MSFinals-1720

A gynaecologist is performing a hysterectomy for leiomyomata and menorrhagia on a 44-year-old woman. Once under anaesthesia, the patient is catheterised, and the surgeon makes a Pfannenstiel incision transversely, just superior to the pubic symphysis. After opening the parietal peritoneum, he identifies the uterus and makes a shallow, transverse incision in the visceral peritoneum on the anterior uterine wall, and then pushes this downwards to expose the lower uterus.

What is the most likely reason for this?