B24. Clinical manifestations and diagnosis of urolithiasis

Kidney stone disease, also called nephrolithiasis or urolithiasis, refers to the presence of symptomatic kidney stones in the urinary tract. When stones are present in the ureter it may be called ureterolithiasis, while stones in the bladder are usually simply called bladder stones or bladder calculi. It's a relatively common condition, with a lifetime prevalence of 10 - 20 percent.

Many have asymptomatic kidney stones (which is not considered kidney stone disease), but in some cases stones can cause urinary obstruction (obstructive uropathy) and resulting damage to the kidney, as well as episodes of severe pain called renal colic. The vast majority of kidney stones pass without intervention within a few days or weeks, but there are options for treatment, including using radiowaves to crush them (ESWL) and removing them surgically.

Clinical features

Kidney stones may be asymptomatic, especially if they are in the renal pelvis. Kidney stones may also cause haematuria. Concurrent fever with renal colic is a sign of infection together with urinary obstruction, which may be severe.

Renal colic

When a kidney stone passes from the renal pelvis into the ureter, it may get stuck. This causes episodes of severe flank pain. This pain is typically colicky, meaning that it starts and stops abruptly. There may be visible haematuria. The pain may radiate to the ipsilateral testicle or labium. The patient usually has a severe urge to move.

Other pain

A kidney stone may also present with pain other than renal colic. Pain may be mild and not localised to the flank. In these cases, the diagnosis is difficult.

Diagnosis and evaluation

A presumptive diagnosis may be made when the patient has typical renal colic, as kidney stone is highly likely in that case.

Haematuria on urine analysis is seen in most cases of kidney stone (90%), but absence of haematuria does not exclude the diagnosis. It may be necessary to measure the serum calcium and uric acid level to look for underlying cause. A first episode of renal colic should be investigated with kidney function tests to rule out acute kidney injury as a complication.

Whether imaging is necessary in case of uncomplicated (no fever or sign of infection, pain can be controlled with NSAIDs, mild-moderately decreased kidney function) is controversial. In Norway, no imaging is obtained during the initial presentation; imaging is obtained after 3 - 4 weeks. According to most other guidelines however, CT is indicated urgently to assess for obstruction.

Imaging

A low-dose non-contrast CT is usually the first choice as this has little radiation exposure and can detect the majority of stones. Ultrasonography is a reasonable alternative first choice, especially in pregnant and children, but many stones are not visible on ultrasound (70% sensitive and specific). Kidney, ureter, bladder (KUB) radiography was previously widely used, but it is not sensitive and so is rarely used nowadays.

If the stone causes urinary obstruction, one may see hydronephrosis and dilated proximal ureters.