Perinatal Approach to Anomalies of the Urinary Tract, Adrenals and Genital System

Prenatal diagnosis of Bardet-Biedl syndrome in a case of hyperechogenic kidneys: Clinical use of DNA sequencing

Bardet–Biedl syndrome (BBS) is a ciliopathy that is responsible for multiple visceral abnormalities. This disorder is defined by a combination of clinical signs, many of which appear after several years of development. BBS may be suspected antenatally based on routine ultrasound findings of enlarged hyperechogenic kidneys and postaxial polydactyly.

Differential diagnosis of fetal hyperechogenic cystic kidneys unrelated to renal tract anomalies: A multicenter study

OBJECTIVES

To identify important factors in the differential diagnosis of renal cysts associated with hyperechogenic kidneys.

METHODS

This was a retrospective multicenter study. We identified 93 fetuses presenting between 1990 and 2002 with hyperechogenic kidneys and which had a diagnosis of nephropathy confirmed later. We analyzed retrospectively the prenatal ultrasound findings of those fetuses which were found sonographically to have renal cysts.

RESULTS

Of the 93 fetuses presenting with hyperechogenic kidneys and with a later diagnosis of nephropathy, there were 28 with autosomal dominant polycystic kidney disease (ADPKD), 31 with autosomal recessive polycystic kidney disease (ARPKD), 11 with Bardet-Biedl syndrome, nine with Meckel-Gruber syndrome, six with Ivemark II syndrome, one with Jarcho-Levin syndrome, one with Beemer syndrome and one with Meckel-like syndrome. One third of the fetuses (30/93) had renal cysts. Cystic characteristics (size, location, number) were not very useful for diagnosis; more useful was diagnosis of an associated malformation. Three (11%) of the fetuses with ADPKD had cysts, as did nine (29%) of those with ARPKD, three (27%) of those with Bardet-Biedl syndrome, all (100%) of those with Meckel-Gruber syndrome, three (50%) of those with Ivemark II syndrome, and each of the three cases with other syndromes (Jarcho-Levin, Beemer and Meckel-like syndromes). None of the cases with trisomy 13 had cysts. There were no associated malformations in the 12 cases with renal cysts and polycystic kidney disease; the other 18 cases with renal cysts were associated with malformations that were often specific, such as polydactyly in Bardet-Biedl and Beemer syndromes, occipital defect and Dandy-Walker malformation in Meckel-Gruber or Meckel-Gruber-like syndromes, and thoracic and/or vertebral abnormalities in Jarcho-Levin and Beemer syndromes.

CONCLUSION

Renal cysts associated with hyperechogenic kidneys are not rare. The clue to diagnosis is the demonstration of an associated malformation. If no malformation is found, the main diagnosis remains polycystic kidney disease, i.e. ARPKD or ADPKD.

Evolution of fetal ultrasonography

The authors wish to highlight the evolution that has occurred in fetal ultrasound in recent years. A first significant evolution lies in the increasing contribution of first trimester ultrasound for the detection of fetal anomalies. Malformations of several organs and systems have been diagnosed during the first trimester. Furthermore the systematic measurement of the fetal neck translucency has led to increasing rate of detection of aneuploidies and heart malformations. For several years now, three-dimensional (3D) and 4D ultrasound (US) have been used as a complementary tool to 2D US for the evaluation of fetal morphology. This brings an improved morphologic assessment of the fetus. Applications of the techniques are increasing, especially for the fetal face, heart and extremities. The third field where fetal US is continuously providing important information is the knowledge of the natural history of diseases. This has brought significant improvement in the postnatal management of several diseases, especially urinary tract dilatation and broncho-pulmonary malformation.

Should determination of the karyotype be systematic for all malformations detected by obstetrical ultrasound?

OBJECTIVE

The aim of this study was to determine whether karyotyping should be performed for every fetal malformation detected in low risk populations.

METHODS

A karyotype was obtained from 428 fetuses examined over a 10-year period after fetal malformation was diagnosed using obstetrical ultrasound. These fetuses were separated into two groups, one with isolated malformations and the other with multiple malformations. The association between each type of malformation and the result of karyotype was evaluated.

RESULTS

Forty-eight chromosomal abnormalities were encountered in 428 fetuses (11.2%). The karyotype was abnormal in 32/343 (9.3%) fetuses with isolated malformations and 16/85 (18.8%) fetuses with multiple malformations (p=0.022). The probability of an abnormal karyotype among the group of isolated malformation depended on the anatomical system involved (p<0.001). Our study demonstrated several isolated malformations without chromosomal abnormality (hydronephrosis with high obstruction, unilateral multicystic dysplastic kidney, gastroschisis, intestinal dilatation, meconium peritonitis, cystic adenomatoid malformation, pulmonary sequestration, tumor, vertebral anomaly).

CONCLUSION

Each fetus with multiple malformations needs a chromosomal analysis. Within the group of isolated malformations, our study emphasizes that medical maternal history and the type of malformation need to be taken into account before performing a fetal karyotype.

[Fetal genitourinary anomalies Perinatal and postnatal management with imaging techniques]

Improvements in ultrasound technology and the appropriate timing of antenatal ultrasound has led to refined prenatal diagnosis and enhanced accuracy of diagnosis of fetal renal anomalies and makes it possible to treat obstructive and/or refluxing uropathies before the onset of clinical symptoms. The third trimester renal sonography is the most important to detect hydronephrosis amenable to treatment.Classically, the prenatal diagnosis of hydronephrosis, unilateral renal agenesis, or MDKD initiates postnatal investigations, including sonography, voiding cystourethrography (VCUG), and isotopic renography. The exact degree of renal pelvic dilatation that requires full postnatal investigation is still not entirely resolved. Most authors accept the upper limit of 7 mm for the AP diameter of the renal pelvis. The US examination should be performed after the physiological dehydration period, namely 3-5 days after birth, in an urgent case on the 1st day. A meticulous ultrasound examination performed by a physician who is familiar with the renal abnormalities shows the whole extent of underlying pathology. The role of MR urography in the work-up of renal anomalies, particularly of hydronephrosis, is currently being investigated. Due to the close developmental relationship of the urinary and genital tracts, malformations frequently occur in both of these systems. Therefore in all patients, especially in girls with renal anomalies (unilateral renal agenesis, multicystic dysplastic kidney disease), the internal genitalia need to be evaluated.