Inclusion Criteria:  Adult (≥ 18 years) with suspected peritoneal endometriosis undergoing elective surgery for pain relief Pain intensity ≥ 5 on Numeric Rating Scale (NRS) in the four weeks prior to giving consent  Exclusion Criteria:  Other known conditions/diseases that may cause pelvic pain Diagnosed personality disorder, schizophrenia or treatment with anti-psychotics Planned pregnancy during study period Women who cannot read or speak Danish