PEDIATRICS: BLADDER ANOMALIES
Background
- Bladder anomalies are often due to infravesical obstruction or part of a more serious disorder rather than a true isolated structural malformation
Bladder and Urachal Development
- The obliterated urachus becomes the median umbilical ligament and connects the apex of the bladder with the umbilicus
- Normal Antenatal Sonographic Findings of the Bladder
- The bladder can be visualized in ≈50% of cases in the fetal pelvis at the 10th week of gestation, almost 100% at 13 weeks
- The fetal bladder empties every 15-20 minutes; therefore a second ultrasound in the same setting is mandatory in case of non-visualization of the bladder.
- Fetal sex is difficult to determine before week 14 and should not be based on the presence or absence of a phallus but on visualization of the testes.
- The measurement of amniotic fluid as an indicator of fetal urine production is a critical portion of every antenatal ultrasound
- The umbilical cord should contain two arteries and one vein without evidence of a fluid-filled urachus
Classification of Bladder Anomalies
- Prenatally detected
- Postnatally detected
- Urachal abnormalities
- Bladder diverticulum
- Bladder duplication
- Other bladder anomalies
Prenatally Detected Bladder Anomalies
- In nondilated conditions, the bladder is either completely absent or is unrecognizable as a fluid-filled structure because of incomplete formation.
- 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
- 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
Postnatally Detected Bladder Anomalies
- Urachal Anomalies
- In a series of 176 patients diagnosed with a urachal anomaly and urachal remnants, children mostly presented with umbilical drainage or on physical examination; of the adults, 66% had hematuria or pain. Surgical treatment in children consisted of simple excision, whereas over 50% of adults required partial or radical cystectomy because of malignancy.
- Imaging possibilities include ultrasound, CT, and VCUG
- Non-resolved urachal remnants should be excised because of the increased risk for later adenocarcinoma formation
- Patent urachus (most common, 50%)
- Suspected in the neonatal period by continuous or intermittent drainage of fluid from the umbilicus
- [SASP] 50% of radiographically confirmed patent urachus will spontaneously close in the first 6 months of life and observation is warranted
- If required, treatment is complete excision of the patent urachus, including a bladder cuff
- Umbilical-urachus sinus (15%)
- Manifestation is similar to that of the patent urachus
- Urachal cyst (30%)
- There is no communication of the cyst with the bladder or umbilicus.
- However, the fluid-filled cyst can drain through the umbilicus or into the bladder intermittently.
- Urachal cysts are found more commonly in the distal part of the urachus and manifest more commonly in adults than in infants or children
- The cyst material consists of desquamated epithelial cells. These cells can become infected; staphylococcus aureus has been identified as the most common organism. Once infected, urachal cysts can manifest as umbilical abscess formation or bladder infections
- Treatment consists of antibiotics and draining the infected cyst, followed by complete excision of the urachal remnant structures. Conservative treatment with observation is justified in asymptomatic cases because of possible spontaneous resolution
- Vesicourachal diverticulum (3%)
- Bladder Diverticulum
- Can be detected on prenatal ultrasound, but the gold standard remains VCUG, which will reveal possible accompanying VUR.
- Caused by infravesical obstruction, iatrogenic after bladder surgery, or as a congenital defect. Independent from the cause, all diverticula develop as herniation of bladder mucosa between defects of bladder smooth muscle fibers. The neck of the resulting diverticulum depends on the size of the muscular defect
- Primary paraureteral diverticula are seen in smooth-walled bladders, occur isolated with no other diverticula, are intermittent in manifestation, happen in children with no infravesical obstruction, and are most likely caused by a congenitally deficient bladder wall
- Secondary paraureteral diverticula are acquired, found in trabeculated bladders as one of many diverticula in the bladder, are always present, and are caused by infravesical obstruction.
- Congenital diverticula are often found in children with generalized connective tissue diseases such as Ehlers-Danlos, Williams elfin-facies, or Menkes syndrome
- Paraureteral diverticula or diverticula located in the lower part of the bladder can become so large that they compress the bladder neck or posterior urethra. The resulting bladder outlet obstruction starts a vicious circle by continuously filling and expanding the diverticulum. This increases the obstructing and subsequently causes complete urinary retention
- Small, asymptomatic congenital diverticula detected during unrelated workups can be treated conservatively with regular observation.
- In acquired bladder diverticula, the infravesical obstruction has to be eliminated first. After bladder outlet resistance is normalized, the bladder can reshape and diverticulectomy might become unnecessary. If symptomatic, especially in conjunction with VUR, the diverticulum should be excised.
- Bladder Duplication
- Duplication of the bladder and urethra can be complete or incomplete
- Can occur in either the coronal or sagittal plane; complete duplication in the sagittal plane the most common
- Often associated with duplication anomalies of the external genitalia and lower GI tract
- Initial treatment is directed toward renal preservation and prevention of infections by relieving possibly obstructed genitourinary tracts.
- Long-term goals include achieving continence and reconstructing the internal and external genitalia.
Other Bladder Anomalies
- Nephrogenic Adenoma
- A rare benign tumor mostly found in adults.
- Sporadic case reports describe the lesion as a reaction to infection, lithiasis, or trauma or in response to surgery.
- Treatment consists of transurethral fulguration or resection and can be combined with long-term antibiotic prophylaxis. Although malignant transformation was not reported, tumor recurrence developed in 80% of the children
- Eosinophilic Cystitis
- Bladder Hemangioma
- Bladder Hernia
References
- Wein AJ, Kavoussi LR, Partin AW, Peters CA (eds): CAMPBELL-WALSH UROLOGY, ed 11. Philadelphia, Elsevier, 2015, vol 4, chap 138
