It is critical that you disclose any previous and current (pre-existing) medical conditions. It doesn’t mean they will be automatically excluded but it does give the insurer an opportunity to cover, offer terms for or exclude the condition. If the insurer decides to not exclude a declared pre-existing condition and it does reoccur they are bound to cover that condition. If you fail to disclose a pre-existing condition and it reoccurs the insurer will generally refuse to pay for any treatment and are entitled to cancel (avoid) your policy.