However, one of the them was treated as perianal abscess with no preoperative imaging  and another one had a cyst centered in the retrorectal space
with extension into the perineal and gluteal areas .
At first, the retroperitoneum was dissected at the sacral promontory to enter the left Toldt's space and retrorectal space
from the right side of the sigmoid mesocolon.
On CT, these lesions are typically well-marginated, thin-walled, uni- or multilocular, nonenhancing lesions in the retrorectal space
TIP] In a case in which the promontory is difficult to find, dissecting the retrorectal space is a simple way to mobilize the bowel away from the sacrum, thus exposing the promontory.
TRICK] Another trick that can help with safe identification of the promontory is mobilization of the sigmoid colon away from the sacrum by developing the retrorectal space.
It is important to exclude these lesions before sorting through the spectrum of congenital, inflammatory, neurogenic or osseous tumours that occur in the retrorectal space
Retrorectal cyst hamartoma (RCH), also commonly known as tailgut cyst, is a rare benign cystic lesion located in the retrorectal space and is believed to derive from persistence of embryologic remnants of the post anal gut (tailgut), which appears at the 3.
In all cases the lesion was located within the retrorectal space, which is defined anteriorly by the rectum, posteriorly by the sacrum, superiorly by the peritoneal reflection, inferiorly by the elevator ani and coccygeus muscle, and laterally by the ureters and iliac vessels.
On rectal examination, the mass was external to the rectum and tethered in the retrorectal space.