I don't like saying that I'm an expert on this, however, I am. My 6 year old has had 4-5 surgeries, 2 of them outpatient and one of them for an undecended testicle. When my son was almost 3 months old, he had to have a gastric feeding tube put in him (he was on a ventilator for longer than 6 weeks and couldn't suck). He was 1 1/2 years old when he had his undecended testicle surgery, so I'll talk about both.
Pre-Surgery: The Surgical Center should be sending you instructions as far as, don't give him anything to eat or drink for 5-7 hours before surgery (I can't remember the time frame, it may be less time for a 5 month old). By not giving him anything to eat, whatever amount of hours the Dr. says before surgery, will not make him as sick when he wakes up from surgery. My son threw up when he had his final surgery when he was 4 1/2-he ate and drank something (big brother forgot, and gave him some juice and string cheese while I was in the shower, with my last words "don't let him eat or drink anything!") When he woke up, he threw up, making his recovery from surgery more messy.
When he Wakes Up: He will wake up groggy & sleepy. He should already be on some pain medications. It will take an hour or so for him to wake up, but he will be sleepy for a few hours. The best thing Not To Do-is do not pick him up right away. Stay close to him, hold his hand, kiss and stroke his head, talk to him softly, try to cradle him without moving him from the bed. When he is waking up, he is dizzy and the room may be spinning for him-and the best thing to do is to let him lay there until he wakes up more (30 min to maybe an hour). Also, because he is having surgery on his groin, KEEP HIS LEGS STILL OR TOGETHER for as long as possible. Watch him, he may want you to pick him up, and if he screams, put him down, and continue to comfort him by having him lay on the bed, with you talking to him, etc. The hardest part is the first 30 minutes afterwards, because you want to pick him up, comfort him and hold him.
After He Wakes Up A Bit: This is about an hour after he's out of surgery. You or your husband should be holding him by now, carefully. The hospital will make sure he is able to drink, and be alert before you leave the hospital (it's outpatient, right?). He will be groggy or sleepy.
When You Go Home: Because of where his incision is, you shouldn't have to buy a bigger diaper, but all babies are different. It may be a good idea to have his regular diapers, as well as one that is 1 size up. Have him wear little sweat pants and a t-shirt- no onesie that snaps near his crotch, no denim, something soft and loose. Depending on where his incision is, use your best judgement. Have a small towel (like a hand towel) with you or on him incase he throws up. The Dr. will probably prescribe pain killers (tylenol with codine or something), get his filled at the hospital or on your way home.
In The Car: I'm assuming that your husband is going with you, if not, have your 12 year old daughter go with you. Someone should be in the back seat with your little one when you are going home. He will be awake (or not, everyone is different). If he is awake, he may still be groggy or disoriented. It's also good to have someone talk with him, be there in case he throws up. When you get him in his car seat, adjust the straps a little so they aren't tight around his crotch area, this is just for this one time. I know some mothers will disagree on compromising safety by loosening his straps, but, this baby has just had surgery, and you don't want any pressure in this sensitive area.
When You Get Home: Hold him, let him sleep, and love on him-it's been a long day for him. Continue to keep his legs still, he may do this himself. Do not put him in a swing, vibrating bouncy chair, or anything that requires things inbetween his legs for several days. If you need to put him down so you can get things done, put him in his car seat.
My now 6 year old had his undecended testi surgery when he was 1 1/2 years old. I took cues from him as far as what he wanted and needed. He was very active and would swing his leg over the couch or ottoman to climb up on it, he did this once when he was home for not even 30 minutes and he screamed for 5 minutes. He walked, but he didn't like too. He kept his legs still, for the first day, and then as it healed, he progressivly got better. I gave him 1 dose of the pain killers that was sent home from the hospital, otherwise, he didn't complain about pain, he was just sore.
I do not work in the medical industry, I'm just a Mom who has been down a long medical road with my son.
Good Luck, feel free to e-mail me with any more questions. I don't have any experience with helmets, I think they are cute, and you should go ahead and put stickers on it to make it more cute. :-)
SAHM of 2 great boys ages 12 and 6 years. Married to the most patient husband and best Dad in the world.