Disease relevance of Amniocentesis

• By selecting for amniocentesis women with serum AFP levels less than or equal to 0.5 MoM at 14-20 weeks' gestation (excluding any of these that ultrasound cephalometry shows to have been due to the overestimation of gestational age) 21% of pregnancies with Down syndrome would be identified as well as 5% of unaffected pregnancies [1].
• Therefore, when maternal serum AFP levels are used to screen for fetal neural tube defects, women referred for a diagnostic amniocentesis on account of a high level are unlikely to have been selected on the basis of a tendency to abort [2].
• A policy of adjusting maternal serum AFP values according to maternal weight among women with borderline positive results could reduce the number having a diagnostic amniocentesis with only a negligible loss of detection for open spina bifida [3].
• The risk for spontaneous abortion related to amniocentesis, combined with increasing confidence in the accuracy of ultrasound diagnosis, has caused us to question the need for amniocentesis in the diagnostic workup of pregnancies complicated by elevated levels of AFP in maternal serum [4].
• STUDY DESIGN: A cohort of 169 afebrile women in preterm labor with intact membranes had amniotic fluid collected by transabdominal amniocentesis for culture and for LBP, sCD14, and interleukin 6 (IL-6) determinations by enzyme-linked immunosorbent assay [5].

High impact information on Amniocentesis

• Between October 1984 and June 1987, we identified 22,748 pregnant women when they underwent screening either by measurement of maternal serum alpha-fetoprotein or by amniocentesis [6].
• They were offered genetic counselling, parental and (if appropriate) CF carrier testing, and amniocentesis for karyotype and CF status if parents were informative [7].
• Children of women who had amniocentesis had a significantly higher rate of haemolytic disease due to ABO isoimmunisation than matched controls [8].
• Early amniocentesis and amniotic fluid AFP levels [9].
• The prevalence of 45,X/46,XX mosaicism is 10-fold higher among amniocenteses than in series of postnatally diagnosed individuals with Turner syndrome, which suggests that most individuals with this karyotype escape detection and that an ascertainment bias exists toward those with clinically evident abnormalities [10].

Chemical compound and disease context of Amniocentesis

• Transabdominal amniocentesis was offered as part of the preoperative evaluation, and amniotic fluid (AF) was sent for glucose and lactate dehydrogenase level determinations, Gram staining, and culture for aerobic and anaerobic bacteria [11].
• The predictive value of an elevated AFP varies with the population screened, and is reduced by routine ultrasonography before amniocentesis, which at least identifies anencephaly [12].
• Because of the potential risk of fetal hypothyroidism, an amniocentesis, with an injection of 500 mug of thyroxine, was performed weekly from week 33 until delivery [13].
• Complete resolution of CMV-associated acute hydramnios by single large volume reduction amniocentesis and maternal indomethacin. A case report [14].
• Fetal death after exposure to methylene blue dye during mid-trimester amniocentesis in twin pregnancy [15].

Biological context of Amniocentesis

• Chromosomes were isolated from primary cultures 2-5 wk after amniocentesis, stained with Hoechst 33258 and chromomycin A3, and analyzed using dual beam flow cytometry [16].
• The second amniocentesis was performed in a woman who was also heterozygous for an electrophoretic variant of glucose 6- phosphate dehydrogenase (G6PD), and a member of a kindred showing genetic linkage of loci for ALD and G6PD [17].
• Elevated maternal serum alpha-fetoprotein caused by midtrimester amniocentesis: a prognostic factor [18].
• In this study, alpha-fetoprotein was obtained from the fluid of 1060 women undergoing genetic amniocentesis for advanced maternal age [19].
• Birth weights and gestational age at delivery were less and time from amniocentesis to delivery was shorter in the polymerase chain reaction-positive group (p < 0.05) [20].

Anatomical context of Amniocentesis

• A new technic is proposed to confirm the diagnosis of rupture of the membranes based on the introduction of sodium fluorescein into the amniotic cavity via transabdominal amniocentesis [21].
• Conventional methods for prenatal fetal RhD status determination involve invasive procedures such as fetal blood sampling and amniocentesis [22].
• OPTIONS: "Triple-marker" screening of maternal serum levels of alpha-fetoprotein, human chorionic gonadotropin and unconjugated estriol; fetal ultrasonographic examination; amniocentesis; and chorionic villus sampling (CVS) [23].
• Ninety-seven postmature pregnancies were monitored by amnioscopy or amniocentesis (to determine presence or absence of meconium), oxytocin challenge tests (OCT), 24-hour urinary oestriol estimations and fetal movement counts [24].
• Middle cerebral artery Doppler studies and serial amniocenteses for Delta OD(450) were performed [25].

Associations of Amniocentesis with chemical compounds

• Thanks to the widespread use of amniocentesis, glucose, insulin, and C peptide have often been measured in amniotic fluid (AF) during late gestation, but little is known about their concentrations during early pregnancy [26].
• There is no rebound phenomenon of AF steroid levels if DEX therapy is interrupted 5 days before amniocentesis [27].
• Dexamethasone was suspended 5-7 days before amniocentesis [28].
• Before random assignment all patients underwent amniocentesis and urogenital cultures and then received 48 hours of therapy with indomethacin and antibiotics [29].
• However, the ability of the test to predict amniocenteses with normal bilirubin levels was less clear [30].

Gene context of Amniocentesis

• STUDY DESIGN: One hundred thirty-four amniotic fluid specimens were obtained from women undergoing amniocentesis at University of North Carolina Hospitals. Each specimen was assayed by enzyme-linked immunosorbent assay for nerve growth factor, brain-derived neurotrophic factor, and neurotrophin 3 [31].
• The concentration of interleukin 2 (IL-2) was measured in amniotic fluids that had been obtained by amniocentesis, transvaginal amniotomy or by transuterine amniocentesis performed at cesarean section in 50 pregnant women [32].
• We conclude that GFAP immunofluorescence examination of routine amniocentesis samples of amniotic fluid is not a useful predictive test for NTDs [33].
• CONCLUSION: A subset of women who had a pregnancy loss after a mid-trimester amniocentesis had higher concentrations of the chemokine MCP-1 than those who had a normal pregnancy outcome [34].
• An elevated MCP-1 concentration in amniotic fluid of patients with a pregnancy loss after a mid-trimester amniocentesis indicates that a pathological condition was present at the time of the procedure [34].

Analytical, diagnostic and therapeutic context of Amniocentesis

• Recent improvements in the accuracy of sonographic diagnosis of neural-tube and ventral-wall defects have raised a question about the wisdom of routinely offering amniocentesis to women who have elevated levels of maternal serum alpha-fetoprotein with a structurally normal fetus as determined by ultrasonography [35].
• Fetal red cells obtained during amniocentesis and amnioscopy should then be a suitable tissue to use to make the prenatal diagnosis of arginase deficiency [36].
• Although 18 of 46 couples initiated at least one more pregnancy after the birth of their DSC, only three couples (2 counseled; 1 non-counseled) utilized prenatal diagnosis by amniocentesis [37].
• Among the women with high maternal serum alpha-fetoprotein levels, 556 (77%) had normal ultrasonographic and amniocentesis studies, and the risk of adverse pregnancy outcome ws 27% (19%, 29%, and 70% in groups 1, 2, and 3, respectively) [38].
• Management consisted of tocolysis with intravenous magnesium sulfate as the primary agent, antenatal steroids, antibiotics, and amniocentesis [39].

References