OBJECTIVETo study the extensibility and retractility of the surgical margins in digestive system neoplasms.

METHODSThe length difference of the digestive tract was measured in vivo and in vitro under different conditions. Five cm of the stomach, small intestine and large bowel and 2 cm of the esophagus were measured as standard control length in vivo just before resection. The length was measured with a ruler under pull of 500 g and 1 000 g in vivo, in fresh status in vitro, and 10% formaldehyde fixed for 6 - 8 h, 12 - 24 h and 48 - 72 h. The extension or retraction ratio was calculated. The length difference was divided by the natural length in vivo.

RESULTSSeventeen cases of the esophagus, 18 cases of the stomach, 15 cases of the small intestine and 25 cases of the large bowel were measured under pull of 500 g and 1 000 g. The esophagus extended 16.5% and 30.5%, stomach 15.0% and 22.6%, small intestine 66.4% and 120.0%, large bowel 36.0% and 56.0% respectively. In natural status ex vivo, the esophagus retracted 44.5%, stomach 13.6%, small intestine 11.4% and large bowel 15.6% respectively; they continue to retract after 10% formaldehyde fixation until 12 - 24 h later. If the length of surgical margin of the fresh specimen ex vivo was x, the natural length of margin in vivo of the esophagus would be 1.80 x, stomach 1.16 x, small intestine 1.13 x, and large bowel 1.18 x. If formaldehyde fixation for 6 - 8 h, the natural length of surgical margin in vivo of the esophagus would be 1.82 x, stomach 1.41 x, small intestine 1.22 x, large bowel 1.55 x. If formaldehyde fixation for 12 - 24 h, the surgical margin length in vivo of the esophagus would be 2.22 x, stomach 1.43 x, small intestine 1.28 x, and large bowel 1.57 x.

CONCLUSIONThe length of surgical margin of digestive system cancers varied under different conditions, and the evaluation of surgical margin during surgery should be performed under natural status in vivo.