<qa>  What is the surgical technique that differs with regards to the layer of the abdominal?The surgical technique differ somewhat with respect to which layer of the abdominal is being used 8, when using a bi-layer- or a single sheet mesh. With the bi-layer mesh you use the abdominal layer that is usually used the pre-peritoneal space in case of re-operation due to recurrence after open mesh repair. Re-operation after bi-layer mesh IHR is incompletely studied and it is unclear if this is a more difficult surgical procedure compared with re-operation for recurrence after standard IHR. 