Screening for the aneuploid fetus

Advances in ultrasound technology have dramatically improved the detection of fetal defects. Although only an invasive test can provide a diagnosis, the incorporation of sonography into current biochemically based screening programs should significantly improve the detection of a host of other physically based fetal abnormalities. This article provides an overview and discussion of the prenatal sonographic features that may suggest the presence of a significant chromosomal abnormality.

Levels of urinary beta-core fragment, total oestriol, and the ratio of the two in second-trimester screening for Down syndrome

Levels of beta-core fragment and total oestriol in second-trimester maternal urine samples were measured in 32 Down syndrome pregnancies and 206 control pregnancies. Beta-core fragment and total oestriol values were corrected for the urinary creatinine level and expressed as multiples of the control medians (MOM). In addition, the ratio of the beta-core fragment level to the total oestriol level, without creatinine correction, was calculated, and expressed as MOM values. The median beta-core fragment, total oestriol, and ratio levels in Down syndrome cases were 5.42, 0.64, and 9.32 MOM, respectively. In the Down syndrome pregnancies, 66 per cent of the beta-core fragment levels were above the 95th centile of control levels, while 22 per cent of the total oestriol levels were below the fifth centile of control levels. In combination with maternal age, measurement of beta-core fragment and total oestriol levels in Down syndrome pregnancy resulted in an 80 per cent detection rate at a 5 per cent false-positive rate. Use of the ratio resulted in a univariate detection rate of 72 per cent. In combination with maternal age, the ratio resulted in a detection rate of 81 per cent at a 5 per cent false-positive rate. Based on this unmatched study, the measurement of a ratio of beta-core fragment to total oestriol levels, without the need for creatinine correction, may be useful in screening for fetal Down syndrome in second-trimester urine.

Noninvasive first-trimester screening for fetal aneuploidy

We reviewed all studies concerning noninvasive first trimester screening for fetal aneuploidy obtained from a MEDLINE search through June 1996 with additional sources identified through cross-referencing. Three screening and diagnostic modalities are of potential application in noninvasive first trimester testing for fetal aneuploidy: ultrasound, maternal biochemical markers, and analysis of fetal cells retrieved from maternal sources. Sensitivities of the sonographic finding of nuchal translucency thickness in combination with maternal age for trisomy 21, performed between 10 and 14 weeks of gestation in experienced hands, and maternal biochemical markers independently may be as high as 86 percent and 60 percent, respectively. Sensitivity, specificity, and predictive values of these diagnostic modalities alone, in combination with each other, or in conjunction with other predisposing factors such as maternal age, in large low risk populations have not currently been established. Analysis of fetal cells retrieved from maternal sources, although more complex, may offer definitive noninvasive prenatal diagnosis yet is not currently available in clinical practice. We conclude that noninvasive first trimester screening for fetal aneuploidy modalities including sonographic examination for nuchal translucency thickness and maternal biochemical markers, is feasible. Clinical feasibility; and all-encompassing clinical management paradigms of these and other early noninvasive first trimester screening methods for fetal aneuploidy, are not yet available.

Prenatal diagnosis of type 2 Pfeiffer syndrome

Pfeiffer syndrome is an autosomal dominantly inherited disorder consisting of craniosynostosis, a flattened midface with a beaked nose and ocular proptosis, and broad and medially deviated thumbs and great toes. Recently, based on clinical findings, the disorder has been divided into three subtypes: type 1, characterized by mild expression; type 2, in which clover leaf skull deformity and multiple congenital anomalies are present at birth; and type 3, which is similar to type 2, but lacks the presence of the clover leaf skull at birth. We describe a fetus in whom sonographic findings of clover leaf skull deformity, ocular hypertelorism, and varus deformity of the great toe led to the prenatal diagnosis of Pfeiffer syndrome type 2. We believe this is the second prenatal diagnosis of Pfeiffer syndrome, and the first time type 2 has been definitely identified in the second trimester of pregnancy.

The genetics of ovarian cancer: an assessment of current screening protocols and recommendations for counseling families at risk

Although the need for effective ovarian cancer screening is apparent, a highly sensitive and specific screening methodology has yet to be elucidated. 42-44 Given that there are more than 43 million women in the United States older than 45 years of age and that the average cost of a pelvic sonogram is $ 275 (and $ 45 for CA125 screening), the screening of this population is estimated to increase health care costs by $ 14 billion per year. 45 The additional cost of BRCA1 screening varies according to the level of diagnostic effort required to establish BRCA1 gene mutations in a particular family and ranges from $ 295 to $ 1,200 per sample. Assuming an average cost of $ 600 per sample, initial screening of these same women would likely increased costs in excess of $ 25 billion. Current knowledge and technology in ovarian cancer screening has not yet proved beneficial for the general population or for women with fewer than two affected family members. For women with two or more affected family members, there is a 3% chance of that patient being a proband in a hereditary cancer syndrome family. 11,46 In this group, who may be at increased risk for developing a malignancy, heightened surveillance is warranted, although there are still no data to confirm that screening even these high-risk women will reduce mortality. Nevertheless, annual bimanual examination, serum CA125, and transvaginal sonography are recommended among this particular subgroup of women at risk, and are likely to be recommended for young, asymptomatic, at-risk women who screen positive for the 185delAG BRCA1 deletion commonly found in persons of Ashkenazi Jewish ancestry. It is only through prospective, randomized trials that reliable data regarding the risk/benefit ratio of ovarian cancer screening among various populations at risk will be determined. The results of the prospective/randomized PLCO trial and the mature data from ongoing prospective, nonrandomized screening trials for women with a family history of cancer may provide this information and are eagerly awaited.

Placental echolucencies: does their presence influence outcome following genetic amniocentesis?

Women undergoing genetic amniocentesis procedures were evaluated for the presence of ultrasonographic echolucencies within the placenta. Non-calcified sonolucencies < 4 to 5 cm were classified as subchorionic hematomas (SH). Of the 1,000 pregnancies evaluated, 153 (15%) pregnancies manifested SH prior to amniocentesis (study group). The indications for referral were similar in the study and control groups. There were 13 (1.3%) losses: 3 and 10 in the study and control groups, respectively, with no statistical difference in fetal losses between the groups: RR 1.52 (95% confidence interval 0.56-4.14; p = 0.32). Placental sonolucencies < 4 to 5 cm in diameter appear to be incidental ultrasound findings not associated with increased fetal loss following genetic amniocentesis. Complications following invasive prenatal diagnosis cannot be attributed to the presence of these common ultrasound findings.

Management of immune thrombocytopenia purpura at a military medical center

OBJECTIVE

To investigate whether fetal platelets in immune thrombocytopenia purpura (ITP) may be predicted by antepartum assessment.

METHODS

A prospective analysis was conducted of 28 pregnant women with ITP out of 8,056 deliveries. Of the 28 patients, 13 were evaluted by fetal scalp sampling and 11 were evaluated by percutaneous umbilical blood sampling (PUBS).

RESULTS

The mean fetal and maternal platelet counts prior to delivery were 146,000 and 176,000, respectively. The mean fetal and maternal platelet counts after delivery were 245,000 and 149,000, respectively. Fetal cord platelet counts could not be predicted by maternal platelet count, the presence/absence of maternal direct/indirect anti-platelet antibodies, steroid therapy, or history of splenectomy. PUBS for fetal platelet assessment correlated well with fetal postdelivery counts.

CONCLUSIONS

Patients with ITP rarely exhibit complications. No antepartum characteristic enhances reliable prediction of neonatal outcome. Method of delivery should be based on obstetric guidelines.

Current maternal age recommendations for prenatal diagnosis: a reappraisal using the expected utility theory

The expected utility theory suggests eliminating an age-specific criterion for recommending prenatal diagnosis to patients. We isolate the factors which patients and physicians need to consider intelligently in prenatal diagnosis, and show that the sole use of a threshold age as a screening device is inadequate. Such a threshold fails to consider adequately patients' attitudes regarding many of the possible outcomes of prenatal diagnosis; in particular, the birth of a chromosomally abnormal child and procedural-related miscarriages. It also precludes testing younger women and encourages testing in patients who do not necessarily require or desire it. All pregnant women should be informed about their prenatal diagnosis options, screening techniques, and diagnostic procedures, including their respective limitations, risks, and benefits.

Procedure-related fetal losses in transplacental versus nontransplacental genetic amniocentesis

OBJECTIVE

We hypothesize that loss rates after amniocentesis do not differ in transplacental and nontransplacental taps performed by experienced operators.

STUDY DESIGN

Subjects were 1000 women undergoing second-trimester amniocentesis: 745 were referred for maternal age; 132 for positive maternal serum alpha-fetoprotein screens, 41 indicating a risk for fetal neural tube defect, 91 indicating a risk for fetal chromosome abnormality; and 123 were referred for other reasons. All procedures were videotaped. The placenta was anterior in 518 cases; in 306 of these the needle went through the placenta. All pregnancies were prospectively evaluated through delivery.

RESULTS

There were 13 losses among the 1000 procedures (1.3%). The transplacental losses occurred from 4 to 71 days after procedure, median 26.5 days; the nontransplacental losses from 12 days after procedure to term, median 25 days. The loss rate was essentially similar in the two categories: six transplacental (1.96%) and seven nontransplacental (1%) (relative risk 1.52 [95% confidence limits 0.84 to 2.75], p = 0.23). If the three patients with elevated maternal serum alpha-fetoprotein values were excluded from data analysis, the loss rates in the two groups were virtually identical (relative risk 0.98 [95% confidence limits 0.38 to 2.54], p = 1.0000).

CONCLUSION

Transplacental amniocentesis does not appear to increase the fetal loss rate in the hands of experienced surgeons. Moreover, in view of the time span between amniocentesis and loss in both groups, a procedural cause seems questionable.

Early genetic amniocentesis and its relationship to respiratory difficulties in paediatric patients: a report of findings in patients and matched controls 3-5 years post-procedure

This study evaluates the long-term pulmonary complications of 25 children from a prospective, matched-control, pilot study evaluating short-term complications of early (11-14 weeks' gestation) versus traditional (15 weeks' gestation and later) genetic amniocentesis. Five children in the early amniocentesis group were found to have various respiratory difficulties, a morbidity rate comparable to that of paediatric patients in the general population. These data identify the need for larger, multicentre trials.

Reproductive genetics for couples older than 40 years of age

The counseling process, which involves genetic screening and prenatal diagnosis, is presented. Also addressed are the recent advances in assisted reproductive technologies, which may prove to be particularly useful for these patients.

Unexplained positive/elevated maternal serum alpha-fetoprotein associated with placenta increta. A case report

Maternal serum alpha-fetoprotein (MSAFP) is a regularly utilized antenatal screening test for the identification of pregnancies at increased risk for a variety of genetic and nongenetic abnormalities. Complete mid-trimester evaluation of the patient with a positive screening test may fail to reveal an etiology for a positive MSAFP value. This case report concerns an unexplained positive/elevated MSAFP screening test for a patient found at delivery to have abnormal placentation.

Molecular analysis and chorionic villus sampling (CVS): opportunities for rapid prenatal diagnosis in the military

Prior to recent advances in the field of molecular biology, prenatal diagnosis of hemoglobinopathies was accomplished by direct analysis of the gene product(s) in samples obtained by fetoscopy or, more recently, percutaneous umbilical blood sampling. The use of the polymerase chain reaction enables quicker diagnosis than with indirect or cumbersome Southern blot techniques. This case, reporting a couple at risk for fetal sickle cell disease, is a model for rapid prenatal diagnosis and demonstrates the capabilities which exist in the military health care referral system. Within 24 hours of a couple's presentation for consultation and accomplishment of chorionic villus sampling (CVS), preliminary results of both cytogenetic and sickle cell status of an at-risk fetus were determined. Final analysis was accomplished by 48 hours. The combination of early referral, early sampling by CVS, and application of advances in DNA laboratory technologies offers tremendous improvements for care heretofore unavailable as a complete "package" in the military. The implications and limitations for prenatal testing for single gene disorders within the military medical health care system will be discussed.

The modulation of prostaglandin synthesis by peritoneal fluids

Biological fluids from several sources (e.g. blood, fetal urine, amniotic fluid) have been shown to contain factors that modulate prostaglandin (PG) synthesis. In this study, we investigated the possibility that peritoneal fluid contains substances that may regulate PG synthesis. Peritoneal fluids were obtained from women undergoing diagnostic laparoscopy for infertility. Fluids from women without evident pelvic pathology were incubated with prostaglandin synthase prepared from bull seminal vesicles in the presence of excess arachidonic acid, and the production of PGE2, PGF2 alpha, and 6-keto-PGF1 alpha was quantified by specific radioimmunoassay. The untreated fluids inhibited potently the synthesis of PGE2 but such inhibitory activity was not extractable by chloroform:methanol. An ultrafiltrate of the fluid containing molecules smaller than 10,000 Daltons stimulated PGF2 alpha synthesis but this activity was also lost after extraction. The extracted fluid did, however, stimulate the synthesis of prostacyclin (as reflected by 6-keto-PGF1 alpha).

Obstetric ultrasonography in a tertiary military medical referral center

Antenatal ultrasonography is an integral component of diagnostic tests available to the practicing obstetrician. Periodic assessment of sonographic services offered and their diagnostic reliability is necessary for good patient care and quality assurance/risk management (QA/RM) documentation. We report the findings from a 1-year review of antenatal ultrasonographic services provided in a military referral center serving the Department of Defense in the southeastern United States. During the study period, 1627 obstetric scans were done by our Department of Radiology. Most of the examinations (139 [85%]) were done on patients served on a continuing basis by USAF Medical Center, Keesler; 236 (15%) studies were done on patients referred by other military hospitals throughout the region. Of all scans available for review, 1529 were normal, whereas 98 (6%) revealed clinically significant abnormalities. We address herein the results of this periodic assessment, as well as implications for referral among Department of Defense hospitals.

Analysis of indications for referral to a multidisciplinary medical genetics clinic: implications for training programs in obstetrics and gynecology

Clinical genetics has become an integral component of obstetric training. Advances in prenatal screening (particularly maternal serum alpha-fetoprotein) and the clinical applications of molecular technologies have broadened the indications for referral to geneticists. During the study period, 1237 patients were referred for genetics consultation. A total of 596 (48%) were referred because of cytogenetic indications (576 for genetic amniocentesis); 252 (20%) because of multifactorial-developmental abnormalities; 204 (17%) because of risk of diseases attributable to single-gene mutations; 58 (5%) because of antenatal teratogen exposure(s); and 127 (10%) because of other reasons. Herein we summarize our experience as a multidisciplinary genetics unit and offer recommendations for broadening resident training curricula to meet current clinical needs. These data will be useful for enhancement of health care use and more effective direction of limited resources.

Maternal serum alpha-fetoprotein (MSAFP) screening: the Keesler experience

Maternal serum alpha-fetoprotein (MSAFP) screening is rapidly becoming a standard of practice in all regions of the United States and Canada. This paper will review the initial results of MSAFP screening in 761 patients at USAF Medical Center Keesler, and offer recommendations for Department of Defense hospitals offering such testing.

Parental decision following prenatal diagnosis of fetal chromosome abnormality

In the event of prenatal diagnosis of fetal chromosome abnormality, parents must choose between continuation and termination of the pregnancy. To determine whether parents are capable of understanding differences in severity among aneuploidy syndromes, we examined the outcome chosen for all pregnancies in which a fetal chromosome disorder was diagnosed at Northwestern Memorial Hospital between January, 1977 and June, 1986. Among amniocentesis cases, 88% with autosomal aneuploidy were terminated, but only 41% with sex chromosome abnormalities and none with de novo structural rearrangements were terminated. Among a smaller group of chorionic villus sampling cases, all with abnormal results were terminated. Similar patterns of parental behavior were noted in other prenatal diagnosis units. We conclude that parents do distinguish among, and respond specifically to, fetal chromosome disorders of differing severity, at least in the second trimester of pregnancy. However, parents appear more inclined to terminate all pregnancies with chromosome abnormalities when the diagnosis has been made in the first trimester.

Anti-inflammatory drugs in experimental atherosclerosis. Part 5. Influence of cortisone acetate on short-term and long-term cholesterol fluxes in atherosclerotic aorta

Previous studies in this series have shown that cortisone and other anti-inflammatory drugs inhibit atherosclerotic plaque development in cholesterol-fed rabbits. The present study was designed to investigate the influence of cortisone on the processes of cholesterol influx and efflux in the aorta wall. Forty-seven New Zealand white rabbits were fed a 1% cholesterol diet for periods up to 12 weeks. In addition 23 of the animals were fed 5 mg cortisone acetate daily. At 0, 5 and 12 weeks, groups were fed a tracer dose of [3H]cholesterol. Plasma cholesterol specific radioactivity was measured at intervals during the next 10 days. Total aorta cholesterol and its specific activity were measured by killing groups of animals at 2 days and 10 days. Atherosclerotic plaque intensity at 12 weeks, measured planimetrically, averaged 68 +/- 12% in controls vs. only 6 +/- 3% in cortisone-treated animals. During the period between 5 and 12 weeks, net cholesterol accumulation by chemical analysis averaged only 11 micrograms/g aorta/day in cortisone-treated animals vs. 117 micrograms/g in controls. [3H]cholesterol influx (measured during a brief 2-day exposure) at 5 weeks averaged 206 and 199 micrograms/g tissue/day and at 12 weeks 586 micrograms and 281 micrograms/day in control and cortisone-treated animals, respectively. Measured over a longer 10-day period, however, the apparent influx of [3H]cholesterol was much less in cortisone-treated animals, averaging only 53 micrograms/day compared to 269 micrograms/day in controls.(ABSTRACT TRUNCATED AT 250 WORDS)