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Prune Belly Syndrome

Eagle-Barret Syndrome

Prune belly syndrome is a rare congenital disorder characterized by anomalies of the urinary tract, deficiency of the abdominal wall musculature, and bilateral cryptorchidism. It may also feature the involvement of other organ systems as well.


Presentation

The clinical picture in children with PBS varies and can include a wide spectrum of complications [7]. Common features include urinary obstruction, vesicoureteral reflux, urethral malformations, and other urogenital abnormalities [5] [8]. As a result, children with PBS may be susceptible to urinary infections.

Additionally, there are consequences that stem from the weak abdominal musculature. For example, these patients have difficulty with increased lung secretions due to their poor cough mechanism. Additionally, they develop constipation since they struggle with performing the Valsalva maneuver.

Physical exam

When inspecting the abdomen, there are remarkable findings. A prominent feature of the abdomen is its wrinkled image and hence its resemblance to a prune since there is an absence of abdominal muscle. It also appears great in size and is lax. Furthermore, the intestinal loops are transparent through the thin wall. Patients may have transverse skin folds and a midline crease the spans the navel to the pubic region. The navel can consist of a vertical slit.

A majority of individuals with PBS will have a horizontal depression under the lower border of the chest, a finding known as Harrison groove. The overall chest appears deformed in many patients.

Pediatric Disorder
  • Initial management of complex pediatric disorders: prune belly syndrome, posterior urethral valves. Urol Clin North Am. 2004;31:399-415. Summaria V, Minordi LM, Canade A, et al. Megaureter and ureteral valves. Rays. 2002;27:89-91. Cromie WJ.[rarediseases.org]
Wound Infection
  • There was one postoperative complication in the form of wound infection. All patients are catheterizing their stomas and are continent at an average follow-up of 14.7 months (range 5-21 months).[ncbi.nlm.nih.gov]
Abdominal Pain
  • An 18 year old male with a history of prune belly syndrome (PBS) presented with acute abdominal pain and palpable left upper quadrant mass.[ncbi.nlm.nih.gov]
Wrinkled Abdominal Skin
  • Examination showed wrinkled abdominal skin, bilateral undescended testes and an hypoplastic rectus abdominis, below the umbilicus. Further evaluation revealed enlarged bladder, bilateral megaureters and right intra-abdominal testis.[ncbi.nlm.nih.gov]
Wrinkled Abdominal Skin
  • Examination showed wrinkled abdominal skin, bilateral undescended testes and an hypoplastic rectus abdominis, below the umbilicus. Further evaluation revealed enlarged bladder, bilateral megaureters and right intra-abdominal testis.[ncbi.nlm.nih.gov]
Myopathy
  • […] afibrinogenemia 失認 agnosia 遺伝性エナメル質形成不全症 amelogenesis imperfecta 無脳症 anencephaly 無虹彩症 aniridia 無精巣症 Anorchia アンチトロンビンIII欠乏症 antithrombin III deficiency アントレー・ビクスラー症候群 Antley-Bixler syndrome 再生不良性貧血 aplastic anemia 関節拘縮症 arthrogryposis ベスレムミオパチー Bethlem myopathy[lsd-project.jp]
Oliguria
  • In addition, the risk of torsion must be at the forefront of the differential diagnosis in a prune-belly renal transplant patient with acute onset of oliguria.[ncbi.nlm.nih.gov]
  • His urine output only possible with catheter, otherwise oliguria, urinary retention and glob vesicale occurs. Urinary ultrasonography showed enlargement of bladder and mild hydroureteronephrosis in left renal pelvis.[alliedacademies.org]
Polyuria
  • Lower urinary tract reconstruction was performed in most children (95.6%); on late follow-up, continence was observed in 81% of them, while incontinence was present in 19% and usually associated with polyuria.[ncbi.nlm.nih.gov]
Cervical Incompetence
  • This outcome followed preterm rupture of membranes and possible cervical incompetence.[ncbi.nlm.nih.gov]

Workup

In the developed world in which women have access to adequate prenatal care, a majority of cases with PBS are detected through obstetric ultrasonography followed by a confirmation at birth [9] [10]. The newborn suspected to have PBS should undergo a thorough evaluation that consists of the antenatal and family history, a physical exam, and key studies.

Laboratory tests

Since renal obstruction is very common in patients with PBS, there are numerous tests that should be obtained such as the serum concentrations of sodium, potassium, chloride, glucose, blood urea nitrogen (BUN), and carbon dioxide, which are collectively known as the SMA-6. Creatinine is also important since it reveals information about the renal function. Furthermore, urinary output and electrolytes are pertinent. Note that findings such as the elevation in creatinine and BUN accompanied by a low urine output are suggestive of obstruction.

Imaging

The medical team should perform the following imaging techniques to ascertain the specific details about the location and number of abnormalities as well as the degree of their involvement.

Ultrasonography of the kidney and bladder should be the initial diagnostic technique in the neonatal period. This can also be performed periodically to track the progress of the patient.

Kidney, ureter, and bladder (KUB) radiography is warranted in neonates. The findings are notable for bowels appearing on the lateral border of the abdominal wall. Additionally, this imaging tool is paramount for surgical planning.

The intravenous pyelogram (IVP) is crucial in the visualization of the genitourinary tract anomalies. Additionally, voiding cystourethrography (VCUG) to evaluate the flow of urine through the tract.

Liver Biopsy
  • Among the former group, atherosclerosis, arthritis, and collagen vascular disease are the most common, whereas liver biopsy or other radiologic interventions (ie, percutaneous abscess drainage) are frequent iatrogenic causes.[ncbi.nlm.nih.gov]

Treatment

The management of PBS is tailored towards the manifestations and their severity.

Urogenital tract abnormalities can be managed through various surgical procedures. For example, urinary retention can be managed with a vesicostomy, which facilitates the elimination of urine. Some cases will benefit from a cystoplasty.

Children with vesicoureteral reflux require prophylactic antibiotics. Those with recurrent infections warrant surgical repair.

Cryptorchidism is managed by a pediatric urologist and can be repaired through an orchidopexy.

Abdominal muscle can be reconstructed in order to improve the respiratory function and cosmetic appearance.

Prenatal intervention

Obstetric cases with a PBS fetus are managed by perinatology specialists. They frequently employ fetal ultrasonography as a mode to monitor the renal function and the volume of the amniotic fluid. Intervention in the prenatal period is crucial in order to preserve the patient's renal function [11]. Procedures such as vesicoamniotic shunting may be an option [12] to help prevent lung hypoplasia and kidney dysplasia. In fact, this may improve the prognosis in the neonate. In certain cases, the perinatologist may recommend early delivery depending on factors such as the severity of renal impairment and neonatal viability .

Other

Special consults will be required for patients with orthopedic, cardiac, and/or gastrointestinal sequelae.

Prognosis

PBS has a mortality rate of 20%. Stillbirths and neonatal deaths are common in this condition. The poor prognosis and fatal outcomes are attributed to lung hypoplasia, kidney failure, and/or the cumulative effects of the congenital diseases present.

The survivors are affected with cryptorchidism, a defective abdominal wall, and various renal anomalies but may have milder clinical manifestations overall.

Etiology

The cause of PBS has not been fully established. It has been suggested though that there is a genetic role in the development of this condition. There are three hypotheses that may explain the etiology.

Some researchers propose that a defect in the developing bladder causes urine to accumulate in the organ, leading to the distension of the bladder, ureters, and kidneys. Consequently, the other features of the triad, abdominal muscle atrophy, and cryptorchidism, may stem from the obstructive effects of the enlarged bladder. Note that obstruction in the urinary tract may be resolved by the time of birth.

Another theory postulates that the abnormal development of abdominal muscles is the etiology of this disorder.

Finally, the third possibility speculates that the urinary and muscular manifestations arise from a common cause that has yet to be identified. Moreover, the abdominal muscle abnormality may have actually developed from a defective nervous system.

Epidemiology

The incidence of PBS is approximately 1 in 30,000 live births [1]. It has a strong gender preference as 96% patients are males [2] [3]. Additionally, there is an association with twinning, in which 4% of patients result from twin pregnancies.

Sex distribution
Age distribution

Pathophysiology

In addition to the clinical triad of PBS, this congenital disorder encompasses a broad range of anatomic defects with various degrees of severity. These manifestations include involvement of the respiratory, cardiovascular, gastrointestinal, skeletal [4]. and central nervous systems.

Genitourinary and pulmonary

Numerous structures may be affected including the kidneys, ureters, and urethra. Findings can include hydronephrosis, hydroureter, and vesicoureteral reflux [5]. The latter may predispose the children to urinary tract infections.

A main complication of PBS is the underdevelopment of the lung.

Musculoskeletal

Musculoskeletal deformities such as hip dysplasia, absent limbs, and clubbed feet are common [5].

Gastrointestinal

Manifestations affecting this system include various malformations such as esophageal atresia, esophageal stenosis, rectal stenosis, and volvulus colon [5].

Other

There is a possible association between PBS and an assortment of disorders such as trisomy 18 and 21 [2] [6]., as well as the tetralogy of Fallot and ventriculoseptal defects.

Prenatal findings

The failure to eliminate urine from the bladder results in oligohydramnios, pulmonary hypoplasia [2]. and Potter's facies.

Prevention

While PBS cannot be prevented since the defects occur during fetal development, early identification through a prenatal ultrasound can lead to appropriate intervention and the possible avoidance of complications such as renal failure and pulmonary hypoplasia. Increasing detection of PBS and other congenital disorders can be achieved by extending the use of ultrasonography to developing regions.

Summary

Prune belly syndrome (PBS) is a rare disorder typified by the clinical triad of urinary tract malformations, abdominal muscle deficiency, and bilateral cryptorchidism (in males). Although the etiology is not fully understood, there are several possibilities regarding the development of this congenital condition.

The clinical presentation varies and may include a broad range of sequelae with different levels of severity. In addition to the typical features of PBS, patients may also have pulmonary, cardiac, musculoskeletal, and/or gastrointestinal conditions. With regards to patient demographics, PBS has a predilection for males.

PBS can be identified through prenatal ultrasonography but is confirmed during the neonatal period through a clinical assessment comprised of a physical exam, laboratory tests, and imaging modalities. The latter includes ultrasonography, radiography, and other techniques to evaluate the degree of involvement of the urogenital tract.

The therapeutic approach in these children is dependent on the clinical picture. Patients may require surgical repair of pathologies such as urinary retention, urinary obstruction, cryptorchidism, abdominal muscle defect, etc.

The poor prognosis in fetuses and neonates is associated with serious complications. Therefore, early recognition and prompt intervention may lead to a better prognosis. In patients with milder manifestations, timely treatment and management can improve the outcomes.

Patient Information

What is Prune Belly Syndrome?

Prune belly syndrome (PBS) is a disorder consisting of three birth defects:

  • Urinary tract abnormalities
  • Absence (partial or complete) of abdominal muscles
  • Undescended testes in males

The developing fetus likely has a urinary tract defect that causes the abdomen to collect fluid and become swollen. This fluid eventually disappears by birth but causes the appearance of a prune-like belly.

The majority of all affected individuals are males.

What causes this condition?

The exact cause of PBS is not known.

What are signs and symptoms of PBS?

In addition to the three main features discussed above, there is a wide range of complications that may occur in these patients:

The following signs are typical features seen on the newborn exam:

  • Wrinkled belly that resembles a prune
  • Large and lax abdomen
  • Intestinal loops are visible through the skin
  • Skin folds that span across the abdomen
  • Crease that spans from the navel to the pubic area
  • Caving of the chest
  • Overall deformed looking chest

How is it diagnosed?

Diagnosis can be made while the baby is still in the womb during a prenatal ultrasound. It is then confirmed after birth when the clinician examines the newborn and performs key studies such as ultrasound, x-ray, and intravenous pyelogram. These imaging techniques can help the medical team determine the extent of defects in the baby's urogenital tract. Also, there are laboratory tests to assess the function of the kidneys.

How is it treated?

It is important to diagnose this disorder early in order to prevent serious medical issues. The treatment depends on what abnormalities the patient has and how severe they are.

Some patients will need surgery to help relieve the bladder or repair the ureters or bladder.

A pediatric urologist will evaluate the patients and likely repair the undescended testes with a procedure called orchiopexy.

The abdominal muscles can be surgically reconstructed.

What is the prognosis?

The prognosis may depend on how soon the condition is diagnosed and treated. Intervention may need to begin while the baby is still in the womb. Additionally, the baby may need to be delivered before the due date (if the baby has reached a viable gestational age).

In unborn babies and newborns with severe complications, stillbirths and newborn deaths are likely to occur.

References

Article

  1. Baird PA, MacDonald EC. An epidemiologic study of congenital malformations of the anterior abdominal wall in more than half a million consecutive live births. Am J Hum Genet. 1981;33(3):470-8.
  2. Tagore KR, Ramineni AK, Vijaya Lakshmi AR, et al. Prune Belly syndrome. Case Reports in Pediatrics. 2011;1-3.
  3. Routh JC, Huang L, Retik AB, et al. Contemporary epidemiology and characterization of newborn males with prune belly syndrome. Urology. 2010;76(1):44-8.
  4. Hassett S, Smith GH, Holland AJ. Prune belly syndrome. Pediatric Surgery International. 2012;28(3):219-28.
  5. Duckett JW, Snow BW. Prune-Belly-Syndrom. In: Hohenfellner R, Thüroff JW, Schulte-Wissermann H, editors. Kinderurologie in Klinik und Praxis. Stuttgart: 1986. pp. 348–65.
  6. Ramasamy R, Haviland M, Woodard JR, et al. Patterns of inheritance in familial prune belly syndrome. Urology. 2005;65(6):1227.
  7. Tonni G, Ida V, Alessandro V, et al. Prune-belly syndrome: case series and review of the literature regarding early prenatal diagnosis, epidemiology, genetic factors, treatment, and prognosis. Fetal Pediatric Pathology. 2013;31(1):13-24.
  8. Zugor V, Schott GE, Labanaris AP. The Prune Belly syndrome: urological aspects and long-term outcomes of a rare disease. Pediatric Reports. 2012;4(2):e20.
  9. Osborne NG, Bonilla-Musoles F, Machado LE, et al. Fetal megacystis: differential diagnosis. Journal of Ultrasound in Medicine. 2011;30(6):833-41.
  10. Yamamoto H, Nishikawa S, Hayashi T, et al. Antenatal diagnosis of prune belly syndrome at 11 weeks of gestation. Journal of Obstetrics and Gynaecology Research. 2001;27(1):37-40.
  11. Yiee J, Wilcox D. Abnormalities of the fetal bladder. Semin Fetal Neonatal Med. 2008;13(3):164-70.
  12. Leeners B, Sauer I, Schefels J, et al. Prune-belly syndrome: therapeutic options including in utero placement of a vesicoamniotic shunt. Journal of Clinical Ultrasound. 2000;28(9):500-7.

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Last updated: 2019-07-11 21:06