2007 ICD-9-CM Procedure 91.1 Microscopic examination of peritoneal and retroperitoneal specimen 91.1 is a non-specific code that should not be used to specify a procedure 91.1 contains 5 index entries View the full Volume 3 91.* hierarchy Index entries containing 91.1: Examination (for) microscopic (specimen) (of) 91.9 cul-de-sac 91.1 mesentery 91.1 omentum 91.1 peritoneum (fluid) 91.1 retroperitoneum 91.1