United States' experience in nuchal translucency measurement: variation according to provider characteristics in over five million ultrasound examinations

OBJECTIVE

The Nuchal Translucency Quality Review (NTQR) program has provided standardized education, credentialing and epidemiological monitoring of nuchal translucency (NT) measurements since 2005. Our aim was to review the effect on NT measurement of provider characteristics since the program's inception.

METHODS

We evaluated the distribution of NT measurements performed between January 2005 and December 2019, for each of the three primary performance indicators of NT measurement (NT median multiples of the median (MoM), SD of log₁₀ NT MoM and slope of NT with respect to crown-rump length (CRL)) for all providers within the NTQR program with more than 30 paired NT/CRL results. Provider characteristics explored as potential sources of variability included: number of NT ultrasound examinations performed annually (annual scan volume of the provider), duration of participation in the NTQR program, initial credentialing by an alternative pathway, provider type (physician vs sonographer) and number of NT-credentialed providers within the practice (size of practice). Each of these provider characteristics was evaluated for its effect on NT median MoM and geometric mean of the NT median MoM weighted for the number of ultrasound scans, and multiple regression was performed across all variables to control for potential confounders.

RESULTS

Of 5 216 663 NT measurements from 9340 providers at 3319 sites, the majority (75%) of providers had an NT median MoM within the acceptable range of 0.9-1.1 and 85.5% had NT median MoM not statistically significantly outside this range. Provider characteristics associated with measurement within the expected range of performance included higher volume of NT scans performed annually, practice at a site with larger numbers of other NT-credentialed providers, longer duration of participation in the NTQR program and alternative initial credentialing pathway.

CONCLUSIONS

Annual scan volume, duration of participation in the NTQR program, alternative initial credentialing pathway and number of other NT-credentialed providers within the practice are all associated with outcome metrics indicating quality of performance. It is critical that providers participate in ongoing quality assessment of NT measurement to maintain consistency and precision. Ongoing assessment programs with continuous feedback and education are necessary to maintain quality care. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Fetal hydrops and the Incremental yield of Next-generation sequencing over standard prenatal Diagnostic testing (FIND) study: prospective cohort study and meta-analysis

OBJECTIVE

To determine the incremental yield of exome sequencing (ES) over chromosomal microarray analysis (CMA) or karyotyping in prenatally diagnosed non-immune hydrops fetalis (NIHF).

METHODS

A prospective cohort study (comprising an extended group of the Prenatal Assessment of Genomes and Exomes (PAGE) study) was performed which included 28 cases of prenatally diagnosed NIHF undergoing trio ES following negative CMA or karyotyping. These cases were combined with data from a systematic review of the literature. MEDLINE, EMBASE, CINAHL and ClinicalTrials.gov databases were searched electronically (January 2000 to October 2020) for studies reporting on the incremental yield of ES over CMA or karyotyping in fetuses with prenatally detected NIHF. Inclusion criteria for the systematic review were: (i) at least two cases of NIHF undergoing sequencing; (ii) testing initiated based on prenatal ultrasound-based phenotype; and (iii) negative CMA or karyotyping result. The incremental diagnostic yield of ES was assessed in: (i) all cases of NIHF; (ii) isolated NIHF; (iii) NIHF associated with an additional fetal structural anomaly; and (iv) NIHF according to severity (i.e. two vs three or more cavities affected).

RESULTS

In the extended PAGE study cohort, the additional diagnostic yield of ES over CMA or karyotyping was 25.0% (7/28) in all NIHF cases, 21.4% (3/14) in those with isolated NIHF and 28.6% (4/14) in those with non-isolated NIHF. In the meta-analysis, the pooled incremental yield based on 21 studies (306 cases) was 29% (95% CI, 24-34%; P < 0.00001; I²  = 0%) in all NIHF, 21% (95% CI, 13-30%; P < 0.00001; I²  = 0%) in isolated NIHF and 39% (95% CI, 30-49%; P < 0.00001; I²  = 1%) in NIHF associated with an additional fetal structural anomaly. In the latter group, congenital limb contractures were the most prevalent additional structural anomaly associated with a causative pathogenic variant, occurring in 17.3% (19/110) of cases. The incremental yield did not differ significantly according to hydrops severity. The most common genetic disorders identified were RASopathies, occurring in 30.3% (27/89) of cases with a causative pathogenic variant, most frequently due to a PTPN11 variant (44.4%; 12/27). The predominant inheritance pattern in causative pathogenic variants was autosomal dominant in monoallelic disease genes (57.3%; 51/89), with most being de novo (86.3%; 44/51).

CONCLUSIONS

Use of prenatal next-generation sequencing in both isolated and non-isolated NIHF should be considered in the development of clinical pathways. Given the wide range of potential syndromic diagnoses and heterogeneity in the prenatal phenotype of NIHF, exome or whole-genome sequencing may prove to be a more appropriate testing approach than a targeted gene panel testing strategy. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Variants of uncertain significance in prenatal microarrays: a retrospective cohort study

OBJECTIVE

To categorise the variants of uncertain significance found with prenatal chromosomal microarray and determine the proportion of such variants that are associated with a well-known phenotype in order to establish how often they remain truly of uncertain significance.

DESIGN

Retrospective cohort study.

SETTING

The University of California, San Francisco.

POPULATION

All patients with a variant of uncertain significance on prenatal microarray between 2014 and 2018.

METHODS

Each variant was classified as a copy number variant that (a) contains Online Mendelian Inheritance in Man (OMIM)-annotated disease-causing genes ('OMIM morbid genes'); (b) confers autosomal recessive carrier status; (c) is associated with incomplete penetrance; (d) is >1 Mb in size without OMIM morbid genes; (e) demonstrates mosaicism; or (f) contains significant regions of homozygosity. For each variant of uncertain significance, we examined the existing literature to determine whether the predicted phenotype(s) was known.

MAIN OUTCOME MEASURE

Prevalence and classification of variants and how much information is available regarding the likelihood of an affected phenotype.

RESULTS

Of 970 prenatal microarrays, 55 (5.8%) had at least one variant of uncertain significance. The most common were copy number variants containing OMIM morbid genes (36.8%). In all, 48 (84.2%) were associated with a known phenotype; 55 (96.5%) had data available regarding the likelihood of an affected phenotype.

CONCLUSIONS

The prevalence of variants of uncertain significance with prenatal microarray was 5.8%. In the large majority of cases, data were available regarding the predicted phenotype.

TWEETABLE ABSTRACT

Variants of uncertain significance occur in 5.8% of prenatal microarrays. In the overwhelming majority of cases, outcome information is available.

Outcomes of pregnancies with more than one positive prenatal screening result in the first or second trimester

OBJECTIVE

To describe adverse outcomes and fetal abnormalities in women with a positive prenatal screening result for more than one disorder.

STUDY DESIGN

Study participants were drawn from a population of 452 901 women pregnant with singletons entering the California Prenatal Screening Program in their first-trimester. Risk assessment was provided for trisomy 21 and trisomy 18 in the first-trimester and trisomy 21, trisomy 18, neural tube defects, and Smith-Lemli-Opitz syndrome in the second-trimester. Inclusion in this study required positive screening for more than one of the screened conditions and a completed outcome of pregnancy survey.

RESULTS

A total of 874 women met our study inclusion criteria. Over 25% of these pregnancies had a fetus with a chromosomal abnormality. Of the euploid pregnancies, 6.9% had a fetus with a major birth defect. Of the pregnancies with a fetus with neither a chromosomal abnormality nor a major birth defect, 9.3% ended in fetal demise. Overall, more than 50% of women with multiple positive screening results had either a fetus with a birth defect or a poor pregnancy outcome.

CONCLUSION

Although it is rare to screen positive for more than one condition, such results indicate a very high risk for chromosomal abnormality, fetal demise, or structural abnormality.

Best ethical practices for clinicians and laboratories in the provision of noninvasive prenatal testing

OBJECTIVE

The goal of this study is to provide an ethical framework for clinicians and companies providing noninvasive prenatal testing using cell-free fetal DNA or whole fetal cells.

METHOD

In collaboration with a National Institutes of Health-supported research ethics consultation committee together with feedback from an interdisciplinary group of clinicians, members of industry, legal experts, and genetic counselors, we developed a set of best practices for the provision of noninvasive prenatal genetic testing.

RESULTS

Principal recommendations include the amendment of current informed consent procedures to include attention to the noninvasive nature of new testing and the potential for a broader range of results earlier in the pregnancy. We strongly recommend that tests should only be provided through licensed medical providers and not directly to consumers.

CONCLUSION

Prenatal tests, including new methods using cell-free fetal DNA, are not currently regulated by government agencies, and limited professional guidance is available. In the absence of regulation, companies and clinicians should cooperate to adopt responsible best ethical practices in the provision of these tests.

Transdisciplinary translational science and the case of preterm birth

Medical researchers have called for new forms of translational science that can solve complex medical problems. Mainstream science has made complementary calls for heterogeneous teams of collaborators who conduct transdisciplinary research so as to solve complex social problems. Is transdisciplinary translational science what the medical community needs? What challenges must the medical community overcome to successfully implement this new form of translational science? This article makes several contributions. First, it clarifies the concept of transdisciplinary research and distinguishes it from other forms of collaboration. Second, it presents an example of a complex medical problem and a concrete effort to solve it through transdisciplinary collaboration: for example, the problem of preterm birth and the March of Dimes effort to form a transdisciplinary research center that synthesizes knowledge on it. The presentation of this example grounds discussion on new medical research models and reveals potential means by which they can be judged and evaluated. Third, this article identifies the challenges to forming transdisciplines and the practices that overcome them. Departments, universities and disciplines tend to form intellectual silos and adopt reductionist approaches. Forming a more integrated (or 'constructionist'), problem-based science reflective of transdisciplinary research requires the adoption of novel practices to overcome these obstacles.

Agenesis of the corpus callosum: an MR imaging analysis of associated abnormalities in the fetus

BACKGROUND AND PURPOSE

Anomalies associated with callosal agenesis (ACC) found postnatally have been well documented. However, to our knowledge, no detailed MR imaging analysis of associated anomalies has been reported in a large cohort of fetuses with ACC. This study will assess those anomalies and compare them with postnatal cohorts of ACC, to identify associated fetal brain abnormalities that may give insight into etiology and outcome.

MATERIALS AND METHODS

All cases of ACC diagnosed on fetal MR imaging during an 11-year period were retrospectively reviewed, including fetal MR imaging, postnatal MR imaging, and autopsy findings. Neurodevelopmental outcome was classified as poor in children with seizures and/or severe neurodevelopmental impairment or in cases of neonatal death.

RESULTS

Twenty-nine cases of ACC were identified. Median gestational age was 26.14 weeks (range, 19.71-36.43 weeks). Twenty-three fetuses had delayed sulcation and/or too-numerous cortical infoldings (abnormal morphology). Fifteen fetuses had cerebellar and/or brain stem abnormalities. Fetal MR imaging findings suggested a genetic syndrome in 5 fetuses and an acquired etiology or genetic/metabolic disorder in 2 fetuses. Findings were confirmed in 8 cases with postnatal MR imaging, except for delayed sulcation and small vermis, and in 4 cases with autopsy, except for periventricular nodular heterotopia and abnormalities in areas not examined by autopsy. Neurodevelopmental outcome was good in 7 and poor in 9 children. Abnormal sulcal morphology and/or infratentorial abnormalities were present in those with poor outcome and absent in those with good outcome.

CONCLUSIONS

ACC is infrequently isolated in fetuses. Abnormal sulcation is common and suggests more diffuse white matter dysgenesis in these fetuses.

Ethnic variation in the prevalence of echogenic intracardiac foci and the association with Down syndrome

OBJECTIVE

To determine whether the prevalence of fetal echogenic intracardiac foci (EIF) differs according to maternal ethnicity.

METHODS

We performed a retrospective cohort study of all women undergoing second-trimester diagnostic ultrasound examination and amniocentesis at a prenatal diagnosis referral center from January 1 2000 to July 1 2003. Data were collected on the presence of EIF, gestational age at time of ultrasound scan, karyotype results, maternal age and ethnicity. Univariate and multivariate analyses of EIF, ethnicity and presence of aneuploidy were conducted.

RESULTS

Among the 7480 women qualifying for the study, EIF were found in 309 (4.1%). When maternal ethnicity was subdivided into Caucasian, African-American, Hispanic, Asian-American, Native American, Asian Indian, and Middle Eastern, the highest rates of EIF were found in fetuses of African-American (6.7%), Asian-American (6.9%), and Middle Eastern (8.1%) mothers compared to a rate of 3.3% in Caucasians (P < 0.001). In all ethnic groups except Hispanics, EIF was associated with an increased risk for Down syndrome (odds ratio range from 1.8 to 15.7).

CONCLUSIONS

African-American, Asian-American, and Middle Eastern patients are more likely than patients of other ethnicities to have a fetus with an EIF. Even controlling for ethnicity, fetuses with an EIF still have an increased risk for Down syndrome. As more data accumulate, the prevalence of EIF and its association with Down syndrome among different ethnic groups can be incorporated into patient counseling.

The impact of the use of the isolated echogenic intracardiac focus as a screen for Down syndrome in women under the age of 35 years

OBJECTIVE

The purpose of this study was to determine the public health impact of the routine offering of amniocentesis to women under the age of 35 years who have an isolated fetal echogenic intracardiac focus on second trimester ultrasound scan.

STUDY DESIGN

A decision analytic model was designed that compared the accepted standard of second trimester triple marker screen for Down syndrome to a policy in which amniocentesis with an isolated echogenic intracardiac focus on ultrasound in addition to the triple marker screen is offered to all women in the United States who are <35 years of age. A sensitivity of 20%, an echogenic intracardiac focus screen positive rate of 5%, and a risk of Down syndrome of 1:1000 were assumed. A sensitivity analysis was performed that varied the screen positive rate, the sensitivity of echogenic intracardiac focus for Down syndrome, and the prescreen risk for Down syndrome in the population.

RESULTS

With the baseline sensitivities, rates, and risks, the use of isolated echogenic intracardiac focus as a screen would result in an additional 118,146 amniocenteses performed annually to diagnose 244 fetuses with Down syndrome. These amniocenteses would result in 582 additional miscarriages. It would be necessary to perform 485 amniocenteses that would result in 2.4 procedure-related losses for each additional Down syndrome fetus that was identified.

CONCLUSION

Although the echogenic intracardiac focus appears to be associated with a small increased risk of Down syndrome, its use as a screening tool in low-risk populations would lead to a large number of amniocenteses and miscarriages to identify a small number of Down syndrome fetuses.

A case of chondrodysplasia punctata with features of osteogenesis imperfecta type II

The osteogenesis imperfecta syndromes constitute a group of heterogeneous, heritable skeletal dysplasias. Of the 4 types, type II is the most severe, with an incidence of 1 per 55,000. It is characterized by malformed bones secondary to abnormal collagen type I synthesis. Affected fetuses are divided into 3 groups: A, B, and C. All groups have long bones described as "wrinkled" or "crumpled" secondary to repeated fractures. Many bones also show evidence of demineralization, which is especially evident in the bones of the face and calvaria. In groups A and C, the chest is generally small, with thickened and shortened ribs, and each rib has characteristic "beading" patterns secondary to repeated fracturing. Sonography has traditionally been successful in the diagnosis of osteogenesis imperfecta at an early gestational age. Chondrodysplasia punctata describes a heterogeneous group of skeletal disorders characterized by abnormal mineralization of bones during gestation. There are many different causes of it, but some of the specific subtypes include rhizomelic, X-linked dominant (also known as Conradi-Hünermann syndrome), X-linked recessive, and tibia-metacarpal. We report a case of severe X-linked dominant chondrodysplasia punctata, which sonographically had common features with osteogenesis imperfecta type II.

Prenatal diagnosis and characterization of an unbalanced whole arm translocation resulting in monosomy for 18p

Monosomy for the short arm of chromosome 18 is one of the most frequent autosomal deletions observed. While most cases result from terminal deletion of 18p, 16% of cases reported were as a result of an unbalanced whole arm translocation resulting in monosomy 18p. The origin and structure of these derivative chromosomes were reported in only a few cases. We report the prenatal diagnosis and characterization of a new case of monosomy 18p as a result of an unbalanced whole arm translocation. Amniocentesis was performed at 15 weeks of gestation on a 34-year-old woman initially referred for advanced maternal age. Holoprosencephaly was identified by ultrasound at the time of amniocentesis. Karyotype analysis showed an unbalanced whole arm translocation between the long arm of one chromosome 18 and the long arm of one chromosome 22, 45,XX,der(18;22)(q10;q10), in all metaphases. In effect, the fetus had monosomy for 18p. Parental karyotypes were normal, suggesting a de novo origin for the der(18;22). Fluorescence in situ hybridization (FISH) analysis was performed with alpha-satellite probes D18Z1 and D14Z1/D22Z1 to identify the origin of the centromere on the der(18;22). Signal was observed with both probes, indicating that the centromere was composed of alpha-satellite DNA from both constituent chromosomes. Genotyping of the fetus and her parents with chromosome 18p STS marker D18S391 showed only the paternal 187 bp allele was present in the fetus, indicating that it was the maternal chromosome 18 involved in the der(18;22). This case and previous reports show that de novo unbalanced whole arm translocations are more likely to retain alpha-satellite sequences from the two chromosomes involved.

Outcome of pregnancy after prenatal diagnosis of umbilical vein varix

Previous studies of umbilical vein varix diagnosed prenatally have been small, and the results have been contradictory. We wanted to determine whether prenatally diagnosed umbilical vein varix is associated with an increased risk of fetal anomalies or poor perinatal outcomes. We identified all cases of fetal intra-abdominal umbilical vein varix diagnosed on the basis of prenatal ultrasonography at Brigham and Women's Hospital between 1988 and 1998. Cases were reviewed to determine the presence of other sonographic findings as well as pregnancy and neonatal outcomes. We identified 25 cases and included those 23 for which follow-up was available. In 11 cases (48%), pregnancies and neonatal outcomes were normal, with full-term delivery, appropriate birth weight, and no evidence of anomalies. Three cases (13%) had preterm deliveries, and 1 had Kell isoimmunization requiring postnatal transfusion. In the remaining 8 cases (35%), structural anomalies were present. One fetus had a chromosomal abnormality (69,XXX). Prenatal diagnosis of fetal umbilical vein varix appears to be associated with a high rate of fetal anomalies. Detection of an umbilical vein varix should prompt a thorough examination of the fetus, including a fetal survey and echocardiogram. Isoimmunization should be ruled out, and consideration of karyotyping should be discussed if other anomalies are present.

Predicting the risk of cystic fibrosis with echogenic fetal bowel and one cystic fibrosis mutation

OBJECTIVE

To assess fetal risk for cystic fibrosis when echogenic bowel and one cystic fibrosis mutation are detected.

METHODS

A hypothetical cohort of 1000 women with singleton pregnancies and echogenic fetal bowel during the second trimester was used to determine the probability of cystic fibrosis when one cystic fibrosis transmembrane conductance regulator mutation was detected. The risk of cystic fibrosis was calculated using the range of prevalence of cystic fibrosis in fetuses with echogenic bowel reported in the literature. Risk calculations for fetuses of Ashkenazi Jewish, Northern European, African-American, Hispanic, and Asian descent accounted for carrier frequencies and mutation detection rates specific to each ethnic group.

RESULTS

As the assumed prevalence of cystic fibrosis increases from 1-25%, the probability that a white fetus with one mutation and echogenic fetal bowel actually has cystic fibrosis increases from 4.8% to 62.5%. Assuming a 2% risk of cystic fibrosis with echogenic fetal bowel, an Ashkenazi Jewish fetus and an Asian fetus with echogenic bowel and one mutation have a 3.1% and 72% risk of cystic fibrosis, respectively. The probability of cystic fibrosis in a nonwhite fetus is between those two extremes.

CONCLUSION

The probability of cystic fibrosis after detection of echogenic bowel and one cystic fibrosis mutation varied among ethnic groups. Even at the highest prevalence of cystic fibrosis, most white fetuses will not have cystic fibrosis. In nonwhite populations almost half of these fetuses will have cystic fibrosis, even at the lowest prevalence of cystic fibrosis.

Cystic fibrosis and chromosome abnormalities associated with echogenic fetal bowel

OBJECTIVE

To determine the prevalence of cystic fibrosis mutations and chromosome abnormalities in the fetuses of a heterogeneous population of pregnant women referred for prenatal testing for echogenic fetal bowel.

METHODS

Fetal or parental samples obtained after a second-trimester sonographic finding of echogenic fetal bowel were submitted to a referral diagnostic laboratory during a 2-year period. Results of DNA testing and karyotyping on these samples were analyzed to determine the prevalence of cystic fibrosis transmembrane reductase gene mutations and chromosome abnormalities.

RESULTS

Of 244 cases tested, two fetuses were positive for two cystic fibrosis mutations. This rate (0.8% or two of 244) is 20 times higher than the general white population rate of one per 2500. In a third case, both parents were carriers but the fetus was not tested. Nine (8%) of 113 fetuses tested had one cystic fibrosis mutation. Of 106 fetuses for whom chromosome results were available, three (2.8%) fetuses had a chromosomal abnormality: two had trisomy 21 and one had Klinefelter syndrome. A fourth fetus carried a de novo, apparently balanced, 5;12 translocation.

CONCLUSION

These laboratory results are representative of a broad spectrum of clinical settings and indicate a generalized increased risk associated with this sonographic finding. Therefore, when a second-trimester sonographic diagnosis of fetal echogenic bowel is made, fetal testing for both cystic fibrosis and chromosome abnormalities is warranted.

Costello syndrome: phenotype, natural history, differential diagnosis, and possible cause

We describe 8 patients affected with Costello syndrome including an affected sib pair and review the literature on 29 previously reported cases. We emphasize an association with advanced parental age, which is consistent with autosomal dominant inheritance with germline mosaicism. The pathogenesis appears to involve metabolic dysfunction, with growth disturbance, storage disorder appearance, acanthosis nigricans, hypertrophic cardiomyopathy, and occasional abnormalities of glucose metabolism. Although the cause is currently unknown, Costello syndrome is interesting because of a potential genetic-metabolic etiology.

Behçet's syndrome associated with intrauterine growth restriction: a case report and review of the literature

BACKGROUND

Behçet's syndrome is an immune-mediated connective tissue disorder, and its primary manifestations are oral and genital ulcerations. To our knowledge no cases of adverse fetal outcome have been reported in pregnancies complicated by this disease.

CASE

A 27-year-old primigravid woman with a diagnosis of Behçet's disease came to our institution during the first trimester. Her pregnancy was complicated by several exacerbations of her disease including vaginal and oral ulcerations and abdominal pain. She was treated with steroids throughout her pregnancy. She had ruptured membranes and evidence of fetal distress at 361/2 weeks and subsequently delivered a severely growth-restricted fetus (< 3rd percentile).

CONCLUSION

Pregnancies complicated by Behçet's disease should be monitored closely for evidence of intrauterine growth restriction and fetal compromise, as are pregnancies complicated by similar connective tissue disorders.

Cost-effectiveness of strategies used in the evaluation of pregnancies complicated by elevated maternal serum alpha-fetoprotein levels

OBJECTIVE

To perform a cost-effectiveness analysis of various protocols used in the diagnostic evaluation of pregnancies complicated by elevated levels of maternal serum alpha-fetoprotein (MSAFP).

METHODS

The variables incorporated in this model were the prevalence of relevant fetal anomalies; the sensitivity and specificity of MSAFP at 2.0 or 2.5 multiples of the median (MoM); and the sensitivity, specificity, cost, and safety of targeted ultrasound and amniocentesis. We expressed the cost-effectiveness of each strategy as the total cost of the diagnostic evaluation divided by the number of anomalous fetuses identified, yielding the cost per identified anomalous fetus.

RESULTS

In a hypothetical cohort of 100,000 singleton pregnancies, a strategy of targeted ultrasound for MSAFP of at least 2.0 MoM detected 90 of 110 structurally abnormal fetuses, without iatrogenic fetal loss, at a cost of $5700 per anomalous fetus. A strategy of amniocentesis with karyo-type determination for MSAFP of at least 2.5 MoM detected 15 additional abnormal fetuses (87 structural abnormalities, ten autosomal aneuploidies, and eight sex chromosomal aneuploidies), with nine iatrogenic fetal losses, at an incremental cost of $46,100 per anomalous fetus.

CONCLUSION

The increased cost and iatrogenic fetal loss rate may not justify the increased diagnostic yield of amniocentesis as compared with ultrasound in the evaluation of pregnancies complicated by elevated MSAFP.

Molecular zygosity studies aid in the management of discordant multiple gestations

OBJECTIVE

Management of multiple gestations often requires identification of chorionicity. Sonographic evidence of dichorionicity can be present or inconclusive. DNA determination of zygosity can aid in the subsequent management of twins who are discordant for growth or anomalies.

STUDY DESIGN

We present four cases in which monochorionicity could not be excluded sonographically. DNA zygosity studies were performed on amniocytes to guide management of the pregnancies.

RESULTS

In two cases, one twin was affected with a significant anomaly. DNA zygosity studies provided a greater than 99% likelihood of monozygous twins in both cases. This altered the counseling regarding selective termination options. The other two cases involved severe intrauterine growth restriction and oligohydramnios in one twin, with a normal co-twin. The small twin appeared nonviable, and DNA studies were used to assess risk to the normal twin in the event of the co-twin's demise. We recommended delivery in the event of monozygous twinning and expectant management if the twins were dizygous.

CONCLUSION

Diagnosis of chorionicity is important in multiple gestations. When chorionicity is unclear and management decisions would be altered by determination of zygosity, DNA studies should be considered.

Interaction of hypertension and diabetes on renal function in black NIDDM subjects

We studied renal function of 194 black subjects with duration of diagnosed NIDDM from 1 month to 36 years to determine the interaction of hypertension and diabetes on nephropathy. Renal function was assessed by isotopic GFR and RPF studies, and serum creatinine. One hundred seventeen of the 194 subjects had 24-hour urinary albumin excretion (AER). AER > 300 mg/24 h correlated with longer duration of NIDDM, decrease in GFR and RPF, and rise in serum Cr, and all subjects were hypertensive. AER 30 to 300 mg/24 h also correlated with a longer duration of NIDDM and 80% had hypertension. When 194 subjects were grouped according to duration of NIDDM and the presence or absence of hypertension, subjects who remained normotensive had normal renal function. In hypertensive subjects a decrease in GFR occurred with duration of NIDDM > 1 year and decrease in RPF with duration of NIDDM > 5 years. In hypertensive subjects with NIDDM > 10 years, 36% had impaired renal function (GFR < 80 ml/min/1.73 m2 or serum creatinine > 1.4 mg/dl) and 75% had microalbuminuria or clinical proteinuria. Within this group, those subjects who developed hypertension after their diagnosis of diabetes were likely to have evidence of nephropathy as compared to those subjects whose hypertension was diagnosed prior to or simultaneous with their diabetes: 17 of 20 (85%) versus 7 of 13 (54%), respectively (P = 0.05). These data provide insight into the relationship between hypertension and diabetes in the development of nephropathy in black NIDDM individuals.

Nonimmune hydrops fetalis

In summary, NIHF is a heterogenous disorder resulting from a vast number of underlying pathologies. A thorough evaluation should be performed in all cases to attempt to establish the etiology. This requires a systematic approach that should logically proceed from least to most invasive testing. Despite increasing availability of treatment for some causes of NIHF, the prognosis for this condition in general remains poor. In cases of fetal or neonatal demise, autopsy should be encouraged to aid in confirming or making a diagnosis. It is especially important to rule out potentially treatable conditions, as well as genetic disorders with a risk of recurrence in future pregnancies.

Uniparental isodisomy for paternal 7p and maternal 7q in a child with growth retardation

Uniparental isodisomy resulting from the simultaneous presence of isochromosomes of the p and q arms of a chromosome and absence of a normal homologue is an exceptionally rare event. We have observed a growth-retarded female infant in whom the normal chromosome 7 homologues were replaced by what appeared cytogenetically to be isochromosomes of 7p and 7q. Polymorphic microsatellite loci spanning the length of 7p and 7q were analyzed in the proband and her parents to ascertain the parental origin and extent of heterozygosity of the proband's rearranged chromosomes. These studies demonstrated that the 7p alleles of the proband were derived only from the father, the 7q alleles were derived only from the mother, and there was homozygosity for all chromosome 7 loci analyzed. The mechanisms leading to the formation of the proband's isochromosomes could reflect abnormalities of cell division occurring at meiosis, postfertilization mitosis, or both. We believe that the present case may result from incomplete mitotic interchange in the pericentromeric regions of chromosome 7 homologues, with resolution by sister-chromatid reunion in an early, if not first, zygotic division. Phenotypically, our proband resembled three previously reported cases of maternal isodisomy for chromosome 7, suggesting that lack of paternal genes from 7q may result in a phenotype of short stature and growth retardation.

Biochemical and ultrasound screening for chromosomal abnormalities

The utility of ultrasound screening for Down syndrome should be judged by whether the pertinent markers are reliably obtained and by whether they efficiently discriminate between fetuses with Down syndrome and euploid fetuses. Furthermore, the markers must be reliable at a gestational age early enough to be clinically useful. Screening for characteristic congenital malformations will result in a low detection rate of Down syndrome, and many of these cases will be identified only after 24 weeks of gestation. The subtlety of many of the ultrasound findings of Down syndrome in the second trimester requires significant technical expertise if ultrasonographic screening is to be used. Investigation thus far has centered on identifying patients at increased risk of Down syndrome, and no data are available on how much a normal ultrasound might decrease the risk associated with advanced maternal age or abnormal biochemical screening. Biochemical screening is currently able to detect at least 60% of Down syndrome in a low-risk population. The ultimate value of ultrasound may be to help further define the risk assigned by age and biochemical screening, to provide each patient with an aggregate risk. The decision on whether or not to offer an amniocentesis could then be based on the findings of these various examinations, with the goal to improve the accuracy of age or biochemical screening alone. It remains for studies to be done to determine whether ultrasound can in fact decrease the prior risk, and for large enough series and formulas to be published that allow us to specifically define how to integrate the information from each screen.

Neonatal complications after the administration of indomethacin for preterm labor

BACKGROUND

The use of indomethacin as a tocolytic agent in pregnant women appears to be accompanied by a low incidence of neonatal complications. However, the neonatal effects of indomethacin have been studied primarily in infants born after 32 weeks' gestation. This study was designed to examine the incidence of neonatal complications in very premature infants.

METHODS

We identified 57 infants delivered at or before 30 weeks' gestation whose mothers had been treated with indomethacin for preterm labor and matched them with 57 infants whose mothers had not received indomethacin. The infants in the two groups were matched for sex, gestational age at delivery (mean [+/- SD], 27.6 +/- 2.0 weeks), exposure to betamethasone for 24 hours or more before delivery, and rupture of membranes 24 hours or more before delivery.

RESULTS

There were no significant differences between the two groups in birth weight, Apgar scores, cord-blood gas values, frequency of multiple gestation, or incidence of respiratory distress syndrome. The proportion of infants who required exogenous surfactant was similar, as were ventilator settings at 24 hours, the incidence of chronic lung disease, and the incidence of sepsis. The infants exposed to indomethacin had a lower urine output and higher serum creatinine concentrations during the first three days after delivery. More indomethacin-exposed infants had necrotizing enterocolitis (29 percent vs. 8 percent, P = 0.005), intracranial hemorrhage grade II to IV (28 percent vs. 9 percent, P = 0.02), and patent ductus arteriosus (62 percent, vs. 44 percent, P = 0.05). More indomethacin-exposed infants with a patent ductus arteriosus required surgical ligation because of either a lack of initial response or a reopening of the duct after postnatal indomethacin therapy (50 percent vs. 20 percent of the unexposed infants, P = 0.05).

CONCLUSIONS

Antenatal indomethacin therapy for preterm labor appears to increase the risk of serious neonatal complications in infants born at or before 30 weeks' gestation.

Facial features of infants exposed prenatally to cocaine

Thirty two infants referred for in-patient genetics evaluation at the University of California at San Francisco, 1987-1992, were found to have a history of maternal cocaine use. Genetics reports and medical records were reviewed on all these infants to identify features distinctive for cocaine exposure. Among these 32 cases, 14 infants were exposed only to cocaine; 18 were exposed to alcohol and cocaine. The infants evaluated displayed a distinctive phenotype, consisting of neurologic irritability, large fontanels, prominent glabella, marked periorbital and eyelid edema, low nasal bridge with transverse crease, short nose, lateral soft tissue nasal buildup, and small toenails. Features consistent with the fetal alcohol syndrome appeared distinct and coexistent with the other described facial findings. Other severe abnormalities included cleft lip/palate, atypical facial cleft, abnormal BSER, intraventricular hemorrhages, arthrogryposes, and genitourinary abnormalities. Forty percent of the infants were born prematurely; 28% were small for gestational age; 43% showed head circumference values less than the 10th percentile. We conclude that these findings may be distinctive for a diagnosis of fetal cocaine syndrome; such findings should be further established by a future blinded prospective study of mothers and neonates.

Maternal serum CA 125 for aneuploidy detection in early pregnancy

Maternal serum CA 125 levels were determined at 9-11 menstrual weeks for 26 cases of trisomy 13 (n = 4), trisomy 18 (n = 7), trisomy 21 (n = 15), and appropriate controls. There were no statistically significant differences between groups.

The clinical significance of predictions based on screening second trimester mean arterial pressure: adverse maternal [corrected] and infant outcomes

The design of a trial of primary prevention of hypertension in pregnancy rests on both the ability to identify women who are at risk and the definition of a clinically important outcome. The risk of developing antepartum hypertension can now be assessed nonivasively by the midpoint of pregnancy. However, maternal hypertension is not always associated with a clinically important adverse outcome for either mother or infant. The purpose of this study was to prospectively assess whether increasing risk of antepartum hypertension is associated with increasing rates of clinically important maternal and/or infant morbidity. We assembled a prospective cohort of 720 women with singleton pregnancies. The proportion of pregnancies complicated by both antepartum hypertension and maternal and/or infant morbidity increased significantly between low, moderate, and high risk groups (0.2, 6 and 58.8%, respectively, p less than 0.0001). We conclude that a trial of primary prevention of hypertension in pregnancy should include a measure of significant morbidity in mother and infant.

Changes in functional status during pregnancy

Changes in self-reported functional status during pregnancy were studied in 100 women. The baseline interview at 20 weeks was used for assessing subsequent change in maximal physical, mental, and emotional function as well as in global function and global sense of health. Although the transition instruments were only tested at three points during pregnancy (30, 35, and 40 weeks), they succeeded in detecting changes. In particular, both maximal physical function and global function tended to deteriorate as pregnancy progressed toward term, although few women considered themselves to be sick. The authors suggest that changes in functional status should be considered an important "outcome" of pregnancy. Patient-specific measures of change in self-reported maximal function might be used in future trials to help assess the impact of interventions on individual patient's maximal function. The timing of the baseline interview and frequency of the transition assessments should depend on the specific clinical problem under study.

Early prediction of antepartum hypertension

We validated a mid-pregnancy screening mean arterial pressure (MAP2) of 85 mmHg or higher as a significant predictor of hypertension in pregnancy. During the 17-month period from October 1984 through February 1986, 730 women, or 16% of all women cared for and delivered at our institution, were screened at or near 20 weeks of amenorrhea. Of the 139 women with a MAP2 of 85 mmHg or higher, 21.6% developed antepartum hypertension, compared with only 0.7% of the 591 women with a MAP2 below 85 mmHg. The screening MAP2 level of 85 mmHg was the optimal cutoff for MAP2 as a screening test. Controlling for the value of the screening MAP2, the only other important predictors of antepartum hypertension were chronic hypertension and diabetes mellitus. Using these three variables, the probability that an individual pregnant woman will develop antepartum hypertension can be assessed with a high degree of accuracy (84.5%) by 20 weeks of amenorrhea. This assessment is noninvasive and simple to use. Three distinct levels of risk have been defined; the moderate- and high-risk groups warrant careful surveillance during pregnancy and may be reasonable groups in which to test preventive interventions.

Ovulation induction with pulsatile gonadotropin-releasing hormone: a study of the subcutaneous route of administration

The efficacy of ovulation induction with the use of intermittent gonadotropin-releasing hormone (GnRH) therapy was examined in seven infertile women with hypothalamic amenorrhea. GnRH was administered every 90 minutes via the subcutaneous route in doses ranging from 50 to 300 ng/kg. Analysis of the induced gonadotropin pulse pattern revealed normal to modestly increased luteinizing hormone secretory parameters (e.g., pulse amplitude) in six of the seven patients. Six of seven women and 15 of 16 treatment cycles (94%) were ovulatory. The conception rate was 43% per woman and 19% per cycle. However, detailed hormonal analysis of 13 treatment cycles revealed that only 1 cycle was entirely normal in terms of duration and/or steroid secretion.