A 55-year-old male presented to the ED with a one-week history of fevers, nausea, vomiting, with mild supra-pubic discomfort in the absence of any other GI complaints. He endorses nocturia and incomplete bladder emptying for 10 years. He reports that at some point in the past he had surgery for a hemorrhoid and the problem seemed to have worsened after the surgery. He is somewhat concerned that his symptoms may be the result of complications from his surgery.

In the ED, he is afebrile. Laboratory findings do not show any leukocytosis (WBC 11K) but his creatinine is 2.5, which is an acute elevation from his baseline of 1.01.

Evaluation of the renal system is performed with Ultrasound:

The above clip shows severe hydronephrosis, which is present bilaterally (only 1 side is shown).

The above clip shows severe dilation of the ureters in addition to a full bladder

ureter1 right ureter


The US shows severe hydronephrosis bilaterally with dilated ureters. The ureters measured approximately 15 mm, which is >4x the normal size. The patient also had a full bladder with a clearly visible enlarged prostate and there was no change in the bladder volume after voiding. A Foley catheter was placed with return of 2 liters of urine.

As we talked more, the patient reported that he was told that he had an enlarged prostate at the time that his hemorrhoid was diagnosed (approximately 10 years prior). He was asked to follow up for enlarged prostate, but only followed up with surgery for the hemorrhoid since it was the part which was causing him discomfort at the time. The prostate, likely, continued to enlarged leading to his current presentation.

Hydronephrosis can be seen in multiple settings. In pediatrics, it is often the result of congenital abnormalities. In adults, it is often a result of obstructive ureterolithiasis. However, bilateral hydronephrosis is rarely seen in the setting of kidney stones due to the lower likelihood of having obstructing stones in both ureters concurrently. Bilateral hydronephrosis is commonly seen in obstructions distal to the bladder, more commonly due to prostate hypertrophy or tumors. In female patients, pelvic tumors of gynecologic origin can be the cause of bilateral obstructions. Although it has not been well reported, it is important to note the possibility of urinary retention in the setting of cauda equina as a cause of bilateral hydronephrosis and that aortic dissections can also lead to unilateral hydronephrosis.

Ultrasound has certainly become a strong modality for diagnosing hydronephrosis. Often times this can help a clinician to predict the possible pathology. In this case, with hydronephrosis, dilated ureters, and a dilated bladder with no significant change in volume after voiding, it was clear that we were dealing with an obstructive pathology, likely prostatic. In the setting of a unilateral hydronephrosis, flank pain, and hematuria, it would be reasonable to suspect a stone. However, it is important to visualize the aorta in the older patient to evaluate for aortic dissection even in the setting of hydronephrosis.

Although the sensitivity of ultrasound to diagnose ureterolithiasis can be somewhat lower (around 60-90%), it increases tremendously (>90%) in stones larger than 5 mm, which are certainly the ones that we need to be more concerned about in the Emergency Department due to the lower likelihood of the stone being passed when compared to smaller stones.

Take Home Points

  • Ultrasound evaluation of the renal system provides valuable information in the patient with flank pain +/- AKI
  • Stones are not the only things that cause hydronephrosis. One has to think of other pathologies.

Anst Gelin, MD



  1. Moak et al. Bedside renal ultrasound in the evaluation of suspected ureterolithiasis. American Journal of Emergency Medicine. 2012; 30: 218-221
  2. Gaspari et al. Emergency ultrasound and urinalysis in the evaluation of flank pain. Acad Emerg Med 2005; 12: 1180-4
  3. Ma JO, Mateer JR, Reardon RF, Joing SA. Ma and Mateer’s Emergency Ultrasound. 3rd edition. McGraw-Hill Education; 2014.
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