Prenatal Detection of Congenital Renal Malformations by Fetal Ultrasonographic Examination: An Analysis of 709,030 Births in 12 European Countries

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Abstract

The study was performed to evaluate the prevalence of prenatal ultrasound diagnoses for renal anomalies in 20 registries of 12 European countries, and to compare the different prenatal scanning policies. Standardized data were acquired from 709,030 livebirths, stillbirths, and induced abortions during the study period of 2.5 years and transmitted for central analysis. At least one renal malformation was diagnosed in 1130 infants and fetuses. Prenatal diagnosis (PD) was given in 81.8% of all cases, 29% of these pregnancies were terminated. The highest detection rate was reported for unilateral multicystic dysplastic kidneys with 97% (102/105). An early diagnosis was documented for exstrophy of bladder at a mean gestational age of 18.5 weeks. Dilatations of the upper urinary tract were seen late in pregnancy at 28.3 weeks. Terminations of pregnancies (TOP) were performed in 67% (58/86) of the detected bilateral renal agenesis/dysgenesis, but only 4% of the unilateral multicystic dysplastic renal malformations (4/102). In about 1/3 of the cases, renal malformations are within the category of associated malformations, which include multiple non-syndromal malformations, chromosomal aberrations, and non-chromosomal syndromes. Renal malformations were detected in 2/3 of the associated category by the first prenatal ultrasound scan. Detection rates vary in the different countries of the European community due to diverse policies, ethical, and religious background. Countries with no routine ultrasound show the lowest rates in detection, and termination of pregnancy. Prenatally detected renal malformations should result in a careful examination for further anomalies. Prenatal ultrasound fulfills the needs of screening examinations and is a good tool in detecting lethal and severe renal malformations.

Introduction

Major birth defects are diagnosed in 2–7 percent of infants and fetuses. Malformations are the single leading cause of infant mortality and account for 1/3 of all pediatric admissions. Optimal treatment and prevention of congenital malformation are essential tasks of perinatal medicine [18], [19].

The idea to use ultrasound (US) as a routine examination in neonates was formed in the late 1970s. First valid studies were undertaken thereafter [14], [28]. Today ultrasound investigations in pregnancy are a part of routine antenatal care in most countries of the western hemisphere. In Europe, the scanning policies vary from none to three routine prenatal US examinations. A recommendation for at least 2 ultrasound scans for the identification of malformations has existed since the beginning of the 1990s [22]. A routine ultrasound scan for major malformations in the mid-trimester of pregnancy was performed in 10 out of 12 participating European countries. The policy for termination of pregnancies (TOP) relies, besides amniocentesis, mainly on prenatal diagnosis (PD) by ultrasound examinations. Prenatally detected renal malformations account for approximately 20–30% of all prenatal detected congenital anomalies [19]. Most diagnoses of this heterogeneous group are detectable by prenatal ultrasound examinations in the second trimester of pregnancy.

The aims of the EUROSCAN study (a multicenter concerted action) were to evaluate the prenatal detection rate of major congenital malformations across Europe, to compare different scanning policies including TOPs, and draw conclusions for an improvement in prenatal care. This report shows the results for renal malformations. Other parts of the concerted action have been published [in ref. 25].

Section snippets

Methods

Twenty congenital malformations registries from 12 European countries provided data (Table 1). Sixteen registries collaborate in the EUROCAT program, applying the same epidemiological methodologies. These methods were also used by the remaining four registries [11]. The study period was from July 1st 1996 to December 31st 1998, but not all registries were able to cover the whole time period. The different scanning policies are described in Table 1. Except two (Styria and Leipzig), all

General descriptive data

Table 1 indicates the distribution of cases by registries, as well as the policies of the different countries concerning terminations of pregnancies (TOP), reflecting the situation in the European Union (EU). Twenty registries reported a total of 709,030 births with 8,126 (1.15/1000) cases of major congenital anomalies, 1,130 (0.16%) of which with renal malformations (Table 1).

The registries, number of cases, the prevalence rates, the prenatally diagnosed cases, and the number of cases

Discussion

Renal malformations are detected in ca. 0.2–2% of all newborns [10], [20], [24], [28]. Prenatal diagnosis of renal malformations was reported in 0.5% of newborns in the late 1990s. Half of these need surgical intervention within the next year [8].

Normal and abnormal development of the kidneys as the patho-physiological base of congenital renal malformations and prenatal ultrasound diagnoses has been described extensively e.g., by Cuckow et al. [7] and Zhou et al. [29]. Only renal diagnoses

Conclusions

The important criteria for screening programs—the existence of preventive or therapeutic interventions, aggravation of the prognosis due to the lack of adequate measures, and health benefit from therapy—are completely fulfilled by US screening examinations in newborns. Early diagnosis of a renal malformation can lead to a more efficient treatment and better outcome by avoiding greater harm, for example recurrent infections. If known before birth even the course of pregnancy and needs of the

Acknowledgements

The EUROSCAN study was funded by the European Union BIOMED II program, Contract no. BMH4CT960539.

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