After the white light (WL) imaging, NIRF imaging will be performed. 2.5 mg of ICG will be administered i.v. up to 5 times if needed. The lesions identified in WL, are inspected in NIRF mode. The surgeon indicated whether the lesions are more easily identified in WL or the NIRF mode and scores the visibility on a 1-10 scale. Next, inspection will take place for lesions that are seen in NIRF mode but not in WL. Biopsies will be taken from the lesions and from normal tissue for reference and sent for histology. Evaluation will take place whether the lesions differ in histological characteristics

By using a fluorescence imaging device (with an adapted light source and camera), a fluorescent dye can be made visible. By injecting the fluorescent dye intravenously, the vascularization will be visible. Thereby, structures with altered vascularization are expected to 'light up' differently than the surrounding.

The number of lesions detected in near-infrared light will be compared to the number of endometriotic lesions seen in white light. Hereby, we aim to investigate whether all lesions seen in white light are also seen in NIRF light and whether NIRF light shows endometriotic lesions that were not visible in white light.

Hereby, we aim to investigate whether the different histological subtypes of endometriosis light up differently in NIRF light. We interested in whether there is another localisation of ICG uptake at cellular level in the different histological subtypes.