Editing Pediatrics: Bladder Anomalies (section)

== Prenatally Detected Bladder Anomalies ==

=== Dilated fetal bladder ===
* '''Due to obstruction or caused by incomplete emptying of the bladder without evidence of a mechanical obstruction; difficult to distinguish in utero if the dilation is due to obstruction'''
* '''Commonly associated with severe anomalies, often the cause for oligohydramnios, and can require fetal or immediate postnatal intervention to prevent fetal demise'''
* Determination of the sex of the child is very important because of the male gender predominance of certain conditions and diseases such as posterior urethral valves or prune belly syndrome.
* '''Dilation Caused by Anatomic Obstruction'''
** '''Mostly due to urethral anomalies or external obstruction'''
*** '''Urethral anomalies include congenital urethral strictures, anterior and posterior urethral valves, and urethral atresia'''
*** '''Compression of the bladder outlet region can be due to obstructing syringoceles, a sacrococcygeal teratoma or pelvic neuroblastoma, an anterior sacral myelomeningocele, or rectum anomalies.'''
* '''Dilation in Non-obstruction'''
** '''Fetuses with nonobstructive dilation appear to pass enough urine to maintain renal function and adequate amniotic fluid levels throughout the pregnancy'''
** '''Prune Belly Syndrome and Neurogenic Bladder Disease'''
*** Affected patients do not demonstrate any sign of obstruction on postnatally performed voiding studies or cystoscopic evaluations, except when urethral atresia is also present
* '''Congenital Megacystis'''
** '''The term megacystis is often used to describe any condition leading to a distended fetal bladder in utero'''
** Bladder dilation is from the continuous recycling of the urine between the upper tract and bladder
** '''Bladder contractility is normal, although a majority of the urine refluxes into the ureters with each void. No neurogenic abnormalities are described.'''
** Most patients are recognized prenatally and should be placed on prophylactic antibiotics after birth.
** '''Correcting the reflux often restores normal voiding dynamics and should be performed after 6 months of age.''' Reduction cystoplasty can be performed but is usually unnecessary
** Congenital megacystis has been recognized in association with microcolon-intestinal hypoperistalsis syndrome. This syndrome is a rare congenital disorder characterized by a dilated, nonobstructive urinary bladder and hypoperistalsis of the gastrointestinal (GI) tract. The syndrome can be identified on antenatal ultrasound by the appearance of a largely dilated bladder. It has been reported mostly in females and is usually considered lethal

=== Non-dilated or Absent Fetal Bladder ===
* In nondilated conditions, the bladder is either completely absent or is unrecognizable as a fluid-filled structure because of incomplete formation.
*'''Differential diagnosis of absent fetal bladder'''
** '''Fetus has recently emptied bladder'''
*** '''To truly diagnose an absent fetal bladder on ultrasound, the examination has to be repeated after 15 to 20 minutes to rule out that the fetus has not simply emptied the bladder'''
** '''Poor renal function and oligohydramnios'''
** '''Cloacal exstrophy'''
** '''Bladder exstrophy'''
** '''Persistent cloaca'''
* '''Normal amniotic fluid levels are found with bladder and cloacal exstrophy.'''
* '''Bladder hypoplasia'''
** '''Causes:'''
*** '''Inadequate bladder outlet resistance (e.g., severe epispadias)'''
*** '''Separation defects (e.g., urogenital sinus abnormalities)'''
*** '''Abnormalities of renal development (e.g., bilateral renal dysplasia or agenesis)'''
*** '''Urine bypassing the bladder (e.g., ureteral ectopia)'''
** Some of these bladders grow once the malformation is corrected; however, later bladder augmentation is often required to reach adequate capacity
* '''Bladder Agenesis'''
** '''Compatible with life only if the ureters drain ectopically''' into normally developed müllerian structures in the female [Chapter 134 says ectopic ureters do not drain directly into Mullerian structures) or in the rectum in males