Monash study reveals Point of Care ultrasound reduces CT scan use in kidney stone diagnosis

Dr Gabriel Blecher

Monash University researchers have shown the benefit of new imaging guidelines for patients with suspected kidney stones.

Led by Monash Health emergency physician Dr Gabriel Blecher, the study, published in the Emergency Medicine Journal, analysed the use of focused ultrasound rather than CT urography (CTU) for diagnosing patients with renal colic.

A condition commonly managed in emergency departments, renal colic presents as severe abdominal pain and is usually caused by kidney stones.

Urinary stone disease in increasingly prevalent, occurring in 12% of men and 6% of women. The age of onset of a first stone episode for men rises from the 20s and peaks at age 40-60 years, with an incidence of three cases per 1000 population per year.

Dr Blecher, a member of the Monash Emergency Research Collaborative (MERC), School of Clinical Sciences at Monash Health (SCS) said that although acute symptoms of renal colic can be severe, the subsequent course of action is usually benign, with up to 80% of kidney stones passing spontaneously.

“In the last decade, CT use has become widespread in suspected renal colic, without any improvement in patient outcomes,” Dr Blecher said.

“The associated harms of CT include over-diagnosis, radiation exposure and waste of hospital resources.”

Despite a documented 12-fold increase in CTU utilisation for suspected renal colic in recent years, diagnostic rates and the number requiring operative intervention have not changed.

In the study, Monash Health Emergency patients presenting with suspected renal colic were enrolled to the new focused ultrasound intervention at one site and their outcomes were compared with patients using existing CTU guidelines at another site.

“We found that using a simple assessment guideline for suspected renal colic led to a 21% lower CTU rate compared with the control site,” Dr Blecher said.

“Our new protocol favours focussed ultrasound performed by the emergency doctor rather than CT scanning in radiology , which is currently performed in about 75% of cases.”

“Our intervention group underwent CT scans in only 54% of cases, lowering the median radiation doses to 2.8mSv compared with the control group at 4.0mSv.”

Dr Blecher said benefits of the new guidelines include faster diagnosis and less radiation dose—and this is important as most patients with renal colic are young.

“Our findings will also lead to significant cost savings by performing fewer CT scans,” Dr Blecher said.