Oligohydramnios: further comment

Early fetal obstructive uropathy produces Potter's syndrome in the lamb

BACKGROUND

If creating an obstructive uropathy early in glomerulogenesis produces MCDK (Multicystic Dysplastic Kidney), then a very early obstruction may produce Potter's Syndrome (PS) with oligohydramnios.

METHODS

Fetal lambs at 50 days' gestation underwent urethral and urachal ligation using fine SILASTIC (Dow Corning, Midland, MI) tubing and were delivered by cesarean section at 145 days' gestation. At the time of death, kidney weight, length, and lung volumes were measured. These samples were examined histologically. Urinary sodium, chloride, potassium, and osmolarity also were measured. These were compared with normal-term fetuses.

RESULTS

One ewe miscarried. Two of 3 of 50-day obstructive uropathy lambs survived. The 2 survivors had dysplastic kidneys. One with large gastroschisis did not have PS but the other had renal, pulmonary, and chest wall hypoplasia. Both male lambs had undescended testes with a large bladder. Kidney weights were 2 g in the PS lamb and 16 g in controls. Lung volume was 84 mL in the PS lamb and 340 mL in controls. The lamb's face was compressed and the fetus was hydropic. Urine sodium, potassium, and osmolarity levels were higher than that of controls.

CONCLUSIONS

This is the first successful model ligating the penile urethra and urachus in a 50-day lamb. The authors' previous 60-day model did not have PS, but an earlier obstructive uropathy caused MCDK with PS.

Cryptophthalmos syndrome. Clinical and histopathological findings

The clinical and histological findings in two cases of complete bilateral cryptophthalmos from two families are described. In one family, the genetic mode of transmission is most probably autosomal recessive. The parents were first cousins and from the ten deliveries only two children were alive. Seven offspring died soon after birth. At least two of these had complete bilateral cryptophthalmic features in addition to the described offspring. In the other family, the mode of transmission is unclear as the offspring was the first born of non-consanguineous parents with negative family history. Both cases showed similar external clinical appearance and anomalies. Chromosomal studies revealed normal female (first case) and male (second case) karyotypes. The latter, who died a few minutes after delivery, had bilateral agenesis demonstrating features compatible with Potter's syndrome. Apart from the complete covering of the eye globes with skin, the lack of eyebrows and eyelids, the two patients showed also similar histological ocular findings. The eyes in both cases demonstrated well developed posterior segment architecture including optic nerves, with a complete early arrest of anterior segment development and differentiation.

Campomelia, cervical lymphocele, polycystic dysplasia, short gut, polysplenia

An aborted fetus, the offspring of consanguineous parents, had the unusual combination of campomelia, cervical lymphocele, polycystic kidneys, pancreas, and liver, short gut, and polysplenia. Births of earlier similarly affected fetuses suggest an autosomal recessive inheritance. Skeletal, lymphatic, and renal lesions were seen at 26 weeks' gestation by ultrasonography, but not at 16 weeks.

Cystic kidneys. Genetics, pathologic anatomy, clinical picture, and prenatal diagnosis

According to the classification of Osathanondh and Potter of cystic kidneys we give an overview of the different types of cystic changes taking genetic aspects into account. Usually pathoanatomic types do not represent genetic entities: All type I kidneys are transmitted in an autosomal recessive way with varying clinical symptoms; in rare cases they even present in adults. The relationship to "congenital hepatic fibrosis", "cystic liver", and to the "Caroli syndrome" is discussed. Type II kidneys are usually not genetic in origin; but they may occur as part of several syndromes. Rarely genetic factors might contribute to type II kidneys that may present as familial cases of Potter syndrome ("renal non-function syndrome"). Type IV kidneys, although different in their pathoanatomic picture can be regarded according to a common pathogenetic theory as part of the spectrum of malformations as in type II. Therefore the genetic interpretation of type II kidneys also applies to type IV lesions. Type III kidneys include autosomal dominant polycystic kidney disease. This type may already present in childhood; the first prenatal diagnosis by ultrasonography is described in detail. Furthermore type III changes are part of syndromes or non-hereditary malformation complexes, and often present only as mild manifestations. Diseases with isolated involvement of the medulla (juvenile nephronophthisis/medullary cystic disease) or cortex are described as part of the differential diagnosis, they are heterogeneous and genetically only partly understood. Syndromes with cystic kidneys are reviewed as well as the possibilities of prenatal diagnosis of cystic diseases. Reliable prenatal diagnosis is only possible in type II, and possible in some of the other types. The nosology is improved if genetic information is taken into account.

Indomethacin and the fetal renal nonfunction syndrome

A pregnancy during which both beta-adrenergics and indomethacin were administered in order to stop preterm uterine contractions is reported. After 8 wk of therapy a Caesarean section was performed. The female neonate had all the characteristics of a Potter's facies, was anuric and died after 47 h of extra-uterine life. A possible relationship between this perinatal death and the prolonged intra-uterine exposure to indomethacin is discussed.

Cryptophthalmos syndrome with bilateral renal agenesis

We conducted a postmortem study of an infant with the abortive form of the cryptophthalmos syndrome. He had syndactyly and anal atresia and also showed features of Potter's (renal nonfunction) syndrome, including bilateral renal agenesis, pulmonary hypoplasia, and the typical facies. Histopathologic examination of both globes disclosed that the superior eyelid folds were partially replaced by skin that fused with the superior third of each cornea; there were also anomalies of the superior canaliculi and scarring of the corneas. We found no specific abnormality of the intraocular contents.

Premature rupture of the membranes, oligohydramnios and pulmonary hypoplasia

The clinical and pathological features of oligohydramnios associated with severe pulmonary hypoplasia are described in 10 infants without renal anomalies. In 8 patients the condition was associated with prolonged premature rupture of the membranes at 16 and 36 weeks of gestation in a study of 244 patients (3.3%). Seven of the infants died of respiratory failure within 24 hours of delivery; the other infant survived. In the remaining 2 patients with severe oligohydramnios at term, but unassociated with premature rupture of the membranes, both infants succumbed. Problems with resuscitation should be anticipated in pregnancies complicated by prolonged leakage of amniotic fluid or oligohydramnios, and pulmonary hypoplasia should be recognized as a cause of respiratory distress. Apart from the ultrasonic predelivery confirmation of normal kidneys to exclude Potter's syndrome it is recommended that ultrasonic assessment of thoracic cage volume should be made before delivery.

Werdnig-Hoffmann disease. The effects of intrauterine onset on lung growth

Thoracic gas volume (TGV), resting lung volume at end expiration, was measured by the plethysmographic technique in 9 infants with Werdnig-Hoffmann disease. Five of these infants were considered to have intrauterine onset of the disease; the mother in each case had reported a pronounced reduction in fetal activity during the last trimester of pregnancy, and 4 were found to be hypotonic at birth. The remaining 4 infants appeared normal at birth and did not develop any signs of the disease until between 2 and 12 weeks postnatally. Those with intrauterine onset of disease had a significantly reduced TGV (mean 20.8 ml kg(-1)), whereas those with postnatal onset had normal lung volumes (means 36.1 ml kg(-1)). The reduction in lung volume correlated only with intrauterine onset of disease, and was not related to either the degree of muscle weakness or the duration of disease. There is increasing evidence that fetal breathing movements may be one of the essential prerequisites for normal fetal lung development. It is therefore possible that diminished fetal breathing movements, resulting from weakness of the respiratory musculature in utero, could be responsible for the reduction in lung volume found in those infants with intrauterine onset of the disease.

Posterior urethral stenosis in newborn with renal nonfunction syndrome

A newborn male infant presented with the "renal nonfunction syndrome" and subsequently was found at autopsy to have congenital stenosis of the posterior urethra. Additional urinary tract malformations included a prostatic diverticulum, bladder hypertrophy, bilateral hydroureter, and bilateral renal hypoplasia with dysplasia. Autopsy evidence suggested that the urethral stenosis had manifested itself very early during embryologic development and accounted for the associated urinary anomalies. The infant had the physical stigmata, clinical course, and pulmonary hypoplasia commonly observed in "Potter's" or the "renal nonfunction syndrome."

Bilateral renal asplasia without Potter's syndrome

A newborn infant with bilateral aplasia of kidneys and ureters and a rudimentary bladder is reported. Other manifestations of Potter's syndrome (oligohydramnios, lung hypoplasia and an abnormal face) were missing as were other congenital malformations. Deviations from the full picture of Potter's syndrome seem to be rare. This case, however, shows that bilateral renal aplasia cannot be excluded as a cause of anuria in a newborn infant, even if all other manifestations of Potter's syndrome are missing.

Bilateral renal agenesis with multiple congenital ocular anomalies

A 920-g male infant born with features of Potter's syndrome had multiple ocular anomalies. Ocular abnormalities included absence of keratocytes in the inner central corneal stroma, cataract with retention of cell nuclei in the nucleus of the lens, hypoplasia of the ganglion cell and nerve fiber layers of the retina, and absence of nerve bundles in the optic nerve. Other ocular findings including microphthalmos, fetal chamber angle, persistent pupillary membrane , retinal avascularity, and prominent Bergmeister's papilla may have been related to the prematurity of the child.