Kidney stones can only be confidently diagnosed by imaging the kidneys.
When a patient presents with symptoms suggestive of a possible renal calculus such as loin pain, blood in the urine or recurrent urinary infections, imaging must be performed to determine if kidney stones are present.
When patients present with renal colic (loin pain) imaging of the kidneys is usually with a CT scan of the abdomen. This scan is normally performed without the need for oral or intravenous contrast and is called a CT KUB (Kidney, Ureter and Bladder). A CT KUB takes only a few minutes and provides very reliable information with regards to the presence of kidney stones, their size and location. Only occasionally a CT will require intravenous contrast to provide more accurate information about the anatomy of the kidney and its function. This is called a CT Urogram or a CT IVP (Intravenous Pyelogram) and takes a little longer to perform.
Other forms of imaging of the kidney are used when stones are not causing pain. This includes the use of Renal Ultrasound or Plain Abdominal X Ray. These investigations are not as reliable as a CT scan, but are perfectly appropriate when a known kidney stone is being followed up (to see if it has changed) or when there are recurrent UTIs (Urinary Tract Infections).
It is important to emphasise that a diagnosis of kidney stone disease cannot be made without appropriate imaging. Pain in the loin and blood in the urine can be caused by other conditions and assumptions regarding a diagnosis must not be made. The commonest cause of loin pain is back problems – bones, joints and muscles.
Patients have previously died because it was assumed their loin pain was due to a kidney stone, when in fact the pain was due to a burst blood vessel.