The parametrium is defined by the tissues that surround the uterine artery between the uterine corpus and the pelvic sidewall cranial to the ureter.
It has two portions, the medial portion corresponding to the vesicouterine ligament, and the lateral portion corresponding to the lateral ligament of the bladder.
It is a very complex area and its dissection is commonly performed in laparoscopic radical hysterectomy. It requires a perfect knowledge of the specific anatomy as this site is a known risk area for major complications such as bleeding and functional disorders.
Concerning functional disorders of bladder, rectum and genital organs, three main sites should be identified in order to avoid damaging the nerves: the external leaf of the uterosacral ligament (inferior hypogastric plexus), the inferior third of the parametrium (pelvic splanchnic root nerves), and the posterior leaf of the lateral ligament of the bladder.