<prompt> The commonest site of an intraperitoneal abscessPelvisSubphrenic spacePeriappendicularParacolic gutter  <response>: Pelvis is the most common intraperitoneal abscess.50-60.It is the collection of pus in rectovesical or rectouterine pouchpouch of Douglas. The pelvis is the commonest site of an intraperitoneal abscess because the vermiform appendix is often pelvic in position and the fallopian tubes are frequent sites of infection. Reference:Bailey Loves sho practise of surgery,25th edition,page no:996;SRBs manual of surgery,5th edition,page no:576. 