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Question: Renal

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You are seeing a 17 year old boy with left flank pain, nausea, and vomiting. There has been no fever, dysuria, hematuria, or urinary frequency. The pain did start after the patient drank a large caffeinated frappuccino and had a brisk diuresis. The patient reports similar pains in the past that self resolved, but never this severe. Urinalysis has 0-2 wbc, 0-2 rbc, no bacteria, and is nitrite negative. Suspecting nephrolithiasis, you obtain a renal US that shows severe left hydronephrosis but no evidence of stone. You then obtain a CT non-contrast that confirms no stone is present. 

What is the most likely diagnosis?

pemsou5_wp • March 22, 2022

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  1. Kelly March 23, 2022 - 3:37 pm Reply

    D) Ureteropelvic junction obstruction
    UPJ obstruction can be congenital, due to an anatomic abnormality such as intrinsic narrowing or kinking or a crossing vessel, or acquired, due to scarring. Congenital UPJ obstruction is typically diagnosed via prenatal US. However, if not diagnosed prenatally, it can present in infancy with palpable mass, UTIs, hematuria, FTT, or in older childhood with flank or abdominal pain +/- nausea & vomiting. The pain is often worse with a brisk diuresis (“Dietl’s crisis”). UPJ obstruction is more common on the left side and in males, and is bilateral in 10%. Patients may present with an associated UTI.

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