Surgeons are developing a new smartphone-based tool that can detect urethral or urine blockage, potentially making it easier for patients to test themselves for the condition from the comfort of their own homes.

The novel technique could take high-speed photography which could capture subtle differences between a normal steady stream of liquid and a stream of liquid with an obstruction. Urethral strictures are a slowing or blocking of the natural flow of urine due to an injury or infection. It is normally diagnosed by uroflowmetry, a test administered at a physician's office."The problem is that patient follow-up after we treat this condition is very poor," said Matthew Gretzer, Associate Professor at the University of Arizona in the US.

"But we need patients to come back to our clinic for a uroflow test to determine if the obstruction is still present," he added.In order to test Gretzer's hypothesis on high-speed photography, the team created a model of a urethral structure using tubing hooked to a saline bag that could drain through.Saline fluid was passed through the tubing with and without blockages, created using 3D printed strictures,placed within the tubing. High-speed photography captured both the regular and blocked stream of liquid exiting the tube. Gretzer contended that photos can be a medium to diagnose blockages and he hopes that patients could send him these images to analyse and make the diagnosis. He plans to create a mobile app which can be downloaded by the patients.

"All patients would need to do is take high-speed images of their urine flow using a strobe light," Gretzer said. "Strobe light apps are readily available right now for people to use on their phones". According to the researchers, as fluid exits an opening, a natural breakpoint occurs where the liquid stream forms droplets, but with obstructions in place, it changes.The results showed that by analysing photos, they could measure the length to this point of droplet formation. This length then directly related to the presence of an obstruction in the tube.