Also known an Eagle-Barrett syndrome.
1 in 40 000.
95 % male, < 5 % female.
Most cases sporadic with a normal karyotype, but there is a familial genetic disposition.
There is no unifying embryological basis or theory to explain Prune Belly syndrome – theories include:
- Early in utero posterior urethral obstruction -> hydro, oligohydramnios
- Primary defect in lateral plate mesoderm (precursor of ureters, bladder, gubernaculum, prostate)
- Intrinsic defect of urinary tract
- Yolk sac defect
Clinical features
Classic triad
- Bilateral undescended testes
- Absence or defect of anterior abdominal wall musculature
- Variable functional and anatomical urinary tract anomalies
Undescended testes:
- Usually well intra-abdominal, lying at the level of the common iliacs adjacent to dilated ureters
- No spontaneous fertility has been achieved – a few cases of paternity with ART/ICSI – likely not just due to testis histology, but problems with spermatic ducts and retrograde ejaculation
Absent abdominal wall musculature:
- Wrinkled, redundant skin at birth that may bulge to the flanks
- Inferior and medial segments most often affected
- Variability in severity of defect and muscle tone as patients get older
- No correlation between severity of abdominal defect and severity of urinary tract
Urinary tract anomalies:
- 50 % of kidneys have a degree of dysplasia
- Typically dilated, redundant, tortuous but non obstructed ureters
- Distal ureters generally worse than proximal
- VUR in 75 %
- Patent urachus in 25 – 30 %
- Thick-walled but smooth bladder, generally with large capacity
- Wide bladder neck opening into a dilated prostatic urethra, with prostatic hypoplasia
- Sometimes vas deferens and SV atresia or obstruction
- Anterior urethra often normal, sometimes urethral atresia (lethal if no patent urachus) or megalourethra
Other issues:
- Half are born premature
- Congenital heart defects up to 10 % – Tetralogy of Fallot, VSD etc
- Pulmonary hypoplasia secondary to oligohydramnios
- Respiratory insufficiency due to inability to generate abdominal pressure
- 30 % GI abnormalities
- Orthopaedic abnormalities common – talipes, hip dysplasia, scoliosis
Presentation and classification
Usually detected on antenatal scans now with upper tract dilation, large bladder and irregular abdominal wall circumference.
Otherwise presents usually with characteristic abdominal wall at birth.
Category 1 – severe oligohydramnios, subsequent pulmonary hypoplasia, usually lethal
Category 2 – full spectrum and triad, may have moderate or unilateral renal insufficiency
Category 3 – mild features or incomplete triad, may have HUN but normal renal function
Management
Initial period:
- Multidisciplinary management with neonatology, nephrology, other specialties as needed – heart and lungs take precedence usually
- Monitoring of creatinine early
- Early ultrasound – assessing parenchymal thickness and degree of dilation
- Prevent UTIs – consider antibiotic prophylaxis, circumcision
- Early MCUG with AB prophylaxis, esp with renal impairment, to exclude outlet obstruction and look for reflux
Category 1 cases need no specific urologic management besides catheter drainage – usually lethal.
Category 3 cases usually don’t need early urologic intervention as they have preserved renal function.
- Will require orchidopexy during first year of life, and some may require VUR intervention or abdominoplasty depending on symptoms.
- Should still be monitored via renal function and ultrasounds through childhood.
Category 2 cases need bespoke management depending on specific conditions and severities.
- Consider early DMSA or MAG3 to clarify renal function and exclude obstruction
- Controversial re: early urinary tract reconstruction (from 3 months) vs observation and surgery if proven obstruction and recurrent infections
- Spontaneous resolution as ureters lengthen etc can occur, and some patients escape need for reconstruction – conversely a proportion of patients end in renal failure
Surgical management
Orchidopexy
- Transabdominal at about 6 months or two-stage Fowler-Stephens
Circumcision
- To reduce UTI frequency – at time of another procedure is appropriate
Urinary diversion
- Typically cutaneous vesicostomy – in very unwell babies and infants with severe upper tract infections/obstruction/reflux – +/- excision of urachal diverticulum
Upper tract reconstruction
- Ureteroplasty and reimplantation – indicated in persistent upper tract infection or progressive dilation and reflux
Lower tract reconstruction
- Reduction cystoplasty – usually excising urachal diverticulum – not very effective / large capacity bladder tends to recur
- Urethral reconstruction for megalourethra
Abdominoplasty
- Definite cosmetic benefits – functional benefits debateable – bespoke timing, can be done in conjunction with urinary tract reconstruction
Long term:
May have long term survival with minimal impairment
Renal function – baseline nadir in infancy is useful predictor – up to 30 % overall develop renal failure
Bladder – typically large volume with high post void residuals but normal compliance – should have timed voiding +/- double voiding and Crede from childhood
Normal growth expected with normal renal function, but some consequences of lack of abdominal muscles develop – e.g. orthopaedic issues
Normal secondary sexual characteristics – but fertility seems impaired with only ART ever being successful