Prospective study of outcome in antenatally diagnosed renal pelvis by MikeJenny

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									Arch Dis Child Fetal Neonatal Ed 1999;80:F135–F138                                                                                         F135



                           Prospective study of outcome in antenatally
                           diagnosed renal pelvis dilatation
                           Mervyn S Jaswon, Laraine Dibble, Sheila Puri, Jacky Davis, Jane Young, Raj Dave,
                           Heulwen Morgan



                           Abstract                                                          viureteric junction (PUJ) obstruction, poste-
                           Aims—To ascertain the outcome associ-                             rior urethral valves, and multicystic kidneys.
                           ated with antenatal renal pelvis dilatation;                      Surgical uropathies feature highly, but this bias
                           to recommend guidelines for postnatal                             may be a reflection of the referral pattern of the
                           investigation and determine an upper                              tertiary paediatric urology units from which
                           limit of normal for the anterioposterior                          these studies come.3 4
                           dimensions of the fetal renal pelvis.                                Where there is an increase in the calibre of
                           Methods—Infants whose antenatal ultra-                            the renal pelvis at the site of the uretero-pelvic
                           sound scan showed a fetal renal pelvis of 5                       junction, but minimal or no dilatation of the
                           mm or greater were investigated using                             intrarenal collecting system (renal pelvis dilata-
                           postnatal renal tract ultrasound and a                            tion) outcome, is less well documented. An
                           micturating cystogram. Isotope studies                            association between antenatal renal pelvis dila-
                           were also performed, where appropriate.                           tation (ARPD) and vesicoureteric reflux
                           Results—Vesicoureteric reflux (VUR), the                           (VUR)5 is particularly important in view of the
                           most common diagnosis, was evident in                             association between VUR and the subsequent
                           23/104 (22%). In 14 infants with VUR the                          development of renal scars.
                           postnatal ultrasound scan was normal.                                However, the incidence of this association
                           There was no evidence of renal scarring or                        and the correct postnatal investigation of these
                           dysplasia in any of the refluxing kidneys.                         cases has not been fully established. Further-
                           Other diagnoses were pelviureteric junc-                          more, there is no consensus on the measure-
                           tion obstruction, renal dysplasia, and                            ments for a normal fetal renal pelvis. Conse-
                           idiopathic dilatation. Antenatal counsel-                         quently, the threshold for investigation diVers
                           ling and parental information facilitated                         among hospitals.
                           postnatal assessment.                                                We therefore conducted a prospective inves-
                           Conclusions—Infants with antenatal renal                          tigation in a district general hospital (with no
                           pelvis measurements of 5 mm or greater                            bias in its referral pattern). All babies were
                           should be investigated postnatally, as a                          enrolled whose routine antenatal scan showed
                           significant percentage will have VUR. A                            that the anterioposterior diameter of one or
                           normal postnatal ultrasound scan does not                         both renal pelves was 5 mm or above. The
                           preclude the presence of VUR.                                     babies were investigated postnatally to deter-
                           (Arch Dis Child Fetal Neonatal Ed 1999;80:F135–F138)              mine whether there was any significant abnor-
                                                                                             mality associated with the ARPD and to ascer-
                           Keywords: vesicoureteric reflux; antenatal renal pelvis            tain whether an upper limit of normal for the
                           dilatation; renal tract anomalies; prenatal diagnosis
                                                                                             fetal renal pelvis could be defined.

                           Anomalies are reported in around 2–3% of                          Methods
                           routine antenatal ultrasound scans1; about a                      The study was conducted over 26 months,
                           third of these are due to abnormalities of the                    during which time there were 7000 deliveries.
Department of              renal tract. Hydronephrosis detected antena-                      All infants whose 20 week anomaly scan
Paediatrics                tally was first reported in the early 1980s, since                 showed that one or both renal pelves was 5 mm
Whittington Hospital       when there have been many case reports and                        or greater (anterioposterior diameter) were
NHS Trust
Highgate Hill, London      studies describing the postnatal diagnosis asso-                  entered. Patients (<10%) who had only renal
N19 5NF                    ciated with these findings.2 In these studies                      pelvis dilatation (RPD) on subsequent scans,
M S Jaswon                 there has been a preponderance of cases of pel-                   which had been done for obstetric reasons,
L Dibble
S Puri
                                                                      Dilatation > 5 mm
Department of
Radiology
J Davis                                                                 USS and MCU
J Young
R Dave

Department of                   Both normal                            VUR                                   PN dilatation without VUR
Obstetrics and
Gynaecology
H Morgan
                                                                                                       >10 mm                     <10 mm
Correspondence to:            Stop prophylaxis                      DMSA
Dr Jaswon.                                                                                            MAG 3                     annual USS
                                 discharge                   continue prophylaxis              continue prophylaxis           stop prophylaxis
Accepted 11 September
1998                       Figure 1   Protocol for investigation of children with antenatal renal pelvis dilatation.
F136                                                                                                     Jawson, Dibble, Puri, et al


       were also enrolled in the study. Investigation                             8
       followed the protocol set out in fig 1.                                                                            Normal
                                                                                  7                                      postnatal
          At the antenatal scan parents of eligible




                                                             Number of patients
                                                                                  6                                      scan
       infants were given an explanatory letter with a
                                                                                                                         Dilatation
       diagram outlining the possible clinical signifi-                            5
                                                                                                                         on
       cance of the ultrasound findings, as well as the                            4                                      postnatal
       rationale for postnatal investigation. They were                           3
                                                                                                                         scan
       also advised that they could talk to one of the
       paediatricians involved (MSJ, LD) for further                              2
       clarification, if they so wished.                                           1
          A urine sample was obtained at birth and the                            0
       baby started on antibiotic prophylaxis. An                                     I             II            III           IV
       ultrasound scan was performed between two                                      Grade of vesicoureteric reflux
       and six weeks after delivery, except for two                                    on micturating cystogram
       infants who had scans when they were 3 and 4          Figure 2 Correlation between grade of vesicoureteric
       days old. A micturating cystogram (MCU) was           reflux and findings at postnatal ultrasound scan.
       performed at two to three months (in girls not        Table 1 Diagnosis in infants with postnatal renal pelvis
       before 3 months for technical ease). All babies       dilatation
       had an MCU whatever the scan results. The
       baby was then reviewed in clinic, growth and          Diagnosis                    N = Comments
       blood pressure measured, and a further urine          VUR             9                No scarring in refluxing kidney
       sample obtained.                                      Idiopathic      8                No VUR or PUJ obstruction, RPD
                                                               dilatation                     10-20 mm
          If both the postnatal scan and MCU were            PUJ obstruction 4                (i) One kidney showed loss of
       normal and the general review was satisfactory,                                        function and underwent pyeloplasty
       antibiotic prophylaxis was discontinued and                                            (ii) Three had no loss of function and
                                                                                              were managed conservatively
       the infant discharged from further follow up. If      Renal dyplasia               4   Contralateral kidney:
       the MCU showed the presence of VUR,                                                    (i) VUR
       antibiotic prophylaxis was continued and a                                             (ii) Mild hydronephrosis -? crossed
       99m                                                                                    ectopia
          technetium labelled dimercaptosuccinic acid                                         (iii) Hypertrophic
       scan (DMSA) was performed.
          VUR was graded as follows: (I) reflux into          VUR=vesicoureteric reflux; PUJ=pelviureteric junction;
                                                             RPD=renal pelvis dilatation.
       the distal ureter, often transient; (II) reflux into
       the ureter, renal pelvis, and calyces with no         elected not to follow our protocol. Two babies
       dilatation; (III) reflux with moderate dilatation      were excluded from the study (termination
       of the ureter, renal pelvis, and calyces; (IV)        because of trisomy 21, stillbirth).
       reflux with gross dilatation and tortuosity of            VUR was the most common clinical signifi-
       the ureter, gross dilatation of the renal pelvis,     cant pathology (23/104 or 22%). There was no
       and calyceal clubbing.                                correlation between the degree of either ante-
          When the MCU was normal but the postna-            or postnatal renal pelvis dilatation (RPD) and
       tal scan showed persistent RPD, further               the severity of VUR. The postnatal ultrasound
       management depended on the degree of                  scan was normal in 14/23 (61%) of infants who
       dilatation. Where the RPD was >10 mm a                had VUR. Fig 2 shows that the degree of VUR
       99m
          technetium labelled mercapto-acetyl trigly-        was, in fact, worse in children with a normal
       cine renogram (MAG 3) with diuretics (fruse-          postnatal ultrasound scan than in those with
       mide 0.5 mg/kg) was performed to assess renal         dilatation on the postnatal scan. In one infant
       drainage and function. Where RPD measured             with grade IV the anomaly scan was normal but
       5–10 mm a further ultrasound scan was                 in subsequent scans (at 32 and 36 weeks gesta-
       arranged when the infant was a year old.              tion) performed for obstetric reasons RPD was
          The antenatal scans were performed by a            noted and VUR diagnosed postnatally.
       senior radiographer (RD) using either an ATL             The DMSA scan showed no evidence of
       UM4 scanner with a 4.0 MHz linear trans-              scarring or renal dysplasia in any of the reflux-
       ducer, or an ALOKA SSD-650 with a curvilin-           ing units. Reduced renal function (34%) was
       ear, multifocusing 3.5 MHz transducer. The            found in the contralateral side to one refluxing
       postnatal scans were performed by a consultant        kidney. There was a male and right sided
       radiologist using an ATL HDI 3000 machine,            preponderance in infants diagnosed with VUR.
       with a 4–7 MHz broadband, multifrequency,                In 47 (45%) infants persisting renal pelvis
       multifocusing transducer.                             dilatation was identified on the postnatal scan,
          Ethical approval for the study was granted by      and the outcome in these cases is detailed in
       the local ethical committee.                          table 1.
                                                                Idiopathic dilatation of >10 mm—persisting
       Results                                               dilatation in the presence of a normal MCU
       One hundred and thirty nine mothers were              and MAG 3—was found in eight cases (7%).
       enrolled prospectively during the study period        There were four cases of PUJ obstruction,
       (May 1994 to July 1996). Their babies were            defined by delay in excretion (less than 50% in
       booked for investigation following the above          10 minutes) on MAG 3, none of whom had
       protocol and investigations were completed in         significant renal impairment, initially, and were
       104 babies. Twenty one babies failed to attend        managed conservatively. However, one of the
       or had incomplete investigations and seven            cases went on to have a pyeloplasty at 18
       moved out of the area during the study and            months because of deteriorating renal func-
       were lost to follow up. In five cases the parents      tion.
Outcome in antenatally diagnosed renal pelvis dilatation                                                                                      F137


                                  Four infants had renal dysplasia, three of         antenatal diagnosis where ultrasonography
                               whom also had an abnormality aVecting the             identifies “soft markers” of fetal anomaly.12
                               contralateral kidney (VUR, mild hydronephro-             The male preponderance in this series, and
                               sis, hypertrophic kidney). This highlights the        in other studies, contrasts with the female bias
                               need to investigate the contralateral kidney in       in postnatally detected VUR and might sup-
                               infants with renal dysplasia (table 1).               port the hypothesis that the VUR detected on
                                  There was generally a high uptake of postna-       the basis of ARPD, as in our study, is a diVer-
                               tal investigations, notably in those parents who      ent entity. However, as discussed by Marra,13
                               had attended for antenatal counselling. Sixty         this diVerence in sexual bias may be a reflection
                               eight of 139 (49%) parents attended for coun-         of case presentation, rather than incidence,
                               selling, and of this group seven (10%) infants        because in postnatally detected VUR the event
                               failed to attend for postnatal investigation, in      leading to its diagnosis is a urinary tract infec-
                               contrast to 14 (20%) infants from those               tion, which is more common in girls. Further
                               parents who were not counselled.                      information regarding kindred clustering of
                                                                                     VUR detected on the basis of ARPD would be
                                                                                     helpful in resolving this issue, because in cases
                               Discussion                                            of postnatally diagnosed VUR there is a
                               Renal tract abnormalities detected on ante-           definite familial bias, with around a 30%
                               natal ultrasound scan are relatively common           incidence in siblings.
                               and occurred in 2% of pregnancies in our pro-            Anderson and Rickwood14 have suggested
                               spective and unselected series. There are few         that VUR detected on the basis of ARPD may
                               data on outcome, or appropriate management,           be a marker of a more generalised poor renal
                               of minor degrees of antenatal renal pelvis dila-      tract development. They found renal impair-
                               tation, which comprise most cases in a district       ment, detected by DMSA, in 75% of cases of
                               general hospital. In our population VUR was
                                                                                     ARPD and VUR, in the absence of docu-
                               the most common postnatal diagnosis, occur-
                                                                                     mented infection, and commented that this
                               ring in 22% of cases. We found four cases
                                                                                     represented dysplastic kidneys due to a prena-
                               (3.8%) of PUJ obstruction, generally the most
                                                                                     tal vascular accident aVecting renal tract devel-
                               common diagnosis in reports of antenatal
                                                                                     opment. However, in our study none of the
                               hydronephrosis.
                                  Our study confirms the findings of Dudley et         refluxing units showed any evidence of renal
                               al6 that vesicoureteric reflux is the most             impairment.
                               common finding in the milder spectrum of                  The rationale for intervention in this area
                               ARPD. However, our investigation protocol             assumes that VUR detected on the basis of
                               diVered significantly in that we performed             ARPD is the same condition as that found in
                               micturating cystograms on all babies even if the      children with urinary tract infections, and
                               postnatal ultrasound scan was normal. Thus a          therefore has the same clinical significance in
                               diagnosis of VUR was made in 14 babies who            terms of the pathogenesis of renal scarring and
                               had a normal postnatal ultrasound scan. The           its long term sequelae. It could be argued that
                               importance of looking for reflux, even in the          the VUR detected in our study is a phenom-
                               presence of a normal postnatal ultrasound             enon of fetal renal tract development (transient
                               scan, is supported by the findings of Zerin et         renal tract dilatation) and is a self limiting con-
                               al,7 and Tibballs.8 However, both of these were       dition which could well be left alone, or is
                               retrospective studies looking at a selected           merely detecting the background incidence of
                               population referred to a specialist centre.           VUR. However, the prevalence of asympto-
                                  In six children subsequently shown to have         matic (and presumably clinically insignificant)
                               VUR only one out of several antenatal scans           VUR as reviewed by Bailey15 is 0.8–1.4%,
                               was abnormal. Thus a single antenatal                 compared with our figures of over 20%. We
                               measurement which shows evidence of renal             therefore consider that VUR detected on the
                               pelvis dilatation seems to put the fetus into the     basis of ARPD represents the detection of a
                               risk category for VUR.                                pathological condition which may lead to renal
                                  The importance of parental information,            scarring and justifies our investigative protocol.
                               explanation, and counselling, as highlighted by          We also set out to determine an upper limit
                               Watson et al9 and Owen,10 is supported in our         of normal for the antenatal renal pelvis.
                               study. Out of 68 couples (49%) who came to            However, as VUR was shown in association
                               discuss the antenatal findings, only seven             with all degrees of ARPD from 5 mm and
                               (10%) failed to complete postnatal investiga-         upwards, it has not been possible to determine
                               tion; of those who did not have any antenatal         an upper limit of normal for the antenatal renal
                               counselling, the baby was not investigated in 14      pelvis. In conclusion, we suggest that a
                               (20%) cases, though it must be acknowledged           measurement of 5 mm, or above, of the fetal
                               that there is an element of self selection in those   renal pelvis is an indication for postnatal inves-
                               parents attending for counselling. There is a         tigation, including MCU, notwithstanding the
                               danger of engendering unnecessary anxiety by          presence of a normal postnatal ultrasound
                               covering in detail all possible outcomes,             scan.
                               particularly where there are likely to be a
                               significant number of false positive results.11
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                               However, this is not an argument against coun-            routine ultrasonography in detecting fetal structural abnor-
                               selling, nor should it act as deterrent. Similar          malities in a low risk population. BMJ 1991;303:1165-9.
                                                                                      2 Harrison MR, Golbus MS, Filly RA, et al. Management of
                               dilemmas are encountered in many branches of               the fetus with congenital hydronephrosis. J Paed Surg
                               medicine, but particularly in the field of                  1982;17:728-40.
F138                                                                                                          Jawson, Dibble, Puri, et al


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