Case Author(s): Jayson R. St. Jacques, M.D. and Tom R. Miller, M.D., Ph.D. , 6/22/02 . Rating: #D3, #Q3

Diagnosis: Acute left renal obstuction

Brief history:

30 year old man with left-sided flank pain.

Images:

Blood-flow images in the posterior projection

View main image(rs) in a separate image viewer

View second image(rs). Twenty-minute dynamic images

View third image(rs). Blood-flow images performed one month later

View fourth image(rs). Dynamic images performed one month later. Note: The patient has a stent in the left collecting system.

Full history/Diagnosis is available below

Diagnosis: Acute left renal obstuction

Full history:

The patient is a 30 year old man who was healthy before presenting with acute left flank pain following a recent canoe trip.

A spiral CT scan from an outside hospital (not available) demonstrated left hydronephrosis without evidence of obstructing calculi, suggesting UPJ obstruction.

Radiopharmaceutical:

initial study - 16.2 mCi Tc-99m DTPA i.v. repeat study - 7.63 mCi Tc-99m MAG3 i.v. followed by 40mg furosemide

Findings:

Initial renal scintigraphy was performed to evaluate left renal function. Decreased blood flow with decreased function and minimal excretion is noted in the left kidney, suggesting an acute obstruction.

Following successful stenting of the left collecting system, repeat renal scintigraphy demonstrated marked improvement in function of the left kidney.

Furosemide was administered (shown below) to evaluate for high-flow obstruction with the stent in place. There was no evidence of obstruction.

Discussion:

An acute high-grade outflow obstuction can decrease excretion, overall function and blood flow to the affected kidney. A chronic obstruction will eventually lead to absence of function of the affected kidney.

Diruetic renal scintigraphy is useful for evaluation of high-flow states that can cause obstruction.

View followup image(rs). Dynamic post-furosemide images performed one month after the initial study are shown. Note: Left collecting system stent in place.

Major teaching point(s):

The patient must be well hydrated before renal scintigraphy. The hydration may be done orally or intravenously.

A Foley catheter is sometimes useful to minimize downstream pressure in patients who cannot void well and in patients with reflux as well as to prevent diaper or urine contamination during the long imaging sequence.

Differential Diagnosis List

The differential diagnosis includes UPJ obstruction, renal artery stenosis/dissection and renal vein thrombosis.

ACR Codes and Keywords:

References and General Discussion of Renal Scintigraphy (Anatomic field:Genitourinary System, Category:Organ specific)

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Case number: rs029

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