[SPOILER]
You should have encountered a long straight vertical corridor. The first one. In that corridor there are 3 turns on the right (the last one will lead you to the nose pliers area) and 1 turn on the left. You have to take the only turn on the left! Then there is a little more try-and-error but you should be able to find the way without too much effort. The exit is on the slaughterhouse's top-right corner... But you have to stay on the left :)
When you find a doll, you'll be close to the exit!