By Miriam Stoppard In answer to a reader’s letter about acid regurgitation, I mentioned a new test – the sponge-on-a-string test – and I thought you’d like to hear about the latest research. It comes from Cambridge University and means patients will no longer need an invasive endoscopy to examine the oesophagus (food pipe), thanks to the capsule sponge test. The NHS pilot on over 8,500 patients shows almost eight out of 10 who completed a test were discharged without the need for further testing. Patients swallow the small capsule which contains a tiny sponge that collects cell samples before …