Fine catheter peritoneal cytology for the acute abdomen: a randomized, controlled trial

A randomized, controlled clinical trial, of sequential design, was undertaken to determine whether fine catheter aspiration cytology of the peritoneal cavity, using the percentage of neutrophils in the sample as the main test marker, reduces errors about urgent laparotomy in patients admitted to a surgical unit with acute abdominal pain. One hundred and forty-four patients with acute abdominal pain were studied. Of these, 26 were excluded because the test was unlikely to be useful and 20 did not consent. Conventional clinical assessment was undertaken and then the subjects were randomly allocated to have a peritoneal cytology test or not. After the test result was made available, the surgeon(s) decided whether to operate or continue conservative treatment. The correct decision was later ascertained by a blinded clinical referee. With the entry of the 98th patient the difference between the groups achieved the 5% significance level. The groups were well-matched in regard to demographic and other variables. The decision about urgent laparotomy was incorrect in only 8.2% of the test patients, compared with 28.6% of the others. It is concluded that fine catheter aspiration cytology of the peritoneal cavity is likely to reduce the numbers of unnecessary or delayed laparotomies when used in most patients admitted with acute abdominal pain.