 [ Symptoms ] how is thrush diagnosed [ Disease ] you could have pinworms the live in your rectum and come out at night do not ask me how they know it is night  and lay eggs around your anal ring this is one common cause of pruritis ani latin for itchy anus you will need to have your medical provider order a pinworm test if this is not the cause then you will need to see your medical provider for an exam to see if their are other treatable reasons