Proteomic but not enzyme-linked immunosorbent assay technology detects amniotic fluid monomeric calgranulins from their complexed calprotectin form

Four proteomic biomarkers (human neutrophil peptide 1 [HNP1], HNP2 [defensins], calgranulin C [Cal-C], and Cal-A) characterize the fingerprint of intra-amniotic inflammation (IAI). We compared proteomic technology using surfaced-enhanced laser desorption-ionization-time of flight (SELDI-TOF) mass spectrometry to enzyme-linked immunosorbent assay (ELISA) for detection of these biomarkers. Amniocentesis was performed on 48 women enrolled in two groups: those with intact membranes (n = 27; gestational age [GA], 26.0 +/- 0.8 weeks) and those with preterm premature rupture of the membranes (PPROM; n = 21; GA, 28.4 +/- 0.9 weeks). Paired abdominal amniotic fluids (aAFs)-vaginal AFs (vAFs) were analyzed in PPROM women. Quantitative aspects of HNP1-3, Cal-C, Cal-A, and calprotectin (a complex of Cal-A with Cal-B) were assessed by ELISA. SELDI-TOF mass spectrometry tracings from 16/48 (33.3%) aAFs and 13/17 (88.2%) vAFs were consistent with IAI (three or four biomarkers present). IAI (by SELDI-TOF mass spectrometry) was associated with increased HNP1-3 and Cal-C measured by ELISA. However, immunoassays detected Cal-A in only 4 of the AFs even though its specific SELDI-TOF mass spectrometry peak was identified in 19/48 AFs. Calprotectin immunoreactivity was decreased in AFs retrieved from women with IAI (P = 0.01). In conclusion, IAI is associated with increased HNP1-3 levels. In the absence of isoform-specific ELISAs, mass spectrometry remains the only way to discriminate the HNP biomarker isoforms. Monomeric Cal-A is not reliably estimated by specific ELISA as it binds to Cal-B to form the calprotectin complex. Cal-C was reliably measured by SELDI-TOF mass spectrometry or specific ELISA.

Sonographic myometrial thickness predicts the latency interval of women with preterm premature rupture of the membranes and oligohydramnios

OBJECTIVE

Term labor is associated with global thinning of the myometrium. We hypothesized that a thickened myometrium at the time of preterm premature rupture of membranes (PPROM) predicts less myometrial wall stress and, consequently, a longer latency interval.

STUDY DESIGN

Myometrial thickness was measured prospectively in 76 pregnant women enrolled in the following groups: PPROM (n=28, mean [range], gestational age [GA]: 29.5 weeks [w] [21.0 w-33.0 w]), preterm nonlabor control group (P-CTR), (n=21, GA: 27.5 w [23.0 w-32.0 w]) and term nonlabor control (T-CTR) (n=27, GA: 38.6 w [37.0 w-41.6 w]). All PPROM women had oligohydramnios (AFI: 1.4 cm [0.0 cm-5.1 cm]). MT was measured ultrasonographically at the midanterior, fundal, posterior, and lower uterine segment wall in cases and controls with an intraoperator variability <10%.

RESULTS

Women in the PPROM group displayed uniform thickness of the uterine body (mean +/- SEM, anterior: 10.6 +/- 0.6 mm, fundal: 10.7 +/- 0.7 mm, posterior: 8.9 +/- 0.5 mm, P=.078). At midanterior site the myometrium of the PPROM group was thicker compared to both P-CTR (P < .001) and T-CTR (P=.025) groups. This difference was preserved at the fundus (PPROM vs P-CTR, P < .001; PPROM vs T-CTR, P=.015). There was a positive correlation between fundal MT and latency period (r=0.43, P=0.02) that persisted after adjusting for GA (P=.04). A fundal MT less than 12.1 mm was 93.7% sensitive and 63.6% specific for the identification of women whose latency period was less than 120 hours.

CONCLUSION

Significant thickening of the anterior and fundal walls of the uterus follows PPROM. A thick myometrium in nonlaboring patients with PPROM is associated with longer latency interval. Sonographic evaluation of MT may represent an alternative clinical tool for the prediction of a short latency interval in women with PPROM.

Detection of viral deoxyribonucleic acid in amniotic fluid: association with fetal malformation and pregnancy abnormalities

OBJECTIVE

To first test the hypothesis that the presence of viral nucleic acid in amniotic fluid (AF) is associated with an abnormal pregnancy outcome, and second, to determine if the overall rate of polymerase chain reaction (PCR) positivity and the distribution of virus types vary geographically.

STUDY DESIGN

Cytomegalovirus (CMV), parvovirus B19, adenovirus, enterovirus, herpes simplex virus, Epstein-Barr virus, and respiratory syncytial virus nucleic acids were sought in 423 AF samples obtained for clinical indications: 284 from the East Coast (EC) and 139 from the Midwest (MW).

RESULTS

Gestational age at sampling was 19.1 weeks for EC and 20.1 weeks for MW. 13.5% of karyotypically normal singleton pregnancies (57/423) had a positive AF PCR. 11% of AF PCR from the EC while 18% of AF PCR from the MW were positive (p = 0.06). The most commonly detected viruses were adenovirus (77%), enterovirus (12%), and CMV and parvovirus B19 (5% each). Twenty-four percent of sonographically abnormal pregnancies (33/136) had a positive AF PCR compared to only 8.4% (24/287) of normal pregnancies (p < 0.001).

CONCLUSION

A positive AF PCR is associated with an increased rate of fetal structural malformations, intrauterine growth restriction, hydrops and other fetal abnormalities. There were no significant geographic differences in the incidence of AF viral PCR positivity.

Proteomic biomarkers that predict the clinical success of rescue cerclage

OBJECTIVE

The origin of incompetent cervix is multifactorial, and the success of rescue cerclage is unpredictable. We tested amniotic fluid from women who were preparing to undergo rescue cerclage for proteomic biomarkers and correlated their presence with clinical outcome.

STUDY DESIGN

Amniocentesis was performed to facilitate rescue cerclage in 37 consecutive women with painless dilation (> 2 cm) and no detectable uterine activity for 4 hours (range, 1-24 hours) before cerclage. Thirty-nine consecutive women with a sonographically normal pregnancy and cervix who underwent amniocentesis for chromosomal testing during the same study interval at the same clinical site provided the control samples. A proteomic fingerprint was generated with the discarded sample and the Mass-Restricted score (MR score) for inflammation calculated. Peaks corresponding to free hemoglobin chains were sought as evidence of decidual hemorrhage or intra-amniotic bleeding.

RESULTS

Amniocentesis was performed at 23.5 weeks in cerclage (mean dilation, 4 cm) versus 19.5 weeks in control subjects. Cerclage subjects were delivered at 28.8 weeks; control subjects were delivered at 39.2 weeks. Thirty-two of 37 of cerclage subjects (86%) were delivered prematurely. Ten of 37 of cerclage subjects (27%), but no control subject, had a MR score that was indicative of inflammation (P < .001). Hemoglobin peaks were present in 12 of 37 of cerclage subject (32%), but no control subjects. Among cerclage subjects, those with a MR score of 3 to 4 were delivered earlier than those with a MR score of 0 to 2 (P < .001). Women with a MR score of 3 to 4 had a shorter latency period (days from amniocentesis to delivery; 3 days) and a shorter percentage of prolongation (1.8%) than women with a MR score of 0 to 2 (35 days; P < .05; 17.9%; P < .05). Women with hemoglobin had a shorter latency period (6 days) and a shorter percentage of prolongation (3.8%) than women without hemoglobin (38 days; P < .05; 21.8%; P < .05). Hemoglobin was present in 7 of 10 of the cerclage subjects (70%) with a MR score of 3 to 4. Women with both a MR score of 3 to 4 and hemoglobin had the shortest intervals to delivery.

CONCLUSION

These findings illustrate 2 pathologic mechanisms that are associated with preterm delivery are also associated with incompetent cervix. Either an intrauterine inflammatory response or decidual hemorrhage predates surgery in one half the women whose condition requires rescue cerclage. The activation of either mechanism predicts cerclage failure.

Rupture of the uterine scar during term labour: contractility or biochemistry?

OBJECTIVE

Vaginal birth after a prior low transverse caesarean section (VBAC) is advocated as a safe and effective method to reduce the total caesarean section rate. However, the risk of uterine rupture has dampened the enthusiasm of practising clinicians for VBAC. Uterine rupture occurs more frequently in women receiving prostaglandins in preparation for the induction of labour. We hypothesised that similar to the cervix, prostaglandins induces biochemical changes in the uterine scar favouring dissolution, predisposing the uterus to rupture at the scar of the lower segment as opposed to elsewhere.

DESIGN

We tested aspects of this hypothesis by investigating the location of uterine rupture associated with prostaglandins and compared it with the sites of rupture in the absence of prostaglandins.

SETTINGS

Two North American University Hospitals.

POPULATION

Twenty-six women with a prior caesarean section, experiencing uterine rupture in active labour.

METHODS

Retrospective review of all pregnancies complicated by uterine rupture at two North American teaching hospitals from 1991 to 2000.

MAIN OUTCOME MEASURE

Site of the uterine rupture.

RESULTS

Thirty-four women experienced rupture after a previous caesarean section with low transverse uterine incision. Ten of the women who ruptured (29%) received prostaglandins for cervical ripening (dinoprostone: n= 8 or misoprostol: n= 2) followed by either spontaneous contractions (n= 3) or oxytocin augmentation during labour (n= 7). In 16 women (47%), oxytocin alone was sufficient for the induction/augmentation of labour. Eight (23%) women ruptured at term before reaching the active phase of labour in the absence of pro-contractile agents or attempted VBAC. There were no differences among the groups in terms of age, body mass index, parity, gestational age, fetal weight or umbilical cord pH measurements. Women treated with prostaglandins experienced rupture at the site of their old scar more frequently than women in the oxytocin-alone group whose rupture tended to occur remote from their old scar (prostaglandins 90%vs oxytocin 44%; OR: 11.6, 95% CI: 1.2-114.3).

CONCLUSION

Women in active labour treated with prostaglandins for cervical ripening appear more likely to rupture at the site of their old scar than women augmented without prostaglandins. We propose that prostaglandins induce local, biochemical modifications that weaken the scar, predisposing it to rupture.

Physical and biomechanical characteristics of rat cervical ripening are not consistent with increased collagenase activity

OBJECTIVE

The cervix progressively softens during pregnancy to allow stretch without rupture in labor. Cervical softening is the product of complex modifications that include increased proteoglycan-to-collagen ratio, increased hyaluronic acid and water content, and breakdown of collagen by matrix metalloproteases. The relative contribution of collagen breakdown to cervical ripening is unclear. We sought to identify, discriminate, and quantify the physical characteristics of rat cervix during pregnancy, labor, and both before and after exposure to either prostaglandin (PGE(2)) or the collagenolytic enzyme matrix metalloprotease-1 (MMP-1).

STUDY DESIGN

Cervices were collected from nonpregnant rats in diestrus (n=4) and pregnant rats on d10 (n=4), d16 (n=11), d20 (n=5), and d22 (term) nonlabor (NL: n=4) and d22 in term labor (TL: n=7). Cervices were also collected from a separate group in preterm labor induced by RU486 (PTL: n=10). The effect of PGE(2) on cervical characteristics was determined after intravaginal placement of PGE(2) gel (0.5 mg PGE(2): n=3) or placebo metylcellulose gel (CRL(PG) n=6) for 20 hours before euthanasia on d16. The effect of collagen was determined by incubating in vitro cervices from untreated d16 rats with (MMP-1: n=3) and without (CRL(MMP): n=7) activated collagenase before tensile testing. Tensile properties were quantitated by using Shimadzu EZ-test instrumentation (Shimadzu North America, Columbia, Md) with a stretching regimen that mimicked labor contractions while recording the force opposed by the tissue. Parameters such as the slope (a measure of stiffness), yield point (YP; moment the tissue changes its proprieties from elastic to plastic), and break point (BP; a measure of tissue strength) were recorded and analyzed. The plateau was defined as the phase after YP but before BP.

RESULTS

Compared with d16, cervical extensibility increased significantly by d20 (slope d16: 0.41 +/- 0.03 N/mm vs d20: 0.19 +/- 0.05 N/mm, P < .01), and during both PTL (slope: 0.17 +/- 0.03 N/mm) and TL (slope: 0.11 +/- 0.02 N/mm). This increase was mimicked by PGE(2) (slope PGE(2): 0.24 +/- 0.03 vs CRL(PG): 0.40 +/- 0.05 N/mm, P=.04), but not by collagenase (slope MMP-1: 0.35 +/- 0.02 vs CRL(MMP): 0.38 +/- 0.05 N/mm, P>.05). YP was significantly reduced as pregnancy advanced, whereas BP increased, suggesting both increased plasticity (compliance) and strength. However, the plateau length increased 3-fold both by d20 and after PGE(2). In contrast, the addition of MMP-1 reduced the plateau. BP occurred significantly earlier in collagenase-treated tissues, but later in PTL-, TL-, and PGE(2)-treated cervices.

CONCLUSION

The changes in physical properties of the rat cervix during physiologic ripening are similar to those induced by PGE(2) and RU486, and consist of increased extensibility, compliance, and strength. These changes cannot be attributed to increased collagenase activity, which would decrease tissue compliance and strength.

The novel antimicrobial peptide beta3-defensin is produced by the amnion: a possible role of the fetal membranes in innate immunity of the amniotic cavity

BACKGROUND

Innate immunity evolved to eliminate microorganisms before, or after their entry into the tissues, but before enough antigen is available to activate an adaptive, immune response. Innate immunity is so successful that the majority of encountered microbes are neutralized. The beta-defensins are antimicrobial peptides produced by skin and mucosal surfaces and are an integral part of the innate immune system. The ability of the amnion cells, which are epithelial derivatives, to produce antimicrobial beta-defensins has not been explored.

OBJECTIVE

This study was undertaken to test the hypothesis that amnion cells synthesize beta-defensins under either basal or stimulated conditions.

METHODS

Amnion epithelial FL cells (ATCC CCL 62) were cultured in Ham's F12 and Dulbecco's modified Eagle medium plus 10% fetal calf serum until confluence, then replated into 24-well plates at 1.5 million cells per well. Cells from triplicate wells were harvested after 1, 3, 6, and 24 hours of exposure to microbial wall components (lipopolysaccharide [LPS]: 1 microg/mL or peptidoglycan [PG]: 10 microg/mL). Reverse transcription real-time polymerase chain reaction was performed with the use of human-specific primers for beta1, beta2, beta3, and beta4 defensins to compare basal messenger RNA (mRNA) levels of defensins and in response to treatment. beta-actin was used for standardization. Protein expression was investigated by immunofluorescence of the cells in culture, and by immunohistochemistry in paraffin sections of human fetal membranes from pregnancies with or without histologic chorioamnionitis.

RESULTS

Amnion FL cells expressed mRNA for all known beta-defensins with beta3-defensin mRNA levels significantly higher compared with others ( P < .001, 1-way analysis of variance [ANOVA]). beta3 was the only beta-defensin whose mRNA was upregulated in response to the microbial mimics LPS (1-way ANOVA, P = .019) and PG (1-way ANOVA, P = .011). Immunofluorescence confirmed that beta3-defensin protein was present in cultured amnion cells, and upregulated in response to PG and LPS in distinct cells. Similarly, in tissue sections of human fetal membranes amnion epithelium was intensely positive for beta3-defensin protein by immunohistochemistry. Conspicuous beta3-defensin staining was also detected in the chorio-decidua.

CONCLUSION

Amnion cells have the ability to produce beta-defensins. The beta3-defensin appears to be the predominant epithelial defensin expressed. Its induction by microbial mimics suggests that the amniotic epithelium may play a role in the innate immunity of the amniotic cavity.

Kleihauer-Betke Testing Is Important in All Cases of Maternal Trauma

BACKGROUND

In maternal trauma, the Kleihauer-Betke (KB) test has traditionally been used to detect transplacental hemorrhage (TPH), so that Rh-negative women could receive appropriate Rh immune prophylaxis. Reasoning that the magnitude of TPH would reflect uterine injury, we evaluated Kleihauer-Betke testing as an independent predictor of preterm labor (PTL) after maternal trauma.

METHODS

Admissions to the Shock Trauma Center, University of Maryland, from January 1996 to January 2002, were reviewed. Of 30,362 trauma patients admitted, 166 were pregnant, and 93 of these underwent electronic fetal monitoring. Their records were abstracted for demographics, injury type, three separate trauma scores, documented uterine contractions, PTL (contractions with progressive cervical change), and serious perinatal complications. In 71 cases, transplacental hemorrhage was assessed by maternal KB test.

RESULTS

TPH, defined as KB-positive for greater than 0.01 mL of fetal blood in the maternal circulation, occurred in 46 women. Forty-four had documented contractions (25 had overt PTL) and 2 had no contractions. In 25 women with a negative KB test, none had uterine contractions. All patients with contractions or PTL had positive KB tests. By logistic regression, KB test result was the single risk factor associated with PTL (p < 0.001; likelihood ratio, 20.8 for positive KB test). Compared with other sites, abdominal trauma was associated more often with uterine contractions (p < 0.001), PTL (p = 0.001), and a positive KB test (p < 0.001, chi). None of the trauma scoring systems predicted PTL.

CONCLUSION

Kleihauer-Betke testing accurately predicts the risk of preterm labor after maternal trauma. Clinical assessment does not. With a negative KB test, posttrauma electronic fetal monitoring duration may be limited safely. With a positive KB test, the significant risk of PTL mandates detailed monitoring. KB testing has important advantages to all maternal trauma victims, regardless of Rh status.

Venous Doppler in the prediction of acid-base status of growth-restricted fetuses with elevated placental blood flow resistance

OBJECTIVE

This study was undertaken to test which venous Doppler parameter offers the best prediction of acid-base status at birth in pregnancies complicated by intrauterine growth restriction (IUGR) caused by placental dysfunction.

STUDY DESIGN

A prospective cross-sectional Doppler study of IUGR fetuses with abnormal umbilical artery Doppler and birth weight less than the 10th percentile. Absence of atrial systolic forward velocities in the ductus venosus (DV) (DV-RAV) and umbilical vein (UV) pulsations were noted and multiple venous indices were calculated for the inferior vena cava (IVC) and DV (IVC and DV preload index, peak velocity index [PVIV] and pulsatility index [PIV] and the DV S/a ratio). Doppler indices, UV pulsations, and DV- RAV were related to an umbilical artery cord pH <7.20, and a pH <7.00 and/or base deficit greater than -13 (severe metabolic compromise) in neonates delivered by cesarean section without labor.

RESULTS

In 122 fetuses all venous Doppler indices were equally predictive of a pH <7.20, with the exception of the IVC PVIV. No Doppler index predicted severe metabolic compromise. Bayesian analysis of individual Doppler parameters showed comparable outcome prediction with the highest sensitivity for the IVC PIV (76%) and the highest specificity for DV-RAV (96%). Combined assessment of the IVC, DV, and UV provided the most accurate outcome prediction. Doppler abnormality in either vessel identified 89% of neonates with pH <7.20 (negative predictive value 92%) and 10 of 11 neonates with severe metabolic compromise. Prediction was most specific (84%) when Doppler parameters were abnormal in all 3 vessels.

CONCLUSION

IVC, DV, and UV Doppler parameters correctly predict acid-base status in a significant proportion of IUGR neonates. Combination, rather than single vessel assessment provides the best predictive accuracy. While the choice of Doppler index can be guided by operator preference, familiarity with the examination technique of all 3 vessels is encouraged to offer the highest flexibility in clinical practice.

The presence and function of phosphodiesterase type 5 in the rat myometrium

OBJECTIVE

Cyclic nucleotide phosphodiesterases (PDEs) are a diverse enzyme group with multiple regulatory properties and wide tissue distribution. Such activity includes cyclic adenosine (cAMP) and guanosine monophosphate (cGMP) breakdown. The type 5 isoform (PDE-5, cGMP specific) is the target of specific antagonists (ie, sildenafil, Viagra). We tested the hypothesis that PDE-5 is present in rat myometrium and modulates myometrial activity.

STUDY DESIGN

Full-thickness uterine wall was collected from nonpregnant (n=3) and pregnant Sprague-Dawley rats on days 10 (n=4), 17 (n=6), 22 nonlabor (n=5), and 22 during term labor (TL, n=4). Preterm labor (PTL, n=3) was induced in some animals on day 16 with 15 mg/kg mifepristone (RU 486). Tissue samples were prepared for Western blotting using a monoclonal antibody against rodent PDE-5. In a second series, cumulative doses of sildenafil (0.005, 0.05, 0.5, 5 mg/kg, intraperitoneal) were administered and the effect on uterine contractility recorded in vivo during term (TL, n=7) and preterm labor (PTL, n=6). Saline solution-injected rats provided temporal control. Uterine contractility was estimated from intrauterine pressure (IP) measured electronically with a sensor tip pressure catheter. Heart rate was recorded simultaneously using electrodes attached to the chest and connected to the same data acquisition system.

RESULTS

PDE-5 immunoreactivity was present in the nonpregnant rat uterus and at all gestational times studied, although the expression was unaffected by either pregnancy or the state of labor (preterm or term). A dominant antibody-specific band was identified at 86 kd in the uterine samples, contrasting with lung where the 100-kd PDE-5 isoform was most abundant. Two additional lower molecular weight (55 and 32 kd) bands were also identified as antibody specific. Despite the lack of change in PDE-5 during pregnancy, sildenafil reduced IP during TL and PTL beginning at 0.5 mg/kg. The highest dose of sildenafil reduced IP during both TL and PTL by 45% and 59% of baseline, respectively (two-way analysis of variance, P<.01). This effect was not accompanied by changes in heart rate.

CONCLUSION

PDE-5 is constitutively present in the rat uterine wall. There was no observed change in the PDE-5 protein expression throughout pregnancy. In contrast to the lung, the uterus expresses an 80-kd PDE-5 isoform. Sildenafil in pharmacologic doses inhibits mechanical uterine activity and might be of benefit if selectively used for treatment of preterm labor.

Qualitative venous Doppler waveform analysis improves prediction of critical perinatal outcomes in premature growth-restricted fetuses

BACKGROUND

Our aim was to test the hypothesis that qualitative ductus venosus and umbilical venous Doppler analysis improves prediction of critical perinatal outcomes in preterm growth-restricted fetuses with abnormal placental function.

METHODS

Patients with suspected intrauterine growth restriction (IUGR) underwent uniform fetal assessment including umbilical artery (UA), ductus venosus (DV) and umbilical vein (UV) Doppler. Absent or reversed UA end-diastolic velocity (UA-AREDV), absence or reversal of atrial systolic blood flow velocity in the DV (DV-RAV) and pulsatile flow in the umbilical vein (P-UV) were examined for their efficacy to predict critical outcomes (stillbirth, neonatal death, perinatal death, acidemia and birth asphyxia) before 37 weeks' gestation.

RESULTS

Seventeen (7.6%) stillbirths and 16 (7.1%) neonatal deaths were observed among 224 IUGR fetuses. Forty-one neonates were acidemic (19.8%) and seven (3.1%) had birth asphyxia. Logistic regression showed that UA-AREDV had the strongest association with perinatal mortality (R(2) = 0.49, P < 0.001), stillbirth (R(2) = 0.48, P < 0.001) and acidemia (R(2) = 0.22, P = 0.002) while neonatal death was most strongly related to DV-RAV and P-UV (R(2) = 0.33, P = 0.007). UA waveform analysis offered the highest sensitivity and negative predictive value and DV-RAV and P-UV had the best specificity and positive predictive values for outcome prediction. Overall, DV-RAV or P-UV offered the best prediction of acidemia and neonatal and perinatal death irrespective of the UA waveform. In fetuses with UA-AREDV, prediction of asphyxia and stillbirth was significantly enhanced by venous Doppler.

CONCLUSION

Prediction of critical perinatal outcomes is improved when venous and umbilical artery qualitative waveform analysis is combined. The incorporation of venous Doppler into fetal surveillance is therefore strongly suggested for all preterm IUGR fetuses.

Is adenovirus a fetal pathogen?

OBJECTIVES

The purpose of this study was to test the relationship between adenovirus genetic material in the amniotic fluid and adverse pregnancy outcome.

STUDY DESIGN

This was a prospective, observational study of women who were referred in the second trimester of gestation for either genetic amniocentesis or evaluation of fetal malformation. A 2-mL aliquot of amniotic fluid was subjected to multiplex polymerase chain reaction for a panel of viruses that included adenovirus and human genome controls. Fetuses with an abnormal karyotype were excluded from analysis.

RESULTS

The prevalence of adenovirus was similar in normal (39/652) and anomalous fetuses (23/364; chi(2) test, P=.376). There was significant seasonal variation in the prevalence in both normal and anomalous fetuses (chi(2) exact test, P<.001), but no significant difference between groups. The monthly proportion of patients who underwent amniocentesis remained constant throughout the year (mean, 8.3%; chi(2) test, P=.67). Central nervous system anomalies and echogenic liver foci were significantly more common among fetuses with positive amniotic fluid polymerase chain reaction results for adenovirus (P<.005, respectively).

CONCLUSION

Adenovirus is found in a similar prevalence and seasonal variation in sonographically normal and abnormal pregnancies. Although a specific fetal presentation was not identified, echogenic liver lesions with or without hydrops and neural tube defects were significantly more common in the presence of adenovirus. The significance of these findings deserves further study.

Beneficial impact of term labor: nonenzymatic antioxidant reserve in the human fetus

OBJECTIVE

Oxidative stress occurs when the production of damaging free radicals and other oxidative molecules exceeds the capacity of the body's antioxidant defenses. Oxidative stress is implicated in diseases that are associated with prematurity (such as retinopathy, cerebral palsy, intraventricular hemorrhage, and necrotizing enterocolitis). Nonenzymatic antioxidant reserve is the first line of defense against free radicals. We hypothesized that an in utero redox imbalance because of stress would diminish the fetal antioxidant reserve. We tested aspects of this hypothesis by investigating whether the presence of labor or gestational age at delivery (term vs preterm) alters the maternal/fetal nonenzymatic antioxidant reserve peripartum.

STUDY DESIGN

Fetal redox consumption was calculated from the difference in the nonenzymatic antioxidant reserve that was measured in umbilical venous and arterial blood that was collected prospectively at delivery from 39 newborn infants. Eight women were delivered at term by elective cesarean delivery in the absence of labor; 31 women labored either at term (n = 20) or preterm (<37 weeks, n = 11). Maternal venous blood was collected on admission and within 1 hour of delivery. Nonenzymatic antioxidant reserve was measured in the plasma and red blood cells of each specimen by the quantitation of glutathione content (glutathione in red blood cell lysate) and the plasma total free radical-trapping antioxidant potential. Glutathione was measured with the use of a colorimetric assay and expressed in nanomoles per milligram of hemoglobin. The plasma total radical-trapping antioxidant potential was estimated with the use of a controlled, kinetic assay based on the time that was required to inhibit peroxyl-free radical generated under controlled conditions. The differences between both umbilical venous and umbilical arterial total radical-trapping antioxidant potential and glutathione were computed to estimate fetal nonenzymatic antioxidant reserve consumption. The differences between maternal total radical-trapping antioxidant potential and glutathione before and after delivery were computed to estimate maternal peripartal nonenzymatic antioxidant reserve consumption.

RESULTS

Fetal red blood cell glutathione content was significantly greater than maternal red blood cell glutathione content, independent of delivery route. The calculation of the fetal nonenzymatic antioxidant reserve consumption and maternal peripartal nonenzymatic antioxidant reserve consumption revealed that women who labored at term experienced an up-regulation in red blood cell glutathione content, while their fetuses had significantly lower red blood cell glutathione consumption. In contrast, there was consumption of plasma antioxidants in preterm fetuses, as illustrated by a doubling of the fetal nonenzymatic antioxidant reserve consumption (elective cesarean delivery in the absence of labor, 0.9 +/- 0.5 min/microL; term labor, 1.0 +/- 0.1 min/microL; preterm labor, 2.0 +/- 0.4 min/microL; one-way analysis of variance; P =.04). This was mostly due to a lower umbilical arterial total radical-trapping antioxidant potential in preterm versus term fetuses (umbilical arterial, 3.3 min/microL versus umbilical venous 5.4 min/microL; paired t test; P =.001; power, 0.98). Generally, maternal total radical-trapping antioxidant potential remained unchanged peripartum.

CONCLUSION

Term labor triggers a compensatory up-regulation of nonenzymatic antioxidant reserve in the fetal red blood cell compartment that may act to protect against the relative hyperoxia that is experienced by the newborn infant at birth. In contrast, the decreased nonenzymatic antioxidant reserve in the fetal red blood cell and plasma compartments after preterm labor and delivery would enhance the vulnerability to free radical damage of the preterm neonate. These findings suggest that the two compartments of nonenzymatic antioxidant reserve have distinct physiologic roles in the peripartal defense against free radicals and that their development is, in some fashion, ontogenes, in some fashion, ontogenetically regulated.

Prevalence of viral DNA in amniotic fluid of low-risk pregnancies in the second trimester

AIM

The association between fetal viral infection and adverse pregnancy outcome is well documented. However, the prevalence of common viral pathogens in the amniotic fluid of normal pregnancies is not established. The purpose of this study was to determine this prevalence in asymptomatic patients.

METHODS

This was a prospective observational study of patients at low risk for viral infection who were referred for second-trimester genetic amniocentesis. In patients with normal fetal anatomy on ultrasound and a normal fetal karyotype, a 2-ml aliquot of amniotic fluid obtained at amniocentesis was analyzed by multiplex polymerase chain reaction for cytomegalovirus (CMV), parvovirus B19, adenovirus, enterovirus, herpes simplex virus (HSV), respiratory syncytial virus (RSV) and Epstein-Barr virus (EBV).

RESULTS

Among 686 patients, advanced maternal age was the most common indication for genetic testing (n = 469, 68.4%), followed by elevated aneuploidy risk on triple screen (n = 164, 23.9%), elevated maternal serum alpha-fetoprotein (n = 20, 2.9%), previous aneuploidy (n = 16, 2.3%) and family history of inheritable disease (n = 14, 2.1%). Forty-four (6.4%) amniotic fluid samples were positive for viral genome. A single genome was amplified in 41 samples (93%). In three samples, two viral genomes were identified. Adenovirus was most frequently identified (37/44), followed by CMV (5/44), EBV (2/44), enterovirus (2/44) and RSV (1/44). Parvovirus and HSV were not identified. There was a bimodal seasonal variation in prevalence, with the highest prevalence during the summer and late winter.

CONCLUSION

Viral genome is commonly found in amniotic fluid with a sonographically normal fetus, and the prevalence follows a seasonal pattern. The mechanism, significance and effects of this asymptomatic viral presence require further study.