The efficacy of diagnostic laparoscopic ultrasound

Precise staging of malignant disease is required to define the optimum therapeutic strategy. In spite of technical advances, the sensitivity of conventional imaging techniques is usually limited to defining lesions of at least 1 cm in size. Laparoscopy is a sensitive technique that is very valuable for visual inspection of the abdominal cavity and the identification of small surface lesions. However, non-superficial lesions may escape detection due to the lack of tactile sensitivity. As an adjunct to laparoscopy, this study, utilizing a young swine model, has analyzed the detectability of intra-abdominal lymph nodes by laparoscopic ultrasound (LU). Lymph nodes in and around the hepatoduodenal ligament, examined and measured by LU, were resected by subsequent open laparotomy in eight young, mixed-breed swine. The numbers and sizes of lymph nodes detected by LU and resected at laparotomy were compared and analyzed statistically. Forty-six lymph nodes were resected by laparotomy, while LU failed to detect 3 small nodes (sensitivity, 43/46 = 93.5%). The sizes of lymph nodes in the LU group correlated strongly with the sizes actually measured in the laparotomy group (r = 0.936, P < 0.001). Twenty-six small lymph nodes, which conventional extracorporeal imaging might have failed to diagnose, were detected accurately by LU (r = 0.877, P < 0.001). This new technology may not only be effective for staging intra-abdominal malignant disease, but adds the benefit of obtaining tissue samples under direct vision using minimally invasive techniques.