Monozygotic twins discordant for trisomy 18.

We report on the pre- and postnatal cytogenetic, molecular genetic and clinical findings in monochorionic-diamniotic twins discordant for trisomy 18. Structural anomalies were identified in one of the twins on prenatal ultrasound examination at 20 weeks' gestation and sampling of amniotic fluid from both sacs was performed for karyotyping. This revealed trisomy 18 in the twin with abnormalities and a normal karyotype in the other twin. Elective Cesarean section was performed at 31 + 5 weeks and the aneuploid twin died shortly after delivery. The surviving twin showed low-grade mosaicism for trisomy 18 on postnatal analysis but has shown normal development. For prenatal diagnosis in monochorionic-diamniotic twin pregnancy the sampling of both amniotic sacs is recommended, especially if one twin has structural anomalies on ultrasound scan.

[Prenatal ultrasound diagnosis in congenital abnormalities of the kidneys and efferent urinary tract from the pediatric nephrology viewpoint]. / Antenatale Ultraschalldiagnostik bei angeborenen Fehlbildungen der Nieren und des ableitenden Harntraktes aus pädiatrisch-nephrologischer Sicht.

Antenatal foetal abnormalities are found in 0.5% of all pregnancies. 30-50% of these abnormalities are related to the urinary tract. Although congenital abnormalities of the urinary tract can be detected as early as in the 15th-18th weeks of gestation, most abnormalities are detected between the 28th-30th weeks of gestation. At this time irreversible damage of the kidneys has taken place and the foetus will not benefit from antenatal therapy. On the other hand, a foetus with late onset of obstruction will benefit from antenatal intervention. Repeated ultrasonography is crucial for initiating further invasive diagnostic procedures, antenatal therapy and for planning the time of labour. There is a great risk of overdiagnosis and inadequate therapy because 25% of all antenatally diagnosed dilatations of the urinary tract could not be confirmed postnatally.

[Prenatal ultrasound diagnosis of the kidneys and efferent urinary tract. Possibilities, applications and dangers]. / Die antenatale Ultraschalldiagnostik der Nieren und der ableitenden Harnwege. Möglichkeiten, Nutzen und Gefahren.

Congenital abnormalities of the urinary tract can be detected as early as during the 15th-18th week of gestation. Nevertheless, most abnormalities are detected between the 28th-30th week of gestation. Antenatal fetal abnormalities vary between physiological dilatation to bilateral hydronephrosis and polycystic kidney disease. Abnormalities in antenatal fetal ultrasonography are found in 0.5% of all pregnancies, 30-50% of these abnormalities are related to the urinary tract. Though most of the abnormalities are diagnosed late in pregnancy, irreversible damage of the kidneys has already taken place by that time and the fetus will not profit from antenatal therapy. On the other hand, a fetus with late onset of urinary tract obstruction may profit from antenatal intervention or early labor. Repeated ultrasonography is crucial for initiating further invasive diagnostic procedures, antenatal therapy and for planing the time of labor. There is a great risk of overdiagnosing and inadequate therapy because too little is known about physiological development of the fetal urinary tract in ultrasonography and so physiological and pathological development cannot be differentiated safely.

Prenatal diagnosis and postpartal therapy of fetal obstructions related to the urinary tract.

114 fetal malformations were diagnosed by ultrasound in the years 1983-1987 at our institute. 32 of these malformations involved the urinary tract. Fetuses with multicystic dysplasic kidneys and oligohydramnios have only a poor prognosis. In obstructive uropathy, however, exact antenatal diagnosis makes early leads to specific postpartal urological therapy. Modern ultrasound equipment makes it possible to localize the site of obstruction and/or dilatation in fetuses. The amount of amnion fluid indicates the degree of obstruction and is an important factor the postpartal prognosis of the children. Relieve of obstruction should be the first step of urological therapy directly after birth. We prefer to perform reconstructive surgery as soon as possible in the first 2 to 3 weeks of life. In children with subpelvic stenosis pyeloplasty is performed in the first weeks of life. Our results of 13 pyeloplasties in newborn are favourable. In children with megaureters dynamic scintigraphy or pressure flow studies (Whitaker test) are performed to diagnose or to exclude obstruction as a cause of dilatation (n = 14). In case of obstruction we perform an ureterocutaneostomy (Ring- or Sober procedure) immediately. Urethral valves causing subvesical obstruction could be treated by transvesical antegrade valve ablation, performed in 9 newborn with good success.