Intraoperative ultrasonography in the detection of liver metastases of gastrointestinal cancer. [L'ecografia intraoperatoria nella diagnosi di metastasi epatiche da neoplasia gastrointestinale]

The authors illustrate their experience in the systematic use of intraoperative ultrasonography of the liver in patients undergoing surgery due to gastrointestinal cancer. The liver is the organ in which mestastases from colorectal, stomach, pancreatic, and biliary cancer are most often localised. Between January 1991 and April 1992 95 patients underwent intraoperative ultrasonographic controls of the liver. In all cases the liver was studied using traditional image diagnosis: standard ultrasonography and CAT. On the basis of their experience the authors observed 12 cases negative for metastases using CAT and traditional ultrasonography which were positive using intraoperative ultrasonography, 2 cases which were positive for secondary hepatic lesions using traditional diagnostic tools but negative following histological tests guided by intraoperative ultrasonography. In the case of false negatives using traditional methods, those metastases revealed by intraoperative ultrasonography were above all located deep down and in segments which are difficult to explore, or were so small that they were not visible or palpable during intraoperative controls of the viscera. Intraoperative ultrasonography of the liver has been found to be a more sensitive test (97% of the best series) than standard ultrasonography (65%) or CAT (43%). Higher resolution due to the characteristics of the method is coupled with the possibility that intraoperative ultrasonography may be used to guide biopsies of the metastases revealed, thus allowing histological confirmation to be obtained: for this reason the risk of false positives is virtually zero. Intraoperative ultrasonography has been found to be a very sensitive method since it enables metastases to be identified which are not revealed by preoperative staging, or, in the event that metastases have been located prior to surgery, to specify their number. Given that the prognosis for patients with gastrointestinal cancer improves if metastases are identified and treated as early as possible (especially in the case of repeated colorectal cancer), intraoperative ultrasonography allows more precise staging of cancer, thus modifying surgical tactics, initially programmed to include the removal of the primary tumour, and extending it to the removal of the metastases. When the latter are multiple and cannot be operated, surgery is therefore shown to be palliative and arterial chemotherapy is indicated. Intraoperative ultrasonography allows the major vascular and biliary structures to be recognised, making surgical procedures safer and easy to perform. Lastly, on the basis of the authors' experience the method is free of complications.