It's a different way of saying the causative-passive 行かせられる, so it means that the speaker was made to go to the hospital.
Note in an earlier version of this answer I confidently asserted that this is a more colloquial example. A comment was posted to the contrary and, after researching it more in depth, I was surprised to find I was indeed wrong in that regard. 行かされる has numerous entries on the corpus of modern written Japanese, and appears to be totally fine in most, if not all contexts, and may actually be considered the standard. Nevertheless it seems to be a debatable concept. In fact, some of the confusion about whether it's 行かされる or 行かせられる seems to come from Japanese people who see Japanese textbooks for foreigners where we are generally taught that 行かせられる is the Right Way. I think this is where my initial confidence and confusion came from (coupled with my general ignorance of course). So this confusion is probably a result of the way Japanese is taught to foreigners, or at least it doesn't do much to remedy the situation. Apparently at least some Japanese educators share in this frustration.
Personally as someone who always struggles to say ～させられる I feel somewhat liberated by this revelation.