Is ultrasonography required to rule out congenital anomalies of the kidneys and urinary tract in babies with isolated preauricular
tags or sinuses?
- 1Infectious Diseases and Microbiology Unit, Institute of Child Health, London, UK
- 2Department of Nephrology, Great Ormond Street Hospital, London, UK
- Correspondence to Dr Andrew James McArdleInstitute of Child Health, 30 Guilford Street, London WC1N 1EH, UK;
Contributors AJM conceived the study, and performed the search, review and meta-analysis. Both authors contributed to the preparation of this manuscript. AJM is the guarantor.
- Received 29 August 2012
- Revised 29 August 2012
- Accepted 29 August 2012
- Urinary Tract/abnormalities
- Urinary Tract/ultrasonography
While performing an examination of a newborn, you note a preauricular sinus (PAS). The examination is otherwise unremarkable. A colleague suggests a need for renal ultrasonography in infants with a PAS or preauricular tag (PAT), but your consultant tells you this is unjustified. You decide to search for evidence to inform your clinical decision.
Structured clinical question
Do infants with isolated PAT or PAS (population) have a higher incidence of congenital anomalies of the kidneys and urinary tract (CAKUT) (outcome) on ultrasound (intervention) than infants without (controls)?
Search strategy and outcome
Cochrane Library (21 August 2012)—preauricular OR ‘pre-auricular’—16 results of which none were relevant.
Pubmed (21 August 2012)—(‘pre-auricular’ OR preauricular OR ‘Ear/abnormalities’(MeSH)) AND (kidney OR renal OR urinary OR genitourinary OR ‘Kidney/abnormalities’(MeSH) OR ‘Kidney/ultrasonography’(MeSH) OR ‘Urinary Tract/abnormalities’(MeSH) OR ‘Urinary Tract/ultrasonography’(MeSH)).
Five hundred and forty-two articles were found. Titles and/or abstracts were reviewed to identify studies where infants and children with isolated PAT/PAS underwent renal tract ultrasonography. Further studies were identified through references of relevant articles.
Twelve articles were identified, comprising six cohort studies,1–6 four case series,7–10 one case-control study which could not be obtained,11 and a previous Archimedes review.12 The cohort studies provide the highest level of evidence and are summarised in table 3.
CAKUT are the commonest cause of chronic kidney disease (CKD) in childhood (34%–59% from national registries).13 Renal malformations detected by ultrasound vary from mild hydronephrosis to high-grade reflux in dysplastic kidneys requiring medical and/or surgical management. Early diagnosis and management of nephro-urological problems may prevent progression of CKD.14
Several clinical syndromes are recognised to give combined ear and renal malformations.15 ,16 However, the association between CAKUT and non-syndromic PAT and PAS has been controversial, and screening has sometimes been recommended.8 A previous Archimedes review found limited and contradictory evidence, and the authors were not able to make clear recommendations.12 Three additional cohort studies and a meta-analysis are presented here.
Table 1 describes the included studies and their strengths and weaknesses. No studies blinded the ultrasonographer to the study group, and only Lizama et al 4 specified diagnostic standards. Two studies were in children rather than neonates.2 ,5 The study by Desphande and Watson1 is at high risk of bias as only control infants with abnormal antenatal scans underwent ultrasound.
Of the 15 subjects with isolated PAT/PAS and CAKUT, seven had significant hydronephrosis and/or reflux, which would require long-term follow-up, and could progress to CKD. Five subjects had grade 1 hydronephrosis, and one a horseshoe kidney, and would not be at risk of CKD. In two subjects, the severity of hydronephrosis was not specified. No data on long-term outcomes is available.
Figure 1 shows a meta-analysis of the relative risks from each study. No statistically significant difference in risk of CAKUT between subjects with isolated PAT/PAS and controls was found (p=0.35). Removing the potentially biased study by Deshpande and Watson1 did not significantly change the estimate (data not shown).
Using a baseline risk of CAKUT of 2% (as per the large control group from Lizama et al 4), the estimated number of infants with isolated PAT/PAS screened to detect one excess renal anomaly would be 96 (95% CI 19 to infinity—that is, the interval includes the possibility of fewer anomalies in the PAT/PAS group).
Even taking the lower confidence limit, ultrasonography of 19 infants to detect one renal tract anomaly above the population rate, with the attendant anxiety, uncertain benefit from identification, and costs involved, is not an appealing prospect, especially since over half of CAKUT may be detected antenatally.17 It certainly does not meet the criteria set out for UK screening programmes.18 However, clinical examination of infants with isolated PAT/PAS to identify syndromic malformations associated with renal anomalies19 (eg, branchio-oto-renal syndrome) would be prudent.
Further research may be better undertaken using case-control studies, comparing rates of PAT and PAS in children with diagnosed CAKUT and matched controls. Although a larger sample size would be needed to achieve the same power as a cohort study, no ultrasound would be required, and there would be no need to examine thousands of infants to obtain a group with PAT/PAS. Additionally, anomalies associated with progression to CKD without early intervention could be selected.
Clinical bottom line
Do not routinely perform renal tract ultrasonography in infants with isolated preauricular tags or sinuses (grade B).
The authors thank Bob Phillips for his advice during the preparation of this manuscript.
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.