoperitoneum is a concern, a horizontal-beam projection can let free gas rise away from the abdominal organs and become easier to see. One described approach is to position the patient in left lateral recumbency, allow time for gas to redistribute, then obtain a horizontal-beam image with the dependent side marked. The left lateral position also helps distinguish free peritoneal gas from gas in the pylorus.
A horizontal beam is not automatically more sensitive than a standard lateral view. In an experimental study of dogs, standard left lateral and lateral horizontal-beam views both performed well for detecting small amounts of free peritoneal gas. Choose the projection that fits the case and interpret it alongside the rest of the study.
A few more habits that improve the study
Match the view to the question. If you are evaluating the pylorus, include a left lateral view. If gas distribution matters, consider both laterals.
Trace the entire gastrointestinal tract. Follow the stomach, small bowel, colon, and rectum rather than focusing only on the most obvious loop.
Use additional views to resolve overlap. A targeted oblique or compression view may clarify whether structures are superimposed.
Recheck the patient if findings are uncertain. Serial imaging, ultrasound, or another modality may provide the answer when radiographs remain equivocal.
Don’t let a clever technique delay care. If the patient is unstable or the clinical picture strongly supports an emergency, prioritize stabilization and timely treatment.
The larger lesson is simple: radiographs are not just a set of standard projections. A deliberate change in position, careful compression, or a focused contrast technique can sometimes turn an unclear image into a useful one.
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