PTH-345 Fat ratio – a novel parameter for predicting conversion in laparoscopic colorectal surgery

Abstract

Introduction Laparoscopic surgery has become the standard for colorectal cancer in the UK but can be technically challenging in obese patients. Many of these patients can be safely operated on laparoscopically but we hypothesised that there is a subgroup whose fat is mainly internal in whom the risk of conversion is unacceptably high. We propose a highly reproducible parameter that may be able to identify this group preoperatively with no additional scans. Method All patients who underwent elective, laparoscopic colorectal cancer resections from March 2010 to November 2013 were included in the study. Data was collected on age, sex, size of tumour, site of tumour, BMI and whether or not the procedure was converted (i.e. any incision larger than that required to extract the specimen). For obese patients (BMI >30), preoperative staging CT scans were used to determine a “Fat Ratio”, which we define as the ratio between anterior abdominal wall fat at the level of the umbilicus and the distance from the rectus sheath to the anterior aspect of the vertebral body at the same level (see Figure 1). Results 197 patients were included. There were 60 patients (30.5%) in the obese group and 137 (69.5%) in the non-obese group. Comparing the two groups we found conversion rates to be 27% and 16% respectively. The median FR of the obese patients that were converted to open surgery was significantly higher at 5.9 (95% CI 4.8–8.1) compared to those completed laparoscopically (3.3, 95% CI 3.2–4.2, p = 0.0001 Mann-Whitney). We found no significant difference in conversion rate when looking at tumour site or size. Conclusion Fat Ratio is a simple, reproducible parameter that was found to be significantly higher in obese patients whose laparoscopic procedures were converted to open. With further work, this has the potential to become an accurate predictor of conversion risk. Disclosure of interest None Declared.