I have always viewed the enema as predominantly a domain of women. A feminine function, by its very nature. Why that is, I am not sure, but I think it may have to do with the procedure being associated with nursing and general maternal domestic care. Which traditionally in our society has been a "woman's job." I think there is a much higher percentage of women that use enemas than men, but I think far, far fewer women sexualize it. Or at least if they do they are not as overt about it and less likely to search it out on the Internet. I feel many women choose to keep the dual benefits of the enema, i.e. constipation relief and pleasure, private.
I feel that men have more of a guilt and shame thing going on about their anal eroticism and love of the enema. The homophobia thing kicks in, the sexual identity crisis rears its ugly head, we are all conflicted and tend to run around in a dither about it. So, we head to the Internet and look for others that are, "just like us." I think men tend to be more focused on strictly the sexual aspects of the enema. Also, it is an area that most men will only feel comfortable talking about on the Internet. That is to say, I think the topic of enemas in the management of constipation is much, much more likely to come up as a topic of conversation among women than men. Homophobic men avoid any serious non-humerus discussion of anal eroticism like the plague. I guess they are afraid they are going to catch the "gay" or something.
My guess is that there are more women that men taking enemas and more men than women talking about taking enemas.