Pericystitis may be due to an extension of an acute inflammation by continuity or by contiguity from one of the neighboring organs or structures, or it may be due of to secondary adhesions causing fixation and distortion of the bladder.
The former variety is quite commonly the result of an extension of a peritonitis of appendicular or tubal origin to the peritoneum covering the bladder. In addition to the usual symptoms accompanying the primary condition, these cases are characterized by pain and tenderness over the hypogastric region, difficulty or even inability to start the flow of urine and pain during the contraction of the bladder as it empties itself. When the bladder forms a part of the wall of an intraperitoneal abscess of appendicular origin or when it lies next to a pyosalpinx, the abscess may perforate the bladder wall liai 0Vacuate itself through this viscus as I have seen
HARRIS ML. PERICYSTITIS. JAMA. 1911;LVII(25):1983-1984. doi:10.1001/jama.1911.04260120173010