Unexplained elevated maternal serum alpha-fetoprotein levels and perinatal outcome in an urban clinic population

Guideline No. 414: Management of Pregnancy of Unknown Location and Tubal and Nontubal Ectopic Pregnancies

OBJECTIVE

To provide an evidence-based algorithm to guide the diagnosis and management of pregnancy of unknown location and tubal and nontubal ectopic pregnancy.

TARGET POPULATION

All patients of reproductive age.

BENEFITS, HARMS, AND COSTS

The implementation of this guideline aims to benefit patients with positive β-human chorionic gonadotropin results and provide physicians with a standard algorithm for expectant, medical, and surgical treatment of pregnancy of unknown location and tubal pregnancy and nontubal ectopic pregnancies.

EVIDENCE

The following search terms were entered into PubMed/Medline and Cochrane in 2018: cesarean section, chorionic gonadotropin, beta subunit, human/blood, fallopian tubes/surgery, female, fertility, humans, infertility, laparoscopy, methotrexate, methotrexate/administration & dosage, methotrexate/therapeutic use, pregnancy (abdominal, angular, cervix, cornual, ectopic, ectopic/diagnosis, ectopic/diagnostic imaging, ectopic/drug therapy, ectopic/epidemiology, ectopic/mortality, ectopic/surgery, heterotopic, interstitial, isthmo-cervical, ovarian, tubal, unknown location), recurrence, risk factors, salpingectomy, salpingostomy, tubal pregnancy, ultrasonography, doppler ultrasonography, and prenatal. Articles included were randomized controlled trials, meta-analyses, systematic reviews, observational studies, and case reports. Additional publications were identified from the bibliographies of these articles. Only English-language articles were reviewed.

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and weak recommendations).

INTENDED AUDIENCE

Obstetrician-gynaecologists, family physicians, emergency physicians, midwives, registered nurses, nurse practitioners, medical students, and residents and fellows.

SUMMARY STATEMENTS (GRADE RATINGS IN PARENTHESES)

RECOMMENDATIONS (GRADE RATINGS IN PARENTHESES).

Association of high maternal blood alpha-fetoprotein level with risk of delivering small for gestational age: a meta-analysis

BACKGROUND

Early identification of pregnant women at risk of delivering small-for-gestational-age (SGA) infants is required to reduce the rates of mortality and morbidity in their whole life. This meta-analysis was performed to determine whether women with higher blood alpha-fetoprotein (AFP) levels are at increased risk of SGA.

METHODS

Studies identified by searching 11 databases, including PubMed, were assessed using the Newcastle-Ottawa Scale. Subgroup and meta-regression analyses and sensitivity analysis removing a potential outlier were performed. Publication bias was assessed using Egger's test.

RESULTS

A total of 39 good-quality cohort studies involving 93,968 women and their newborn infants or fetuses ensured both internal and external validity. Relative risk of SGA among women with higher in comparison to lower blood AFP levels was 2.021 (95% CI: 1.751-2.334). Maternal blood AFP levels showed a dose-response relationship with risk of SGA. Relative risk was higher with diagnosis of SGA by ultrasound than actual birth weight (P = 0.004). Sources of heterogeneity, subgroups, confounding factors, or potential outliers did not alter the interpretations without publication bias (P = 0.320).

CONCLUSIONS

Pregnant women with higher blood AFP levels are at increased risk of SGA compared to those with lower blood AFP levels.

IMPACT

Pregnant women with higher blood alpha-fetoprotein levels (AFP) levels are at increased risk of small for gestational age (SGA) compared to those with lower blood AFP levels. High-quality evidence showed a dose-response relationship of maternal blood AFP levels with risk of delivering SGA and was robust to sources of heterogeneity, subgroups, confounding factors, potential outliers, or publication bias. Politically and practically, monitoring of maternal blood AFP level is strongly recommended to identify women at risk of delivering SGA.

Directive clinique no 414 : Prise en charge des grossesses de localisation indéterminée et des grossesses ectopiques tubaires et non tubaires

OBJECTIF

Fournir un algorithme fondé sur des données probantes pour orienter le diagnostic et la prise en charge de la grossesse de localisation indéterminée et de la grossesse ectopique tubaire ou non tubaire.

POPULATION CIBLE

Toutes les patientes en âge de procréer. BéNéFICES, RISQUES ET COûTS: La mise en œuvre de la présente directive a pour objectif de bénéficier aux patientes ayant obtenu un résultat positif pour la sous-unité bêta de la gonadotrophine chorionique et de fournir aux médecins un algorithme normalisé pour l'expectative et le traitement pharmacologique ou chirurgical en cas de grossesse de localisation indéterminée et de grossesse ectopique tubaire ou non tubaire. DONNéES PROBANTES: Les termes de recherche suivants ont été entrés dans les bases de données PubMed-Medline et Cochrane en 2018 : cesarean section, chorionic gonadotropin, beta subunit, human/blood, fallopian tubes/surgery, female, fertility, humans, infertility, laparoscopy, methotrexate, methotrexate/administration & dosage, methotrexate/therapeutic use, pregnancy (abdominal, angular, cervix, cornual, ectopic, ectopic/diagnosis, ectopic/diagnostic imaging, ectopic/drug therapy, ectopic/epidemiology, ectopic/mortality, ectopic/surgery, heterotopic, interstitial, isthmo-cervical, ovarian, tubal, unknown location), recurrence, risk factors, salpingectomy, salpingostomy, tubal pregnancy, ultrasonography, doppler ultrasonography et prenatal. Les articles retenus sont des essais cliniques randomisés, des méta-analyses, des revues systématiques, des études observationnelles et des études de cas. Des publications supplémentaires ont été sélectionnées à partir des notices bibliographiques de ces articles. Seuls les articles en anglais ont été examinés. MéTHODES DE VALIDATION: Les auteurs ont évalué la qualité des données probantes et la solidité des recommandations en utilisant la méthodologie GRADE (Grading of Recommendations Assessment, Development and Evaluation). Voir l'annexe A en ligne (tableau A1 pour les définitions et tableau A2 pour l'interprétation des recommandations fortes et faibles). PUBLIC VISé: Obstétriciens-gynécologues, médecins de famille, urgentologues, sages-femmes, infirmières autorisées, infirmières praticiennes, étudiants en médecine, résidents et moniteurs cliniques. DÉCLARATIONS SOMMAIRES (CLASSEMENT GRADE ENTRE PARENTHèSES): RECOMMANDATIONS (CLASSEMENT GRADE ENTRE PARENTHèSES).

Update and Review: Maternal Serum Screening

Maternal serum levels of alpha fetoprotein (AFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) can be used to screen pregnancies for neural tube defects, Down syndrome, Trisomy 18, and pregnancy complications. This article summarizes the most recent information regarding maternal serum screening, including genetic counseling issues.

First- and second-trimester tests to predict stillbirth in unselected pregnant women: a systematic review and meta-analysis

BACKGROUND

Several biophysical and biochemical tests have been proposed to predict stillbirth but their predictive ability remains unclear.

OBJECTIVE

To assess the accuracy of tests performed during the first and/or second trimester of pregnancy to predict stillbirth in unselected women with singleton, structurally and chromosomally normal fetuses through use of formal methods for systematic reviews and meta-analytic techniques.

SEARCH STRATEGY

Electronic databases, bibliographies and conference proceedings.

SELECTION CRITERIA

Observational studies that evaluated the predictive accuracy for stillbirth of tests performed during the first two trimesters of pregnancy.

DATA COLLECTION AND ANALYSIS

Two reviewers selected studies, assessed risk of bias and extracted data. Summary receiver operating characteristic curves, pooled sensitivities, specificities and likelihood ratios (LRs) were generated. Data were synthesised separately for stillbirth as a sole category and for specific stillbirth categories.

MAIN RESULTS

Seventy-one studies, evaluating 16 single and five combined tests, met the inclusion criteria. A uterine artery pulsatility index >90th centile during the second trimester and low levels of pregnancy-associated plasma protein A (PAPP-A) during the first trimester had a moderate to high predictive accuracy for stillbirth related to placental abruption, small-for-gestational-age or pre-eclampsia (positive and negative LRs from 6.3 to 14.1, and from 0.1 to 0.4, respectively). All biophysical and biochemical tests assessed had a low predictive accuracy for stillbirth as a sole category.

CONCLUSIONS

Currently, there is no clinically useful first-trimester or second-trimester test to predict stillbirth as a sole category. Uterine artery pulsatility index and maternal serum PAPP-A levels appeared to be good predictors of stillbirth related to placental dysfunction disorders.

Biochemical markers predictive of preterm delivery

Preterm delivery is the leading cause of perinatal morbidity and mortality worldwide. Despite a great deal of research into this disease, we still do not understand its pathophysiology. Our treatments for this disease are only marginally effective. Biochemical markers were developed with the hope of giving us new tools to prevent preterm deliveries. Specifically the hope was that they could predict which patients were destined to have a preterm delivery. At the present time these markers perform only satisfactorily at predicting preterm labor. They are expensive and not convenient to use at present. Perhaps more importantly, though, these markers have given us insight into the complexities of preterm delivery. Preterm delivery can arise from many different etiologies. This will lead to research into new treatments as knowledge about preterm delivery is amassed. We know that any number of pathological processes may be involved in any given patient with preterm labor. Biochemical markers have the distinct advantage of being able to determine the specific pathophysiology in a given patient and may allow us to tailor therapy according to the specific problem. In the future it is likely that a careful search for specific pathophysiology will be the only way we can treat this disease effectively. For the present time the biochemical markers will be used only to predict preterm delivery. Ultrasound measurements of the cervix during the pregnancy are likely a faster and less expensive way to accomplish that goal.

Serum screening with Down's syndrome markers to predict pre-eclampsia and small for gestational age: systematic review and meta-analysis

Background

Reliable antenatal identification of pre-eclampsia and small for gestational age is crucial to judicious allocation of monitoring resources and use of preventative treatment with the prospect of improving maternal/perinatal outcome. The purpose of this systematic review was to determine the accuracy of five serum analytes used in Down's serum screening for prediction of pre-eclampsia and/or small for gestational age.

Methods

The data sources included Medline, Embase, Cochrane library, Medion (inception to February 2007), hand searching of relevant journals, reference list checking of included articles, contact with experts. Two reviewers independently selected the articles in which the accuracy of an analyte used in Downs's serum screening before the 25^th gestational week was associated with the occurrence of pre-eclampsia and/or small for gestational age without language restrictions. Two authors independently extracted data on study characteristics, quality and results.

Results

Five serum screening markers were evaluated. 44 studies, testing 169,637 pregnant women (4376 pre-eclampsia cases) and 86 studies, testing 382,005 women (20,339 fetal growth restriction cases) met the selection criteria. The results showed low predictive accuracy overall. For pre-eclampsia the best predictor was inhibin A>2.79MoM positive likelihood ratio 19.52 (8.33,45.79) and negative likelihood ratio 0.30 (0.13,0.68) (single study). For small for gestational age it was AFP>2.0MoM to predict birth weight < 10^th centile with birth < 37 weeks positive likelihood ratio 27.96 (8.02,97.48) and negative likelihood ratio 0.78 (0.55,1.11) (single study). A potential clinical application using aspirin as a treatment is given as an example.

There were methodological and reporting limitations in the included studies thus studies were heterogeneous giving pooled results with wide confidence intervals.

Conclusion

Down's serum screening analytes have low predictive accuracy for pre-eclampsia and small for gestational age. They may be a useful means of risk assessment or of use in prediction when combined with other tests.

Endothelial Nitric Oxide Synthase Polymorphism Is Not Associated with Placental Abruption in Finnish Women

OBJECTIVE

To study whether genetic variability in the gene encoding endothelial nitric oxide synthase (eNOS) affects individual susceptibility to the development of placental abruption during pregnancy.

METHODS

One hundred and sixteen pregnant women with placental abruption and 113 healthy controls were genotyped for Glu298Asp polymorphism in the eNOS gene. Chi-square analysis was used to assess the differences in genotype and allele frequencies between the two groups.

RESULTS

A statistically similar allelic distribution of eNOS Glu298Asp polymorphism was observed in the two groups, with the frequency of the variant G allele being 66.8% in the abruption group and 68.1% in the control group (OR 0.94, 95% CI: 0.64-1.39; p = 0.76). The genotype distribution of the eNOS polymorphism was also found to be statistically similar (p = 0.72).

CONCLUSIONS

The observed genotype data in subjects from eastern Finland suggest that the Glu298Asp polymorphism of the eNOS gene does not contribute to placental abruption in this population.

Screening for pre-eclampsia by using maternal serum inhibin A, activin A, human chorionic gonadotropin, unconjugated estriol, and alpha-fetoprotein levels and uterine artery Doppler in the second trimester of pregnancy

AIMS

To analyse the predictive power of maternal serum inhibin A, activin A, human chorionic gonadotropin (hCG), unconjugated estriol (uE(3)), alpha-fetoprotein (AFP) levels and uterine artery Doppler in the second trimester of pregnancy in screening for pre-eclampsia.

METHODS

Maternal serum inhibin A, activin A, hCG, uE(3), and AFP levels and uterine artery Doppler were determined in 178 healthy, pregnant women in the second trimester of pregnancy. Serum samples were collected between the 16th and 18th weeks of gestation, and Doppler investigation was performed between the 24th and 26th weeks of gestation. Receiver operating characteristic curves were created to analyse the predictive powers of the above parameters in screening for pre-eclampsia. Different combinations also were analysed.

RESULTS

The rate of pre-eclampsia was 7.9% (14/178). Maternal serum inhibin A, activin A, hCG, AFP levels, the rate of presence of the prediastolic notch and uterine artery resistance index (RI) values in pre-eclamptic pregnancies were significantly higher than those in healthy pregnancies. Presence of the prediastolic notch, uterine artery RI, maternal serum activin A and inhibin A levels had high predictive efficacy, and each had a sensitivity between 70 and 93% and a specificity between 87% and 98%. The addition of inhibin A or activin A measurement to the Doppler velocimetry improved the specificity to 99-100%.

CONCLUSIONS

Maternal serum inhibin A and activin A levels and uterine artery Doppler appear to be useful screening tests during the second trimester for pre-eclampsia. However, addition of these hormonal markers to Doppler velocimetry only slightly improves the predictive efficacy, which appears clinically insignificant.

Prediction of preeclampsia: can it be achieved?

In this review, the various biochemical tests that have been proposed for the prediction of preeclampsia are described and evaluated. Placenta hormone markers do not predict future disease. They denounce the early placental changes that are part of the evolving disease and only predict the imminent of preeclamptic syndrome. This explains why tests are better predictors when preeclampsia supervenes shortly, and why screening in the first trimester is unlikely to work as well as in the second trimester. The use of multiple markers in the screening should reflect different aspects of the disease process and could increase the specificity and sensitivity of the screening and work on different etiologic factors. The possible use of second-trimester biochemical screening to predict the risk of preeclampsia remains to be investigated in the high-risk population.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader should be able to list the various theories on the etiology of preeclampsia, to relate the various risk factors for the development of preeclampsia, and to describe the various screening tests for preeclampsia.

Total protein concentration in human amniotic fluid is negatively associated with infant birth weight

Our objectives were 2-fold: 1) to assess the concentration and distribution of total protein in human amniotic fluid (AF) using 3 standard assays [Bradford, bicinchoninic acid solution (BCA), and Lowry] and 2) to establish whether these total protein concentrations were associated with and predictive of infant birth weight. Birth outcomes were determined using recently developed birth-weight-for-gestational-age categories (percentiles) for fetal growth where infants < 10% were classified as SGA (small-for-gestational-age), those between 10 and 90% as appropriate-for-gestational-age (AGA) and those infants >/= 90% as large-for-gestational-age (LGA). AF samples were collected from women undergoing routine amniocentesis for genetic testing (mean = 15 +/- 0.04 wk, range 12-20 wk), frozen, and later analyzed for total protein in 617 singleton-expectant mothers in Montréal, QC, Canada. Maternal and fetal characteristics were obtained from questionnaires and medical chart review. Mothers giving birth to LGA infants had uniformly lower AF protein concentrations at 12-20 wk gestation compared with AF protein concentrations for mothers of AGA infants. Multiple regression analyses demonstrated that total AF protein, collected during routine amniocentesis and later analyzed by the Lowry method, was negatively associated with birth weight at term in our population. These data suggest that one or more AF proteins might emerge as biomarkers of fetal growth.

Maternal medical disease: risk of antepartum fetal death

Although certain maternal medical conditions increase the risk of antepartum fetal death, improvements in medical and obstetric care have decreased the likelihood of stillbirth. This article examines the current stillbirth rates reported in pregnancies complicated by common medical diseases. The reported stillbirth rates are expressed as the number of stillbirths occurring at > or = 20 weeks of gestation per 1,000 births in patients with the condition. Overall, about 10% of all fetal deaths are related to maternal medical illnesses such as hypertension, diabetes, obesity, systemic lupus erythematosus, chronic renal disease, thyroid disorders, and cholestasis of pregnancy. The early recognition of maternal medical diseases provides an opportunity for increased surveillance and interventions that may lead to more favorable pregnancy outcomes.

Pregnancy outcomes and community health: the POUCH study of preterm delivery

In light of the social/ethnic disparity in preterm delivery (PTD) rates, the Pregnancy Outcomes and Community Health (POUCH) Study takes a broad view of the determinants of PTD by attempting to link underlying biological and psychosocial factors. The relationships between placental pathology, maternal biomarkers, and antecedent psychosocial factors are evaluated in three hypothesised pathways of PTD - one characterised primarily by infection, one by maternal vascular disease, and one by premature elevations in corticotropin releasing hormone in the absence of histological evidence of placental pathology. Within each pathway, an emphasis is placed on understanding the roles of stress and of maternal serum alpha-fetoprotein, an early biomarker associated with PTD. The POUCH Study enrolls pregnant women from five Michigan communities. Information about these women and their environments is gathered through detailed interviews and collection of biological samples including hair, urine, saliva, blood, vaginal fluid, and vaginal smear at 15-26 weeks of gestation. We have chosen to focus on the second trimester--a time when pathological processes may have evolved to a detectable stage, but generally before the onset of biological changes that accompany labour. This focus is consistent with the long-range goal of early detection/intervention and prevention of PTD.

A discrepancy between gestational age estimated by last menstrual period and biparietal diameter may indicate an increased risk of fetal death and adverse pregnancy outcome

OBJECTIVE

To determine if the discrepancy between gestational age estimated by last menstrual period and by biparietal diameter (GALMP - GABPD) is associated with adverse pregnancy outcome.

DESIGN

Population-based follow up study.

POPULATION

Singleton pregnancies were studied when a reliable date of last menstrual period and biparietal diameter measured between 12 and 22 weeks of gestation was available (n = 16,469).

METHODS

Logistic regression analysis and Kaplan-Meier survival analysis were used to analyse the association between GALMP - GABPD and adverse pregnancy outcome.

MAIN OUTCOME MEASURES

Adverse outcome was defined as abortion after 12 weeks of gestation, still-birth or postnatal death within one year of birth, delivery < 37 weeks of gestation, a birthweight < 2,500 g or a sex-specific birthweight lower than 22% below the expected.

RESULTS

The risk of death was more than doubled if GALMP - GABPD of > or = 8 days was compared with GALMP - GABPD of < 8 days (OR 2.2; 95% CI 1.6-3.1). The risk of death was a factor of 6.1 higher if GALMP - GABPD of > or = 8 days was combined with increased (> 2 x multiple of median) maternal alpha-fetoprotein measured in the 2nd trimester.

CONCLUSIONS

A discrepancy between GALMP and GABPD generally reflects the precision of the two methods used to predict term pregnancy. However, a positive discrepancy of more than seven days, particularly with high maternal alpha-fetoprotein, might indicate intrauterine growth retardation and an increased risk of adverse perinatal outcome.

Unexplained elevated midtrimester maternal serum levels of alpha fetoprotein, human chorionic gonadotropin, or low unconjugated estriol: recurrence risk and association with adverse perinatal outcome

OBJECTIVE

To determine if women experiencing an unexplained elevated maternal serum alpha fetoprotein (MSAFP; > or =2.0 MoM) or human chorionic gonadotropin (hCG; > or =2.0 MoM), or low unconjugated estriol (E3; < or =0.5 MoM) in one pregnancy are at increased risk for similar results in a subsequent pregnancy, and to determine if recurrence of these analyte extremes is associated with adverse perinatal outcome.

METHODS

We identified all women delivering two consecutive singleton pregnancies at one hospital between 1992-1997 for whom second trimester trisomy 21 serum screen was performed in each pregnancy. All screens were performed in a single laboratory. Each pregnancy delivered after 20 weeks and had gestational age confirmed by ultrasound prior to 24 weeks. Subjects were excluded if a fetal anomaly or aneuploidy was present. Adverse outcomes included abruption, oligohydramnios, preeclampsia, preterm membrane rupture, preterm delivery, stillbirth, birthweight <10th centile, and admission to neonatal intensive care unit (NICU).

RESULTS

A total of 538 women had 1,076 pregnancies meeting inclusion criteria; 12/515 (2.3%) of women with a normal MSAFP, 28/470 (6.0%) with a normal hCG, and 11/504 (2.2%) with a normal E3 in the first pregnancy had an anomalous result for the respective analyte in the second pregnancy. In contrast, only 4/23 (17.4%) patients with an elevated MSAFP (P = 0.003), 14/44 (31.8%) with an elevated hCG (P < 0.001), and 2/10 (20.0%) with a low E3 (P < 0.025) in the first pregnancy had the same analyte anomaly recur in the second pregnancy. The odds ratios for recurrent elevated MSAFP, hCG, and low E3 were 7.5, 5.3, and 9.2, respectively. Adverse perinatal outcomes occurred with similar frequency, regardless of MSAFP, hCG, or E3 results in consecutive pregnancies, using women with normal MSAFP, hCG, and E3 results in one or both pregnancies as controls.

CONCLUSIONS

Women experiencing an anomalous serum analyte in one pregnancy are at significant risk to experience the same analyte result in a subsequent pregnancy.

Amniotic fluid alpha-fetoprotein is not a useful biological marker of pregnancy outcome

The aim of our study was to determine if the amniotic fluid alpha-fetoprotein (AFP) level could be a useful predictive biochemical marker of pregnancy outcome. Amniotic fluid AFP measurement was prospectively carried out over a three-year period. After excluding factors susceptible to modifying AFP measurements, 587 subjects with gestational age between 14 and 20 weeks were selected to compare the amniotic fluid AFP mean levels depending on the occurrence of an adverse outcome. No significant associations between amniotic fluid AFP level and poor pregnancy outcome, i.e. pre-eclampsia, preterm delivery, premature rupture of fetal membranes, fetal growth retardation and placental abnormalities were observed. The routine measurement of amniotic fluid alpha-fetoprotein during an amniocentesis procedure was not considered useful in predicting pregnancy complications.

The association of early-onset fetal growth restriction, elevated maternal serum alpha-fetoprotein, and the development of severe pre-eclampsia

From Antenatal Diagnostic Center referrals over 22 months, consultations for early-onset fetal growth restriction versus skeletal dysplasia were retrospectively identified. Those with elevated maternal serum alpha-fetoprotein (MSAFP) levels are the focus of this report. All had an early ultrasound confirming menstrual dates and subsequent sonography at < 28 weeks with at least two fetal biometric measures delayed by > or = 2 standard deviations from mean values. Of the five patients identified, the mean gestational age at the time of diagnosis of fetal growth restriction was 23.3 +/- 2.9 weeks. All had normal karyotypes and normal amniotic fluid AFP. None of the patients had evidence of hypertension or pre-eclampsia at diagnosis of fetal growth restriction. All five gravidas subsequently developed severe pre-eclampsia from 5.5 to 12.5 weeks after documentation of fetal growth delay. Three developed HELLP syndrome. Pregnancies were continued a mean duration of 10-2 weeks, with all five delivering at preterm gestations (mean = 33.5 +/- 1.7 weeks) for maternal indications of severe pre-eclampsia. Unexplained early-onset fetal growth restriction in conjunction with unexplained elevations of MSAFP together consistently heralded the subsequent development of severe pre-eclampsia.

Maternal serum alpha-fetoprotein in placental abruption associated with preterm labor

OBJECTIVE

To evaluate maternal serum alpha-fetoprotein levels in women with preterm labor.

METHOD

Maternal serum alpha-fetoprotein level was measured in 58 women in preterm labor with intact membranes. Maternal levels and multiples of the median were compared in groups with preterm labors of different etiologies and between those with and without placental abruption. Women with vaginal bleeding were also studied separately. Sensitivity, specificity and predictive values were calculated for 2 multiples of the median. Chi squared, Fisher exact test, Mann Whitney U-test, Kruskal-Wallis test and logistic regression were all used.

RESULTS

Those cases with placental abruption (n = 9) had a higher maternal serum alpha-fetoprotein level than the other groups (P = 0.033) and than that of all of them, in total, (n = 49) without placental abruption (P = 0.001). If only women with vaginal bleeding were taken into consideration (n = 13) the maternal serum alpha-fetoprotein level was higher in those with placental abruption (P = 0.001). If we had the criterion of 2 multiples of the median, sensitivity was 66.67%, specificity 95.92%, the positive predictive value 75%, and the negative predictive value 94%. In women with vaginal bleeding sensitivity was 100%, specificity 71.43%, the positive predictive value 75%, and the negative predictive value 100%.

CONCLUSIONS

Maternal serum alpha-fetoprotein level is higher in women with preterm labor and placental abruption. This measurement could be used as a biochemical marker of placental abruption in cases of preterm labor.

Rare trisomy mosaicism diagnosed in amniocytes, involving an autosome other than chromosomes 13, 18, 20, and 21: karyotype/phenotype correlations

In order to determine the significance of trisomy mosaicism of an autosome other than chromosomes 13, 18, 20, and 21, 151 such cases diagnosed prenatally through amniocentesis were reviewed. These rare trisomy mosaicism cases include 54 from 17 cytogenetic laboratories, 34 from a previous North American mosaicism survey, and 63 from published reports. All were cases of true mosaicism with information available on pregnancy outcome, and with no evidence of biased ascertainment. There were 11 cases of 46/47, +2; 2 of 46/47, +3; 2 of 46/47, +4; 5 of 46/47, +5; 3 of 46/47, +6; 8 of 46/47, +7; 14 of 46/47, +8; 25 of 46/47, +9; 2 of 46/47, +11; 23 of 46/47, +12; 5 of 46/47, +14; 11 of 46/47, +15; 21 of 46/47, +16; 7 of 46/47, +17; 1 of 46/47, +19; and 11 of 46/47, +22. As to the risk of an abnormal outcome, the data showed a very high risk (> 60 per cent) for 46/47, +2, 46/47, +16, and 46/47, +22; a high risk (40-59 per cent) for 46/47, +5, 46/47, +9, 46/47, +14, and 46/47, +15; a moderately high risk (20-39 per cent) for 46/47, +12; a moderate risk (up to 19 per cent) for 46/47, +7 and 46/47, +7 and 46/47, +8; a low risk for 46/47, +17; and an undetermined risk, due to lack of cases, for the remaining autosomal trisomy mosaics. Most cases were evaluated at birth or at termination, so subtle abnormalities may have escaped detection and developmental retardation was not evaluated at all. Comparison of the phenotypes of prenatally diagnosed abnormal cases and postnatally diagnosed cases with the same diagnosis showed considerable concordance. Since the majority of anomalies noted are prenatally detectable with ultrasound, an ultrasound examination should be performed in all prenatally diagnosed cases. In cytogenetic confirmation studies, the data showed much higher confirmation rates in cases with abnormal outcomes than in cases with normal outcomes [81 per cent vs. 55 per cent for fibroblasts (from skin, fetal tissue, and/or cord); 88 per cent vs. 46 per cent for placental cells; 22 per cent vs. 10 per cent for blood cells]. The confirmation rate reached 85 per cent when both fibroblasts and placental tissues were studied in the same case (with trisomic cells found in one or the other, or both). Therefore, one must emphasize that both fibroblasts and placental tissues should be studied. Except for 46/47, +8 and 46/47, +9, PUBS is of limited value for prenatal diagnosis of rate trisomy mosaicism. DNA studies for UPD are suggested for certain chromosomes with established imprinting effects, such as chromosomes 7, 11, 14, and 15, and perhaps for chromosomes 2 and 16, where imprinting effects are likely.

The relation between serum markers in the second trimester and placental pathology. A study on extremely small for gestational age fetuses

OBJECTIVES

To examine whether in women who are delivered of an extremely small for gestational age infant, raised levels of second trimester maternal serum alpha-fetoprotein (MSAFP) or human chorionic gonadotrophin (MShCG) levels are related to the presence of placental pathology detected at birth.

DESIGN

Retrospective cross-sectional study.

SETTING

Department of Obstetrics and Gynaecology, Antenatal Diagnosis Unit, Groningen University Hospital, The Netherlands.

PARTICIPANTS

Eighty-four women who were delivered of an extremely SGA infant (< 2.3rd centile) in whom the MSAFP and the MShCG levels were known and placental pathology reports were available (study group), and 8692 women in whom the MSAFP and MShCG levels were known and the pregnancy outcome was normal (control group). Pregnancies with congenital anomalies were excluded. Analyte levels were expressed in multiples of the median (MoM) for gestational age. Statistical analysis between groups was performed by ANOVA, after logarithmic transformation of the MoMs, to normalise their distribution.

MAIN OUTCOME MEASURES

1. The means of the MSAFP and MShCG concentrations in the study group with and without placental lesions were compared with those in the control population. 2. The means of the MSAFP and MShCG levels in the study group with placental lesions were compared with those in the study group without placental lesions.

RESULTS

1. Comparison of study groups with controls: in the study group without placental lesions, the mean log MSAFP MoM (0.062), as well as the mean log MShCG MoM (-0.033), was not significantly different (P = 0.11 and P = 0.68, respectively) from the mean analyte levels in the control population (0.002 and 0.006, respectively). The mean logs of these analytes in the study group with placental lesions (0.162 and 0.129, respectively) were significantly higher compared with the MSAFP and MShCG levels in the control population (P < 0.001 for both analytes). 2. Comparison of study groups with each other: the mean log of the MSAFP level of 0.162 in the group with placental lesions was significantly different from the mean of 0.062 of the study group without placental lesions (P < 0.025). The higher mean log MShCG MoM of 0.129 in the group with placental lesions was significantly different from the mean log MShCG MoM of -0.033 in the study group without placental lesions (P < 0.025).

CONCLUSIONS

Raised levels of second trimester MSAFP and MShCG in women who are subsequently delivered of an extremely small for gestational age infant are related to the presence of pathological changes in the placenta, detectable at birth. It is speculated that these placental pathological changes, which frequently accompany small for gestational age pregnancies, have their origin in the second trimester, when the normal physiological changes of the placenta occur.

Abnormal levels of maternal serum human chorionic gonadotropin and alpha-fetoprotein in the second trimester: relation to fetal weight and preterm delivery

The aim of this prospective descriptive cross-sectional study was to examine the clinical significance of abnormal maternal serum human chorionic gonadotropin (MShCG) and alpha-fetoprotein (MSAFP) in the second trimester of pregnancy. The study group comprised 8892 women with a singleton pregnancy, who were screened for a neural tube defect and Down's syndrome. Exclusion criteria were unknown pregnancy outcome, a congenital anomaly, delivery before 25 weeks of amenorrhoea, or known insulin-dependent diabetes. MSAFP and MShCG were determined between 15 and 20 weeks' amenorrhoea. An abnormal result was defined as (a) MSAFP or MShCG > or = 2.5 MOM, (b) MSAFP or MShCG < or = 0.5 MOM, and (c) MSAFP and MShCG > or = 2.5 MOM. Birth weight percentiles and the duration of amenorrhoea at the time of delivery were employed as outcome parameters. Of the women with an abnormally elevated MSAFP, 9.4 per cent had an extremely small-for-gestational age (SGA) infant (< 2.3rd percentile; P < 0.01, relative risk 4.5), 27.1 per cent had an SGA infant (< tenth percentile; P < 0.01, relative risk 2.7), and 14.3 per cent had an appropriate-for-gestational age (AGA) infant that was delivered preterm (< 259 days; P < 0.01, relative risk 2.4). In the cases where the MShCG level was elevated, 4.4 per cent had an extremely SGA infant (P < 0.01, relative risk 2.1) and 15.5 per cent had an SGA infant (P < 0.01, relative risk 1.5). No significant association was found between an elevated MShCG level and preterm delivery. Low MShCG was significantly associated with SGA infants (P < 0.01, relative risk 1.2) but not with extremely SGA or preterm deliveries. In the group whose MSAFP and MShCG levels were both elevated, 23.8 per cent delivered an extremely SGA infant (P < 0.01, relative risk 10.9), 38.1 per cent an SGA infant (P < 0.01, relative risk 3.7) and 47.6 per cent had a preterm delivery or an SGA infant (P < 0.01, relative risk 3.0). Isolated or combined elevation of the MSAFP and MShCG levels in the second trimester of pregnancy is an indication for extra vigilance during further prenatal care. This applies to a lesser extent to a low MShCG level.