Hi I Was Sent In For Neck Major Surgery On

Hi i was sent in for neck major surgery on Monday this week. The surgeon aborted the surgery because when the turned me on my stomach my neck and face swelled and they were concerned i would bleed out. I have been for CT Scans and there is nothing to show the cause. The surgeon thinks it is my weight which is 107kg at 186cm as a male. What are your thoughts on possible causes