Ultrasonic ratio of fetal thoracic to abdominal circumference: an association with fetal pulmonary hypoplasia

Application of ultrasonographic human estimated foetal weight formulas to cynomolgus monkeys (Macaca fascicularis) at 129-132 days of gestation: A comparative study of estimated and actual birthweight

BACKGROUND

Cynomolgus monkeys (Macaca fascicularis) are essential in biomedical research, including reproductive studies. However, the application of human estimated foetal weight (EFW) formulas using ultrasonography (USG) in these non-human primates is not well established.

OBJECTIVES

This study aims to evaluate the applicability of human EFW formulas for estimating foetal weight in cynomolgus monkeys at approximately 130 days of gestation.

METHODS

Our study involved nine pregnant cynomolgus monkeys. We measured foetal parameters, including biparietal diameter, head circumference, abdominal circumference and femur length using USG. The EFW was calculated using 11 human EFW formulas. The actual birthweight (ABW) was recorded following Cesarean section, the day after the EFW calculation. For comparing EFW and ABW, we employed statistical methods such as mean absolute percentage error (APE) and Bland-Altman analysis.

RESULTS

The ABW ranged between 200.36 and 291.33 g. Among the 11 formulas, the Combs formula showed the lowest APE (4.3%) and highest correlation with ABW (p < 0.001). Notably, EFW and ABW differences for the Combs formula were ≤5% in 66.7% and ≤10% in 100% of cases. The Bland-Altman analysis supported these results, showing that all cases fell within the limits of agreement.

CONCLUSIONS

The Combs formula is applicable for estimating the weight of cynomolgus monkey fetuses with USG at approximately 130 days of gestation. Our observations suggest that the Combs formula can be applied in the prenatal care and biomedical research of this species.

Lung Volume Head Ratio: A Potential Parameter for Prediction of Respiratory Distress in Newborn

OBJECTIVE

This study aimed to evaluate the role of fetal lung biometry profile including fetal lung volume head ratio (LVHR) in predicting the occurrence of respiratory distress (RD) in early preterm newborn.

STUDY DESIGN

Prospective analytical cohort study was done to evaluate the clinical value of fetal sonographic measures, such as the total lung area (TLA), total lung volume (TLV), TLA head ratio (TLHR), LVHR, in pregnant women between 30 to 34 weeks' gestation who were expected to deliver within the next 72 hours. The cases with RD were compared with controls who had normal outcome.

RESULT

A total of 30 (27.4%) out of 110 patients, who underwent early preterm delivery, with RD rest 80 (72.6%) were controls. The TLA was 694.1 ± 373.1 mm2 in cases whereas 1,149.0 ± 506 0.7 mm2 in controls with significant difference between the two groups (p < 0.001). Similarly the lung volume (p < 0.001) and the LVHR were significantly less (p < 0.001) in cases compared with controls. The TLV was a better parameter (sensitivity, 73.7% and specificity, 86.4%) compared with TLA (sensitivity, 68.4% and specificity, 81.5%). Among the lung head ratios, LVHR had the best sensitivity of 95.5%, specificity: 80.3%, positive predictive value (PPV): 58.3%, and negative predictive value (NPV): 97.0% at the cut-off of 46.5.

CONCLUSION

RD was observed in nearly one-third of the preterm infants born between 30 and 34 weeks of gestation and could be predicted accurately in over 9 out of 10 cases using the novel parameter TLVR.

KEY POINTS

· Preterm newborn.. · Fetal lung volume.. · Respiratory distress..

Lung Hypoplasia in Fetuses with Skeletal Dysplasia Determined by Fetal Lung Weight: Which Ultrasound Measurement/Ratio Has the Highest Detection Rate

INTRODUCTION

To determine lung hypoplasia in cases with fetal skeletal dysplasia based on the total lung weight at autopsy as the most accountable surrogate marker for pulmonary hypoplasia.

METHODS

This retrospective cohort study included all pregnancies with antenatal diagnosis of skeletal dysplasia (2012-2018). We included only cases in which information on fetal biometry was available within 2 weeks before delivery and had autopsy and skeletal X-rays + molecular analysis using extracted fetal DNA. We compared the predictive accuracy of fetal sonographic body-proportional ratios (BPRs) including: (1) thoracic circumference-to-abdominal circumference ratio, (2) the femur length-to-abdominal circumference (FL/AC) ratio, (3) head circumference-to-abdominal circumference ratio, and (4) foot length-to-femur length ratio. Lung hypoplasia was defined as total lung weight below -2 SD from the expected mean for gestational age.

RESULTS

Fifty three pregnancies with antenatal diagnosis of skeletal dysplasia underwent autopsy included. Lung hypoplasia was determined in 34 (64.1%). Median of gestational age at last sonographic assessment was 21.3 (19.9-24.9) weeks. FL/AC ratio demonstrated the highest area under the curve of 0.817 (95% CI: 0.685-0.949; p < 0.0001). FL/AC ≤0.1550 demonstrated the highest detection rate of 88.2% along with the highest negative predictive value of 75%.

CONCLUSION

Using a novel, more practical approach to predict lung hypoplasia in skeletal dysplasia, fetal sonographic BPRs and, specifically, FL/AC ratio demonstrate a high detection rate of lung hypoplasia.

Fetal thoracic circumference in mid-pregnancy and infant lung function

BACKGROUND AND AIM

Impaired lung function in early infancy is associated with later wheeze and asthma, while fetal thoracic circumference (TC) predicts severity of neonatal lung hypoplasia. Exploring fetal origins of lung function in infancy, we aimed to determine if fetal TC in mid-pregnancy was associated with infant lung function.

METHODS

From the prospective Scandinavian general population-based PreventADALL mother-child birth cohort, all 851 3-month-old infants with tidal flow-volume measurements in the awake state and ultrasound fetal size measures at 18 (min-max 16-22) weeks gestational age were included. Associations between fetal TC and time to peak tidal expiratory flow to expiratory time (t_PTEF /t_E ) were analyzed in linear regression models. To account for gestational age variation, we adjusted TC for simultaneously measured general fetal size, by head circumference (TC/HC), abdominal circumference (TC/AC), and femur length (TC/FL). Multivariable models were adjusted for maternal age, maternal asthma, pre-pregnancy body mass index, parity, nicotine exposure in utero, and infant sex.

RESULTS

The infants (47.8% girls) were born at mean (SD) gestational age of 40.2 (1.30) weeks. The mean (SD) t_PTEF /t_E  was 0.39 (0.08). The mean (SD) TC/HC was 0.75 (0.04), TC/AC 0.87 (0.04), and TC/FL 4.17 (0.26), respectively. Neither TC/HC nor TC/AC were associated with infant t_PTEF /t_E while a week inverse association was observed between TC/FL and t_PTEF /t_E  ( β ^ $\hat{\beta }$  = -0.03, 95% confidence interval [-0.05, -0.007], p = 0.01).

CONCLUSION

Mid-pregnancy fetal TC adjusted for fetal head or abdominal size was not associated with t_PTEF /t_E in healthy, awake 3-month-old infants, while a weak association was observed adjusting for fetal femur length.

Assessment of the fetal lungs in utero

Antenatal diagnosis of abnormal pulmonary development has improved significantly over recent years because of progress in imaging techniques. Two-dimensional ultrasound is the mainstay of investigation of pulmonary pathology during pregnancy, providing good prognostication in conditions such as congenital diaphragmatic hernia; however, it is less validated in other high-risk groups such as those with congenital pulmonary airway malformation or preterm premature rupture of membranes. Three-dimensional assessment of lung volume and size is now possible using ultrasound or magnetic resonance imaging; however, the use of these techniques is still limited because of unpredictable fetal motion, and such tools have also been inadequately validated in high-risk populations other than those with congenital diaphragmatic hernia. The advent of advanced, functional magnetic resonance imaging techniques such as diffusion and T2* imaging, and the development of postprocessing pipelines that facilitate motion correction, have enabled not only more accurate evaluation of pulmonary size, but also assessment of tissue microstructure and perfusion. In the future, fetal magnetic resonance imaging may have an increasing role in the prognostication of pulmonary abnormalities and in monitoring current and future antenatal therapies to enhance lung development. This review aims to examine the current imaging methods available for assessment of antenatal lung development and to outline possible future directions.

Chylous Ascites in an Infant with Thanatophoric Dysplasia Type I with FGFR3 Mutation Surviving Five Months

BACKGROUND

Thanatophoric dysplasia (TD) results from sporadic de novo mutations in the FGFR3 gene. Upon confirming intrauterine diagnosis of this perinatal disease, pregnancy termination is recommended. There is limited information on the natural history of longer-term survivors with type 1 TD.

CASE REPORT

A full-term neonate was confirmed via postnatal genetic testing to have type 1 TD. At 28 days, chylous ascites developed. Medium-chain triglyceride use improved the ascites. Cerebral ventriculomegaly worsened throughout life. Death due to respiratory failure occurred at age 5 months.

CONCLUSION

The chylous ascites in this child with type 1 TD and survival past the neonatal stage suggests that type 1 TD may be accompanied by abnormalities of the lymphatic channels. Moreover, ventriculomegaly can be progressive.

Evaluating skeletal dysplasias on prenatal ultrasound: an emphasis on predicting lethality

Lethal skeletal dysplasias can be diagnosed by prenatal ultrasound (US) using several sonographic parameters. Degree of femoral shortening, lung volumes, femur length to abdominal circumference ratio, and chest circumference to abdominal circumference ratio are the most sensitive and specific predictors. Although there are more than 450 different skeletal dysplasias, only a few are lethal in the perinatal period. We review current fetal US literature and present an updated algorithmic approach to first establish lethality and, second, evaluate for hallmark sonographic features to help determine a specific diagnosis.

Sonographic Detection of Fetal and Neonatal Intrathoracic and Pulmonary Abnormalities

High resolution ultrasound has allowed increased definition and detailed study of the fetal thorax. From the second trimester, congenital anomalies arising from or involving the fetal chest can be visualized. Early detection and diagnosis of fetal intrathoracic abnormalities are rapidly becoming an integral part of modern obstetrical care and neonatal management. The potential exists to diagnose most intrathoracic anomalies before the 20th week of pregnancy.

A Case of Thanatophoric Dysplasia Type I with Fetal Hydrops in the First Trimester

During a routine prenatal exam, a 36-year-old female in her third pregnancy was diagnosed with fetal hydrops at 11 weeks of gestation. The pregnancy was monitored with periodic ultrasounds; however, spontaneous resolution was not observed. Amniotic fluid examination at 16 weeks of gestation showed a normal karyotype; however, macrocephaly, a narrow thorax, and shortening of the long bones were observed on ultrasonography. With the strong suspicion of a fetal skeletal disease, specifically thanatophoric dysplasia (TD), and after extensive genetic counseling, termination of the pregnancy was performed per the parents' wishes with mechanical cervical dilation and gemeprost (PGE1) administration. Following delivery, the fetus was found to have macrocephaly, a narrow bell-shaped thorax, and a protuberant abdomen, as well as curved long bones, H-shaped platyspondyly, and curved clavicles on skeletal radiography. As a result, the fetus was diagnosed with TD type I. This case illustrates that although TD is a rare disease, an accurate prenatal diagnosis can be made with the use of ultrasonography.

A case of fetal osteogenesis imperfecta type 2A: longitudinal observation of natural course in utero and pitfalls for prenatal ultrasound diagnosis

We present a case of osteogenesis imperfecta (OI) type 2A in which a natural course in utero was observed from 23 weeks' gestation to term. At 23 weeks' gestation, a sonographic examination showed a cloverleaf skull-like head, a narrow thorax, and marked shortening of the long bones with bowing of the femurs and humeri. Follow-up examinations showed that the cloverleaf skull-like head was not evident at 28 weeks' gestation. Discontinuity of the ribs and femurs was observed at 26 and 30 weeks' gestation, respectively. This finding suggested bone fractures, which were confirmed by three-dimensional computed tomography at 32 weeks' gestation. Ultrasonographic findings of bones, including the long bones and calvarium, changed with advancing gestation during the second trimester. Characteristic features of OI type 2A were evident during the late second to early third trimesters. Repeated ultrasonographic examinations together with three-dimensional computed tomography are necessary for the definitive diagnosis of OI type 2A in the second trimester.

Thanatophoric dysplasia in a dichorionic twin confirmed by genetic analysis at the early second trimester: A case report and literature review

Thanatophoric dysplasia (TD) is caused by mutation of the gene that encodes fibroblast growth factor 3 (FGFR3). Owing to the poor prognosis for TD, prenatal diagnosis is critical to optimal perinatal management. We report here a case of TD in twin pregnancy, which was prenatally diagnosed by DNA analysis following amniocentesis at 15 weeks, and was managed by selective fetal termination. Prenatal ultrasonography and molecular analysis to detect TD-specific mutations enable accurate diagnosis of FGFR3-related TD in utero and appropriate obstetrical management at early gestation during twin pregnancy.

Accuracy of imaging parameters in the prediction of lethal pulmonary hypoplasia secondary to mid-trimester prelabor rupture of fetal membranes: a systematic review and meta-analysis

In women who have suffered mid-trimester prelabor rupture of membranes (PPROM), prediction of pulmonary hypoplasia is important for optimal management. We performed a systematic review to assess the capacity of imaging parameters to predict pulmonary hypoplasia. We searched for published articles that reported on biometric parameters and allowed the construction of a 2 × 2 table, comparing at least one of these parameters with the occurrence of pulmonary hypoplasia. The selected studies were scored on methodological quality and we calculated sensitivity and specificity of the tests in the prediction of pulmonary hypoplasia and lethal pulmonary hypoplasia. Overall performance was assessed by summary receiver-operating characteristics (sROC) analyses that were performed with bivariate meta-analysis. We detected 13 studies that reported on the prediction of lethal pulmonary hypoplasia. The quality of the included studies was poor to mediocre. The estimated sROC curves for the chest circumference/abdominal circumference ratio and other parameters showed limited accuracy in the prediction of pulmonary hypoplasia. In women with mid-trimester PPROM, the available evidence indicates limited accuracy of biometric parameters in the prediction of pulmonary hypoplasia.

Pattern and prenatal diagnosis of skeletal dysplasias in Qatar population

OBJECTIVE

To determine the pattern of skeletal dysplasias in Qatar population and to assess the accuracy of prenatal diagnosis and prognosis.

METHODS

This was a retrospective descriptive study of 30 women with high risk for skeletal dysplasias. The recruited women were submitted to clinical assessment, ultrasound scanning using 2-dimensional, 3-dimensional/4-dimensional and colour Doppler technique with possible molecular diagnosis. The findings were compared with the postnatal or postmortem assessments. Final diagnosis was based on clinical examination, skeletal survey, autopsy and molecular testing as deemed necessary.

RESULTS

Thirty cases of skeletal dysplasia were antenatally diagnosed over 4-year period with family history in few cases. Among many entities thanatophoric dysplasia showed largest prevalence [7(23%)]. Prenatal diagnosis was accurate in 76% of foetuses while the first indicator of abnormality was a suspected anomaly found during routine ultrasound assessment in most cases [17(56%)]. Prediction of lethality based on ultrasound findings was 100% accurate.

CONCLUSIONS

This study confirmed the possibility of good prenatal diagnosis of skeletal dysplasias present among Qatar population. Diagnosis based on ultrasound assessment will improve by adding molecular techniques with positive impact on prenatal care.

Pena-Shokeir phenotype (fetal akinesia deformation sequence) revisited

BACKGROUND

Pena and Shokeir described the phenotype of two sisters in 1974, and subsequently their features have become recognized as a sequence of deformational changes related to decreased or absent fetal movement (fetal akinesia deformation sequence [FADS]), because of the work of Moessinger (1983).

METHODS

Identification of reported cases by searching Online Mendelian Inheritance in Man, Medlines, the London Dysmorphology Database, and the references found in these articles. These case reports were reviewed, tabulated, and summarized.

RESULTS

It is now possible to recognize at least 20 familial types of Pena-Shokeir phenotype (PSP), based on the differences found in the reports of the natural history and pathology found at fetal and newborn autopsy. In addition, characteristic changes in the central nervous system seen with embryonic/fetal vascular compromise have been recognized in many reported cases. Most of the reported cases of PSP/FADS related to vascular compromise are sporadic, but familial cases have also been reported.

CONCLUSION

Lack of fetal movement (fetal akinesia) in humans produces a recognizable sequence of deformations. Many developmental processes must be accomplished for fetal movement to be normal, and for extra-uterine life to be sustainable. Prenatal diagnosis is possible through real-time ultrasound studies as early as 12 weeks. Most reported cases die in utero, at birth, or in the newborn period. Advances in embryo/fetus pathology have led to the recognition of the many familial subtypes, allowing improved genetic counseling and early recognition in subsequent pregnancies.

Oligohydramnios and associated fetal complications

During intrauterine life the fetus is bathed in amniotic fluid which provides a low resistance space for free movement and a buffer against external trauma. This fluid is produced in early pregnancy largely as a maternal dialysate, then as a fetal transudate. Fetal urine is the most important source of amniotic fluid after 16 weeks gestation. The control of amniotic fluid is complex and poorly understood; it arises from secondary partitioning of water within the fetoplacental extracellular space and reflects fetal fluid balance.

Fetal skeletal dysplasia: an approach to diagnosis with illustrative cases

Skeletal dysplasias are a heterogeneous group of conditions associated with various abnormalities of the skeleton. These conditions are caused by widespread disturbance of bone growth, beginning during the early stages of fetal development and evolving throughout life. Despite recent advances in imaging, fetal skeletal dysplasias are difficult to diagnose in utero due to a number of factors, including the large number of skeletal dysplasias and their phenotypic variability with overlapping features, lack of precise molecular diagnosis for many disorders, lack of a systematic approach, the inability of ultrasonography (US) to provide an integrated view, and variability in the time at which findings manifest in some skeletal dysplasias. US of suspected skeletal dysplasia involves systematic imaging of the long bones, thorax, hands and feet, skull, spine, and pelvis. Assessment of the fetus with three-dimensional US has been shown to improve diagnostic accuracy, since additional phenotypic features not detectable at two-dimensional US may be identified. The radiologist plays a major role in making an accurate diagnosis; however, representatives of other disciplines, including clinicians, molecular biologists, and pathologists, can also provide important diagnostic information.

A guide to the recognition of skeletal disorders in the fetus

The discovery of fetal skeletal abnormality on prenatal US mandates an extended study of the fetus. This extended examination includes specific views and measurements of the fetal skeleton. Lethality can be predicted if severe pulmonary hypoplasia is present. Specific diagnosis of a fetal osteochondrodysplasia is difficult; a collaborative approach among obstetric, neonatal and genetic services is necessary to provide the parents with all available information regarding the pregnancy. Pediatric radiologists who have experience in radiologic assessment of osteochondrodystrophies of infants and children can provide expertise in this area.

Antenatal detection of skeletal dysplasias

OBJECTIVE

To assess the accuracy of the prenatal diagnosis of skeletal dysplasias.

METHODS

All antenatally detected anomalies are coded in our ultrasound database, which is linked with a genetics database that includes outcomes. A final diagnosis is sought on the basis of radiographic studies, molecular testing, or both. Our ultrasound and genetics databases were queried for "skeletal dysplasias." All cases were reviewed specifically for the degree of bone shortening and other distinguishing characteristics on antenatal sonography.

RESULTS

Thirty-seven cases of skeletal dysplasia were antenatally diagnosed over an 8-year period. Complete follow-up was available in 31 cases. The mean gestational age at diagnosis was 22.7 weeks (range, 14-32.3 weeks). Twenty-one cases were diagnosed before 24 weeks. A final diagnosis was obtained in 80% of cases. The antenatal diagnosis was correct in 20 (65%) of 31 cases. There were 2 false-positive diagnoses. Specific final diagnoses included thanatophoric dysplasia (8), osteogenesis imperfecta (6), Roberts syndrome (2), achondroplasia (3), Ellis-van Creveld syndrome (1), metaphyseal dysplasia (1), spondyloepiphyseal dysplasia (1), distal arthrogryposis (1), caudal regression (1), and glycogen storage disorder (1). The condition was correctly thought to be lethal in 16 of the fetuses on the basis of early severe long bone shortening (13), femur length-abdominal circumference ratio of less than 0.16 (12), hypoplastic thorax (10), marked bowing or fractures (4), short ribs (4), caudal regression (1), and cloverleaf skull (1). The ability to predict lethality was 100%. There were no false-positive findings with respect to lethality.

CONCLUSIONS

Accurate antenatal diagnosis of skeletal dysplasias is problematic; in this series, only 20 of 31 cases were correctly diagnosed. However, the antenatal prediction of lethality was highly accurate. The most common predictors of lethal skeletal dysplasias included early and severe shortening of the long bones, femur length-abdominal circumference ratio of less than 0.16, hypoplastic thorax, and certain distinguishing characteristics.

Three-dimensional ultrasound fetal lung volume measurement: a systematic study comparing the multiplanar method with the rotational (VOCAL) technique

OBJECTIVES

This study was designed to compare a conventional multiplanar technique for three-dimensional (3D) ultrasound measurement of fetal lung volume with a rotational method using VOCAL trade mark (Virtual Organ Computer-aided AnaLysis).

METHODS

Thirty-two fetuses with a variety of conditions at risk for pulmonary hypoplasia were studied. 3D volume data sets of the fetal lungs were acquired using a commercially available ultrasound system. The right and left lung volumes were calculated separately using VOCAL and the multiplanar technique. The level of agreement between two independent observers in categorizing the 3D volume data set as measurable or non-measurable was determined. The interobserver and intermethod variabilities were also evaluated for both methods.

RESULTS

The intermethod variability was excellent (correlation r = 0.93 and r = 0.96 for the left and right lung, respectively), and there was substantial agreement between the results of both approaches (limits of agreement - 4.4 to 8.9 and - 3.4 to 4.8 mL for the right and left lung, respectively). Fetal lung estimation with VOCAL had a significantly higher interobserver variability than the multiplanar technique. Interobserver agreement in categorizing lung volume data sets as measurable or non-measurable was lower when VOCAL was used.

CONCLUSION

Fetal lung volume measurements can be undertaken interchangeably using the multiplanar technique or the rotational method with VOCAL. However, the latter was less reproducible (lower degree of agreement and significantly higher interobserver variability) than the former.

Antenatal prediction of pulmonary hypoplasia by acceleration time/ejection time ratio of fetal pulmonary arteries by Doppler blood flow velocimetry

OBJECTIVE

The purpose of this study was to develop a new method for the antenatal prediction of pulmonary hypoplasia by Doppler blood flow velocimetry.

STUDY DESIGN

One hundred seventy-seven fetuses (160 normal fetuses and 17 fetuses with congenital anomalies that may affect fetal lung growth and/or development) were studied. Blood flow waveforms at the main branches of the pulmonary arteries were recorded by Doppler echocardiography from 20 to 39 weeks of gestation. The ratio of acceleration time to ejection time was calculated from the waveform as a parameter to predict pulmonary hypoplasia.

RESULTS

Doppler waveform of normal fetal pulmonary artery showed a "spike-and-dome" pattern. The normal values of acceleration time/ejection time ratio from the right and left pulmonary arteries were 0.17 +/- 0.04 and 0.15 +/- 0.04, respectively. These values were not significantly altered through the gestational age observed in this study. The acceleration time/ejection time ratio of either right or left pulmonary artery was measured successfully in all cases of fetal congenital anomalies. In 8 of 17 fetuses, acceleration time/ejection time ratio was measured at both of the pulmonary arteries. Because of a congenital anomaly that affected the fetal lung or thorax asymmetrically (as in congenital diaphragmatic hernia or congenital cystic adenomatoid malformations of the lung), the acceleration time/ejection time ratio of both of the pulmonary arteries could be measured in only 5 of 13 fetuses. The technical difficulties for the measurement always existed in the affected side. Eleven of the 17 fetuses with congenital anomalies survived without signs of clinical pulmonary hypoplasia or persistent pulmonary hypertension of the newborn infant. The fetuses revealed normal acceleration time/ejection time ratio from at least one pulmonary artery. The remaining 6 fetuses died of pulmonary hypoplasia, and the diagnosis was confirmed by autopsy or clinical findings. Of those 6 fetuses, 5 fetuses demonstrated the acceleration time/ejection time ratio below normal in one side, and the ratio could not be obtained on the other side; 1 fetus showed the acceleration time/ejection time ratio below the normal range in both sides.

CONCLUSION

The acceleration time/ejection time ratio by Doppler velocimetry that was obtained at the main branches of fetal pulmonary artery was consistent throughout gestational age from 20 to 39 weeks. This ratio appears to be an accurate parameter with which to predict the subsequent development of pulmonary hypoplasia and clinical outcomes of the newborn infants with high positive and negative predictive values (positive predictive value, 100%; negative predictive value, 100%).

Prenatal prediction of lethal pulmonary hypoplasia: the hyperoxygenation test for pulmonary artery reactivity

OBJECTIVE

The purpose of this study was to determine the predictive accuracy of a test for neonatal death from pulmonary hypoplasia by measuring changes in fetal pulmonary artery blood flow on room air and during maternal hyperoxygenation.

STUDY DESIGN

Women who were carrying fetuses with congenital anomalies that may cause pulmonary hypoplasia were offered participation in the study as part of a comprehensive fetal echocardiogram. Each fetus at > or =30 weeks of gestation underwent Doppler measurement of the blood flow pattern in the first branch of either the right or the left pulmonary artery before and again during exposure to maternal breathing of 60% oxygen by mask. An increase in the fetal pulmonary blood flow with oxygen (a decrease of > or =20% of the pulsatility index) was considered a reactive test. A change of <20% in the flow pattern during maternal hyperoxygenation was a nonreactive test and suggested pulmonary hypoplasia. The primary outcome for this study was neonatal death from pulmonary hypoplasia.

RESULTS

Twenty-nine pregnancies met the criteria for inclusion in our study. Of the 14 fetuses who had a nonreactive hyperoxygenation test, 11 fetuses (79%) died of pulmonary hypoplasia. Of the 15 fetuses who had a reactive hyperoxygenation test, only one fetus (7%) died in the neonatal period. Sensitivity, specificity, and positive and negative predictive values were 92%, 82%, 79%, and 93%, respectively, with an odds ratio of 51 (95% CI, 4.6-560).

CONCLUSION

Testing fetal pulmonary vascular reactivity with maternal hyperoxygenation is highly predictive of pulmonary hypoplasia. A reactive test predicted 92% of surviving infants; a nonreactive test predicted 79% of fetal deaths from pulmonary hypoplasia.

The fetal lung. 2: Pulmonary hypoplasia

This review describes the pathogenesis of pulmonary hypoplasia and highlights its clinical, radiological and pathologic features, with emphasis on oligohydramnios-related 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.

Serial fetal lung volume measurement using three-dimensional ultrasound

OBJECTIVE

To establish reference intervals for fetal lung growth.

DESIGN

Longitudinal observational study.

SUBJECTS

Fifty-eight women with initially uncomplicated singleton pregnancies were recruited from the antenatal population of a teaching hospital. Four women were excluded from the final analysis because of complications arising in their pregnancy.

METHODS

Each subject was serially scanned at monthly intervals. At each visit lung volume was measured using an ultrasound-based computerized three-dimensional imaging system. Multilevel models were used to determine conditional and unconditional reference intervals.

RESULTS

Reference intervals for fetal lung growth were derived. Fetal lung volume increases in a non-linear way with gestation.

CONCLUSIONS

Our computerized system has the capacity to be used in conjunction with any standard two-dimensional ultrasound scanner in order to measure volume. Lung volume measurement may be useful in predicting pulmonary hypoplasia.

Prenatal sonographic chest and lung measurements for predicting severe pulmonary hypoplasia

Pulmonary hypoplasia was diagnosed sonographically in 32 fetuses from 20 to 33 weeks of gestation. In addition to standard biometry, transverse thoracic diameter (TTD), sagittal thoracic diameter (TSD), thoracic circumference (TC) and lung diameter (LD) were measured in all cases and compared with known nomograms. The fetuses were divided into five groups according to the main sonographic findings: group 1-skeletal dysplasia; group 2-renal agenesis; group 3-diaphragmatic hernia; group 4-hydrothorax; and group 5-others. Severe pulmonary hypoplasia (PH) was diagnosed prenatally in all cases on the basis of LD measurements. In 17 (53.1 per cent) out of 32 cases TTD was below the 5th percentile while lower TSD measurements were recorded in 15 (46.8 per cent) fetuses. A thorax circumference below the 5th percentile for the respective gestational age was found in 15 cases (46.8 per cent) and a decreased LD/TC ratio in 25 cases (78.1 per cent). In 13 out of 32 fetuses pulmonary hypoplasia was diagnosed before, and in 19 cases after 24 weeks of gestation. Pulmonary hypoplasia was confirmed by autopsy in all cases.

CONCLUSION

pulmonary hypoplasia can be sonographically detected before 24 weeks of gestation. In cases of skeletal dysplasia and renal agenesis pulmonary hypoplasia can be diagnosed by chest and lung measurements, whereas in diaphragmatic hernia and hydrothorax diagnosis of pulmonary hypoplasia is possible only by lung measurement.

The changes in magnetic resonance properties of the fetal lungs: a first result and a potential tool for the non-invasive in utero demonstration of fetal lung maturation

OBJECTIVE

To measure magnetic resonance parameters T1 and T2 of the fetal lungs and investigate the relationship of these parameters to changes in volume and gestation.

DESIGN

Prospective cross-sectional study.

SETTING

Large teaching hospital in Nottingham and the Magnetic Resonance Centre at the University of Nottingham.

POPULATION

Normal pregnancies from 20 weeks to term.

METHODS

T1, T2, and lung volume were measured in the fetus using echo-planar magnetic resonance imaging.

MAIN OUTCOME MEASURES

The relationship of T1 and T2 to gestational age and lung volume.

RESULTS

Linear regression demonstrated a significant relationship (P < 0.001) between gestational age and lung volume, T1 and T2. There was also a significant relationship between lung volume and T1 and T2 (P < 0-001).

CONCLUSIONS

Relaxation time measurements give additional information to lung volume estimation in the assessment of lung physiology in utero. We have demonstrated the progressive changes which take place in the fetal lungs between 20 weeks and term. The physiological changes which can be demonstrated with this non-invasive technique may have an important application in the demonstration of fetal lung maturity in a prospective non-invasive manner.

[Congenital diaphragmatic hernia. II. Is pulmonary hypoplasia an indefinable obstacle?]

Despite major insights into the pathogenesis and pathophysiology of congenital diaphragmatic hernia, and despite the availability of an antenatal diagnosis and continuous progress in neonatal intensive care, little improvement has been obtained in the prognosis of this malformation. Thus obstetricians, neonatologists and pediatric surgeons are still facing a several dilemma: dilemma before birth to predict the prognosis, i.e., to evaluate the severity of the associated pulmonary hypoplasia in order to decide whether or not to interrupt pregnancy; dilemma after birth in case of severe respiratory failure to decide how far to go in life support. Based on a review of the literature and their own experience, the authors attempt to recapitulate the perinatal management and outcome of this severe malformation.

Management of preterm premature rupture of the membranes

In many cases, the management of preterm PROM will be dictated by the presence of advanced labor, intrauterine infection, placental abruption, or nonreassuring fetal testing. These patients should be delivered expeditiously, with group B streptococcus prophylaxis given where possible, and cesarean delivery reserved for routine obstetric indications. The stable patient with PPROM and documented fetal pulmonary maturity is best treated by early induction. Alternatively, the patient with PPROM remote from term can benefit from conservative treatment. Adjunctive antibiotic treatment and serial evaluation of maternal and fetal well-being offer significant potential for the reduction of perinatal morbidity. Although corticosteroid and tocolytic administration remain controversial, there is a theoretical benefit to their administration, particularly if concurrent antibiotic treatment is given to treat subclinical intrauterine infection.

Can blood gas values predict pulmonary hypoplasia in antenatally diagnosed congenital diaphragmatic hernia?

The prognosis of antenatally diagnosed congenital diaphragmatic hernias (CDH) is clearly related to the degree of pulmonary hypoplasia (PH). After birth, controversies remain regarding the implementation of various therapies, especially the use of extracorporeal membrane oxygenation (ECMO). In the literature, the persistence of a Pao2 below 100 mm Hg and of Paco2 above 40 mm Hg despite optimal conventional therapy indicates poor prognosis. Therefore, since 1992, published and personal experiences led the authors to exclude CDH patients from ECMO when conventional therapy (including high-frequency oscillatory ventilation and nitric oxide) did not obtain Pao2 of above 80 mm Hg and Paco2 of below 60 mm Hg. The aim of this retrospective study is to determine whether blood gas results correlate with postmortem findings. Between July 1990 and July 1994, 32 cases of CDH were monitored antenatally and managed postnatally at the authors' institution. Six patients survived; 26 died, including one immediately at birth. Thirteen were treated by ECMO. Seventeen had a best Pao2 of above 80 mm Hg, including the six survivors. Fourteen did not reach this level, and none of them survived. Twenty-three infants underwent postmortem examination. PH was assessed using two criteria: (1) lung weight to body weight ratio (LW/BW) and (2) radial alveolar count (RAC). Two patients did not have hypoplasia (LW/BW > 0.018). Twenty-one patients had PH; 12 of them had an LW/BW ratio of less than .009; for 9, the LW/BW ratio was between .009 and .018, and the RAC (< 3.1) confirmed PH. All infants with a best Pao2 of less than 80 mm Hg had PH. Patients with a best Pao2 of greater than 80 mm Hg included two infants who died from complications without PH, eight infants with demonstrated PH, and the six survivors. In conclusion. (1) No infant with nonhypoplastic lungs has been deprived of ECMO by the authors' criteria. (2) Adequate values of blood gases may not eliminate PH. Therefore, this probably justifies starting ECMO when conventional therapy fails. (3) Conversely, permanent poor values of Pao2 allowed the prediction of PH in all cases. Such patients probably can be excluded from ECMO treatment.

Defining limits of survival: lethal pulmonary hypoplasia after midtrimester premature rupture of membranes

OBJECTIVE

Our purpose was to determine prospectively whether sequential ultrasonographic assessment of amniotic fluid volume (< 1 cm vertical pocket constitutes severe oligohydramnios), in conjunction with other readily available clinical data, could predict the occurrence of pulmonary hypoplasia and neonatal mortality in pregnancies complicated by second-trimester premature rupture of membranes.

STUDY DESIGN

Singleton pregnancies complicated by premature rupture of membranes at < 29 weeks' gestation were prospectively monitored by weekly ultrasonographic assessments. Stepwise multiple logistic regression analysis was used to determine the independent predictive value of ultrasonographically determined factors in the development of lethal pulmonary hypoplasia, neonatal mortality, and skeletal deformations.

RESULTS

Neonatal mortality and pulmonary hypoplasia were statistically predicted by gestational age at rupture of membranes and interaction of premature rupture of membranes of > 14 days' duration with severe oligohydramnios. The occurrence of skeletal deformations was related to the interaction of duration of premature rupture of membranes and severe oligodramnios (p < 0.0001). Fetal breathing, fetal movements, and thoracic circumference/abdominal circumference ratios were not predictive of outcome.

CONCLUSIONS

Both duration of severe oligohydramnios exposure and gestational age at premature rupture of membranes were independent significant predictors of increased neonatal risk. Severe oligohydramnios > 14 days after premature rupture of membranes at < 25 weeks' gestation has a predicted neonatal mortality of > 90%.

Ultrasonographic prediction of lethal pulmonary hypoplasia: comparison of eight different ultrasonographic parameters

OBJECTIVE

The aim of this study was to determine the usefulness of eight different ultrasonographic fetal parameters for predicting fetal pulmonary hypoplasia.

STUDY DESIGN

Nomograms of eight different ultrasonographic fetal parameters were evaluated by studying uncomplicated single fetus pregnancies with well-established dates between 18 and 40 weeks of gestation. The eight parameters, which could reflect fetal lung mass, were as follows: thoracic circumference, thoracic area, thoracic area minus heart area, lung area, thoracic circumference/abdominal circumference ratio, thoracic area/heart area ratio, thoracic area minus heart area/thoracic area ratio and lung area/thoracic area ratio. The relative efficacy of the eight parameters was determined by studying 21 fetuses at high risk for development of lethal pulmonary hypoplasia and 30 fetuses with premature rupture of membranes within 1 week.

RESULTS

The lung area (gestational age-dependent parameter) and the thoracic circumference/abdominal circumference (gestational age-independent parameter) ratio had the best diagnostic accuracy (sensitivity 81.3% and 90.5%, specificity 100% and 90.0%, positive predictive value 100% and 86.4%, negative predictive value 90.9% and 93.1%, respectively). There were significant linear relationships between lung weight and lung area and between the lung weight/body weight ratio and the thoracic circumference/abdominal circumference ratio.

CONCLUSION

These data suggested that the application of lung area and the thoracic circumference/abdominal circumference ratio are clinically useful for the evaluation of fetal pulmonary hypoplasia.

Can Prenatal Ultrasound Predict Pulmonary Hypoplasia?

Pulmonary hypoplasia is often associated with sonographically detectable conditions: oligohydramnios, prolonged premature rupture of membranes, and, not infrequently, fetal anomalies. In their efforts to improve prenatal sonographic diagnosis of this condition, investigators have used an array of different sonographic biometric measurements and fetal behavioral patterns. Definitions of these measurements and their respective successes in predicting pulmonary hypoplasia are presented. The sonographic parameters that have been of most value in the prediction of pulmonary hypoplasia are chest circumference, direct measurements of the lung, lung length, lung span to hemithorax diameter, and more complex formulas, such as lung area/heart area x 100/chest area. Although fetal measurements may help predict pulmonary hypoplasia, no single sonographic finding consistently leads to a prediction of the presence of pulmonary hypoplasia. Therefore, obstetric management (i.e., nonintervention) cannot currently be altered with the finding of abnormal biometric parameters unless a known lethal anomaly is observed.

Prenatal ultrasonographic diagnosis of acardiac twin

Acardiac twinning is a rare complication of monozygotic twin gestation occurring in 1/35,000 pregnancies or in 1% of all monozygotic twins. This condition is characterized by partial or complete lack of development of the heart in one of the twins, and requires that the normal twin (pump twin) provides circulation for itself as well as the acardiac sibling (perfused twin) by means of reverse circulation through large artery-to-artery and vein-to-vein anastomoses. The acardiac anomaly is uniformly fatal for the perfused twin, and the perinatal mortality for the normal twin is about 50%, usually as the result of congestive heart failure, polyhydramnios, and preterm delivery. In this report we present two cases of acardiac twin prenatally diagnosed by ultrasound. The principal sonographic features for prenatal diagnosis and the clinical management are briefly discussed.

Prenatal evaluation and obstetrical management of fetuses at risk of developing lung hypoplasia

The aim of this study was to measure the fetal lung area of normal human fetuses using ultrasound and them to test the predictive values of a nomogram in the identification of fetal lung hypoplasia. A nomogram for ultrasound-measured fetal lung area were constructed from 264 normal fetuses from 17 to 39 weeks of gestation. In 19 cases running the risk of developing lung hypoplasia, the sensitivity, specificity, and positive and negative predictive values of lung area measurements below the mean -2 SD were 75%, 100%, 94% and 100%, respectively, with total lung area showing a significant relation to the combined lung weight (Y = -1.05 + 2.06 X, r2 = 0.88). These results indicate that lung area measured by ultrasound is a good indicator of lung weight, and this nomogram of lung area may be useful in evaluating lung growth prenatally, as well as in the direct obstetrical management of fetuses at risk of developing lung hypoplasia.

A case report: vesico-rectal fistula with ano-urethral atresia

Vesico-rectal fistula is a rare congenital abnormality causing severe early second trimester oligohydramnios. Prenatal diagnosis of such a case is reported here. Ultrasound diagnosis could be aided by transabdominal amnio-infusion and, if necessary, fetal intraperitoneal saline installation. In a karyotypically normal fetus with normal somatic growth, demonstration of normal fetal kidneys together with a functioning urinary bladder, in presence of severe oligohydramnios, is very suggestive of the diagnosis. Since pulmonary hypoplasia is the major cause of neonatal mortality in these cases, restoration of normal amniotic fluid volume by serial amnio-infusion was attempted. Although amnio-infusion is an important diagnostic aid in the evaluation of severe midtrimester oligohydramnios, the role of multiple therapeutic amnio-infusion in improving lung growth remains to be evaluated.

Lethal Pena-Shokeir 1 syndrome in three male siblings

A consanguineous family with no living children and three male siblings with Pena-Shokeir 1 syndrome is described. Two children died antepartum and the third shortly after delivery. The importance of early prenatal diagnosis, appropriate counseling and thorough evaluation of the neuromuscular system is discussed.

Serial thoracic versus abdominal circumference ratios for the prediction of pulmonary hypoplasia in premature rupture of the membranes remote from term

OBJECTIVES

The purpose of this study was to evaluate the fetal thoracic versus abdominal circumference ratio in the prediction of pulmonary hypoplasia after preterm premature rupture of the membranes.

STUDY DESIGN

A standard curve of thoracic versus abdominal circumference ratio versus gestational age was derived from 120 uncomplicated pregnancies. Thoracic versus abdominal circumference ratio and amniotic fluid estimations were obtained serially in 16 women with premature rupture of the membranes at less than 26 weeks' gestation.

RESULTS

An abnormal thoracic versus abdominal circumference ratio predicted lethal pulmonary hypoplasia in six infants. A progressive decline in thoracic versus abdominal circumference ratio was identified in all of these patients. Six of eight women with persistent oligohydramnios had abnormal thoracic versus abdominal circumference ratios and lethal pulmonary hypoplasia. Two surviving infants had restriction deformities and pulmonary complications.

CONCLUSIONS

In the setting of premature rupture of the fetal membranes at less than 26 weeks, serial thoracic versus abdominal circumference ratio measurement is a reliable predictor of pulmonary hypoplasia. Persistent oligohydramnios is ominous because of the risk of restriction deformities and pulmonary complications in the survivors.

Prenatal diagnosis of lethal osteogenesis imperfecta in twin pregnancy

Lethal osteogenesis imperfecta was diagnosed at 27 weeks amenorrea in one fetus of a bichorial twin pregnancy. Sonographic findings included: short-limb dwarfism, hypotrophy and hypoechoic bones. The affected fetus was so translucent that only the normal fetus could be seen on plain in utero radiography. The affected fetus died immediately after birth. Postmortem radiography and histology were typical of lethal osteogenesis imperfecta of type IIA. Aids to the etiological diagnosis of in utero dwarfism are presented. Sonographic features correlated with neonatal death are described.

Direct ultrasonographic measurement of fetal lung length in normal pregnancies and pregnancies complicated by prolonged rupture of membranes

Fetal lung length was measured directly with ultrasonography in 20 patients with prolonged rupture of membranes, commencing before 25 weeks' gestation. Measurements were made weekly and compared with data collected from 310 normal pregnancies. Measurement of fetal lung length by ultrasonography was a good predictor of pulmonary hypoplasia, predicting greater than 90% of cases. There was a good correlation between lung size assessed by the last ultrasonographic examination and lung weight postmortem (r = 0.783, p less than 0.05). Lung length measurements were superior to fetal chest circumference measurements in the identification of pulmonary hypoplasia. There was a significant negative association between the amount of amniotic fluid and pulmonary hypoplasia (p less than 0.05). There were fetuses with pulmonary hypoplasia that had respiratory movements seen at the majority of ultrasonographic examinations.

Disorders of the fetal thorax and abdomen

Many disorders of the fetal thorax and abdomen can be evaluated using ultrasound. Even when a definitive diagnosis cannot be made prenatally, sonography can provide valuable clinical information regarding the nature and location of the abnormality, associated anomalies, and the presence of secondary complications. An awareness of these disorders and their sonographic appearance is important to impact upon obstetrical management and overall prognosis.

Ductus arteriosus flow velocity modulation by fetal breathing movements as a measure of fetal lung development

A test is needed that would accurately predict favorable neonatal lung performance in the presence of prolonged severe oligohydramnios caused by ruptured membranes so that optimal obstetric care can be provided. We propose such a test that is based on the degree of modulation of fetal ductal blood flow velocity by fetal breathing movements after maternal glucose loading. In a prospective cross-sectional study of 49 normal pregnancies (50 fetuses) between 25 and 38 weeks an exponential increase in breathing-related ductal blood flow velocity modulation was observed with advancing gestational age, reflecting the developing pulmonary vascular bed. Fetal ductal flow velocity waveforms were also recorded in 13 cases of prolonged severe oligohydramnios after ruptured membranes before 28 weeks' gestation. Normal ductal blood flow velocity modulation values were associated with normal neonatal lung performance, whereas reduced ductal blood flow velocity modulation values were associated with pulmonary hypoplasia. Fetal breathing-related ductal flow velocity modulation appears to be a promising predictor of neonatal lung performance.