
Jonathan C. answered 04/20/20
BA in Japanese with 3+ Years of Teaching Experience
Hello Sandy.
Very good question and a pretty high level of Japanese! Japanese grammar can get a little hard and their nuances can get a little difficult as well so I hope that this explanation helps.
To begin, the grammar phrase ~してみると is taken from the grammar verb phrase ~すると which means "thereupon" or "upon that", "after that". It shows an expected event that will happen after; however when used with the verb みる to become ~してみると it still carries that same meaning of "thereupon" or "after that", "upon that", however now this shows that you are attempting something and the event that will happen after that action can be an expected result, but you don't know until you do it.
Example:
お隣さんにお土産をあげようと思っていたけど、チャイムを押してみると誰もいなかったです。
(I thought about giving a gift to my neighbor, however when I rang on their doorbell, nobody was there).
ジェットコースターに乗ったことがなかったけど、乗ろうとしてみるとやっぱ楽しかったなー。
(I had never ridden a roller coaster before, but when I decided to ride one it sure was a lot of fun).
As for the 退院してみると, this can be translated as "when I decided (that it was time) to leave the hospital". It shows that you, or the hospital staff, believed that you were ready and give it a try to leave the hospital and the result that happened afterwards was probably to be expected. The example sentence provided above by another tutor is a perfect example of this.
Example:
病院から退院してみると、お父さんが「私の」家に住んでいた。
(My father started to live with me after I was released from the hospital).
I hope this explanation helps!