Below is an instruction that describes a task. Write a response that appropriately completes the request. ### Instruction: Thank you this sounds similar, I will have to ask my Gp as in the UK we can't book direct with specialists, you need a gp to do so if they feel it's necessary.I cant find anything on ventil stones, but have found a lot of info on ureter stones which sounds very similar. Thanks again. ### Response: Ventil stones are rare, i have only 2-3 cases per year. I don't know if the name in english is same as in german, we call them ventil stones because they act as a ventil or imagine as a Gate, the ventil stone moves a bit=blocks urinary tract causing hydronephrosis and massive pain, then a bit later this stone moves again and opens the way so to say and then urine flows normally and hydronephrosis dissappear so pain goes away. The native CT scan can 100% detect it. If you experience fever with the pain you rush to the Er, otherwise go to your gp as you said..