I Don't Get It?

I took the certification exam for CNS recently and failed. I was surprised to see how many medical surgical questions were on the exam. I am not well versed in Med-Surg as I am an ED nurse by trade. I've never practiced on a Med-Surg unit. And the online review course offered by the ANCC was not helpful at all. Are practicing Med-Surg nurses the ones who take this exam? Just trying to figure out if other specialized nurses took this exam. Are there any other methods that others have used to study for this exam? I rocked on all of the CNS related questions, but scored low on the Med-Surg questions. Debating if I should take it again. I am so confused. Any advice would be helpful. Thanks for listening.