Correspondence *Division of Urology, Department of Surgery, St Joseph Mercy Oakland Hospital & Medical Center, 44405 Woodward Avenue, Pontiac, MI 48341, USA

Email strikermd@hotmail.com

The case

A 37-year-old female presented to the emergency room with a chief complaint of pain in the right lower lateral abdomen. Onset of pain had been approximately 36 hours before presentation, described as 'knifelike', intermittent and radiating to the right groin. She had experienced similar pain in the past, attributed to a ureteral stone that she had spontaneously passed; however, the present pain was more intense. She complained of nausea but denied vomiting, recent trauma or any problems moving her bowels. Although she did not complain of dysuria, she did mention increased micturition frequency. Serum electrolytes, blood urea nitrogen (BUN) and creatinine levels were normal, while the peripheral blood count revealed a slightly elevated white blood cell count at 12.1 10⁹ cells/l, and urinalysis detected red blood cells in the urine.

A CT scan (Figures 1 and 2) was obtained which depicted a 4 mm calculus at the right ureterovesical junction. The patient was admitted to the urological service and started on an aggressive hydration regimen in an attempt to "flush" the stone. Twelve hours later, with her pain worsening, she was taken to the operating room where a cystoscopy and right retrograde pyelography was performed (Figure 3). A 6-French stent was deployed under fluoroscopic control. The subsequent hospital course was uncomplicated. The patient was discharged the following day and instructed to follow up as an outpatient.

Figure 1 Axial images of a CT scan of the abdomen and pelvis, showing a 4 mm calculus in the right distal ureter near the ureterovesical junction causing mild hydronephrosis.

 

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Figure 2 Coronal images of a CT scan of the abdomen and pelvis, showing a 4 mm calculus proximal to the ureterovesical junction.

 

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Figure 3 Cystoscopy of the right ureter depicting the calculus.

 

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Discussion of diagnosis

Urolithiasis continues to be a frequent cause of presentation to hospital. It has been estimated that approximately 122 of every 100,000 hospital admissions can be attributed to urolithiasis.^{1, 2} Furthermore, once a patient is diagnosed with 'stones' there is an increased likelihood that new stones will develop. Some studies have shown that 50–70% of patients with a history of calcium urolithiasis will have another bout of urolithiasis within 10 years.^{3, 4} Although kidney and ureteral stones are seldom fatal, they do cause considerable discomfort that results in hospital admissions and time away from work.

The diagnosis of urolithiasis is largely dependent on analyzing the clinical presentation and physical examination. Suspicion is usually confirmed with radiologic tests, particularly the non-contrast enhanced CT scan. The advent of non-enhanced CT has not only provided detection and/or confirmation of calculi, but also accurate detection of size and location.⁵ Pain is the most common symptom, especially when the stone passes into the ureter. The movement of the calculus irritates the ureter, facilitating spasms that occur periodically, and thus contributing to the intermittent pain often described by symptomatic patients. As the calculus propels distally, the pain migrates in a parallel fashion. Stones in the upper ureter often produce flank pain, while calculi that have migrated to the lower ureter can masquerade as groin pain, as seen in this patient. Hematuria, either gross or microscopic, has also been attributed to urolithiasis. Dysurias, urgency and increased frequency of micturation are all potential signs and symptoms of patients suffering from urolithiasis.

Multitudes of differential diagnoses exist in relation to urolithiasis. Acute intestinal pathology such as obstruction, ischemia or volvulus can mimic the symptoms of ureteral colic. Vascular entities such as abdominal aortic aneurysms rarely present with flank pain. It is imperative that these diagnoses be ruled out. Gynecological issues, such as ovarian pathology or ectopic pregnancy, can occasionally present with similar complaints ascribed to renal or ureteral colic. Pelvic ultrasonography accompanied with pregnancy tests and/or human chorionic gonadotropin tests have been exceedingly beneficial in differentiating these diagnoses from urolithiasis.⁶ The role of ultrasonography in the diagnosis of urolithiasis has been extended primarily in pregnancy and the pediatric population. The sensitivity, however, does not match that of CT.⁷

Non-contrast CT has become the test of choice for confirming urolithiasis. Although abdominal radiography will reveal radio-opaque calculi such as struvite, cystine and calcium composition stones, they do not identify uric acid stones and small stones that can be obscured by adjacent bony structures. Intravenous pyelography offers detailed images of the urological anatomy; however, pyelograms take longer to obtain than CT scans and are more prone to producing adverse reactions.

Treatment and management

Management of urolithiasis depends on stone size and clinical symptoms. Patients with large calculi accompanied with excruciating pain are often taken to the operating room for ureteroscopy, shock wave lithotripsy, percutaneous nephrostomy or, rarely, surgery to facilitate relief. Patients who present with calculi as the etiology of persistent fevers, sepsis or significant comorbidities, such as a solitary or horseshoe kidney, might also benefit from early operative intervention. Recent literature has attempted to evaluate stone size and location and the need for eventual operative management. One study showed that size and location were statistically relevant to the stone passage interval.⁸ Studies have also been undertaken to show the average length of time necessary to excrete the stone. These studies show that stones can take a significant amount of time to pass, particularly those measuring 4–6 mm, which took an average of 39 days to pass spontaneously.⁸ Recent trends towards increased operative management can be attributed to flexible and improved ureteroscopes.⁹

Operative intervention has shifted to minimally invasive approaches. Rigid and flexible ureterorenoscopy, shock wave lithotripsy and percutaneous nephrostolithotomy constitute the majority of operative interventions.¹⁰

Ureterorenoscopy, whether it is flexible or rigid, involves cannulation of the urethra and bladder. Once the ureteral orifices are identified, balloon catheters, stone baskets or grasping forceps can be introduced to facilitate stone retrieval. As fiber optic technology continues to evolve, flexible ureterorenoscopes have the capability to reach the proximal ureter or even the intrarenal collecting system.¹¹

Shock wave lithotripsy delivers high-energy shock waves directly to the stone in an attempt to fragment it. This modality should be used with caution; primarily because the high energy delivered does have the potential to inflict damage to the kidney itself.¹² A single study did report a high efficacy and low morbidity of extracorporeal shock wave lithotripsy when used with low energy.¹³

Percutaneous nephrostolithotomy is used once the attempts made with fiber optic technology are unsuccessful. Difficult urological systems, however, such as horseshoe kidneys, anatomical abnormalities in the ureteropelvic junction, and complex or exceedingly large calculi (>2 cm) are sometimes not amenable to ureterorenoscopy or shock wave lithotripsy. These situations warrant a percutaneous approach under fluoroscopic guidance to cannulate the renal collecting system and extract the calculi, with or without initial ultrasonic or pneumatic fragmentation of the stones. Recent studies at Washington University showed that, although the number of percutaneous stone removals performed remained stagnant and open stone surgery was markedly decreased, the number of ureteroscopies increased by 53%, likely owing to the advances in technology and technical abilities.⁹ A role for medical therapy in urolithiasis management does exist. Specific drugs such as thiazides, allopurinol and citrate address underlying medical disorders that contribute to calculi formation. Recently, phytotherapeutic agents such as Phyllanthus niruri have been utilized to inhibit crystallization of calcium oxalate.¹⁴

Stone size is not the only characteristic that determines whether or not a patient will pass the stone spontaneously or require operative intervention, but it is paramount.

Operative intervention has become an exceedingly viable option in the management of urolithiasis. These procedures, however, are not completely benign. This often raises a dilemma of whether to simply observe patients with urolithiasis or facilitate stone passage with operative management. There have been several studies documenting the variability of spontaneous stone passage.¹⁵

It is our recommendation that the threshold for operative intervention be lowered for someone with a calculus measuring 6.1 mm or greater, since over half of these patients will not resolve the stone spontaneously.

Conclusions

Urolithiasis continues to require urgent patient care. It is imperative that the diagnosis is confirmed quickly to eliminate other potentially dangerous pathology. Non-contrast CT is the main tool for diagnosing urolithiasis after a detailed history and clinical exam. Should operative intervention become necessary, ureterorenoscopy and/or shock wave lithotripsy offer minimally invasive yet highly efficacious approaches to successful patient care.

Successful management of urolithiasis benefits not only the patient but society as well. Alleviating urolithiasis early would help curb lengthy hospital stays and facilitate an earlier return to work and the patients' responsibilities.

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Subject areas under which this article appears: Endourology and stones