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LHR proved to be a good predictor for fetal outcome, independent of gestational age at the time of the measurement. To substantiate our observation, a prospective multicenter study is warranted.

This review describes the pathogenesis of pulmonary hypoplasia and highlights its clinical, radiological and pathologic features, with emphasis on oligohydramniosrelated pulmonary hypoplasia. Since pulmonary hypoplasia may lead to severe respiratory distress immediately after birth and even to neonatal death, an accurate and patient-friendly prenatal test for early detection and distinction between lethal and non-lethal pulmonary hypoplasia is still highly desirable. An extended overview of the proposed methods for the prenatal prediction of pulmonary hypoplasia is presented.

The objective of this preliminary study was to evaluate three-dimensional ultrasonographic lung volume measurement in the normally developing fetus in the second half of pregnancy. Total fetal lung volume was determined by subtraction of fetal heart volume from thoracic volume, using the perpendicular transverse, sagittal and frontal planes of the fetus. Technically acceptable lung volume measurements were obtained in 29 out of 34 women with an uncomplicated pregnancy. A statistically significant increase in normal fetal lung volume was established with advancing gestational age and with increasing fetal estimated weight, demonstrating an approximately seven-fold rise in fetal lung volume during the second half of pregnancy. Three-dimensional ultrasonography can be applied for estimation of fetal lung volume. Whether this technique is useful in the prenatal prediction of pulmonary hypoplasia remains to be determined.

Our objectives were to describe the normal pulmonary venous blood flow velocity waveform and to establish reference ranges for the second half of pregnancy in healthy human fetuses. A total of 123 women with uncomplicated pregnancies of between 20 and 40 weeks were examined, using a combined color-coded Doppler and two-dimensional real-time ultrasound system. Pulsed Doppler flow velocity waveforms of pulmonary venous drainage into the left atrium were obtained from a transverse cross section of the fetal chest at the level of the cardiac four-chamber view. All waveforms were obtained during fetal apnea. The success rate in obtaining the pulmonary venous waveform was 81%. The waveform displayed a biphasic forward flow profile with a systolic and diastolic component. Peak systolic, peak diastolic and time-averaged velocities demonstrated a gestational age-related rise, whereas the peak systolic/peak diastolic ratio showed a gestational age-related reduction. The nature of the fetal pulmonary venous flow velocity waveform pattern suggests positive pressure towards the left atrium throughout the cardiac cycle. We speculate that an increase in volume flow and the pulmonary venous pressure gradient play a role in the gestational age-related changes in pulmonary venous flow velocities.

Congenital diaphragmatic hernia (CDH) is a relatively common birth defect with a high mortality. Although little is known about its etiology, there is increasing evidence for a strong genetic contribution. Both numerical and structural chromosomal abnormalities have been described in patients with CDH. Partial trisomy 11q and partial trisomy 22 associated with the common t(11;22) has been reported in several cases of CDH. It has been assumed that the diaphragmatic defect seen in these individuals was primarily due to duplication of material from chromosome 22q11. However, in this report we describe a family with a t(11;12) in which one of two brothers with partial trisomy 11q has a left sided posterolateral CDH. This is the second case of CDH in partial trisomy 11q due to an unbalanced translocation other than t(11;22). Using array-based comparative genomic hybridization and fluorescent in situ hybridization, we mapped the breakpoints in both brothers and their mother who is a balanced translocation carrier. Our results suggest that duplication of one or more genes on a approximately 19 Mb region of 11q23.3-qter predisposes to the development of CDH. These effects may be the primary cause of CDH in individuals t(11;22) or may be additive to effects from the duplication of chromosome 22 material. We also conclude that the partial trisomy 11q syndrome has a variable phenotype and that CDH should be added to the spectrum of anomalies that can be present in this syndrome.

A literature survey is presented on normal fetal development during the embryonic, pseudoglandular, canalicular, saccular and alveolar stages in the human fetus. Normal anatomical and physiological aspects of fetal lung development including the fetal pulmonary circulation are described. Factors which may influence fetal lung growth and consequently may play a role in the development of pulmonary hypoplasia are discussed, such as intrauterine and intrathoracic space, lung fluid, fetal breathing movements, normal balance of volume and pressure in the lung and interference with the blood supply.

Alteration in pulmonary vascular resistance may play a role in gestational age-related changes, whereas changes in vessel branching/diameter and in the distance between the heart and more distal arterial pulmonary vessels may cause inter-pulmonary differences.