Fetal vesico-amniotic shunt for lower urinary tract outflow obstruction (interventional procedures consultation)
NATIONAL INSTITUTE FOR HEALTH AND CLINICAL EXCELLENCE
Interventional Procedure Consultation Document
Fetal vesico-amniotic shunt for lower urinary tract outflow obstruction
Fetal lower urinary tract outflow obstruction prevents the unborn baby from passing urine. This can result in a reduction in the volume of amniotic fluid, and problems with the development of the baby's lungs and kidneys. A vesico-amniotic shunt is a tube that it is inserted into the unborn baby's bladder to drain the excess fluid into the surrounding space.
The National Institute for Health and Clinical Excellence is examining fetal vesico-amniotic shunts and will publish guidance on its safety and efficacy to the NHS in England, Wales and Scotland. The Institute's Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisors, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about fetal vesico-amniotic shunt for lower urinary tract outflow obstruction.
Note that this document is not the Institute's formal guidance on this procedure. The recommendations are provisional and may change after consultation.
The process that the Institute will follow after the consultation period ends is as follows.
For further details, see the Interventional Procedures Programme manual, which is available from the Institute's website (www.nice.org.uk/ipprogrammemanual).
Closing date for comments: 25 July 2006
Note that this document is not the Institute's guidance on this procedure. The recommendations are provisional and may change after consultation.
Current evidence on the safety and efficacy of fetal vesico-amniotic shunt for lower urinary tract outflow obstruction does not appear adequate for this procedure to be used without special arrangements for consent and for audit or research.
Clinicians wishing to undertake insertion of a fetal vesico-amniotic shunt for lower urinary tract outflow obstruction should take the following actions.
|1.3||This procedure should only be performed in centres specialising in invasive fetal medicine and in the context of a multidisciplinary team, which may include a consultant in fetal medicine, a paediatric urologist, a neonatologist and a specialist midwife.|
|1.4||Publication of safety and efficacy outcomes will be useful. A randomised trial (PLUTO) comparing fetal vesico-amniotic shunt with no treatment is in progress. There is also a registry linked to the trial. Clinicians are encouraged to enter patients into this trial or into the registry [http://www.pluto.bham.ac.uk/ and https://www.trials.bham.ac.uk/PLUTO]. The Institute may review the procedure upon publication of further evidence.|
|2.1.1||Fetal lower urinary tract outflow obstruction may be associated with various developmental abnormalities. Lower urinary tract outflow obstruction may develop in a fetus from a number of pathologies, including urethral atresia and posterior urethral valves, and can be partial or complete. Severe obstruction may lead to oligohydramnios (that is, a reduction in amniotic fluid volume) and abnormal development of the lungs and kidneys (pulmonary and renal dysplasia). Pulmonary and renal dysplasia may cause death soon after birth from respiratory or renal failure, respectively, or the baby may require ventilatory support, renal dialysis or kidney transplantation. The long-term prognosis for children who require dialysis or transplantation in infancy is poor.|
|2.1.2||There is uncertainty about the criteria for appropriate selection of fetuses for treatment by vesico-amniotic shunting.|
|2.1.3||Fetal lower urinary tract outflow obstruction is usually managed expectantly or by repeat vesicocentesis. Termination of pregnancy may be advised.|
|2.2||Outline of the procedure|
|2.2.1||The aim of a fetal vescico-amniotic shunt for lower urinary tract outflow obstruction is to decompress the obstructed bladder and restore amniotic fluid dynamics and volume, thereby preventing oligohydramnios and consequent pulmonary and renal dysplasia. Fetal blood is also sampled for chromosomal analysis to help diagnose or exclude concomitant chromosomal abnormalities that may influence management decisions or treatment choices.|
The procedure is performed under maternal local anesthesia and ultrasound guidance. A cannula on a trochar is inserted through the mother's abdominal and uterine walls into the amniotic cavity and subsequently into the bladder of the fetus. A catheter is inserted through the cannula and positioned with one end in the bladder and the other in the amniotic cavity. The cannula is then removed and the final position of the catheter confirmed by ultrasound. If the fluid re-accumulates or the catheter is dislodged, the procedure can be repeated.
A meta-analysis of three controlled trials that compared outcomes following vesico-amniotic shunting with no treatment found that vesico-amniotic shunting was associated with a statistically significant improvement in perinatal survival, with an odds ratio (OR) of 2.53 (95% confidence intervals [CI] 1.08 to 5.93, p = 0.03). Postnatal survival was also better in the vesico-amniotic shunting group, but the results were not statistically significant (OR 2.24, 95% CI 0.89 to 5.59, p = 0.09). In four case series, survival into infancy ranged from 40% (2/5) to 91% (21/23).
|2.3.2||In three of the case series, with a maximum of 5.5 years' follow-up, between 25% (2/8) and 33% (2/6 and 6/18) of children required dialysis or underwent renal transplantation. A case series study reported renal function as acceptable in 44% (8/18) of infants followed up for a mean period of 5.8 years. Another case series reported good renal function in 75% (6/8) of infants at 1 year's follow-up. One case series reported asthma in 39% (7/18), recurrent pulmonary infections in 28% (5/18) and bladder dysfunction requiring catheterisation in 17% (3/18).|
|2.3.3||In a case series of 18 children, the mean child self-reported quality-of-life score was 84.19 points at 5.8 years' follow-up, which compared well with a score of 83.0 points in a control healthy child population and 77.19 points in chronically ill children in another study. For more details, refer to the sources of evidence (see appendix).|
The Specialist Advisors considered vesico-amniotic shunting to be an established procedure but acknowledged that there were limited data to assess efficacy. They stated that there is uncertainty about selection criteria and about whether the procedure improves outcomes.
|2.4.1||The evidence on safety came from five case series. The most frequent prenatal complication was shunt displacement, which occurred in 22% (2/9), 28% (5/18) and 60% (9/15) of fetuses and often required insertion of a replacement shunt. A single case out of 18 procedures (6%) of premature rupture of the amniotic membranes 4 days after placement of a shunt was reported in one case series.|
|2.4.2||Postnatal complications included one report of bladder prolapse at birth and one report of requirement for intermittent catheterisation. For more details, refer to the sources of evidence (see appendix).|
|2.4.3||The Specialist Advisors stated that the main potential adverse events for the fetus include preterm labour or spontaneous abortion, shunt blockage or displacement, fetal trauma, fetal hydrops and urinary ascites. Potential complications for the mother include trauma to the maternal organs and infection.|
|3.1||This guidance requires that clinicians undertaking the procedure make special arrangements for audit. The Institute has identified relevant audit criteria and is developing an audit tool (which is for use at local discretion), which will be available when the guidance is published.|
Chairman, Interventional Procedures Advisory Committee
|Appendix:||Sources of evidence|
The following document, which summarises the evidence, was considered by the Interventional Procedures Advisory Committee when making its provisional recommendations.
Available from: www.nice.org.uk/ip332overview
This page was last updated: 08 February 2011