**6.5 Retroperitoneal dissection with round ligament incision**

During hysterectomy, the first structure usually incised is the round ligament. The round ligament incision allows for entry into the retroperitoneum by cutting the broad ligament parallel to the infundibulum of the ligament. Initially, the m. psoas muscle should be identified from this entry point. Then, the a. iliaca externa and v. iliaca externa, which run immediately medial to the muscle, should be easily located. Subsequently, the broad ligament is pushed medially, and separation from the external vascular structures is attempted. This enables the visualization of the ureter adhered to the broad ligament. Further dissection medially along the ureter reveals the a. iliaca interna just below, and entry into the pararectal avascular space between the a. iliaca interna and the ureter is achieved. This dissection allows for easy ligation of the a. iliaca interna for subsequent control of pelvic bleeding after hysterectomy. When following the a. iliaca interna anteriorly, the umbilical artery will be visible, and by dissecting the umbilical artery medially while keeping the a. and v. iliaca externa laterally, the paravesical space can be reached. In the inferior aspect of the paravesical space, the a. and v. obturatoria are found, while caudally, an aberrant v. obturatoria is present in approximately 30% of cases, along with the n. obturatorius in the inferior aspect. The exploration of this space also allows control over the paravaginal region in an inferio-caudal direction, facilitating the evacuation of hematomas, repair of tears, and suture ligation of ongoing bleeding in this area.
