Study Proposal

IS “EXTRINSIC” PELVIURETERIC JUNCTION OBSTRUCTION ASSOCIATED WITH AN “INTRINSIC” DEFECT?

 Milan Gopal on behalf of Young Pediatric Urology Group

Back round:

The cause of PUJ obstruction in children can be intrinsic or extrinsic. Crossing lower polar vessels constitute the most common extrinsic cause. Dismembered pyeloplasty is the treatment of choice for intrinsic PUJ obstruction. The vascular hitch has been proposed as an effective method for the relief of obstruction at the PUJ caused by lower polar crossing vessels. Despite long term follow up of children who had a vascular hitch showing sustained good results 1, there is reluctance in the paediatric urology community to accept that extrinsic PUJ obstruction is not associated with an accompanying intrinsic defect necessitating a dismembered pyeloplasty.

The suitability for a vascular hitch is determined based on the preoperative history and imaging, intra operative visual inspection of the PUJ after elevation of the vessels, intraoperative response to a diuretic challenge and even intra operative Whitaker tests. Pathological analysis of the PUJ has been variously reported as being similar or different with regards to fibrosis, muscular hypertrophy and interstitial cells of Cajal distribution between the two groups.2-9

Hypothesis:

Crossing lower polar vessels causing extrinsic PUJ obstruction is associated with an intrinsic defect.

Materials and Methods:

A prospective, multicentre trial of patients undergoing pyeloplasty for PUJ obstruction.  Data will be collected using a proforma.

Participating surgeons would do a dismembered pyeloplasty IRRESPECTIVE of whether crossing vessels were present or not. That is, they believe that the vascular hitch is NOT an appropriate procedure, as they believe that there is often an intrinsic abnormality. Currently the majority of paediatric urologists subscribe to this view.

The history and preoperative imaging will be collated. Intra operatively, the operating surgeon will give a visual assessment after elevation of the vessels +/- diuretic test of whether he/she thinks the PUJ is now open. They will then go on to perform a dismembered pyeloplasty and send the specimen for histopathological analysis.

The pathologist will be blinded to the intra operative findings. They will assess the width at the PUJ and then comment on histological abnormalities like extent of fibrosis, muscular hypertrophy and distribution of interstitial cells of Cajal.

Primary outcomes:

  1. Is extrinsic obstruction associated with an intrinsic abnormality ?
  1. Is there a histological difference between surgeon perceived intrinsic and extrinsic PUJ obstruction

Secondary outcomes:

  1. Can preoperative history and imaging (in the absence of angiography) predict the presence of crossing vessels ?
  1. What proportion of PUJ with crossing vessels may have been suitable for a vascular hitch based on visual inspection and intra operative manoeuvres like a diuretic test after elevation of the vessels?

PROFORMA

 

References

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