quote from "Pediatric Colorectal Conundrums: Case Studies: From Fundamental to Advanced (Pediatric Colorectal Surgery)" by Marc Levitt, Thomas Xu, Hussein Wissanji -

"When the common channel is <3 cm, it is possible to mobilize the UG complex as a unit to the perineum, the TUM. In general, a urethral length of >1.5 cm is required to avoid urine leakage and to avoid pulling down the bladder neck out of the urogenital diaphragm with the mobilization. When the length of the common channel is >3 cm or the urethra is <1.5 cm, a UG separation is utilized, leaving the common channel untouched and adding to it the native urethra. With the UG separation, the vagina and rectum are dissected off of the common channel and mobilized to bring them each down to the perineum independently. When the common channel is >3 cm, a UG separation is required to gain the necessary mobilization for the vagina to reach the perineum. After separation, the common channel is repaired, and the urethra and common channel together become the new urethra now with adequate length."

quote from "Pediatric Colorectal Conundrums: Case Studies: From Fundamental to Advanced (Pediatric Colorectal Surgery)" by Marc Levitt, Thomas Xu, Hussein Wissanji -

"Urethral loss or urethrovaginal fistula can occur due to ischemia related to over-dissection of the common channel. If the surgeon underestimates the common channel length and begins a TUM dissecting the anterior urethra but then realizes intraoperatively that there is insufficient mobilization to reach the perineum, changing to a UG separation and dissecting the posterior urethral wall risks significant ischemia of the now circumferentially dissected common channel. Such complications can lead to an acquired bladder neck closure and the need for a Mitrofanoff."

quote from "Pediatric Colorectal Conundrums: Case Studies: From Fundamental to Advanced (Pediatric Colorectal Surgery)" by Marc Levitt, Thomas Xu, Hussein Wissanji -

"Vaginal loss or acquired vaginal atresia, like urethral loss, occurs from ischemia related to excessive dissection and tension. When UG separation is required, it is important to maintain the vaginal blood supply from the lateral attachments bilaterally. For this reason, older techniques such as the vaginal switch have been abandoned. Optimal mobilization of the vagina is achieved by full separation from the common channel and fully dividing the central pelvic and retroperitoneal attachments posteriorly. The blood supply then depends on the round ligaments from both sides. A vaginal length of 4 cm is predictive of a successful native vaginal pull-through. When the Müllerian structures are smaller or absent, delayed vaginal reconstruction or bowel vagina replacement should be considered. If a bowel neovagina is used to bridge the gap to the perineum, this could be removed later in life with a pull-through, at that time, of the native vagina."