The rectal dissection on the posterior side starts just above the promontory. Leaving the hypogastric nerves aside, the presacral space is entered. In the correct plane we expect minimal bleeding. At the S3 or S4 level, we see the retrosacral fascia (Waldeyer). This structure varies from a thin layer to a thick ligament. It is important to sharply cut this structure by turning the scissors or electrocautery now parallel to the pelvic floor. If downwards dissection is to be carried out, the presacral venous plexus may be injured, which can lead to life-threatening bleeding. Once Waldeyer's fascia is cut, the tip of the coccyx is reached. Nowadays a 2-cm distal margin is acceptable, but coning of the mesorectum must be avoided.
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