Cell block D is chaos, with a lot of non-speaking roles putting up a piss-poor defense until Rick, Daryl and Glenn roll in and take over the fighting and the evacuation. Several people have been turned already and Glenn kills one of them from off a guy who just got bit on the arm. Carol swoops into bring that guy into her cell and prepares for an emergency amputation, until she notices the gash on the back of his neck. So the good news is she won't be amputating anything.
By now the battle in block D is all but over and Tyreese reunites with Karen, who is watching a young mother sob over a blanket-covered bundle. Daryl and Glenn go upstairs to check the mezzanine level, and Glenn is grabbed by a zombie coming out of a sheet-covered cell. Daryl puts a crossbow bolt in the attacker's head and after helping Glenn up, identifies the body as that of Patrick. First in, last out.
Our heroes do the mopping up, which by necessity includes pre-killing Patrick's very last victim and Rick reluctantly entering one quiet cell with a clean knife and coming out with a bloody one. Carol is still kneeling over Ryan, the unfortunate fellow who still has his arm but is pretty much waiting to die. He asks Carol to look out for his daughters, Lizzie and Mica, which she agrees to do. She also tells him that they'll need to say goodbye to him. Taking right over, I see.
There's one last walker inside a locked cell, who comes up to the grate. Rick has less compunction about grabbing this one by the shirt and stabbing its face through the bars while Daryl watches. Then Rick opens the cell and some of the guys -- himself, Daryl, Hershel, a new character who goes by the name Dr. S. and former Army medic Bob -- gather around the bloody-faced body. Rick sees that the body has no bites or wounds and Dr. S. diagnoses that he died of pleurisy aspiration. "Choked to death on his own blood," Hershel translates. People always use phrases like "choked on his own blood" or "sitting in his own feces,", as though somebody else's would be better. I submit that it would not be. Whatever the case, Dr. S's diagnoses explains the blood trails on his face like the ones we saw on Patrick, which I thought was from bashing his face on the tile floor. Rick has also seen that blood-muzzle look on a walker outside the fence, and Daryl recognizes it from Patrick as well. Dr. S. explains that it's from lung pressure building up: "Like if you shake a soda can and pop the top, only imagine your eyes, ears, nose and throat are the top." Well, that sounds just lovely.