Objective: To investigate the guiding effect of carbon nanoparticles injection on lymph node clearance during surgery for carcinoma of the ampulla of Vater. 
Methods: Sixty patients with carcinoma of the ampulla of Vater were selected and allocated to observation group and control group, with 30 cases in each group. Patients in observation group underwent injection of 1 mL carbon nanoparticles with 4 points (top, bottom, left and right) into the serosa of the descending duodenum and the capsule of the pancreatic head around the tumor after laparotomy and the operative field exposure, while those in control group underwent saline injection in the same fashion. The number of dissected lymph nodes and other relevant clinical variables were compared between the two groups of patients.
Results: The total number of dissected lymph nodes in observation group was 468, including 416 (88.9%) dark stained lymph nodes. The total number of dissected lymph nodes in control group was 268. The average number of dissected lymph nodes per case in observation group was significantly greater than that in control group (15.23±2.13 vs. 9.77±1.33, P<0.01), which was mainly responsible for the N1 station lymph nodes (P=0.002), and the differences in N2 and N3 dissected lymph nodes showed no significant differences between the two groups (both P>0.05). The operative time, incidence of lymphatic leakage and length of hospital stay showed no significant differences between the two groups (all P>0.05), but the intraoperative blood loss was significantly reduced in observation group compared with control group [(318±30) mL vs. (592±60) mL, P<0.05].
Conclusion: Carbon nanoparticle injection in radical surgery for carcinoma of the ampulla of Vater can increase the number of dissected lymph nodes, reduce intraoperative blood loss, and with no increase of occurrence of complications. It is a safe and effective tracer.