Editing Pediatrics: UPJO & Megaureter (section)

== Megaureter ==

* '''Definition of megaureter: dilatation of the ureter irrespective of cause'''

=== Classification ===
*'''Classified as primary vs. secondary'''
** '''Primary obstructed megaureters (POM)'''
*** '''A condition intrinsic to the ureter itself;''' '''obstruction results from the presence of an abnormal adynamic segment at the terminal end of the ureter near or at the ureterovesical junction (UVJ)'''
**** Insufficient peristalsis at the UVJ leads to obstruction and upstream dilatation
** '''Secondary''' to bladder pathologic processes, such as neurogenic bladder dysfunction, bladder outlet obstruction, and/or infection
* '''Subclassified based on cause (4):'''
*# '''Obstructed'''
*# '''Refluxing'''
*# '''Non-obstructed non-refluxing'''
*# '''Refluxing with obstruction'''

=== Management ===
* The goal is to prevent renal functional deterioration with either conservative or surgical treatment
* '''Conservative'''
** '''> 90% of antenatally detected non-refluxing, non-obstructing megaureters will improve with conservative management within the first few years of life'''
** '''Patients with ureteral diameters > 10 mm were more prone to complications'''
* '''Surgery'''
** '''Indications for surgery of POM (5):'''
**# '''Symptoms'''
**# '''Infections''' (recurring UTIs)
**# '''Increasing hydronephrosis/hydroureter'''
**# '''< 40% differential renal function'''
**# '''≥ 5% decrease in differential renal function of on sequential “comparable” nuclear functional studies'''
**#* '''The T 1/2, or Lasix washout time, especially in neonatal megaureters is not a reliable indicator of obstruction'''
**#** Washout curves in neonates and infants can be affected by many factors other than restriction of flow.
**#** A normal creatinine and symmetric renal function support initial observation in a child
** '''Options (3):'''
**# '''Decompression'''
**#* '''Indications for prompt decompression:'''
**#*# '''Neonate with a megaureter and sepsis'''
**#*# Ipsilateral reduced function (< 35% in a neonate)
**#*# Marked or increasing hydroureteronephrosis
**#* '''Options (2):'''
**#*# '''Distal cutaneous ureterostomy (preferred)'''
**#*# Nephrostomy tube
**#*#* Nephrostomy tubes are difficult to keep in place
**# '''Endoscopic'''
**#* '''Endoscopic dilatation and stenting of the UVJ in POM is an alternative''' that is less invasive than formal open or laparoscopic surgical intervention, with short- to medium-term success rates ≈70%
**# '''Surgical repair'''
**#* '''Excision and tapered re-implant'''
**#** The stenotic distal part of the ureter is excised
**#** The megaureter is straightened and then tapered to facilitate reimplantation in a nonrefluxing fashion with '''adequate ratio of length to diameter of 5:1 to improve coaptation of the ureteral lumen''', whereby effective peristalsis and urine transportation are achieved
**#*** '''Ureteral tailoring is usually necessary''' to achieve the proper length-to-diameter ratio required of successful reimplants. Especially in small children, the reimplant can be otherwise impossible.
**#*** '''Folding techniques for ureteral tailoring are not applicable in ureters >1.75 cm in diameter.'''
**#*** The most serious complication to ureteral tailoring is compromise of the distal vasculature of the ureter with subsequent fibrosis.
**#**** Fibrosis can lead to recurrent obstruction and require a redo. However, when performed with care, the risk of vascular compromise should be minimal
**#** Most surgeons advocate temporary postoperative stenting
**#* '''Complications: obstruction, vesicoureteric reflux, and persistent dilatation'''
**#* A concomitant reimplantation and dismembered pyeloplasty should be discouraged, as the ureteral blood supply may be compromised.