Isaac Matthias1, Joseph Harryhill2, Brian Curtis3
2Division of Urology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
3Department of Radiology, Thomas Jefferson University Hospitals, Philadelphia, Pennsylvania, USA
A 59 year old woman with minimal past medical history presented to the emergency department with one day of acute onset left lower quadrant abdominal pain accompanied by nausea and 6 episodes of nonbilious emesis. Review of systems was positive for malaise and shaking chills. Vital signs were T 102.7, HR 116 sinus tachycardia, BP 82/42, O2 sat 100% on room air. On examination the patient had left lower quadrant abdominal tenderness without rebound or guarding. Labs were significant for WBC 17.5 with 7% bands, creatinine 1.3 (baseline 0.8), lactate 3.3, urinalysis with 10 – 20 WBC, occasional WBC clumps, moderate blood. Broad spectrum antibiotics were initiated, and the patient was volume resuscitated with four liters of normal saline. Systolic blood pressures remained in the 80s and a central venous catheter was placed with initiation of pressors. A noncontrast CT abomen/pelvis was obtained:
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Urology and interventional radiology were consulted. The patient was taken urgently to the IR suite, where a left percutaneous nephrostomy tube was placed with immediate return of 10 mL of frank pus. Blood cultures returned three out of four bottles positive for e. coli. With source control and antibiotics the patient’s septic shock resolved. She was ultimately discharged to home to follow up with urology and interventional radiology.
An 11 mm stone is impacted at the left ureteropelvic junction (UPJ), causing moderate hydronephrosis, with an additional 13 mm stone in the lower pole of the left kidney. The left kidney has surrounding fat stranding, with Gerota’s fascia (the fascia containing the kidney and perinephric fat) clearly visible, indicating inflammation. All three findings can be seen on the axial image:
The same image, annotated:
Symptoms of a ureteral stone
The classic presentation of a ureteral stone includes flank pain caused by renal capsule distension from obstruction of urine flow from the kidney resulting in hydronephrosis. However, symptoms such as abdominal pain or pain radiating to the groin may be present rather than flank pain, particularly as the stone moves distally in the ureter. Nausea/vomiting is common in patients with a ureteral calculus. In this patient who presented with left lower quadrant abdominal pain, left lower quadrant abdominal tenderness on palpation, and nausea/vomiting, the initial clinical concern was for diverticulitis.
How do stone size and position affect management?
Smaller, distal stones are more likely to pass spontaneously. Stones less than 5 mm in diameter pass over 80% of the time with conservative management, while stones greater than 10 mm in size pass spontaneously in only 25% of cases and typically require surgical intervention.1 In this patient with an 11 mm stone at the ureteropelvic junction causing hydronephrosis, surgical intervention would be required regardless of other clinical factors.
What is the ureteropelvic junction (UPJ)?
The ureteropelvic junction (UPJ) is the site where the ureter connects to the kidney. It is a common site for stones to become impacted as the size of the renal pelvis is larger than the size of the proximal ureter. The most common location for ureteral impaction of stones is at the ureterovesical junction, as the intramural tunnel to the bladder is the narrowest diameter of the length of the ureter.
What is the preferred imaging modality for diagnosing ureterolithiasis?
Noncontrast CT scan. Ureteral stones (with the rare exception of indinavir stones) are highly radiopaque on CT, and IV contrast is not needed to visualize ureteral dilation or hydronephrosis. CT scan visualizes the exact size and location of the stone, which is important in management decisions. If radiation needs to be avoided (e.g. in a pregnant patient), ultrasound can detect hydronephrosis and visualize proximal ureteral stones, but is an overall less sensitive and specific test.
If imaging is being performed to rule out complications of pyelonephritis, such as perinephric or renal parenchymal abscess, CT scan with IV contrast is preferred. Pyelonephritis may appear as focal decreased enhancement in infected areas of the renal parenchyma.
Who needs imaging?
An initial presentation of suspected ureteral stone needs imaging to confirm the diagnosis. If the patient is presenting with symptoms similar to their past episodes of ureteral stone and does not have signs of clinical instability, such as signs of infection, acute kidney injury, or intractable pain/nausea/vomiting, it is reasonable to defer CT imaging for a trial of expectant management. Concern has been raised by experts in radiology that patients with recurrent ureteral stones are at risk for unnecessary and excessive cumulative radiation exposure from repeated CT imaging.
Patients being admitted to the hospital for sepsis due to urinary tract infection need urgent imaging to rule out ureteral obstruction. Exceptions can be made based on clinical scenario, such as a patient with a chronic indwelling Foley catheter and past admissions for urinary tract infection. Ultrasound or CT scan are acceptable, but CT scan may be preferable as it can be obtained rapidly after hours and is superior to ultrasound at visualizing ureteral stones.
What is the preferred intervention in ureteral obstruction with sepsis?
In a patient with ureterolithiasis and resultant pyelonephritis, retrograde double-J ureteral stenting by urology can be performed if the patient is hemodynamically stable. A stent is placed past the stone, allowing the infected urine to drain from the obstructed kidney to the bladder. The stone is left in place to be removed at a later time. The backpressure created by retrograde pyelography can cause transient bacteremia with worsening of hemodynamics, and therefore if there are signs of hemodynamic instability the preferred intervention is percutaneous nephrostomy placement by IR. In this patient with pressor dependent septic shock, percutaneous nephrostomy placement by IR was urgently performed overnight.
In a patient with hydronephrosis due to extrinsic ureteral compression, such as from retroperitoneal metastatic malignancy or retroperitoneal fibrosis, percutaneous nephrostomy is often performed initially, as externally compressed ureters may not drain well with double-J stents, and ureteral stents are likely to occlude due to progression of retroperitoneal disease.2
What are the timing and method of stone removal?
Once the obstructed kidney is decompressed with either ureteral stenting or percutaneous nephrostomy tube placement, the patient is managed medically until discharge from the hospital to follow up for outpatient ureteral stone removal.
Retrograde ureteroscopy with laser fragmentation of the stone and mechanical removal of the fragments using grapsers, baskets etc. is the first line intervention in most clinical scenarios. Post procedure stone free rates are 80 to 90%.3
Shock wave lithotripsy, in which high energy waves are focused on the stone in order to fragment it into smaller pieces which are then passed with expectant management, can be used for stones smaller than 1cm located in the proximal ureter. Stones meeting these criteria can be removed with similar efficacy using ureteroscopy or shock wave lithotripsy, while stones in other locations or larger in size require ureteroscopy.4
Percutaneous nephrolithotomy (PCNL), in which a percutaneous sheath is placed into the kidney and a scope passed into the collecting system to fragment and remove the calculi, is used for stones in the kidney and proximal ureter larger than 2 cm. This method is particularly useful for multiple stones and staghorn calculi, which can take up the entire renal pelvis. This procedure has nearly replaced open surgical intervention for large, complex kidney stones.
Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the editor of this site.