CT KUB Report Template: Negative Study and Urinary Stone Examples

Define the scope of a renal colic CT report

CT KUB describes an examination covering the kidneys, ureters, and bladder to assess for urinary stones. In this context, KUB means urinary tract CT coverage, not a plain abdominal radiograph. A typical stone protocol is performed without intravenous contrast. This article focuses on reporting noncontrast CT obtained for acute flank pain, primarily in adults.

Imaging pathways vary with age, pregnancy status, prior imaging, and local protocol. The 2026 European Association of Urology (EAU) guideline recommends ultrasound initially for acute flank pain, with noncontrast CT when needed to confirm the diagnosis; the 2023 ACR Appropriateness Criteria generally rate noncontrast CT of the abdomen and pelvis as an appropriate initial study for suspected stone disease. Record the actual acquisition and coverage before using a framework.

Clinical safety note: Noncontrast CT can show stones and signs of upstream obstruction, but it does not assess renal enhancement or all soft-tissue conditions with the same confidence as an appropriately contrast-enhanced study. A template cannot create negative findings for structures that were not assessed.

Brief pre-report checklist

• Indication and side; prior stone history and relevant comparison
• Scan coverage, contrast status, dose approach, and image quality
• Anatomic location of each stone: kidney, ureter, or bladder
• Number and largest dimension when clinically useful; use a consistent local measurement plane
• Hydronephrosis, ureteral dilatation, and periureteric or perinephric change
• Both kidneys and ureters, bladder, and relevant alternative findings in the scanned field
• Whether the report answers the question and whether urgent communication is required

Editable complete report framework

Replace bracketed text with what was actually assessed. Do not leave unvisualized findings as automatic negatives.

Examination: [Low-dose / routine-dose] noncontrast CT abdomen and pelvis (urinary tract / CT KUB).

Indication: [Flank pain, hematuria, or other clinical question].
Comparison: [Date and prior examination / none available].

Technique: [Coverage and reconstructions]. No intravenous contrast was administered. [State limitations from motion, body habitus, or other factors when relevant.]

Findings: Both kidneys are [size and contour]. [No calculus / number, location, and largest dimension] in the right/left kidney. [No calculus / location and measurement] along the right/left ureter. [No hydronephrosis or ureteral dilatation / degree and side]. Perinephric and periureteric fat is [ ]. Urinary bladder is [ ]. Relevant additional finding in the scanned field: [ ].

Impression:
1. [Stone location and measurement with obstruction findings / no urinary calculus or evidence of obstruction].
2. [Clinically relevant alternative finding or technical limitation, if present].

Example 1 — no calculus or obstruction identified

Fictional case. Use “normal” only for the structures and scope that were adequately assessed.

Examination: Low-dose noncontrast CT abdomen and pelvis.

Indication: Right flank pain; suspected renal colic.
Comparison: None available.

Technique: Noncontrast thin-section CT from the diaphragmatic domes through the bladder base. Coronal and sagittal reformations reviewed. Diagnostic image quality.

Findings: No calculus is identified in either kidney, ureter, or the urinary bladder. No hydroureteronephrosis. Perinephric fat planes are preserved. No acute finding in the imaged abdomen or pelvis explains the right flank pain.

Impression:
1. No urinary calculus or evidence of obstruction.
2. No acute CT finding in the imaged field to explain the right flank pain.

On an unenhanced examination, avoid a sweeping conclusion such as “no other disease.” If clinical concern persists, state the limited soft-tissue assessment of the protocol.

Example 2 — distal ureteral stone with mild obstruction

Fictional case.

Examination: Low-dose noncontrast CT abdomen and pelvis.

Indication: Left renal colic.
Comparison: None available.

Technique: Noncontrast thin-section CT from the diaphragmatic domes through the bladder base. Coronal and sagittal reformations reviewed.

Findings: A 4 × 3 mm calculus is present in the distal left ureter, approximately 2 cm proximal to the ureterovesical junction. There is mild left hydroureteronephrosis and subtle adjacent periureteric fat stranding. No additional left renal calculus. No right-sided urinary calculus or dilatation. No perinephric collection or other acute finding in the imaged field.

Impression:
1. 4 × 3 mm distal left ureteral calculus with mild left hydroureteronephrosis.

Lead with the stone, side, and obstruction finding in the impression. “Ureteral stone” alone forces the clinical team to recover the location and associated dilatation from the findings section.

Describing stones and obstruction

• Location: State the renal calyx or pelvis, or the ureteral segment. For a distal ureteral stone, distance from the bladder or relationship to the ureterovesical junction may help.
• Size: Give the largest dimension in millimetres. If you use multiple axes, state the dimensions consistently. The EAU guideline discusses linear stone measurement; volume is not a uniform reporting standard.
• Obstruction: State whether hydroureter or hydronephrosis is present and on which side. Add edema, fat stranding, or perinephric fluid when relevant, without presenting a nonspecific sign alone as a precise obstruction grade.
• Multiple stones: Localize each clinically relevant stone separately. Do not conflate renal stone burden with the ureteral calculus causing obstruction.
• Alternative cause: When no stone is seen, look for a visible alternative explanation while keeping the limited soft-tissue contrast of a noncontrast protocol in mind.

Common wording pitfalls and examination limits

Stone diameter and degree of hydronephrosis describe different things. A small renal calculus does not, by itself, prove that a ureter was obstructed. When no stone is found, make the result concrete by stating whether ureteral calibre is normal; do not claim to exclude conditions outside the limits of an unenhanced study.

Low-dose technique, motion, large body habitus, incomplete coverage, and very small stones can affect detection. State if either kidney or the bladder is outside the scan range. Children, pregnancy, and repeated-imaging scenarios require a separate patient-specific imaging pathway.

Final check before signing

• Are the side and anatomic segment clear?
• Is the measurement in millimetres and on a consistent axis?
• Are obstruction findings matched to the correct side?
• Were the bladder, opposite kidney and ureter, and important alternatives reviewed?
• Do the findings and impression reflect the limits of a noncontrast protocol?
• Does the first impression statement name the stone and clinically important obstruction?

Useful references

• European Association of Urology. EAU Guidelines on Urolithiasis (2026) — imaging for acute flank pain, noncontrast CT, and stone size/location. Guideline (opens in a new tab)
• American College of Radiology. ACR Appropriateness Criteria®: Acute Onset Flank Pain–Suspicion of Stone Disease (Revised 2023). Guideline (opens in a new tab)
• Abdomen and Pelvis CT Reporting Checklist
• First Radiology On-Call Starter Pack

Educational note: The examples are fictional and contain no patient data. This material does not replace patient-specific interpretation, current guidance, local protocols, or specialist judgment.