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 1 Chitty LS, Hunt GH, Moore J, Lobb MO. EVectiveness of 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 3 Dell’Agnola CA, Tomaselli V, Ferazzi J, et al. Perinatal ultra- 10 Owen RJT, Lamont AC, Brookes J. Early management and sound monitoring: early detection and treatment of postnatal investigation of prenatally diagnosed hydroneph- congenital uropathy. Br J Urol 1983;55:469-72. rosis. Clin Radiol 1996;51:173-6. 4 Thomas DFM, Gordon AC. Management of prenatally 11 Marteau TM, Cook R, Kidd J, et al. The psychological diagnosed uropathies. Arch Dis Child 1989;64:58-63. eVects of false-positive results in prenatal screening for 5 Najmaldin A, Burge DM, Atwell JD. Fetal vesicoureteric reﬂux. Br J Urol 1990;65:403-6. fetal abnormality:a prospective study. Prenatal Diagn 6 Dudley JA, Haworth JM, McGraw ME, Frank JD, Tizard 1992;12:205-14. EJ. Clinical relevance and implications of antenatal 12 Whittle M. Ultrasonographic “soft markers” of fetal hydronephrosis. Arch Dis Child 1997;76:F31-4. chromosomal defects. BMJ 1997;314:918. 7 Zerin JM, Ritchey ML, Chang ACH. Incidental vesicouret- 13 Marra G, Barbieri G, Moioli C, Assael BM, Grumieri G, ric reﬂux in neonates with antenatally detected hydrone- Caccamo ML. Mild fetal hydronephrosis indicating phrosis and other renal abnormalities. Radiology vesicoureteric reﬂux. Arch Dis Child 1994;70:F147-F50. 1993;187:157-60. 14 Anderson PAM, Rickwood AMK. Features of primary vesi- 8 Tibballs JM, De Bruyn R. Primary vesicoureteric reﬂux - how useful is postnatal ultrasound? Arch Dis Child coureteric reﬂux detected by prenatal sonography. Br J 1996;75:444-7. Urol 1991;67:267-71. 9 Watson AR, Readett D, Nelson CS, Kapila L, Mayell MJ. 15 Bailey RR. Vesicoureteric reﬂux in healthy infants and chil- Dilemmas associated with antenatally detected urinary dren. In:Hodson J, Kincaid Smith P, eds. Reﬂux Nephropa- tract abnormalities. Arch Dis Child 1988;63:719-22. thy. New York: Masson, 1979:57-61.
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