Introduction The appropriate operative management of a macroscopically normal appendix at diagnostic laparoscopy for Right Iliac Fossa (RIF) pain remains controversial. Advocates for appendicectomy state that removal of microscopic inflammation or faecoliths may resolve symptoms and prevent future episodes. Those who leave the appendix in situbelieve microscopic inflammation is not clinically significant. We aim to establish the accuracy of intra-operative assessment of the appendix to inform this debate.

Method A prospective observational study was undertaken between February 2012 and December 2013. Patients aged ≥18 years presenting with RIF pain with suspected Acute Appendicitis (AA) were recruited. Operative notes were compared with histological findings to assess the diagnostic accuracy of intra-operative assessment at appendicectomy. The histological criterion for AA was transmural inflammation.

Results 74 participants were recruited (35% male), median age 33 (range 18–84). 31 patients underwent appendicectomy with a negative appendicectomy (NA) rate of 32% (10/31). 26 (83.9%) were started laparoscopically, 3 of which were converted to open (11.5%).

Intra-operative assessment reported 10 normal appendices, two of which revealed AA on histological assessment. 2 out of 21 intra-operative diagnoses of AA were considered histologically normal. 4 cases were described as perforated in the operation note, however, histological assessment failed to report perforation in all cases. The sensitivity and specificity of macroscopic assessment of all forms of AA was 90.5% (19/21) and 80% (8/10), respectively.

Conclusion Even in our relatively small study 2 cases of AA would have been missed by macroscopic assessment and could have been erroneously left in situ. Our study supports the argument for routine excision of macroscopically normal appendices at surgery for RIF pain when no other pathology is found. Conversely, perforation was under reported on histological assessment and is therefore an important element of the operative assessment.

Disclosure of interest None Declared.