Renal colic or ureterolithiasisresults from stones or renal calculi in the ureter. The stonesare solid concretions or calculi (crystalaggregations) formed in the kidneys from dissolved urinary minerals.Nephrolithiasis refers to the condition of having kidney stones. Urolithiasisrefers to the condition of having calculi in the urinarytract (which also includes the kidneys), which may form or pass into the urinarybladder. Ureterolithiasis is the condition of having acalculus in the ureter,the tube connecting the kidneys and the bladder. The term bladder stones usually applies toUrolithiasis of the bladder in non-human animals such as dogs and cats.
Kidney stones typically leave the body by passage in the urine stream, andmany stones are formed and passed without causing symptoms. If stones grow tosufficient size before passage on the order of at least 2-3 millimeters theycan cause obstruction of the ureter. The resulting obstruction causes dilationor stretching of the upper ureter and renalpelvis (the part of the kidney where the urine collects before entering theureter) as well as muscle spasm of the ureter, trying to move the stone.This leads to pain,most commonly felt in the flank, lower abdomen and groin (a conditioncalled renalcolic). Renal colic can be associated with nausea and vomiting. Therecan be blood in the urine, visible with the naked eye or under the microscope (macroscopic or microscopic hematuria) due to damage to the lining of theurinary tract.
There are several types of kidney stones based on the type of crystals ofwhich they consist. The majority are calciumoxalate stones, followed by calciumphosphate stones. More rarely, struvite stonesare produced by urea-splittingbacteria inpeople with urinary tract infections, and people withcertain metabolicabnormalities may produce uric acid stones or cystine stones.
The diagnosisof a kidney stone can be confirmed by radiologicalstudies or ultrasound examination; urine testsand bloodtests are also commonly performed. When a stone causes no symptoms, watchfulwaiting is a valid option. In other cases, pain controlis the first measure, using for example non-steroidal anti-inflammatorydrugs or opioids.Using sound waves, some stones can be shattered into smaller fragments (this iscalled extracorporeal shock wavelithotripsy). Sometimes a procedure is required, which can be through atube into the urethra,bladder and ureter (ureteroscopy), or a keyholeor opensurgical approach from the kidney's side. Sometimes, a tube may be left inthe ureter (a ureteric stent) to prevent the recurrence of pain.Preventive measures are often advised such as drinking sufficient amounts ofwater, although the effect of many dietary interventions has not beenrigorously studied.
- Colicky pain: "loin to groin". Often described as "the worst pain ever experienced". This can also occur in the lower back
- Nausea or vomiting: embryological link with intestine– stimulates the vomiting center.
- Hematuria: blood in the urine, due to minor damage to inside wall of kidney, ureter and/or urethra.
- Pyuria: pus in the urine.
- Dysuria: burning on urination when passing stones (rare). More typical of infection.
- Oliguria: reduced urinary volume caused by obstruction of the bladder or urethra by stone or extremely rarely, simultaneous obstruction of both ureter by a stone.
- Postrenal azotemia: the blockage of urine flow through a ureter.
- Hydronephrosis: the distension and dilation of the renal pelvis and calyces.