Q-tip Test

To determine whether you will be able to easily get a vertical hood piercing, you can take a Q-tip (cotton bud), lubricate it, and try to place it under the clitoral hood alongside the clitoris. If it fits without difficulty or discomfort, then you've got enough room for the piercing — and for the piercer to do the piercing in the first place (since they'll normally insert a receiving tube under the hood to do this piercing).