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Less-invasive ways to remove stones from the kidneys and ureters

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ABSTRACTLess-invasive interventions for upper tract urolithiasis are extracorporeal shock-wave lithotripsy, ureteroscopy, and percutaneous nephrolithotomy. Each has advantages and disadvantages, depending on the location, size, and composition of the stone and on the patient’s renal anatomy, body habitus, and comorbidities.

KEY POINTS

  • Stones that obstruct the flow of urine or that are associated with infection (ie, struvite or “staghorn” stones) should be removed promptly.
  • For small stones in the distal ureter, medical therapy is an option: pain control, hydration, and control of ureteral spasms with calcium channel blockers and alpha-blockers help the patient pass the stone spontaneously.
  • Extracorporeal shock-wave lithotripsy is the mostly commonly used option, but it is less effective for large stones and in obese patients.
  • The ureteroscope can now be used to extract stones as high up as the kidney. Catheters that contain lasers and lithotripsy devices can break up large stones in situ for removal.
  • Percutaneous nephrolithotomy is very effective for large stones in the kidney and is especially indicated for struvite stones.


 

References

Very few patients undergo surgery for stones in the kidney or ureters anymore, now that less-invasive interventions are available, such as extracorporeal shock-wave lithotripsy, ureteroscopic stone removal, and percutaneous nephrolithotomy. Each of these options has advantages and disadvantages, depending on the characteristics of the stone or stones, such as size, number, location, and composition, as well as patient factors such as renal anatomy, body habitus, and comorbidities.

See related article

This article reviews the current interventional management of upper tract urolithiasis.

NOT ALL STONES NEED INTERVENTION

From 10% to 15% of people in the United States develop a stone at some point in their life,1,2 and this number is increasing.3 Not all of them need intervention (Table 1).

In a patient who has symptoms of urinary obstruction or sepsis, the decision to intervene is obvious. Stones that obstruct the flow of urine often cause symptoms due to distension of the ureter, the renal pelvis, or the renal capsule in a relatively predictable and characteristic pattern of pain originating in the flank and often radiating to the groin, testicle, or labia. And untreated struvite (“staghorn”) stones, a result of infection, can lead to life-threatening sepsis.

However, in patients with asymptomatic stones, the decision may not be clear-cut. Approximately 32% of patients with asymptomatic renal calculi go on to develop symptoms in the next 2.5 years, increasing to 49% at 5 years.3 Of the patients who develop symptoms, half will require a procedure to remove the stone, while half will pass the offending stone spontaneously.3

If even a small amount of stone is left in the kidney after surgery or other intervention, a large stone can form again, and ultimately, the function of that renal unit can decline. For this reason, most renal calculi should be treated or at least followed for signs of progression with serial imaging studies.

Today, although some patients are followed with kidney-ureter-bladder radiographic studies, most undergo computed tomography, which has the advantages of clearly delineating the stone location and size, the presence of small ureteral stones, and the presence and magnitude of hydronephrosis.

If the patient has no refractory symptoms related to obstruction and no signs of infection or of parenchymal damage, then observation with close follow-up is reasonable. However, infection with urinary tract obstruction, urosepsis, intractable pain or vomiting, acute kidney injury, obstruction in a solitary or transplanted kidney, or bilateral obstructing stones are all indications for urgent intervention.

Additionally, some patients who have asymptomatic stones should undergo evaluation and treatment because of their occupation. Examples are airline pilots and soldiers, in whom an episode of intractable renal colic could prove dangerous.

Stones in women

Women who are pregnant or of childbearing age and have an asymptomatic renal stone are not at any higher risk of stone growth and so should be treated the same as any other patient—except that ultrasonography should be used for imaging to minimize radiation exposure. Urine should be sent for culture. From 50% to 80% of these patients will pass their stones spontaneously with hydration and analgesia.4

If intervention is required, percutaneous nephrostomy and placement of ureteral stents can be done to expose the patient to the least possible amount of anesthesia or radiation.5

Ureteroscopic stone extraction in pregnant patients has also been shown not to cause pregnancy-related complications, and it entails minimal fluoroscopic exposure.6

Although lithotripsy has been used inadvertently in pregnant patients, its routine use in pregnant patients remains contraindicated.7

MEDICAL EXPULSIVE THERAPY

Conservative management, consisting of oral or intravenous hydration and analgesia, can be tried in patients with renal calculi whose condition is otherwise stable. Typically, intravenous hydration is given at a maintenance rate.8 Analgesia can be provided with both nonsteroidal anti-inflammatory drugs (NSAIDs) and narcotics, although NSAIDs, in particular ketorolac (Toradol), provide the best pain control.9

Calcium channel blockers and alphablockers inhibit ureteral spasms and promote the spontaneous passage of ureteral calculi.10 Compared with hydration alone, nifedipine (Procardia) has been shown to lead to an absolute increase of 9% in stone passage rates, and alpha-blockers have produced an absolute increase of 29%.11 These drugs can be given in conjunction with corticosteroids to reduce ureteral edema, which may contribute to stone retention in the ureter.12

As of this date, medical expulsive therapy is well established only for stones in the lower (distal) ureter. The applicability of this treatment for stones in the proximal ureter and kidney is still being investigated. In patients who have stones smaller than 1 cm in diameter and whose symptoms are under control, observation with medical expulsive therapy may well be appropriate. However, after 4 weeks, intervention is indicated, as the risk of complications and renal deterioration increase.

STONE SURGERY HAS BECOME RARE

Before the advent of lithotripsy and ureteroscopy (see below), most patients with symptomatic upper tract calculi underwent open surgical lithotomy. Many variations of pyelolithotomy and nephrolithotomy were performed, even bench surgery with autotransplantation (ie, removing the kidney, removing the stone, and then reimplanting the kidney). However, lithotripsy and ureteroscopic extraction have dramatically reduced the role of open stone surgery: it is currently done in only 0.3% to 0.7% of cases.13,14

Laparoscopic surgery for renal calculi is also rarely done. Although almost every type of stone procedure has been done laparoscopically,15–19 this approach is indicated only in situations in which lithotripsy or ureteroscopic treatment is expected to fail.

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