Prognostic value of negative intraoperative ultrasonography in primary colorectal cancer

Surgical management of colon cancer

The primary mode of therapy for colon cancer continues to be surgery. Although little has changed in the technical aspects of colonic resection, a great deal of research has taken place to develop procedures that enhance staging of disease, optimize postoperative recovery, and improve outcomes in obstructed patients without compromising cancer-related morbidity and mortality. This review explores the current use of laparoscopy, sentinel node biopsy, intraoperative ultrasound, and colonic stents in the elective and emergent management of colon cancer.

Laparoscopic ultrasonography: a training model

PURPOSE

The purpose of this study was to develop a surgical training program and to test the accuracy of laparoscopic ultrasound in detecting injected lesions in pig livers.

METHODS

Pig livers were divided into eight segments and injected with Surgilube "malignant" and silicone "benign" lesions. All were examined by laparoscopic ultrasound followed by liver explantation to confirm results. First, a pilot study was conducted on six swine by injecting Surgilube lesions and performing laparoscopic ultrasound through 3 different ports (left upper quadrant (I), umbilicus (II), and right lower quadrant (III)) to determine per-segment accuracy and to optimize port placement. Second, blinded injection of Surgilube and silicone implants was done on 18 pigs with laparoscopic ultrasound conducted through the two most accurate ports from the pilot study. This model was then tested during a resident training workshop.

RESULTS

In the pilot study, per-lesion and per-segment sensitivity was 96 percent, with no difference among the three ports used. Ports I and II were chosen for the blinded study for their convenience in performing laparoscopic colectomy. In the blinded study, per-segment sensitivity, specificity, and accuracy were 97 percent, 94 percent, and 96 percent and 99 percent, 94 percent, and 97 percent for ports I and II, respectively. At the conclusion of a pilot workshop, trainee per-segment sensitivity, specificity, and accuracy were 60 percent, 80 percent, and 70 percent, respectively. The major difficulty was differentiating benign from malignant lesions.

CONCLUSIONS

A useful liver laparoscopic ultrasound training model for surgeons was developed with good preliminary results. It is anticipated that further training will enhance laparoscopic ultrasound accuracy rates before application of this modality in humans.

Intraoperative and laparoscopic ultrasound

Intraoperative ultrasound, whether during celiotomy or laparoscopy, plays an important role in assisting the surgeon in directing appropriate therapy for intra-abdominal diseases, particularly primary or metastatic malignancies involving the liver and primary malignancies of the pancreas and upper gastrointestinal tract. It is the most sensitive imaging technique for detecting small intraparenchymal lesions of the liver, pancreas, and other solid organs. Owing to its increased sensitivity over all commonly used preoperative imaging studies, it is responsible for changing the intraoperative treatment plan of these tumors in a significant percentage of cases. This is particularly true with respect to resectability. In the era of laparoscopic surgery, it replaces the surgeon's inability to palpate the liver and other organs during surgery. As surgeons use a laparoscopic approach with increasing frequency to treat intra-abdominal disease, they will have an increasing need to master the use of intraoperative ultrasound in order to render optimal care to their patients.