UNIVERSITY HOSPITALS OF COVENTRY & WARWICKSHIRE NHS TRUST
NEONATAL UNIT – WALSGRAVE HOSPITAL
GUIDELINES FOR THE INVESTIGATION
AND MANAGEMENT OF
ANTENATAL RENAL PELVIS DILATATION
CLINICAL GUIDELINE REPORT
This guideline has been developed to ensure appropriate, effective and efficient investigation
and management of the infant and his/her parents with renal pelvis dilatation has been
diagnosed antenatally by an Obstetrician or Obstetric Ultrasonographer.
It replaces the Paediatric Departmental Guideline of April 1995 written by Dr N Coad.
The significant additions to the 1995 Guideline are the inclusion of a locally adapted
algorithm, a parent information leaflet, a standard GP letter and current references with
grading of evidence.
The impetus for the development of this guideline was professional concern and the findings
of a retrospective audit of local management of renal pelvis dilatation from April 1997 to
March 1998 by Drs V Ganesan, N Coad and T Goodfellow with the support of the Clinical
Audit Department.
The above Audit was presented at the Coventry and Warwickshire Paediatric Consortium
Audit Meeting in March 1999. The main findings were:1. 40% of babies with antenatally detected renal pelvis dilatation did not have a postnatal
renal and bladder ultrasound scan at 4 to 6 weeks of age.
2. 40% of babies with antenatally detected renal pelvis dilatation did not have a micturating
cystourethrogram.
3. All babies with antenatal RPD had an early (first week) renal and bladder ultrasound
scan.
4. 30% of those investigated with MCU had vesico-ureteric reflux (4 of 14) – grade of VUR
not known.
5. The Department guideline for investigation and management of RPD was followed in only
about 60% of the babies whose case notes were reviewed.
6. It was agreed that a Parent Information Leaflet might empower and encourage parents
thereby ensuring that the appropriate postnatal investigations are performed.
7. It was felt that a Standard RPD Discharge letter to the GP might improve communication
and the continuing prescription of prophylactic antibiotics as appropriate.
Anomalies are reported in around 2 to 3% of routine antenatal ultrasound scans and about
one third of these are due to abnormalities of the renal tract. 1
The presence of hydronephrosis at any stage of gestation is generally the first indicator of a
potential urinary tract anomaly. There is, however, no agreed definition of ‘significant’
antenatal hydronephrosis that warrants further investigation and little consensus on
appropriate management. Significance probably varies depending on the gestation of the
fetus at the time of ultrasound examination.
Detailed antenatal ultrasonography performed on 18,766 pregnant women between 1980 and
1994 in Bristol detected antenatal hydronephrosis, defined as renal pelvis diameter greater
than 5 mm in 100 cases (0.59%). 2 64 infants had postnatal hydronephrosis at 1 and/or 6
weeks after delivery; 21 of these had urological anomalies. 12 infants had vesico-ureteric
reflux and in all refluxing units the renal pelvis diameter was less than 10 mm. 3 patients had
pelvi-ureteric junction obstruction and all required surgery. In this and other studies, vesicoureteric reflux is the most common urological finding in infants with antenatal hydronephrosis
and is likely to be missed if kidneys with renal pelvis diameter of 5 to 10 mm are not further
investigated. 3 Renal pelvis dilatation was less than 10 mm in all cases of reflux. The
frequency of VUR in infants with mild hydronephrosis in a number of studies is reported to be
around 20%. 4
In a prospective study of outcome in antenatally diagnosed renal pelvis dilatation amongst
7000 deliveries where the 20 week anomaly scan showed that one or both renal pelves was 5
mm or greater, 139 mothers were enrolled and postnatal investigations were completed in
104 babies. 21 failed to attend or had incomplete investigations, 7 moved out of the area and
were lost to follow up, 5 cases the parents elected not to follow the investigation protocol and
2 were excluded (1 termination and 1 stillbirth). Vesico-ureteric reflux was the most common
pathology (23 of 104 or 22%). There was no correlation between the degree of either
antenatal or postnatal renal pelvis dilatation and the severity of VUR. The postnatal
ultrasound was normal in 14/23 (61%) of infants who had VUR. There was a greater uptake of
postnatal investigations in those parents who had attended for antenatal counselling. 5
The importance of parental information and counselling has been demonstrated in several
studies 5, 6 and this is not straightforward because of our limited understanding of the natural
history of many of the anomalies found and the significant number of false positive results.
ALGORITHM FOR INVESTIGATION AND MANAGEMENT (see figure)
Renal pelvis dilatation detected on antenatal ultrasonography should be quantified and
recorded in the maternal notes at the relevant gestational age. The Obstetrician or
Ultrasonographer should explain the findings to the parents and give them a Parent
Information Leaflet. Antenatal counselling will usually be with the Obstetrician/Midwife but in
cases of gross renal tract abnormality may also include the Paediatrician and Paediatric
Surgeon.
A Neonatal Alert Form should be completed and processed as previously agreed.
Following clinical examination in the first 24 hours, the baby should be started on prophylactic
Trimethoprim at a dose of 2 mg/kg once daily and the parents should be advised that this
should continue until all the postnatal investigations have been completed and the baby has
been reviewed in the out patient clinic with the results of the ultrasound scan and micturating
cystourethrogram.
Most abnormalities are unilateral and therefore the risk to overall renal function is small.
With severe bilateral abnormalities, or in a male baby with bladder wall thickening, the initial
postnatal ultrasound scan must be done before discharge home because of the possibility of
posterior urethral valves, where assessment is more urgent.
In less urgent cases, the initial ultrasound scan should be done within the first 7 days – this is
arranged by discussion with either Dr Goodfellow or Dr Duncan, Consultant Radiologists. The
baby can be discharged home and come back for the scan.
At discharge, the Paediatric SHO must ensure that a request form is sent to the X-ray
Department for a further ultrasound scan and a micturating cystourethrogram in 4 – 6 weeks
hence, and must also arrange an out patient clinic appointment for 6 – 8 weeks with the
involved/on service Neonatal Consultant (Dr Ahmad, Blake or Coe). Some parents will have
already met Dr Coad antenatally and in those cases, follow up should be in his Renal Clinic.
If the initial postnatal ultrasound scan suggests obstruction, this should be discussed with the
Neonatal Paediatrician – a MAG 3 isotope scan should be requested.
If the initial postnatal ultrasound scan shows abnormally sized or multicystic kidneys – a
DMSA isotope scan should be requested to assess relative renal function.
PARENT INFORMATION LEAFLET AND STANDARD GP LETTER
As outlined above the Parent Information leaflet should be given to the parent(s) at the time of
antenatal diagnosis. The postnatal wards also keep a supply of these leaflets for parents who
do not have one.
The standard Renal Tract Anomaly GP letter should be completed and posted to the GP.
DISSEMINATION OF THE CLINICAL GUIDELINES
1. Guidelines to be presented at Coventry and Warwickshire Paediatric Consortium Audit
Meeting for discussion on 15.09.99.
2. Copy of Guidelines to be laminated and inserted in Protocol folder on NICU.
3. Neonatal SHOs and SpRs to be sent copy of guidelines.
4. Directorate Clinical Governance Group to be notified of guideline.
5. Guideline to be discussed with Obstetricians and Ultrasonographers.
6. Postnatal Ward Midwives to be informed of guidelines – copy to each postnatal ward.
7. Dr Goodfellow to be sent copy of guidelines.
8. Neonatal Nurses to be informed re guidelines.
9. Guideline could be used with local adaptations in Nuneaton and Warwick.
10. Copy to Paediatric Nursing Consortium.
11. Copy to PCG Clinical Governance Group.
12. Department of Clinical Audit to advise re any other groups to whom guidelines relevant.
LEVEL OF EVIDENCE
Grade III (AHCPR 1992)
REFERENCES:
1.
2.
3.
4.
5.
6.
Chitty LS, Hunt GH, Moore J, Lobb MO. Effectiveness of routine ultrasonography in detecting fetal structural
abnormalities in a low risk population. BMJ 1991; 303: 1165-9
Dudley JA, Haworth JM, McGraw ME, Frank JD, Tizard EJ. Clinical relevance and implications of antenatal
hydronephrosis. Arch Dis Child 1997;76: F31-4.
Marra G, Barbieri G, Moioli C, Assael BM, Caccamo ML. Mild fetal hydronephrosis indicating vesico-ureteric
reflux. Arch Dis Child 1994; 70: F147-150.
Jaswon MS, Dibble L, Puri S, Davis J, Young J, Dave R, Morgan H. Prospective study of outcome in
antenatally diagnosed renal pelvis dilatation. Arch Dis Child 1999; 80:F135-138.
Watson AR, Readett D, Nelson CS, Kapila L, Mayell MJ. Dilemmas associated with antenatally detected urinary
tract abnormalities. Arch Dis Child 1988;63:719-22.
Owen RJT, Lamont AC, Brookes J. Early management and postnatal investigation of prenatally diagnosed
hydronephrosis. Clin Radiol 1996;52:173-6.
09/99
Revised Date 11/04