Hey Magnru! I had issues with pseudocysts forming. I had one that formed in my abdomen in march of 2005 and blocked that end of the shunt resulting in a revision. I'm not sure if I was having much pain due to that or not cause at the same time I had an ovarian cyst rupture and a kidney stone so its hard to tell what pain was what! I didn't have another issue until after I had 2 back to back shunt revisions in August and September of 2006. They were within 10 days of each other due to a broken valve. At the time the fluid pushed through my stitches and allowed infection to get in through there which led to me being back in the hospital in october with an infected Pseudocyst. I did have to have surgery to drain it since it was making me have a 104 fever. I was having stomach pain at the time so I thought it was another ovarian cyst and I didn't realize I had a fever.

After that one was drained, I was fine for the rest of the month(but since I got out of the hospital the day before halloween thats not saying much!) and for november, but in december I started having the same stomach pains and ended up spending most of the time after the first week or so of the month with a heating pad on my stomach. I went back to the same doctor who handled my stomach surgery before(since the shunt wasn't a shunt infection my neuro was consulted and present during surgery but wasn't the primary) and she sent me for an ultra sound which showed the cyst. Due to the time of year nothing was done until the first days of January(around the 5th I think?) when I had another minor surgery(out patient) to drain that cyst.

I met with my neuro concerning the pseudocysts on I think the 8th of January and he said that the scar tissue in my stomach (due to the 2 shunt revisions I had had, one as a baby and the one in 2005) was trapping the fluid that the shunt was draining into my stomach and causing it to form the pseudocysts. Because of that he said the my stomach was no longer a viable option for my shunt. Around a week later I had surgery to move it to the lining around my lungs(pleural cavity). They said when they did the surgery that another cyst had grown and was blocking my shunt again. They didn't have to do surgery to remove it that time as it wasn't causing me any pain and after they removed the shunt from my stomach nothing was feeding the cyst and it dissolved.

So basically for me, I had one pseudocyst form in march of 2005, and didn't have another until october of 2006. After that though I had another one grown by december, had it drained in january only to have another one formed about a week and a half later. So I guess how quick they grow can vary. Mine did require surgery except for the last one that dissolved after the shunt was removed. Hope all this helps!