1. Department of Gynaecology and Obstetrics, Leiden University Medical Center, Leiden, the Netherlands
2. Nederlandse Endometriose Kliniek, Reinier de Graaf hospital, Delft, the Netherlands
3. Department of Anesthesiology, Isala Hospital, Zwolle, the Netherlands
4. Department of Anesthesiology, Leiden University Medical Center, Leiden, the Netherlands