Elevated amniotic fluid ferritin levels are associated with inflammation-related pregnancy loss following mid-trimester amniocentesis

OBJECTIVE

Occult infection accounts for up to 12% of pregnancy losses following genetic amniocentesis. Elevated serum and cervical fluid levels of ferritin, an acute-phase reactant, have been associated with spontaneous preterm delivery. We determined the association between amniotic fluid (AF) ferritin levels and post-amniocentesis pregnancy loss.

METHODS

We performed a case-control study involving 66 women with a non-anomalous fetus who had a spontaneous pregnancy loss within 30 days following genetic amniocentesis and 66 term controls matched for maternal age, gestational age, time of test and indication for amniocentesis. Amniotic fluid ferritin and interleukin-6 (IL-6) levels were measured using commercially available kits.

RESULTS

Mean (+/- SD) AF ferritin levels were similar between the cases (19.3 +/- 21.4 ng/ml) and the controls (19.8 +/- 22.7ng/ml) (p = 0.9). Mean (+/- SD) AF IL-6 levels were significantly higher in the women with post-amniocentesis pregnancy loss (4.0 +/- 13.1 ng/ml) than in controls (0.5 +/- 0.7 ng/ml) (p = 0.04). A significant proportion (12.1%, 8/66) of the women with post-amniocentesis pregnancy loss had elevated amniotic fluid IL-6 levels (> 3 SD, 2.5 ng/ml) indicating inflammation, as compared to none in the control group (p = 0.01). In this subgroup of women with pregnancy loss and elevated IL-6 levels, AF ferritin levels were significantly elevated (52.0 +/- 45.5 ng/ml) compared to the level in women who had a term delivery (19.8 +/- 22.7 ng/ml) (p = 0.002), and were strongly correlated with IL-6 levels among the cases (r = 0.67, p < 0.001).

CONCLUSION

The strong correlation of AF ferritin with IL-6 levels, along with the high ferritin values in cases with high AF IL-6, indicates that ferritin is a marker of inflammation in asymptomatic women destined to have an early pregnancy loss.

Can prenatal ultrasound findings predict ambulatory status in fetuses with open spina bifida?

OBJECTIVE

To determine whether prenatal sonographic findings in fetuses with open spina bifida can predict ambulatory potential and the need for postnatal shunt placement.

STUDY DESIGN

Ongoing pregnancies complicated by isolated open spina bifida from January 1996 to March 2000 were studied retrospectively. Static images and reports generated every 3-4 weeks from diagnosis until delivery were reviewed for lesion level and type, ventricular width, and lower extremity appearance. Operative summaries as well as neonatal and pediatric charts were reviewed. Ambulatory was defined in infants > or =2 years old as walking with or without appliances. In those <2 years of age, ambulatory was defined as at least 4/5 lower extremity muscle strength.

RESULTS

Thirty-three cases of isolated open spina bifida were identified. Lower (more caudal) lesion levels and smaller ventricular size were associated with ambulatory status in univariate analyses (P <.001, P =.003, respectively). No infant with a thoracic lesion was ambulatory (n = 11); all had ventriculomegaly diagnosed prenatally and all required shunt placement. In contrast, all infants with L4-sacral lesions (n = 10) were ambulatory, and 60% had ventriculomegaly diagnosed prenatally. Of patients with L1-L3 lesions (n = 12), 50% were ambulatory. In this group, ambulatory potential could not be determined by the presence of ventriculomegaly, ventricular size, or the presence of club foot. In the entire cohort, no infant with a myeloschisis was ambulatory, and all infants except one with a sacral lesion required postnatal shunt placement.

CONCLUSIONS

Sonographic determination of lesion level and type is useful in predicting the ambulatory potential of fetuses with open spina bifida.

Association of the C677T methylenetetrahydrofolate reductase mutation and elevated homocysteine levels with congenital cardiac malformations

OBJECTIVE

The aim of this study was determine whether the cytosine-to-thymine mutation at base 677 of the gene for methylenetetrahydrofolate reductase (C677T MTHFR ), which has been associated with neural tube defects, is also associated with congenital cardiac malformations.

STUDY DESIGN

Amniotic fluid homocysteine levels were measured and the presence or absence of the C677T MTHFR mutation in amniocytes was determined in stored amniotic fluid obtained from 26 pregnancies complicated by isolated (presumed multifactorial) fetal cardiac defects and from 116 normal pregnancies.

RESULTS

The pregnancies affected by fetal cardiac defects had higher amniotic fluid homocysteine levels (1.7 +/- 1.7 vs 1.0 +/- 0.7 micromol/L; P =.07) and included more samples with homocysteine levels >90th percentile (27% vs 9%; P =.02) and more cases with the C677T MTHFR mutation (35% vs 13%; P =.01). Fifty percent of cases had either a high homocysteine level or the C677T MTHFR mutation (50% vs 20%; P =.003) and 12% had both (12% vs 0%; P =.0006).

CONCLUSION

Fifty percent of these isolated congenital cardiac defects were associated with either the C677T MTHFR mutation or elevated amniotic fluid homocysteine levels, or both. This finding adds to what is already known about the multiple and complex biochemical and developmental functions of the homocysteine pathway.

Amniotic fluid homocysteine levels, 5,10-methylenetetrahydrafolate reductase genotypes, and neural tube closure sites

A specific gene mutation leading to altered homocysteine metabolism has been identified in parents and fetuses with neural tube defects (NTDs). In addition, current animal and human data indicate that spine closure occurs simultaneously in five separate sites that then fuse. We sought to determine whether either this mutation or abnormal amniotic fluid homocysteine levels are associated with all five neural tube closure sites. We retrieved stored amniotic fluid from cases of isolated fetal neural tube defect diagnosed from 1988 to 1998 (n = 80) and from normal controls matched for race, month and year of amniocentesis, and maternal age. Cases were categorized according to defect site by using all available medical records. The presence or absence of the 677C-->T mutation of 5, 10-methylenetetrahydrafolate reductase (MTHFR) gene was determined, and homocysteine levels were measured; case and controls were compared. Significantly more cases than controls were heterozygous or homozygous for the 677C-->T MTHFR mutation (44% vs. 17%, P < or = 0. 001). Likewise, cases were significantly more likely than controls to have amniotic fluid homocysteine levels >90th centile (>1.85 micromol/L), 27% vs. 10%, P = 0.02. Most (83%) of control cases had both normal MTHFR alleles and normal amniotic fluid homocysteine levels (normal/normal), whereas only 56% of NTD case were normal/normal (P = 0.001). When evaluated by defect site, only defects involving the cervical-lumbar spine, lumbosacral spine, and occipital encephalocele were significantly less likely to be normal/normal than controls (P = 0.007, 0.0003, and 0.007, respectively), suggesting a strong association with the 677C-->T allele. In contrast, anencephaly, exencephaly, and defects confined to the sacrum included many cases that had both normal MTHFR alleles and normal homocysteine and were not significantly different from controls. The 677C-->T MTHFR mutation and elevated homocysteine levels appear to be disproportionately associated with defects spanning the cervical-lumbar spine, lumbosacral spine, and occipital encephalocele. In contrast, anencephaly, exencephaly, and defects confined to the sacrum may not be related to altered homocysteine metabolism.

Role of amniotic fluid homocysteine level and of fetal 5, 10-methylenetetrahydrafolate reductase genotype in the etiology of neural tube defects

A mutation in the gene 5,10-methylenetetrahydrofolate reductase (MTHFR), leading to altered homocysteine metabolism, has been identified in parents and fetuses with fetal neural tube defects. We sought to determine which is of greater importance in fetal neural tube defect formation: the fetal MTHFR mutation or elevated amniotic fluid homocysteine level. We retrieved stored amniotic fluid from cases of isolated fetal neural tube defect diagnosed from 1988 to 1998 (n = 80), and from normal controls matched for race, month and year of amniocentesis, and maternal age. The presence or absence of the 677C-->T mutation of MTHFR was determined and homocysteine levels were measured; cases and controls were compared. Significantly more cases than controls were heterozygous or homozygous for the 677C-->T MTHFR mutation (44% vs 17%, P < or = 0.001). Cases were also significantly more likely than controls to have an amniotic fluid homocysteine level above the 90th centile (>1.85 micromol per liter); 27% vs 10%, P = 0.02. Thirty one cases and 12 controls had an abnormal genotype; however, amniotic fluid homocysteine levels were not significantly different between these two groups (6/31, or 19% of cases had an elevated homocysteine compared to 1/12, or 8% of controls; P = 0.65). In contrast, 40 cases and 60 controls had a normal genotype; the neural tube defect cases had significantly higher homocysteine levels (13/40, or 32% of cases had an elevated homocysteine level compared to only 6/60, or 10% of controls; P = 0.008). Although both abnormal fetal MTHFR genotype and abnormal amniotic fluid homocysteine concentration are significantly associated with neural tube defects, the association with amniotic fluid homocysteine concentration is significant regardless of the fetal MTHFR genotype. The relationship between maternal and fetal homocysteine metabolism is complex.

Ultrasound findings and multiple marker screening in trisomy 18

OBJECTIVE

To compare detection of trisomy 18 in the second trimester by ultrasound and multiple-marker testing.

METHODS

A computerized genetics database was used to identify fetuses of 14-22 weeks' gestation who had comprehensive ultrasound examinations, multiple-marker screening tests (alpha-fetoprotein [AFP]), hCG, unconjugated estriol [E3], and trisomy 18 karyotype. A positive trisomy 18 screen was defined as AFP up to 0.75 multiples of the median (MoM), hCG up to 0.55 MoM, and unconjugated E3 up to 0.60 MoM. A risk of at least 1:190 defined a positive Down syndrome screen. Ultrasound abnormalities were diagnosed prospectively and were confirmed later by retrospective review of sonographic images.

RESULTS

From 1988-1997, 30 trisomy 18 fetuses who had comprehensive ultrasounds and multiple-marker testing were identified. Twenty-one (70%) had abnormalities detected by ultrasound, of which the most common isolated finding was choroid plexus cyst. Eleven fetuses (37%) had positive trisomy 18 screens, and two had positive Down syndrome screens, for a total of 13 of 30 (43%) fetuses with positive multiple-marker screening tests.

CONCLUSION

We found that ultrasound was more likely to be abnormal than multiple-marker screening tests in fetuses with trisomy 18 (70%) (95% confidence interval [CI] 54, 86 versus 43% CI 25, 61). However, combining the two testing methods yielded the highest detection rate (80% [CI 66%, 94%]).

Value of perinatal autopsy

OBJECTIVE

To determine how often a perinatal autopsy identified the cause of death, and how frequently this information changed recurrence risk estimates or altered parental counseling.

METHODS

We reviewed all autopsies of fetal stillbirths and briefly viable neonates performed by one perinatal pathologist at the University of Alabama Hospital from 1992 to 1994.

RESULTS

Four hundred sixteen fetal and early neonatal deaths occurred at our hospital from January 1, 1992, to June 1, 1994. Consent for an autopsy examination was granted for 139 of these (33%), and all autopsies were performed by a single perinatal pathologist. Abnormalities likely to be the cause of death were identified in 130 of 139 cases (94%). Ninety-one subjects did not have structural anomalies: In 14 cases autopsy revealed previously unsuspected pathology that altered parental counseling; in 68 cases autopsy findings were consistent with the clinical obstetrical diagnosis; and in nine cases the cause of death could not be identified. Forty-eight subjects were anomalous. Thirty-seven of these (79%) had been evaluated by antenatal ultrasonography, and autopsy identified additional abnormalities in 51% (19 of 37). In the 11 deaths evaluated neonatally, a previously unsuspected diagnosis likely to be the cause of death was identified in three. Overall, autopsy findings changed recurrence risk estimates and/or parental counseling in 36 of 139 cases (26%).

CONCLUSION

The cause of fetal or perinatal death was determined by autopsy in 94% of cases in our series. Counseling and recurrence risk estimates were altered by autopsy findings in 26%.

Hydramnios prediction of adverse perinatal outcome

OBJECTIVE

To determine whether hydramnios is associated with an increased risk of adverse perinatal outcomes.

METHODS

Computerized records of all ultrasound examinations done at the University of Alabama at Birmingham from 1986 to 1996 (n = 40,065) were reviewed to identify 370 women with singleton pregnancies beyond 20 weeks' gestation and hydramnios diagnosed sonographically by amniotic fluid index of 25 cm or more, largest vertical pocket of 8 cm or more, or subjective impression. Controls were all women with singleton gestations with normal amniotic fluid volumes (n = 36,426). Obstetric outcomes were determined by cross-reference to our database. Cases with hydramnios were compared with controls for perinatal death, anomaly rate, fetal growth restriction (FGR), cesarean delivery, fetal aneuploidy, and maternal diabetes. Cases were sorted according to diabetes status, after which perinatal death, anomaly rate, FGR, cesarean delivery, and fetal aneuploidy were compared again.

RESULTS

The incidence of hydramnios was 1%. The perinatal mortality rate in all women with hydramnios was 49 per 1000 births, compared with 14 per 1000 births in the control group (P < .001). Women with hydramnios had 25 times more anomalies than controls (8.4% versus 0.3%; P < .001), although the prevalence of fetal aneuploidy was not significantly different (one in 370 versus one in 3643; P = .10). The cesarean rate was three times higher in women with hydramnios compared with controls (47.0% versus 16.4%; P < .001). When hydramnios cases were divided according to diabetes status, all of the increased risk was in nondiabetic women: Perinatal mortality was 60 per 1000 in nondiabetic women versus 0 per 1000 in diabetic women (P = .03); the anomaly rate was 10.4% versus 0%, respectively (P = .005).

CONCLUSION

Hydramnios indicated an increased risk of adverse perinatal outcomes, especially if not associated with diabetes. A comprehensive fetal evaluation, a workup to rule out maternal factors, and fetal surveillance are warranted; amniocentesis for fetal karyotype analysis might not be necessary.

A five-year experience with fragile X screening of high-risk gravid women

OBJECTIVE

We sought to compare our 5-year program of fragile X screening of high-risk gravid women with our program of fragile X testing of affected individuals (probands).

STUDY DESIGN

All women referred to the prenatal genetics clinic from 1994 to 1998 who had a family history of unspecified mental retardation or learning or behavioral disorders (known fragile X families excluded) were offered fragile X screening. Results were compared with those of probands with the same diagnoses who underwent fragile X testing during the same time period.

RESULTS

We counseled 12,349 prenatal patients from 1994-1998, of whom 263 (2.1%) had a positive family history and underwent fragile X screening. No mutations or premutations were identified. In contrast, 31 (1.9%) of 1637 affected probands who underwent fragile X testing during the same time period had positive results, which was a significant difference (0/263 vs 31/1637; P <.05).

CONCLUSIONS

Testing the affected proband is superior to screening the pregnant relative of the proband for identification of families at risk for fragile X syndrome.

Prospective evaluation of free beta-subunit of human chorionic gonadotropin and dimeric inhibin A for aneuploidy detection

OBJECTIVE

Our goal was to prospectively evaluate the use of the free beta-subunit of human chorionic gonadotropin and dimeric inhibin A for the detection of fetal Down syndrome and other aneuploidies.

STUDY DESIGN

Women who had a second-trimester multiple-marker screening test (alpha-fetoprotein, unconjugated estriol, human chorionic gonadotropin) and genetic amniocentesis from August 1996 to August 1998 were included. Serum was also analyzed for inhibin and the free beta-subunit of human chorionic gonadotropin. Detection and false-positive rates for 4 analyte combinations at 5 different screening risk cutoff points for Down syndrome were determined and compared.

RESULTS

We evaluated 1256 patients, including 23 with aneuploidy (13 with Down syndrome, 10 others). The maternal age was 35.9 +/- 4.6 years (mean +/- SD). At the optimal risk cutoff point for Down syndrome detection (1:190; false-positive rate, 19%), the multiple-marker screening test plus inhibin was superior, detecting 85% of Down syndrome cases, in comparison with 69% when the multiple-marker screening test alone was used and 62% when the other 2 combinations were used. The multiple-marker screening test plus inhibin also detected 60% of the other aneuploidies.

CONCLUSIONS

When evaluated prospectively in a high-risk population, the multiple-marker screening test plus inhibin was superior to the traditional multiple-marker screening test and 2 other analyte combinations, with a lower false-positive rate and increased detection of all aneuploidies in a high-risk population.

Terbutaline pump maintenance therapy for prevention of preterm delivery: a double-blind trial

OBJECTIVE

This study's aim was to determine whether maintenance therapy with terbutaline administered by pump prolongs gestation in women after treatment with intravenous magnesium sulfate tocolysis for suspected preterm labor.

STUDY DESIGN

Consenting women with a singleton gestation and intact membranes who had uterine contractions and >1 cm cervical dilation, 80% effacement, or progressive cervical change and whose contractions were successfully arrested with intravenous magnesium were randomly assigned to receive either terbutaline or normal saline solution placebo by subcutaneous infusion pump. Pump therapy was administered with a standardized protocol. Pump therapy was discontinued and parenteral magnesium was resumed if recurrent preterm labor developed while women were on the therapeutic regimen at <34 weeks' gestation and no contraindication for tocolysis existed. If recurrent labor was arrested, pump therapy was restarted according to the original treatment group. A sample size of 48 women was required to detect a 2-week intergroup difference in mean time to delivery. Analyses were based on intent to treat.

RESULTS

Fifty-two women received terbutaline (n = 24) or placebo (n = 28). At random assignment the groups were similar with respect to age, race, parity, previous preterm delivery, gestational age, and cervical examination. Overall there was a 1-day difference in mean time to delivery between the groups (terbutaline 29 +/- 22 days and placebo 28 +/- 23 days, P = .78). There were no differences in the rates of preterm delivery at <34 and <37 weeks' gestation. Neonatal outcomes were similar.

CONCLUSIONS

Maintenance terbutaline therapy administered by pump does not prolong gestation in women successfully treated for suspected preterm labor.

Maternal serum alpha-fetoprotein and dimeric inhibin A detect aneuploidies other than Down syndrome

OBJECTIVE

Our purpose was to determine whether the combination of maternal serum alpha-fetoprotein, free human chorionic gonadotropin-beta, dimeric inhibin A, and maternal age detects aneuploidies other than Down syndrome.

STUDY DESIGN

We retrieved stored serum from pregnancies complicated by aneuploidies other than Down syndrome from 1988 to 1997 (n = 55, mean maternal age 35.2 +/- 5.6 years). Alpha-fetoprotein levels were obtained from our database, and free human chorionic gonadotropin-beta and dimeric inhibin A levels were measured in the thawed serum with use of commercial assays. Analyte values were used in both 3-analyte and 2-analyte multiple-marker screening tests; detection rates were determined at several different Down syndrome risk-positive cutoff values.

RESULTS

In the 3-analyte test 58% (32/55) of all aneuploidies were detected with use of both the Down syndrome protocol at a screen-positive risk cutoff value of 1:300 (false-positive rate 17%) and a novel trisomy 18 screening algorithm. However, 67% (37/55) detection was obtained with use of the 2-analyte combination of alpha-fetoprotein and dimeric inhibin A, with both the Down syndrome protocol (screen positive cutoff value 1:300) and the trisomy 18 algorithm: 12 of 13 trisomy 18 (92%), 9 of 17 Turner's syndrome (53%), 10 of 17 other sex chromosome aneuploidies (59%), 1 of 1 trisomy 22 (100%), and 5 of 7 trisomy 13 (71%).

CONCLUSIONS

The combination of maternal serum alpha-fetoprotein, dimeric inhibin A, and maternal age detects autosomal trisomies other than Down syndrome at a rate superior to that of the traditional analyte combination.

Intrauterine viral infection at the time of second trimester genetic amniocentesis

OBJECTIVE

To determine whether preexisting intrauterine viral infection is associated with postamniocentesis pregnancy loss.

METHODS

We accessed our bank of second-trimester amniotic fluid (AF) samples obtained aseptically and stored at -20C from all 11,971 women who underwent genetic amniocentesis between 1988 and 1995. Samples were retrieved from every case of spontaneous pregnancy loss within 30 days of the amniocentesis (excluding aneuploidy and anomalies, n = 66). Sixty-six control samples were randomly chosen from subjects who delivered at term and were matched for year of test, gestational age, maternal age, and indication for amniocentesis. Investigators were blinded to the status of the samples, which were studied by polymerase chain reaction (PCR) for the presence of adenovirus, parvovirus, cytomegalovirus, Epstein-Barr virus, herpes simplex virus, enterovirus, influenza A virus, and beta-actin DNA. Results were compared with interleukin-6 (IL-6) levels previously measured by enzyme-linked immunosorbent assay in the same samples.

RESULTS

Sixty-two study cases and 60 controls were sufficient for all PCR studies. Fourteen AF samples contained a single virus: five (8%) of 62 study cases and nine (15%) of 60 controls (P = .27). Adenovirus accounted for nine (64%) of 14 viruses identified: four of 62 cases and five of 60 controls (P = .74). Cytomegalovirus was not identified in any study cases but was found in three controls. The mean IL-6 levels in samples with and without virus were not significantly different (4.8+/-15.9 ng/mL with virus compared with 2.0+/-8.8 ng/mL without virus; P = .53).

CONCLUSION

Presence of virus in second-trimester AF is not significantly associated with elevated IL-6 levels or with early postamniocentesis pregnancy loss.

Elevated second-trimester amniotic fluid interleukin-6 levels predict preterm delivery

OBJECTIVE

Our purpose was to determine whether early second-trimester amniotic fluid interleukin-6 levels predict delivery before 34 weeks' gestation.

STUDY DESIGN

We used stored second-trimester amniotic fluid samples obtained from women undergoing genetic amniocentesis from 1988 to 1996. Interleukin-6 levels were measured by enzyme-linked immunosorbent assay in samples from every case known to result in delivery from 20 to 34 weeks' gestation (n = 290), and 290 matched controls delivering at > or =37 weeks. Fetal aneuploidies, anomalies, and all cases delivering within 30 days of the amniocentesis (which were thought to be possibly procedure related) were excluded.

RESULTS

Interleukin-6 levels were higher in cases than controls (1.9 +/- 5.2 vs 1.0 +/- 2.4 ng/ml, p = 0.004). Cases were grouped according to whether the preterm delivery was indicated or spontaneous: The mean interleukin-6 levels were significantly higher than controls in the spontaneous group (1.6 +/- 3.2 vs 0.8 +/- 1.2 ng/ml, p = 0.01) but not in the indicated group (1.4 +/- 4.0 vs 0.8 +/- 1.2 ng/ml, p = 0.12). In all samples the interleukin-6 level was negatively correlated with the gestational age at delivery (R = -0.11633, p = 0.007).

CONCLUSION

Elevated early second-trimester amniotic fluid interleukin-6 levels are associated with preterm delivery, confirming that in some women this indicator of very early intrauterine inflammation predicts birth before 34 weeks' gestation.

Insulin-like growth factor binding protein-3 in the detection of fetal Down syndrome pregnancies

OBJECTIVE

To study the usefulness of maternal serum insulin-like growth factor binding protein-3, a potential cell growth inhibitor, in second trimester prenatal screening for fetal Down syndrome.

METHODS

Three hundred and forty-two samples from normal pregnancies and nine fetal Down syndrome pregnancies were analyzed for insulin-like growth factor binding protein-3 levels by radioimmunoassay. Data were converted to multiples of median (MoM) and analyzed statistically to compare the differences between control and Down syndrome pregnancies.

RESULTS

The mean insulin-like growth factor binding protein-3 MoM of Down syndrome-affected pregnancies (1.09) was significantly higher than that of the normal pregnancies (1.00) (P < .01). Insulin-like growth factor binding protein-3, in combination with maternal serum alpha-fetoprotein (MSAFP), hCG, and maternal age, detected 89% of Down syndrome pregnancies at a screen positive rate of 2.1%. This compares favorably to the standard combination of MSAFP, hCG, and unconjugated estriol (E3), which had a 66.7% Down syndrome detection rate and a 4.1% screen positive rate in our study samples.

CONCLUSION

This retrospective analysis suggested that the inclusion of insulin-like growth factor binding protein-3 into the triple screen program to replace unconjugated E3 might enhance the detection rate of fetal Down syndrome pregnancies. These data need to be confirmed by a larger prospective study.

Significance of a false-positive trisomy 18 multiple-marker screening test

OBJECTIVE

To determine if a false-positive trisomy 18 multiple-marker screening test (all three analytes low: maternal serum alpha-fetoprotein [AFP] at most 0.75 multiples of the median [MoM], unconjugated estriol at most 0.60 MoM, and hCG at most 0.55 MoM) indicates increased risk for obstetric complications or is related to maternal weight.

METHODS

We accessed our genetic database to obtain multiple-marker screening test results, fetal karyotypes, and pregnancy outcomes from all patients with a normal multiple-marker screening test (n = 3900) and from all patients with a positive trisomy 18 screening test (n = 103) seen in the prenatal diagnosis clinic from 1992 to 1996. During this period, only maternal serum AFP was adjusted for maternal weight.

RESULTS

A positive trisomy 18 screen identified five of 12 trisomy 18 fetuses. Women with a false-positive trisomy 18 screen were heavier (175.6 +/- 43.8 lb versus 159.9 +/- 37.9 lb, P < .001) and younger (29.7 +/- 6.5 years versus 32.3 +/- 6.5 years, P < .001) than women with a normal multiple-marker screening test, but were not at increased risk for pregnancy complications. Weight-adjusting all three analytes reduced the false-positive trisomy 18 screen rate by 42% (from 1.9% to 1.1%) but did not change the trisomy 18 detection rate.

CONCLUSION

A false-positive trisomy 18 screening test does not indicate increased risk to develop pregnancy complications and may be related to inadequate correction for increased maternal weight.

Elevated second-trimester dimeric inhibin A levels identify Down syndrome pregnancies

OBJECTIVE

Our purpose was to determine whether second-trimester dimeric inhibin A levels distinguish Down syndrome pregnancies from euploid pregnancies.

STUDY DESIGN

With use of a commercially available enzyme-linked immunosorbent assay (Serotec, Oxford) inhibin A medians were established in stored sera from 40 to 50 euploid pregnancies at each week of gestation from 14 to 20 weeks and from 33 Down syndrome pregnancies. Maternal serum alpha-fetoprotein, unconjugated estriol, and human chorionic gonadotropin levels measured in each sample before storage were retrieved. The performance of inhibin A in the multiple-marker screening test was evaluated.

RESULTS

The mean inhibin A multiple of the median was significantly higher in the Down syndrome group than in the euploid group (2.84 +/- 2.0 vs 1.22 +/- 1.0, p = 0.0001). An inhibin A level > or = 1.6 multiples of the median identified 70% of all Down syndrome pregnancies at a false-positive rate of 22%. Replacing estriol with inhibin A in the multiple-marker screening test resulted in a higher Down syndrome detection rate at a lower screen-positive rate.

CONCLUSION

Elevated second-trimester maternal serum inhibin A levels identify Down syndrome pregnancies; replacing estriol with inhibin A in the multiple-marker screening test improves test performance.

Alpha-fetoprotein, free beta-human chorionic gonadotropin, and dimeric inhibin A produce the best results in a three-analyte, multiple-marker screening test for fetal Down syndrome

OBJECTIVE

The purpose of this study was to determine, among six second-trimester maternal serum analytes, the best three-analyte combination for fetal Down syndrome detection.

STUDY DESIGN

With use of commercially available assay kits, medians for free beta-human chorionic gonadotropin, CA 125, and dimeric inhibin A were established in stored sera from 45 to 50 euploid pregnancies at each week of gestation from 14 to 22 weeks and from 33 Down syndrome pregnancies. Maternal serum alpha-fetoprotein, unconjugated estriol, and intact human chorionic gonadotropin levels measured in each sample before storage were retrieved. All 20 possible three-analyte combinations were evaluated in the multiple-marker screening test for Down syndrome.

RESULTS

The mean maternal age of the study population was 35.6 +/- 5.3 years. The best three-analyte combination was maternal serum alpha-fetoprotein, free beta-human chorionic gonadotropin, and dimeric inhibin A: 97% of Down syndrome cases were detected at a false-positive rate of 16%. At a slightly higher false-positive rate (18%) maternal serum alpha-fetoprotein, estriol, and intact human chorionic gonadotropin detected only 79% of cases.

CONCLUSIONS

Of six second-trimester maternal serum analytes, the best three-analyte combination for fetal Down syndrome detection was maternal serum alpha-fetoprotein, free beta-human chorionic gonadotropin, and dimeric inhibin A. This retrospective analysis should now be confirmed prospectively.

Antenatal screening for factor V Leiden mutation: a critical appraisal

Thromboembolic disease is a leading cause of maternal mortality in the United States. Recently, inherited resistance to activated protein C has been recognized as a major risk factor for thrombosis and has been demonstrated in 20-60% of patients with clinically evident thrombosis. The factor V Leiden mutation, which is readily detectable by molecular DNA techniques, is responsible for 90-95% of cases of activated protein C resistance. Because 5% of whites and 1% of blacks in the United States are heterozygous for the Leiden mutation, at least one group has suggested that screening of asymptomatic gravidas for the mutation should be considered. Therefore, we conducted a combined MEDLINE and bibliographic literature search for relevant data and evaluated screening for the factor V Leiden mutation in the context of well-elucidated desirable characteristics for a successful screening program. Based on this evaluation, we conclude that routine antenatal screening for the factor V Leiden mutation cannot be recommended at the present time.

Free beta-hCG subunit versus intact hCG in Down syndrome screening

OBJECTIVE

To assess the ability of second-trimester maternal serum free beta-hCG to detect fetal Down syndrome and to compare free beta-hCG to intact hCG in the multiple-marker screening test for Down syndrome.

METHODS

From our bank of stored maternal sera, we selected 40-50 samples from euploid pregnancies at each week of gestation from 14 to 20 weeks and 31 samples from Down syndrome pregnancies. Free beta-hCG was measured by enzyme-linked immunosorbent assay, and week-specific multiples of the median (MoM) were derived. The free beta-hCG Down syndrome detection and false-positive rates were determined. Free beta-hCG was then substituted for intact hCG in the multiple-marker screening test, and the Down syndrome detection and false-positive rates at various risk cutoffs were compared.

RESULTS

The mean (+/-standard deviation) maternal age of all study samples was 35.6 +/- 5.3 years. The mean Down syndrome free beta-hCG MoM was significantly higher than the mean euploid MoM (2.4 +/- 1.1 versus 1.2 +/- 1.0; P < .001). A free beta-hCG level of at least 1.7 MoM identified 68% of Down syndrome pregnancies at a false-positive rate of 20%. When intact hCG was replaced with free beta-hCG in the multiple-marker screening test, a higher Down syndrome detection rate was achieved at a lower false-positive rate at each of several screen positive risk cutoffs.

CONCLUSION

Elevated free beta-hCG levels identify Down syndrome pregnancies. Replacing intact hCG with free beta-hCG in the multiple-marker screening test results in a higher Down syndrome detection rate at a lower false-positive rate.

Pregnancy outcomes following false-positive multiple marker screening tests

Pregnancy outcomes in women with a false-positive midtrimester multiple marker screening test (MMST) were reviewed. A genetic database was used to identify all women > or = age 30 who had a MMST at 15-20 weeks of gestation, a targeted ultrasound, and amniocentesis, and complete pregnancy outcome data. All patients with an abnormal fetal ultrasound (US) or karyotype were excluded. The incidence of adverse outcomes (defined as fetal death, preterm delivery, or a birth weight less than the 10th percentile for gestational age), in those women with a positive MMST (risk of Down's syndrome > or = 1:190) was compared to the incidence of adverse outcomes in control women with negative MMST. Chi-square analysis and Fisher's exact tests were used for comparisons as appropriate. Complete data was available from 1135 women. Seventy-seven percent were over age 35. Two hundred and forty-six women (22%) had a positive multiple marker test. No significant differences in outcomes were discovered after comparisons to controls: fetal death 1 of 246 (0.4%) versus 12 of 889 (1.3%), p = 0.32; preterm delivery 32 of 246 (13.0%) versus 147 of 889 (16.5%), p = 0.17; birth weight less than the 10th percentile, 9 of 246 (3.7%) versus 30 of 889 (3.4%), p = 0.83. Our data suggest that women > or = age 30 with a false-positive MMST and a normal midtrimester obstetrical sonogram are not at an increased risk for adverse pregnancy outcomes in later gestation.

Second-trimester maternal serum CA-125 versus estriol in the multiple-marker screening test for Down syndrome

OBJECTIVE

To determine the ability of second-trimester maternal serum CA-125 levels to detect fetal Down syndrome.

METHODS

From stored, second-trimester maternal serum analyzed previously with the multiple-marker screening test for fetal Down syndrome, we selected 306 samples from euploid pregnancies and 22 samples from Down syndrome pregnancies at 14-20 weeks' gestation. CA-125 levels were measured by enzyme-linked immunosorbent assay and converted to gestational week-specific multiples of the median (MoM).

RESULTS

The mean maternal age (+/- standard deviation) of the study population was 35.5 +/- 5.3 years. The Down syndrome group CA-125 mean MoM was significantly higher than the euploid group mean MoM (1.47 +/- 0.51 MoM versus 1.05 +/- 0.44 MoM; P < .001). CA-125 at or above 1.5 MoM identified 10 of 22 (45%) Down syndrome cases. Substituting CA-125 for estriol (E3) in the multiple-marker screening test resulted in a lower screen-positive rate (67 of 328, 20% [95% confidence interval {CI} 16, 25] versus 91 of 328, 28% [95% CI 23, 33]) with a similar Down syndrome detection rate (18 of 22, 82%). Alternatively, when the screen-positive rate was held constant, the Down syndrome detection rate improved (20 of 22, 91% [95% CI 71, 99] versus 18 of 22, 82% [95% CI 60, 95]).

CONCLUSIONS

Down syndrome pregnancies have higher second-trimester maternal serum CA-125 levels than euploid pregnancies. CA-125 may be superior to E3 in the multiple-marker screening test for fetal Down syndrome.

A placebo-controlled randomized trial of the terbutaline pump for prevention of preterm delivery

To determine the efficacy of the terbutaline pump for the prevention of preterm delivery, patients in preterm labor defined by progressive cervical change underwent intravenous magnesium sulfate tocolysis (with or without oral indomethacin, as necessary), and once labor was arrested, were randomized to one of three treatment arms: terbutaline by pump, saline by pump (blinded), or oral terbutaline. If recurrent preterm labor occurred despite maximization of therapy, the treatment arm was determined and therapy was changed; saline pump and oral terbutaline were switched to terbutaline pump, terbutaline pump was switched to oral terbutaline. Patients who continued to labor were readmitted for aggressive intravenous therapy. Women randomized to the terbutaline pump (n = 15), saline pump (n = 12), and oral terbutaline (n = 15) groups were similar in terms of gravidity, parity, days of tocolysis before study entry, gestational age at entry, and cervical dilatation at entry. The mean gestational age at delivery was the same in all three groups (35 weeks), as were neonatal outcomes. Terbutaline by pump, saline by pump, and oral terbutaline appear equivalent for the prevention of preterm delivery. The terbutaline pump should remain experimental.

Second-trimester cystic hygroma: prognosis of septated and nonseptated lesions

OBJECTIVE

To compare karyotypic, ultrasonographic, and prognostic features of septated cystic hygromas and nonseptated cystic hygromas in second-trimester fetuses.

METHODS

A computerized ultrasound data base was used to identify fetuses diagnosed with cystic hygromas at 14-22 weeks' gestation. Photographs from the initial ultrasound were reviewed retrospectively for hygroma type (septated or nonseptated) and any abnormal structural findings. Fetal karyotypes were obtained from amniotic fluid, aspiration of hygroma pouches, or fetal tissue culture. Pregnancy outcome information was obtained from hospital charts and physician office records. Ultrasound findings were then compared with fetal karyotype results and pregnancy outcome data.

RESULTS

From 1990 to 1995, 61 fetuses with cystic hygromas were identified. Karyotypes were obtained in 55 fetuses, and pregnancy outcome was available for 59. Abnormal karyotype was present in 42 of 55 fetuses (76%). The most common chromosomal abnormality in septated hygromas was the 45,X karyotype. Trisomy 21 was the most common chromosomal abnormality in nonseptated hygromas. Compared with fetuses with nonseptated cystic hygromas, those with septated cystic hygromas were more likely to be aneuploid (33 of 39 [85%] versus nine of 16 [56%]; P = .03), more likely to develop hydrops (27 of 45 [60%] versus three of 16 [19%]; P = .005), and less likely to be live-born (one of 44 [2%] versus four of 15 [27%]; P = .01).

CONCLUSIONS

Fetuses with septated cystic hygromas are more likely to be aneuploid and to develop hydrops, and thus are less likely to be survive than fetuses with nonseptated hygromas.

Elevated amniotic fluid interleukin-6 levels at genetic amniocentesis predict subsequent pregnancy loss

OBJECTIVE

Our purpose was to determine the proportion of pregnancy loss after genetic amniocentesis that is related to preexisting subclinical intrauterine inflammation.

STUDY DESIGN

We accessed our bank of stored second-trimester amniotic fluid and maternal serum samples obtained from women undergoing genetic amniocentesis at our institution from 1988 to 1995 (N = 11,971). Interleukin-6 levels were measured by enzyme-linked immunosorbent assay in samples from every case resulting in spontaneous postprocedure loss (excluding fetal aneuploidy and anomalies) within 30 days after the procedure (n = 66) and from 66 normal control women delivered at term and matched for year of test, gestational age, maternal age, and indication for amniocentesis.

RESULTS

Mean maternal serum interleukin-6 levels were the same in each group (0.02 +/- 0.07 ng/ml for cases and 0.06 +/- 0.25 ng/ml for controls, p = 0.45). Mean amniotic fluid interleukin-6 levels were higher in cases (4.0 +/- 13.1 ng/ml) than in controls (0.5 +/- 0.7 ng/ml, p = 0.04). The higher mean amniotic fluid interleukin-6 levels in the cases resulted from the inclusion of eight very high values (> or = 3 SD or > or = 2.5 ng/ml). When these samples were excluded, the means and range of values were the same in each group (0.4 +/- 0.4 ng/ml for cases and 0.5 +/- 0.7 ng/ml for controls, p = 0.58). Twelve percent (8/66) of the cases and 3% (2/66) of the controls had amniotic fluid interleukin-6 levels > or = 2.5 ng/ml (p = 0.048, odds ratio 4.1, 95% confidence interval 1.0 to 31.2). Although the overall correlation between maternal serum and amniotic fluid interleukin-6 levels was good (r = 0.50, p < 0.002), only one of the eight cases would have been identified by a maternal serum interleukin-6 level > or = 3 SD above the mean (> or = 0.8 ng/ml).

CONCLUSION

Analysis of our complete unselected group of postamniocentesis pregnancy losses indicates that up to 12% may result from preexisting subclinical intrauterine inflammation. This inflammation is most likely localized and may not be identified by a maternal serum interleukin-6 level before the procedure.

Effect of parity correction on Down syndrome detection by the multiple-marker screening test

OBJECTIVE

Our purpose was to determine whether maternal parity affects analyte levels in the multiple-marker screening test for Down syndrome and to derive a correction factor and determine its effect on Down syndrome detection and screen-positive rates.

STUDY DESIGN

Our database consisted of 3039 multiple-marker screening test results and corresponding fetal karyotypes (2983 euploid and 56 Down syndrome). Cases were grouped by maternal parity as follows: 0 (n = 848), 1 (n = 1140), or > or = 2 (n = 1051). The mean multiple of the median of maternal serum alpha-fetoprotein, estriol, and human chorionic gonadotropin was determined for each group. A correction factor was derived for each parity group and applied to the database. Parity-corrected Down syndrome detection rates and screen-positive rates were determined.

RESULTS

Parity significantly affected the mean multiple of the median of human chorionic gonadotropin levels (p = 0.0001) but did not affect the values for estriol or maternal serum alpha-fetoprotein. Application of a parity correction factor for human chorionic gonadotropin increased the Down syndrome detection rate in women who had two or more pregnancies from 71% to 82% without increasing the overall screen-positive rate.

CONCLUSION

Human chorionic gonadotropin levels are significantly lower in multiparous women. Correcting human chorionic gonadotropin for maternal parity increases Down syndrome detection for women who had two or more pregnancies without affecting the overall screen-positive rate.

Prognostic significance of unexplained elevated amniotic fluid alpha-fetoprotein

OBJECTIVE

To compare the prognostic values of unexplained elevated amniotic fluid alpha-fetoprotein (AF AFP > or = 2.0 multiples of the median [MoM]) and unexplained elevated maternal serum alpha-fetoprotein (MSAFP > or = 2.5 MoM).

METHODS

We accessed a data base containing the results of MSAFP screening tests, genetic amniocenteses, and pregnancy outcome data on all women undergoing second-trimester genetic amniocentesis from October 1988 through August 1994. After excluding all patients whose elevated AFP levels had any identifiable cause (positive AF acetylcholinesterase, AF blood contamination, fetal malformation or aneuploidy, multiple gestation, etc), 5743 cases were analyzed. Relative risks (RR) for selected pregnancy complications were determined.

RESULTS

Elevated MSAFP, with any AF AFP, was associated with fetal growth restriction (RR 2.5, 95% confidence interval [CI] 1.4-4.4), stillbirth (RR 3.5, 95% CI 1.4-8.3), preeclampsia (RR 2.8, 95% CI 1.1-7.0), and preterm delivery (RR 2.8, 95% CI 2.3-3.4). Elevated AF AFP, with any MSAFP, was associated with preeclampsia (RR 4.4, 95% CI 2.0-10.0) and preterm delivery (RR 1.7, 95% CI 1.3-2.4). Elevation of both AF AFP and MSAFP was associated with preterm delivery (RR 4.0, 95% CI 2.8-5.7). When elevated AF AFP was found in association with a normal MSAFP, the RR to develop preeclampsia was 4.6 (95% CI 1.9-11.2).

CONCLUSION

Maternal serum alpha-fetoprotein is a better predictor of late pregnancy complications than AF AFP. However, unexplained elevated AF AFP appears to be especially predictive of preeclampsia.

Multiple marker screening test: identification of fetal cystic hygroma, hydrops, and sex chromosome aneuploidy

The goal of this study was to determine if the multiple marker screening test (maternal serum alpha-fetoprotein, unconjugated estriol, human chorionic gonadotrophin, and maternal age) detects fetal Turner syndrome or just cystic hygroma/hydrops. Multiple marker screening tests from 4 groups were compared: 1) Turner syndrome with hydrops/ hygroma group (n = 10) = fetuses with cystic hygroma/hydrops and a 45X karyotype, 2) Turner syndrome without hydrops/hygroma (n = 9) = sonographically unremarkable fetal Turner syndrome or Turner mosaic, 3) hydrops group (n = 8) = all cases of fetal cystic hygroma/hydrops excluding Turner syndrome, 4) sex chromosome aneuploidy group (n = 16) = other sonographically normal fetal sex chromosome aneuploidies. Positive screening tests (Down syndrome risk > or = 1:190 or MSAFP > or = 2.5 MOM) were found in 60% (6/10) of the Turner syndrome with hydrops/hygroma group, but only 11% (1/9) of the Turner syndrome without hydrops/hygroma group (P = .04). The incidence of positive screening tests in the Hydrops group was 75% (6/8), while it was only 12.5% (2/16) in the other sex chromosome aneuploidy group. We conclude that the multiple marker screening test identifies fetuses with cystic hygroma/hydrops, and may do so independently of the etiology of the hydrops.

The influence of maternal weight on human chorionic gonadotropin in the multiple-marker screening test for fetal Down syndrome

OBJECTIVE

Our purpose was to determine the effect of maternal weight on human chorionic gonadotropin concentration in the multiple-marker screening test for fetal Down syndrome.

STUDY DESIGN

Two genetics databases were used: database I contained the results of 8297 multiple-marker screening tests and database II contained the results of 1936 multiple-marker screening tests and fetal karyotypes.

RESULTS

The overall screen-positive rate in database I was 7.1%; it was 7.5% in patients weighing < 180 pounds and 5.1% in patients weighing > or = 180 pounds (p = 0.001). Weight significantly affected the screen-positive rate only in women > or = 30 years old (p = 0.003 for 30 to 34 years, p = 0.00004 for > or = 35 years). A weight correction formula was derived; when applied to database II it eliminated individual weight-related differences but had no effect on the overall screen-positive rate or Down syndrome detection rate.

CONCLUSIONS

Human chorionic gonadotropin concentration is affected by maternal weight. A weight correction formula eliminates individual weight-related differences in the screen-positive rate but has no discernible effect on the overall screen-positive or Down syndrome detection rates.

The effect of low-dose aspirin on pregnancies complicated by elevated human chorionic gonadotropin levels

OBJECTIVE

Our purpose was to determine whether elevated second-trimester human chorionic gonadotropin levels identify women likely to benefit from low-dose aspirin therapy.

STUDY DESIGN

We evaluated second-trimester human chorionic gonadotropin levels obtained from healthy nulliparous women before screening for participation in a double-blind randomized trial of aspirin therapy: 262 women took 60 mg of aspirin daily and 420 did not.

RESULTS

Among women who did not take aspirin, those with human chorionic gonadotropin levels > or = 2.0 multiples of the median had a significantly lower mean birth weight (2859 vs 3159 gm, p = 0.04) than did those with normal human chorionic gonadotropin levels. All women who took aspirin had a higher mean birth weight than women who did not, but women with human chorionic gonadotropin levels > or = 2.0 multiples of the median had the greatest increase (416.2 gm higher in those with human chorionic gonadotropin levels > or = 2.0 multiples of the median, p = 0.02; 96 gm higher in those with human chorionic gonadotropin levels > or 2.0 multiples of the median, p = 0.04). Regression analysis suggested that the higher birth weight was partly explained by a higher gestational age at delivery and partly by increased weight independent of gestational age.

CONCLUSIONS

Aspirin therapy increased birth weight in all women, especially in women with high human chorionic gonadotropin levels, partly by increasing gestational age at delivery. This observation needs to be confirmed by further studies.

Comparison of multiple-marker screening with amniocentesis for the detection of fetal aneuploidy in women > or = 35 years old

OBJECTIVE

Our purpose was to compare the multiple-marker screening test with elective amniocentesis for the detection of fetal Down syndrome and other aneuploidies in women aged > or = 35.

STUDY DESIGN

Our database included the multiple-marker screening test (maternal serum alpha-fetoprotein, human chorionic gonadotropin, unconjugated estriol, and maternal age) and genetic amniocentesis results from 1942 women aged > or = 35. A Down syndrome risk > or = 1:190 was considered screen positive. An algorithm to detect trisomy 18 was also used.

RESULTS

The multiple-marker screening test Down syndrome screen-positive rate was 26.1% (507/1942). The Down syndrome detection rate was 75% (33/44); the trisomy 18 detection rate was 75% (3/4). However, the multiple-marker screening test detection rate for all aneuploidies was only 61%. Missed aneuploidies included trisomy 21, sex chromosome abnormalities, trisomy 13, trisomy 22, and trisomy 18.

CONCLUSIONS

The multiple-marker screening test fails to detect approximately 39% of all fetal aneuploidies in women aged > or = 35. These data should be provided to women considering prenatal diagnosis so that they can make an informed decision regarding the multiple-marker screening test versus amniocentesis for advanced maternal age.

Web neck anomaly and its association with congenital heart disease

To investigate the relationship between congenital heart disease and jugular lymphatic obstruction as manifested in web neck anomaly, we used the Iowa Birth Defects Registry to determine the incidence of congenital heart defects (CHD) in infants with and without web neck. Sixty percent of infants with web neck had CHD, with a high incidence of flow-related defects such as hypoplastic left heart, coarctation, and secundum atrial septal defect. Sixty-eight percent of infants with web neck had a genetic syndrome (37% Down syndrome, 13% Ullrich-Turner syndrome, and 5% Noonan syndrome), and 24% had dysmorphic features consistent with lymphatic obstruction sequence. When infants with Down, Ullrich-Turner, and Noonan syndrome and web neck were compared to infants with the same syndrome but without web neck, those with web neck were significantly more likely to have flow-related heart defects. Infants with Ullrich-Turner syndrome and web neck had an 11-fold higher incidence of coarctation, compared to those with a normal neck. Our data suggests web neck is associated with both flow and nonflow-related heart defects. This association implies a pathogenetic relationship and appears to be independent of causal factors. The finding of web neck or nuchal cystic hygroma on a prenatal ultrasound or newborn examination should prompt a search for CHD.

The utility of fetal biometry as an adjunct to the multiple-marker screening test for Down syndrome

OBJECTIVE

Our purpose was to investigate fetal biometry as an adjunct to the multiple-marker screen (maternal age, serum alpha-fetoprotein, estriol, and human chorionic gonadotropin) for Down syndrome.

STUDY DESIGN

Fifty-two cases of Down syndrome were compared with 7514 normal fetuses. The measured/predicted femur length ratio had the best discriminant value (1.0 +/- 0.11 vs 0.93 +/- 0.13, p < 0.0001). Multivariate gaussian algorithms were developed and each computed a likelihood ratio for Down syndrome. The trivariate algorithm incorporated the three maternal analytes, whereas the quadrivariate version also included the femur length ratio. The study population included 38 cases of Down syndrome and 1098 euploid controls. The midtrimester risk was the product of the age-related risk and the likelihood ratio.

RESULTS

The relative difference in the femur length ratio between normal and affected fetuses was small in comparison to that of the maternal serum analytes. At a risk cutoff of > or = 1:190 the detection rates were similar and actually favored the trivariate algorithm but differed only by one case of Down syndrome.

CONCLUSION

The addition of the measured/predicted femur length ratio had a negligible effect on the performance of the multiple-marker screening test.

Elevated second-trimester human chorionic gonadotropin levels in association with poor pregnancy outcome

OBJECTIVE

Our purpose was to determine whether abnormal pregnancy outcome is associated with elevated maternal serum human chorionic gonadotropin levels.

STUDY DESIGN

Maternal serum alpha-fetoprotein and human chorionic gonadotropin levels were measured in stored second-trimester serum obtained before scheduled genetic amniocentesis from 126 women with poor pregnancy outcomes, excluding aneuploidy and structural abnormalities (complications group), and 126 matched women with normal outcomes (control group).

RESULTS

More women with complications had elevated human chorionic gonadotropin levels (> or = 2.0 multiples of the median) (14%) than did control women (3%) (p = 0.01). Both elevated human chorionic gonadotropin and maternal serum alpha-fetoprotein levels were significantly associated with preterm delivery and fetal death. Elevated maternal serum alpha-fetoprotein was significantly associated with early postamniocentesis complications and fetal growth restriction, whereas elevated human chorionic gonadotropin was associated with preeclampsia.

CONCLUSION

Elevated human chorionic gonadotropin, similar to unexplained elevated maternal serum alpha-fetoprotein, is significantly associated with abnormal pregnancy outcomes.

Outcome of alloimmunized fetuses managed solely by cordocentesis but not requiring antenatal transfusion

A published algorithm for the frequency of fetal blood sampling in the management of fetal hemolytic disease allows many pregnancies to continue 1-3 months after the last sample until delivery at term. Though the positive predictive value for antenatal anemia is known, the likelihood of either neonatal hyperbilirubinemia or an unexpected anemia (< 30%) is not. The perinatal records of 51 antigen-positive neonates who did not require treatment antenatally were abstracted. As fetuses, these neonates had been prospectively coded as either low risk (pattern 1), moderate risk (pattern 2) or high risk (patterns 3 and 4) for antenatal anemia (hematocrit < 30%) based on their hematocrit, reticulocyte count, and the strength of the direct Coombs' test performed on their first sample. Delivery occurred at 38 +/- 2 weeks. Neonatal complications of hemolytic disease were common. Sixty-four percent required phototherapy, 17% one or more double-volume exchange transfusions, and 13% one or more simple transfusions for late-developing anemia. In all, 29% of neonates received postnatal transfusion therapy. The only correlation between the antenatal hematologic/serologic studies and the need for postnatal transfusion therapy was the strength of the indirect Coombs' test performed on the first fetal blood sample. Two neonates unexpectedly had anemia (4% risk). In the first, the hematocrit at 35 weeks was 40% and the ultrasound 1 week later normal. In one, the algorithm had been erroneously applied. Stability of the hematocrit in fetuses at risk to develop antenatal anemia can be accurately predicted by fetal blood tests performed weeks prior to delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Amniotic fluid embolism after saline amnioinfusion: two cases and review of the literature

BACKGROUND

Amnioinfusion is an intrapartum intervention with proven benefit in certain clinical situations. It is thought to be a safe treatment with few adverse effects.

CASES

Two cases of fatal amniotic fluid (AF) embolism occurred in women who were treated during labor with a saline amnioinfusion. In both cases, amnioinfusion was administered after finding thick meconium staining of the AF. In addition to the amnioinfusion, common factors in these cases and three previously reported AF embolisms associated with amnioinfusion are the presence of rapid labor, meconium-stained fluid, or both.

CONCLUSIONS

Amniotic fluid embolism is a rare cause of maternal morbidity and mortality. It is not known whether amnioinfusion increases the rate of its occurrence in laboring patients. No change in clinical practice is warranted on the basis of these reports; however, future reports must be examined so that any common factors can be identified.

Detection of fetal Turner syndrome with multiple-marker screening

OBJECTIVE

Our purpose was to examine the ability of the multiple-marker screening test (maternal serum alpha-fetoprotein, human chorionic gonadotropin, unconjugated estriol, and maternal age) to detect fetal Turner syndrome.

STUDY DESIGN

We reviewed 27,282 screening tests performed at our institution between July 1, 1990, and June 30, 1992. All cases in which fetal Turner syndrome was detected as a result of a positive Down syndrome screening test (Down syndrome risk > or = 1:190) or in which a positive screening test was obtained before an amniocentesis scheduled for other reasons were included. Serum marker levels, Down syndrome risk, and ultrasonographic findings were reviewed. To clarify the relative contributions of estriol and human chorionic gonadotropin to the positive screen, the risks were recalculated using only maternal serum alpha-fetoprotein and hCG or maternal serum alpha-fetoprotein and estriol.

RESULTS

Eight cases were identified. Four fetuses had cystic hygroma and hydrops, two had hygroma only, and two had no abnormality on ultrasonography. Both human chorionic gonadotropin and estriol contributed to the positive screen.

CONCLUSION

The multiple-marker screening test appears to detect Turner syndrome, as well as trisomies 21 and 18.

Fetal echogenic bowel on ultrasound: is there clinical significance?

Though echogenic fetal bowel has been associated with meconium ileus and/or peritonitis, it may be a normal finding in the second trimester. The purpose of this study is to determine which characteristics might distinguish fetuses ultimately having abnormal outcomes in a population at low risk for cystic fibrosis. Seven fetuses with echogenic bowel were identified: 5 fetuses < or = 20 weeks gestation (group 1) and 2 fetuses 20-25 weeks gestation (group 2) at diagnosis. Four of 5 group 1 fetuses had resolution of the echogenic bowel during the second trimester. One group 2 fetus had a persistent mass associated with growth deficiency and trisomy 18. The neonatal bowel evaluation was normal in the remaining 2 fetuses although echogenic findings persisted into the third trimester. In a low-risk population, echogenic bowel usually resolves without neonatal sequelae. Even when persistent into the third trimester, echogenic bowel does not uniformly herald an abnormal outcome. Echogenic bowel coexistent with other abnormalities (such as growth deficiency or structural malformations) may be a comarker for aneuploidy.

Evaluation of multiple-marker screening for Down syndrome in a statewide population

OBJECTIVE

Our purpose was to evaluate our experience with a statewide, multiple-marker Down syndrome screening program.

STUDY DESIGN

The results of 18,712 screening tests performed from July 1, 1991, to Oct. 31, 1992, were reviewed. Amniocentesis and aneuploidy detection rates were compared with the experience of a previous year (1989-1990) in which material serum alpha-fetoprotein was used for detection of Down syndrome.

RESULTS

Positive screening tests (Down syndrome risk > or = 1/190) occurred in 665 of 18,712 (3.5%) patients; 516 of 665 (78%) patients accepted amniocentesis. Fifteen aneuploidies were identified: 12 trisomy 21, one trisomy 18, one trisomy 13, and one 48,XXXY. The overall detection rate was one in 34 amniocenteses performed; for trisomy 21 it was one in 43. In a previous year in which maternal serum alpha-fetoprotein alone was used, 3.6% had positive screening tests (Down syndrome risk > or = 270); the detection rate for all aneuploidies was one in 57 amniocenteses, and for trisomy 21 it was one in 114. The expanded maternal serum alpha-fetoprotein test was well accepted by clinicians, with 36% of gravid state residents undergoing screening.

CONCLUSION

The multiple marker test is a good screening tool and is superior to material serum alpha-fetoprotein alone.

Increased risk of monochorionic twinning associated with assisted reproduction

OBJECTIVE

To determine the incidence of monochorionic twinning in pregnancies resulting from assisted reproduction technologies (ARTs).

METHODS

We reviewed our experience with 218 ART pregnancies achieved over 3 years. All patients underwent transvaginal ultrasound 26 and 36 days after oocyte retrieval. The presence of two yolk sacs or two fetal poles within one sac suggested monochorionicity, and was confirmed by follow-up ultrasound and placental pathology. The various ARTs were compared to determine if any method had an increased incidence of monochorionicity compared to any other method. Statistical analysis was performed employing Chi Square analysis.

RESULTS

The incidence of monochorionicity in all gestations was 3.2% (8 times background rate); among multiple gestations it was 9.8%. The rates of monochorionicity for each ART appeared similar.

CONCLUSION

The incidence of monochorionic twinning is increased in pregnancies resulting from ART. Careful ultrasound evaluation of such pregnancies for monochorionicity is strongly recommended, both for planning of prenatal care and when considering a multifetal pregnancy reduction procedure.

Prediction of pregnancy outcome with single versus serial maternal serum alpha-fetoprotein tests

OBJECTIVE

The purpose of our study was to determine whether the trend of three maternal serum alpha-fetoprotein samples was more predictive of pregnancy outcome than the initial sample in the evaluation of patients with unexplained alpha-fetoprotein elevations.

STUDY DESIGN

A total of 432 patients with unexplained elevation of their first two maternal serum alpha-fetoprotein samples had a third sample drawn. Pregnancy outcomes were determined. Patients were grouped for analysis according to the level of the initial sample, the final sample, and the trend of three samples. Statistical analysis was by chi 2 and logistic regression, with p < 0.05 considered significant.

RESULTS

The initial maternal serum alpha-fetoprotein was most predictive of preterm delivery (p < 0.001), size small for gestational age (p < 0.001), and intrauterine fetal death (p = 0.009). Neither the final value nor the trend of three values was as prognostic.

CONCLUSION

The first maternal serum alpha-fetoprotein is the best predictor of pregnancy outcome. Obtaining a second sample to confirm the elevation is appropriate, but additional samples provide minimal information.

Antenatal treatment of fetal alloimmune thrombocytopenia

OBJECTIVE

To review our experience with, and to evaluate the efficacy of, antenatal pharmacologic treatment of pregnancies complicated by alloimmune thrombocytopenia.

METHODS

We reviewed the records of six pregnancies complicated by alloimmune thrombocytopenia recently cared for at the University of Iowa Fetal Diagnosis and Treatment Unit. All patients had a history consistent with alloimmune thrombocytopenia in a previous gestation. All fetuses had thrombocytopenia on funipuncture at 20-32 weeks' gestation, and all patients and fetuses demonstrated a platelet antigen incompatibility. Three women initially received weekly gamma globulin infusions, two received gamma globulin and dexamethasone, and one had no initial treatment but was given gamma globulin and dexamethasone at 32 weeks' gestation. Repeat funipuncture was performed at 3.5- to 7-week intervals, and therapeutic modifications were made as necessary.

RESULTS

In five cases, the last funipuncture before delivery documented platelet counts adequate for vaginal delivery. One woman, who received gamma globulin alone with good initial response, was delivered by cesarean for a platelet count of 25,000/microL at 39 weeks. Following delivery, all infants were thoroughly evaluated, and none had evidence of intracranial hemorrhage or other alloimmune thrombocytopenia-associated morbidity. All had normal platelet counts at discharge from the hospital.

CONCLUSIONS

Our experience confirms the efficacy of gamma globulin treatment, but indicates that not all fetuses will respond to it alone. Serial funipunctures are essential to evaluate patient response and allow appropriate therapeutic modifications. Randomized studies are needed to determine the optimal antenatal pharmacologic therapy for this disease.

Frequency, distribution, and theoretical mechanisms of hematologic and weight discordance in monochorionic twins

OBJECTIVE

The purpose of this study was to determine the frequency, distribution, and most likely etiology of hematologic and weight discordance in pathologically proven monochorionic twins, and to use this information to reevaluate the neonatally derived definition of the twin-twin transfusion syndrome.

METHODS

We reviewed our experience with 97 pathologically proven monochorionic twin pregnancies. The frequency and distribution of weight and hemoglobin-hematocrit (hb-hct) discordance were determined for all twin pairs. Factors that may have contributed to the discordance were identified, and theoretical mechanisms were proposed.

RESULTS

All combinations of weight and hb-hct discordance were observed. Thirty-four twin pairs (35%) were discordant for weight. In half of these (17 of 34), the hb and hct were concordant. In 18% (six of 34), the smaller twin had the higher hb-hct, and in 32% (11 of 34), the smaller twin had the lower hb-hct. Twenty-three of 63 size-concordant pairs (36%) were discordant for hb-hct. Ten infants were infected at birth, eight had malformations, and 25 likely suffered an acute transfusion event.

CONCLUSIONS

Any combination of weight and hb-hct discordance can occur in monochorionic twins. Acute and chronic twin-twin transfusion, uteroplacental insufficiency, infection, malformations, or other factors may have accounted for the discordance observed. Thorough antenatal evaluation with invasive testing and marker studies (to identify a physiologically unbalanced placental anastomosis) may be necessary to establish an accurate diagnosis. We conclude that weight and/or hb-hct discordance is relatively common in monochorionic twins and in itself is not sufficient to diagnose twin-twin transfusion.