Within Normal Limits — What It Means on Your Imaging Report
Quick Answer
Within Normal Limits (WNL) means the finding falls inside the expected range for a healthy person — it is the radiologist's way of saying "normal."
What Is "Within Normal Limits"?
When a radiologist writes that something is "within normal limits," they are telling your doctor that what they see on your images falls within the range of what is expected for a healthy person of your age and sex. It is one of the most reassuring phrases in a radiology report.
The phrase is often abbreviated as WNL in medical notes. You might see it written as "The heart size is within normal limits" or "WNL" next to a measurement. Either way, the meaning is the same: that measurement or appearance is normal.
Why do radiologists say "within normal limits" instead of simply "normal"? Because human anatomy varies from person to person. A heart, kidney, or lymph node can be slightly larger or smaller than average and still be perfectly healthy. "Within normal limits" acknowledges this natural variation while confirming that what the radiologist sees is nothing to worry about.
When You Might See This on Your Report
"Within normal limits" shows up across all imaging types and body regions:
- Chest X-ray — "The heart size is within normal limits" (meaning your heart is a normal size)
- CT scan — "The liver measures within normal limits" or "Lymph nodes are within normal limits"
- MRI — "Signal intensity of the brain parenchyma is within normal limits"
- Ultrasound — "The thyroid gland is within normal limits in size and echogenicity"
- Mammogram — "Breast tissue density is within normal limits"
You will often see this phrase used alongside specific measurements. For example, if the aorta is measured at 3.0 cm and the normal range is up to 3.5 cm, the radiologist may write "aortic diameter within normal limits."
Should I Be Worried?
No. "Within normal limits" is good news. It means the radiologist compared what they see on your images to established standards and everything checks out.
This phrase is essentially interchangeable with "unremarkable" and "normal." Radiologists may use any of these terms depending on their personal style or the reporting standards at their institution. All three carry the same reassuring meaning.
If parts of your report say "within normal limits" but the Impression section mentions other findings, focus on those other findings — the WNL portions are the areas where nothing concerning was found.
What Should I Do Next?
- Relax — this is a normal finding. "Within normal limits" means the radiologist sees nothing concerning in that area.
- Review the full Impression section to understand whether any other parts of the report do require attention or follow-up.
- Discuss the report with your doctor at your next appointment. They will explain how the imaging results fit into your overall health picture.
- Keep the report on file. Future scans may be compared to this one, and having a baseline where everything was "within normal limits" is valuable for tracking your health over time.