The danger of operating by numbers in incisional hernia surgery

Abstract Background Fascial closure is held as a key step in abdominal wall repair. How ‘tight’ the abdomen can be closed to effect this, or when other intra-operative techniques are required to gain closure is not clear, and are likely surgeon dependent. Methods Popular pre-operative measurements: hernia width; hernia area; rectus hernia ratio; and component separation index were considered. Theoretical modelling of a variety of incisional hernias was undertaken. Results Following modelling of incisional hernias, all of these measurements are adversely affected by the state of play once abdominal contents are restored to the abdominal cavity. Fascial closure is also influenced by the actual elasticity of the abdominal wall, the effect of pre-operative muscle relaxation, and weight loss by the patient if they can lose weight or indeed have weight to lose. Pre-operative planning that no additional intra-operative techniques are necessary to facilitate abdominal wall closure (techniques which can have a significant learning curve) is difficult except in very small hernias. Conclusion Surgery by numbers in predicting fascial closure during incisional hernia repair (with a plan to leave easy cases in the hands of generalists) is a dangerous strategy. Intra-operative plans may need to change in light of the intra-operative findings, and AWR surgeons need to be competent to move to plan B or C, minimising the risk to patients.