I had to have my chemo through my right arm where 3 nodes taken as they couldn't put a cannula in on the left. I eventually had a portacath put in after 3 cycles as was going on to weekly and the plan was for 12 months herceptin. I always try to have them do all on my left arm if possible including BPs now as I had one scary few days of an enlarged arm which resolved and has never returned. I now wear a lymphodema sleeve when traveling and had some laser under my armpit area with a lymphodema physio which seemed to fix it long term. But only 3 or not it can still happen so it doesn't hurt to be cautious. If you do have proven lymphodema though...then don't let them puncture that arm.
I don't kniw that chemo can increase seroma but I did get fluid retention issues towards the end which was horrendous, but completely resolved once off steroids and chemo very quickly.
