Katharine D. Wenstrom

Risk factors for cordocentesis and fetal intravascular transfusion

There is little information on the impact of technical aspects or patient characteristics on the risks of accessing the fetal circulation. We performed 594 diagnostic cordocenteses and 156 intravascular transfusions over 6 years. Pancuronium was administered during 52% of procedures. The number of needle punctures per successful procedure was unrelated to the placental location. However, the number of punctures required was lower if the placental cord origin rather than a midsegment was targeted (p less than 0.0001). Bleeding from either the uterine or umbilical cord puncture site was not believed to be clinically significant, although the duration of bleeding was greater after arterial puncture than after venous puncture (p = 0.01) and after intravascular transfusion than after diagnostic cordocentesis (p less than 0.0001). Amnionitis (suspected plus verified) complicated 0.5% of procedures. Preterm premature rupture of membranes (with or without amnionitis) followed 0.4% of procedures. Fetal bradycardia occurred in 6.6% (6.6 +/- 0.8 minutes; range, 0.1 to 35 minutes). There were five perinatal losses after a diagnostic procedure, yielding an uncorrected loss rate of 0.8% (5/594). Each was associated with a prolonged bradycardia; each fetus was ultimately demonstrated to have been unsalvageable. Two independent risk factors for bradycardia were identified--arterial puncture and severe, early onset intrauterine growth retardation. The administration of pancuronium reduced the incidence of bradycardia in appropriately grown fetuses (6% to 1.5%; p less than 0.05), but did not alter the incidence in growth-retarded fetuses. We conclude that cordocentesis performed with a needle guide is a safe procedure but that its risk varies with both the indication and the vessel punctured.

Prothrombin Gene G20210A Mutation and Obstetric Complications

OBJECTIVE: To estimate whether maternal carriage of the prothrombin gene G20210A mutation is associated with pregnancy loss, preeclampsia, placental abruption, or small for gestational age (SGA) neonates in a low-risk, prospective cohort. METHODS: This was a secondary analysis of the Eunice Kennedy Shriver National Institute of Child Health and Human Development factor V Leiden study, a multicenter, prospective, observational cohort of 5,188 unselected singleton gestations. A total of 4,167 first-trimester samples were available for analysis and were tested for the prothrombin G20210A mutation. Obstetric complications were compared between women with and without the prothrombin G20210A mutation by univariable and multivariable analysis. RESULTS: A total of 157 (3.8%) women had the prothrombin gene mutation (156 heterozygous and one homozygous). Carriers of the prothrombin G20210A mutation had similar rates of pregnancy loss, preeclampsia, SGA neonates, and abruption compared with noncarriers. Results were similar in a multivariable analysis controlling for age, race, prior pregnancy loss, prior SGA neonates, and family history of thromboembolism. Three thromboembolic events occurred in women testing negative for the mutation. CONCLUSION: There was no association between the prothrombin G20210A mutation and pregnancy loss, preeclampsia, abruption, or SGA neonates in a low-risk, prospective cohort. These data raise questions about the practice of screening women without a history of thrombosis or adverse pregnancy outcomes for this mutation. LEVEL OF EVIDENCE: II

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%.

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.

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.

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 β-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.

A five-year statewide experience with congenital diaphragmatic hernia

Antenatal in utero surgery for congenital diaphragmatic hernia has been justified by reported perinatal mortality rates of 77% to 80%. Such rates may have been subject to bias of ascertainment and may include fetuses with additional severe malformations who would not be surgical candidates. We used the Iowa Birth Defects Registry to conduct a complete population survey to determine the incidence of congenital diaphragmatic hernia, the frequency of associated severe malformations, and the morbidity and mortality of infants with isolated congenital diaphragmatic hernia who were not subjected to antenatal surgery. The incidence of congenital diaphragmatic hernia was 1 in 3715. Twenty-eight percent of affected fetuses had associated severe malformations that were potentially identifiable prenatally and that would have precluded antenatal surgery. Of those with isolated congenital diaphragmatic hernia, 55% survived in spite of delivery (88.5%) and/or surgical repair (44%) in a level I or II hospital. Any decision for in utero surgery to repair congenital diaphragmatic hernia must be based on this or similarly obtained information.

Prognostic significance of unexplained elevated amniotic fluid alpha-fetoprotein

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

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.

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.