Albeit the role of laparoscopy in the treatment of acute small bowel obstruction (SBO) has grown significantly over the last decade, the inability to obtain an adequate evaluation of compromised bowel segments has been considered as real limitation. This is essentially due to a reduced field of view owing to intestinal distension, the minimized haptic feedback obtained and limited bi-dimensional visualization. As a consequence, the presence of normal visual clues to irreversible vascular insufficiency is much reduced.
Such signs include stable discoloration of the bowel wall, absence of peristaltic movements and apparent mesenteric pulsation. Intestinal perfusion and viability are largely assessed by means of the clinical eye. However, this method lacks objectivity and accuracy, irrespective of a surgeon's experience. Routinely clinical judgment may be appropriate, but the rate of conversion due to concerns regarding bowel viability can be high. Where there are concerns for intestinal ischaemic injury without absolute indications to bowel resection (areas of mural gangrene or bowel necrosis with perforation) intestinal compromise can be appraised by real-time fluorescent analysis of the vascular supply.
Some authors reported their experience on the use of the ICG fluorescent angiography (FA) to assess bowel viability during laparoscopic approach in emergency surgery for SBO, with promising results. Nowadays, an important drawback of qualitative intraoperative assessment of bowel compromise with FA is the interpretation and definition of the boundaries between bowel viability and irreversible ischemia in order to avoid or reduce the rate of delayed bowel necrosis and perforation. An instrument more objective as possible to help surgeons during the intraoperative decision-making is lacking. A resectability score could be resolutive but a large amount of data from a multicentric data registry is needed.
Finally, when the registry will be completed, a logistic regression analysis will be used to identify independent predictive factors of bowel resectability by calculation of odds ratios and its 95% CI based on delayed bowel resection rate too. Significant continuous variables will be transformed into categorical variables using receiver operating characteristic (ROC) curves. The sample size required for the development of the Score was determined according to previous reports. The number of unnecessary bowel resections has been estimated around 46%. Two studies on ICG-fluorescence angiography use during laparoscopic surgery for SBO reported 28.6% of resection rate. The investigators adopted this degree of difference as the maximum error tolerance of 17.4%. Considering a power of 0.9 , a significance level of 0.05 , a 95% CI with its two sides of 0.112 and 0.46, the required sample size will be of 26 subjects that will undergo to bowel resection that must be associated with other 26 subjects with no bowel resection and other 26 will undergo delayed bowel resection, for a total of 78 patients. According to this sample size the score will have a sensitivity of 0.28, a specificity of 0.73, a positive predictive value of 0.22, a negative predictive value of 0.73 and a precision value of 0.39.
The optimal cut-off point with the highest sum of sensitivity and specificity will be chosen for each variable, also the overall predictive value of the Score will be assessed. Finally, a score will be developed by assigning coefficient points to each variable.
