Should fetal scalp blood sampling be performed in the case of meconium-stained amniotic fluid?

Objective: To investigate the effect of using fetal scalp blood sampling on the risk of neonatal respiratory distress syndrome (NRDS) with meconium-stained amniotic fluid (MSAF).

Methods: Prospective data collection with regard to MSAF during labor for low-risk term cephalic singleton live birth from 2012 to 2014. Maternal, obstetric and neonatal data were compared according to the occurrence of respiratory distress syndrome (RDS group) or not (no RDS group).

Results: Of 515 newborns born through MSAF, 46 experienced RDS and from them 10 experienced meconium aspiration syndrome. No difference was observed according to maternal characteristic, abnormal fetal heart rate tracing pattern irrespective of its category and cesarean rate. Apgar at one?minute was lower in the group RDS (7.6 versus 8.5, p?<?0.05). The mean umbilical artery pH values did not differ between the two groups. Significant difference between newborns with and without RDS in terms of fetal scalp lactate sampling during the labor (71.1% versus 55.1%, p?<?0.05), and neonatal care unit (NCU) admissions (22.8% versus 10.8%, p?<?0.05). Secondary rather than primary meconium was associated with RDS when performing fetal scalp blood assessment (p?<?0.05). A significant correlation between RDS, fetal scalp blood assessment and MSAF diagnosed during the first stage of labor (after spontaneous rupture of membranes or at amniotomy) was found.

Conclusion: In case of MSAF, fetal scalp blood sampling did not reduce the risk of RDS.     

Hematologic parameters in the cord blood labor complicated by meconium-stained amniotic fluid

The aim of our study was to compare hematological values of the cord blood in the presence and absence of meconium-stained amniotic fluid (MSAF). MSAF was associated with decreased total platelet count, increased values of platelet distribution width and red blood cell distribution width. The mean nucleated red blood cells was significantly higher in meconium group. The values of red blood cells, white blood cells, reticulocytes counts and their fractions (HFR,MFR,LFR,IFR) were no different in cord blood of neonate exposed to meconium and in those who were not. These findings can suggest that MSAF contribute to fetal infection rather than hypoxia.     

Investigation of maternal and cord blood erythropoietin and copeptin levels in low-risk term deliveries complicated by meconium-stained amniotic fluid

Objective: To compare maternal, cord blood erythropoietin (EPO), and copeptin levels in low-risk term deliveries which are complicated by meconium-stained amniotic fluid (MSAF) to those with clear amniotic fluid. Also, to evaluate the relations between these markers and cord blood pH values.

Methods: Low-risk term pregnant women with MSAF at an active phase of labor were defined as the study group (n?=?39). Pregnant women with clear amniotic fluid were selected for the control group (n?=?41). The two groups were matched for age, body mass index and gestational age. Maternal, cord blood EPO and copeptin levels with cord blood pH values were also measured.

Results: Maternal, cord blood EPO, and copeptin levels of study and control groups were 42.6?±?9.0 versus 40.7?±?9.2, 134.2 (20.5–834.6) versus 38.4 (10.3–114.2), 4.9 (0.1–31.1) versus 4.0 (3.1–28.4), and 4.7 (2.6–25.5) versus 3.6 (2.0–23.2), respectively. The differences were statistically significant for cord blood EPO, maternal and cord blood copeptin levels (p?p?=?0.004, p?p?p?p?=?0.005, and p?=?0.009, respectively).

Conclusion: We suggest that higher cord blood EPO and maternal and cord blood copeptin levels may be an indicator of fetal acidosis in low-risk term deliveries complicated by MSAF.     

Secreted phospholipase A2 is increased in meconium-stained amniotic fluid of term gestations: potential implications for the genesis of meconium aspiration syndrome

Abstract

Background: Meconium-stained amniotic fluid (MSAF) represents the passage of fetal colonic content into the amniotic cavity. Meconium aspiration syndrome (MAS) is a complication that occurs in a subset of infants with MSAF. Secreted phospholipase A₂ (sPLA₂) is detected in meconium and is implicated in the development of MAS. The purpose of this study was to determine if sPLA₂ concentrations are increased in the amniotic fluid of women in spontaneous labor at term with MSAF.

Materials and methods: This was a cross-sectional study of patients in spontaneous term labor who underwent amniocentesis (n?=?101). The patients were divided into two study groups: (1) MSAF (n?=?61) and (2) clear fluid (n?=?40). The presence of bacteria and endotoxin as well as interleukin-6 (IL-6) and sPLA₂ concentrations in the amniotic fluid were determined. Statistical analyses were performed to test for normality and bivariate analysis. The Spearman correlation coefficient was used to study the relationship between sPLA₂ and IL-6 concentrations in the amniotic fluid.

Results: Patients with MSAF have a higher median sPLA₂ concentration (ng/mL) in amniotic fluid than those with clear fluid [1.7 (0.98–2.89) versus 0.3 (0–0.6), p?<?0.001]. Among patients with MSAF, those with either microbial invasion of the amniotic cavity (MIAC, defined as presence of bacteria in the amniotic cavity), or bacterial endotoxin had a significantly higher median sPLA₂ concentration (ng/mL) in amniotic fluid than those without MIAC or endotoxin [2.4 (1.7–6.0) versus 1.7 (1.3–2.5), p?<?0.05]. There was a positive correlation between sPLA₂ and IL-6 concentrations in the amniotic fluid (Spearman Rho?=?0.3, p?<?0.05).

Conclusion: MSAF that contains bacteria or endotoxin has a higher concentration of sPLA₂, and this may contribute to induce lung inflammation when meconium is aspirated before birth.     

Meconium staining of the amniotic fluid and the presence and severity of acute placental inflammation: a study of term deliveries in a predominantly African-American population

Objective: To determine frequency, stage and grade of placental histologic acute maternal inflammatory response (MIR) and fetal inflammatory response (FIR) in meconium-stained amniotic fluid (MSAF) in our predominantly African-American population.

Methods: Term placentas with MSAF (n?=?310) were evaluated for MIR/FIR, including stage/grade, and compared with placentas with clear amniotic fluid (AF) (n?=?250). MIR/FIR were also evaluated in thick compared to thin MSAF subgroups. Selected demographic and clinical features were compared.

Results: MIR and FIR were present in 57.7 and 40.3% of the MSAF compared to 44.0 and 29.2% of the clear AF group, respectively (p?=?.001 and .008). MIR with FIR was present in 35.8% of the MSAF compared to 25.2% of the clear AF group (p?=?.008); however, there was no significant difference in frequency of MIR without FIR between groups. There was no significant difference in frequency of MIR/FIR in thick compared to thin MSAF; however, thick MSAF was associated with higher FIR stage compared to thin MSAF (29.2 versus 5.4%, p?=?.004). This association was not seen with MIR stage or MIR/FIR grade.

Conclusions: Histologic MIR and FIR are frequent findings in MSAF. Thick MSAF is associated with higher FIR stage when compared to thin MSAF.     

Meconium-stained amniotic fluid in term pregnancies-a clinical view.

The objective of this study was to explore details of the clinical relationship between meconium-stained amniotic fluid (MSAF) in labour, abnormal fetal heart pattern and meconium aspiration (MA). This was a prospective study carried out in Princess Badeea Teaching hospital during a 6-month period from March to September 1997. During the study period 344 (8.5%) of the deliveries had MSAF (344 women). Continuous fetal heart monitoring was routinely used and 36 women with MSAF (10.5%) needed to be delivered by caesarean section because of fetal distress (diagnosed by abnormal fetal heart pattern) in early labour, compared with 0.95% in those with clear amniotic fluid (CAF), (P <0.00001). Many infants in the MSAF group had a low Apgar score and required ventilation at birth. Nineteen infants (5.5%) developed MA, three of whom (15.8%) died. We conclude that there is an association between MSAF, abnormal fetal heart pattern in labour and a low Apgar score and that it should be considered a high risk situation. MA a problem that occurs with particulate meconium was significantly related to abnormal fetal heart pattern and longer length of labour.     

An assessment of the use of meconium alone as an indication for fetal blood sampling.

OBJECTIVE: To assess the validity of meconium as an indication for fetal blood sampling. METHODS: The study design was a prospective observational study in a teaching hospital. Fetal blood samples were taken from 401 women. One hundred sixty-five patients had meconium-stained amniotic fluid (77 of whom had no cardiotocographic abnormalities). In the remaining 236 patients, the indication for fetal blood sampling was cardiotocographic abnormalities without meconium. The main outcome measures were the values of pH and base excess obtained at fetal blood sampling, 1-minute Apgar scores, and umbilical artery pH values. RESULTS: Patients with meconium alone as an indication for fetal blood sampling had higher scalp sample pH values (P < .001) and 1-minute Apgar scores (P < .01) than laboring patients with both meconium and cardiotocographic abnormalities. The patients with meconium alone had higher scalp pH values than patients with cardiotocographic abnormalities but no meconium (P < .001). In only two patients with meconium alone was a fetal scalp pH less than 7.20 (both infants had good Apgar scores at delivery). However, when cardiotocographic abnormalities were present, the finding of meconium was significant, resulting in lower 1-minute Apgar scores (P < .01) despite a lack of difference in fetal blood sample pH values. CONCLUSION: In the absence of cardiotocographic abnormalities, meconium is not an indication for fetal blood sampling.     

Significance of meconium-stained amniotic fluid in the preterm population.

OBJECTIVE: Numerous studies have assessed the significance of meconium-stained amniotic fluid (MSAF) at term. However, to date, there has been very little documentation on the incidence and significance of meconium in the preterm population. Our objective was to define the incidence of MSAF in patients delivering prematurely (<37 weeks) and examine its association with underlying fetal acidosis, Apgars and admission to the neonatal intensive care unit (NICU). METHOD: All patients delivering at a single tertiary care center between June 1994 and September 1997 were reviewed for the presence of meconium and gestational age <37 weeks at delivery. Maternal demographics and birth outcomes including cord gases, Apgar scores and admission to the NICU were collected. Exclusion criteria included multiple gestations, breech presentations, fetal anomalies and patients not in labor. RESULTS: Out of a total of 9570 patients there were 506 (5.3%) preterm births meeting the inclusion criteria, of whom 24 (4.8%) had MSAF noted either during labor or at delivery. Comparing the preterm group with and without meconium, there were no differences in maternal age, gravidity, rate of Cesarean section, or gestational age at delivery. Cord pH (7.27 meconium vs. 7.29 no meconium) and base excess (-5.1 meconium vs. -4.0 no meconium) were similar in both groups. There were no clinically significant differences in mean Apgar scores at 1 and 5 minutes. However, an increased number of NICU admissions were noted in the group with meconium (75% vs. 53%, p=0.04). CONCLUSION: The incidence of meconium staining of the amniotic fluid in labor in the preterm population is less than 5% and by itself is not a significant marker of fetal acidosis.     

New onset of meconium during labor versus primary meconium-stained amniotic fluid – is there a difference in pregnancy outcome?

Abstract

Objective: To compare pregnancy outcome between deliveries complicated by new onset of meconium during labor following prior evidence of clear amniotic fluid and labors in which meconium was present to begin with.

Methods: A retrospective cohort study of all singleton term (≥37?+?0 weeks) deliveries complicated by intrapartum meconium-stained amniotic fluid in a tertiary referral medical center during the year 2012. Outcome was compared between deliveries with new onset of meconium during labor following prior evidence of clear amniotic fluid (secondary meconium group) and those in which meconium was already evident at the time of membranes rupture (primary meconium group).

Results: Of the 9167 deliveries during the study period, 694 were eligible for the study group. Of these, 537 were complicated by primary meconium and 157 by secondary meconium. Only secondary meconium, but not primary meconium, was independently associated with an increased risk of operative vaginal delivery (OVD) and adverse neonatal outcome. Pregnancies complicated by secondary meconium were independently associated with a higher rate of OVD (28.0% versus 11.4%, p?<?0.001), POP position of the fetal head (6.4% versus 2.6%, p?=?0.02), and adverse neonatal outcome (17.2% versus 8.9%, p?=?0.003).

Conclusion: Secondary meconium is associated with a higher rate of adverse obstetrical and neonatal outcome compared with primary meconium.     

The effect of meconium on perinatal outcome: a prospective analysis

Objective: To evaluate the effect of meconium-stained amniotic fluid (AF) on perinatal outcome. Methods: A prospective observational study was performed, comparing perinatal outcome of parturients with thick and thin meconium-stained AF to those with clear AF. Results: The rate of meconium-stained AF was 18.1% (106/586). Of those, 78 (13.3%) patients had thin and 28 (4.8%) had thick meconium-stained AF. The rate of oligohydramnios was significantly higher among pregnancies complicated with thick meconium-stained AF (OR 7.2, 95% CI 2.1-24.1; p = 0.002). A significant linear association, using the Mantel-Haenszel test for linearity, was found between the thickness of the meconium and abnormal fetal heart rate patterns during the first and second stages of labor, low Apgar scores at 1 min and the risk for Cesarean section. A statistically significantly higher risk for neonatal intensive care unit admission was observed among patients with thick meconium as compared to those with clear AF (OR 11.4, 95% CI 2.0-59.3; p = 0.006), even after adjustment for oligohydramnios and abnormal fetal heart rate patterns. Conclusions: Thick, and not thin, meconium-stained AF, was associated with an increased risk for perinatal complications during labor and delivery. Therefore, thick meconium-stained AF should be considered a marker for possible fetal compromise, and lead to careful evaluation of fetal well-being.     

Borderline amniotic fluid index and perinatal outcomes in the uncomplicated term pregnancy

Objective: To determine perinatal outcomes in uncomplicated term pregnancies with a borderline amniotic fluid index (AFI).

Methods: A retrospective review was conducted of uncomplicated singleton pregnancies at term (>37 weeks). Borderline and normal AFI were defined as 5.1?≤?AFI?≤?8.0?cm and 8.1?≤?AFI?≤?24?cm, respectively. Adverse perinatal outcomes, cesarean delivery for non-reassuring fetal heart rate testing, meconium-stained amniotic fluid, a 5-min Apgar score of <7, admission to the neonatal intensive care unit (NICU), and whether the neonate was small for gestational age were compared between the borderline and normal AFI groups.

Results: Borderline AFI was not significantly associated with cesarean delivery for non-reassuring fetal heart rate testing (p?=?0.513), meconium-stained amniotic fluid (p?=?0.641), admission to the NICU (p?=?0.368), or a 5-min Apgar score of <7 (p?=?1.00). However, the number of neonates who were small for gestational age (p?=?0.021) and rates of induction of labor (p?<?0.001) were significantly higher in the borderline group. Multiple logistic regression analysis showed that borderline AFI was not associated with cesarean delivery for non-reassuring fetal heart rate testing (odds ratio [OR]?=?0.72, 95% confidence interval [CI] 0.27–1.91, p?=?0.52).

Conclusion: In uncomplicated term pregnancies, a borderline AFI does not increase the risk of adverse perinatal outcomes.     

Use of maternal plasma level of Zinc-Coproporphyrin in the prediction of intrauterine passage of meconium: A pilot study

Objective: To evaluate the usefulness of maternal plasma zinc-coproporphyrin (ZCP) level as a marker for intrauterine passage of meconium.

Methods: A pilot study consisting of 10 pregnancies with meconium-stained amniotic fluid and 10 pregnancies with clear amniotic fluid was used. The corresponding plasma and amniotic fluid levels of ZCP were measured using spectrofluorometry. ZCP levels in plasma and amniotic fluid were compared between the two groups and the relation between plasma and amniotic fluid ZCP levels in the clear and meconium-stained groups was assessed using Spearman rank-order correlation.

Results: Mean amniotic fluid ZCP was significantly higher in the meconium-stained amniotic fluid as compared to the clear amniotic fluid group. Although mean plasma ZCP levels were higher in the meconium-stained amniotic fluid group, this difference was not statistically significant. There was no significant correlation between plasma ZCP levels and amniotic fluid ZCP, but we could categorize patients according to plasma ZCP levels into four categories with different risks for having meconium-stained amniotic fluid.

Conclusions: Plasma ZCP might be a promising test for prediction of intrauterine passage of meconium in high-risk patients if confirmed by larger studies. The implications of this prediction on management remain unknown.     

Risk factors for meconium aspiration in meconium stained amniotic fluid.

Meconium aspiration syndrome (MAS) is a life-threatening respiratory disease in infants born through meconium stained amniotic fluid (MSAF). The purpose of this study was to determine risk factors for MAS in the newborns of mothers who had meconium stained amniotic fluid in labour. A retrospective study of all full-term pregnancies with MSAF from May 2003 to October 2004 was designed at a teaching hospital. Development of MAS was the primary outcome. Maternal details, mode of delivery and neonatal details (Apgar score, reassuring or non-reassuring fetal heart rate tracing and birth weight) were evaluated. During the study period, there were 2,603 deliveries of whom 302 (11.6%) had MSAF. MAS developed in 64 of these infants (21.1%). Compared with healthy neonates with MSAF, those with MAS had higher rate of non-reassuring fetal heart rate (FHR) tracing, thick meconium and Apgar score < or =5 at 5 min. The neonatal birth weight was lower in the MAS group, maternal age, parity, gestational age and mode of delivery were not significantly different in the two group. We found the severity of meconium, low Apgar score at 5 min and non-reassuring FHR tracing was associated with MAS in MSAF pregnancies.     

Influence of postdatism and meconium on fetal erythropoietin.

OBJECTIVE: To determine whether fetal erythropoietin (Epo) concentrations are increased in pregnancies extending beyond 41 weeks' gestation and whether this is influenced by the presence of meconium-stained amniotic fluid. METHODS: Epo concentrations were measured in 116 fetal umbilical cord blood samples from otherwise uncomplicated pregnancies between 37 to 43 weeks' gestation during the period of October 1996 to October 1997. An enzyme-linked immunosorbent assay kit was used to measure Epo. Maternal demographics and birth outcomes including Apgar score, cord blood pH, and base deficit were obtained. Fetuses born between 41 and 43 weeks' gestation (post-term) were compared with matched controls born between 37 and 40 weeks' gestation (term). In addition, both post-term and term fetuses with meconium-stained amniotic fluid were compared with matched controls without meconium. RESULTS: Post-term fetuses without meconium had significantly higher Epo levels compared with term fetuses (mean +/- SEM: 50.6 +/- 6.5 versus 29.5 +/- 3.3 mIU/ml, p = 0.002). When matched for gestational age, fetuses with meconium-stained amniotic fluid had significantly greater Epo concentrations compared with controls without meconium (post-term, 80.7 versus 50.6 mIU/ml; term, 61.4 versus 29.5 mIU/ml; p < 0.05). However, no significant difference in Epo levels was found between post-term fetuses with meconium and term fetuses with meconium (80.7 +/- 15.7 mIU/ml versus 61.4 +/- 12.8 mIU/ml, respectively). Mean cord blood pH and base deficit values for all groups were within normal clinical range. CONCLUSION: Cord blood Epo concentrations were significantly increased in pregnancies extending beyond 41 weeks. Irrespective of gestational age, meconium-stained amniotic fluid was associated with a significant rise in Epo. High Epo levels in these pregnancies imply subacute or chronic fetal hypoxia. Close clinical monitoring of post-term fetuses and those with meconium-stained amniotic fluid is warranted.     

Nucleated red blood cells in human fetal scalp capillary blood samples: a feasibility study

Objective: Elevated umbilical cord nucleated red blood cell (NRBC) counts have been suggested as a predictor of adverse perinatal outcome. We sought to evaluate the feasibility of obtaining fetal scalp capillary blood NRBC counts during labor and to assess their correlation with umbilical cord NRBC counts. Methods: Fetal scalp capillary blood specimens were prospectively collected in laboring patients who underwent scalp sampling because of the presence of an abnormal fetal heart rate pattern. Matched umbilical cord blood samples were collected immediately after birth. Outcome measures were the feasibility of obtaining fetal scalp NRBC counts and their correlation with umbilical cord NRBC counts. Results: Thirteen term singleton pregnancies formed the study population. In four patients, fetal scalp capillary blood sampling was performed twice. Of the attempts to evaluate fetal scalp capillary samples for NRBC counts, 16 out of 17 (94.1%) were successful. The mean fetal scalp capillary blood NRBC count per 100 white blood cells was 12.6 ± 7.6 (± SD). Umbilical cord mixed, venous and arterial NRBC counts were 15.5 ± 8.8, 13.4 ± 10.7 and 12.6 ± 10.7, with p = 0.09, p = 0.59 and p = 0.68, respectively, when compared to the corresponding scalp sample. The Spearman rank correlation between fetal scalp capillary samples and umbilical cord mixed, venous and arterial NRBC counts were r = 0.86, r = 0.92 and r = 0.95, respectively, with all p values < 0.001. Conclusion: Previous studies have established the clinical utility of umbilical cord NRBC counts. Our study demonstrated that it was possible to obtain NRBC counts from a fetal scalp capillary sample and that these counts correlated highly with umbilical cord NRBC counts. Future studies are needed to evaluate fetal scalp NRBC counts as a predictor of perinatal outcome.     

Endothelin-1 concentrations in cord blood of neonates with meconium-stained amniotic fluid

BACKGROUND: The effects of meconium-stained amniotic fluid (MSAF) on cord blood endothelin-1 (ET-1) concentrations have not been explored. OBJECTIVE: The aim of this study was to verify whether MSAF influences ET-1 cord blood concentrations in healthy term neonates. METHODS: Using an enzyme-linked immunosorbent assay, plasma ET-1 concentrations were determined in 30 healthy term neonates with MSAF, and in 15 healthy term neonates without MSAF. The two groups were of the same gestational age, weight, Apgar score, cord blood pH, base excess, and hematocrit values, as well as systolic and diastolic blood pressures. RESULTS: ET-1 plasma concentrations were not significantly different between the two groups and did not correlate with cord blood pH or base excess values. CONCLUSION: Our data demonstrate that meconium passage does not induce ET-1 secretion.     

Accuracy of the lamellar body count in amniotic fluid contaminated by meconium

Objective: To determine whether meconium-contaminated amniotic fluid falsely elevates the lamellar body count in fetal lung maturity testing.

Methods: Thirty mothers undergoing amniocentesis for fetal lung maturity testing were prospectively consented. A 2?mL portion of the patient’s sample was mixed with a 10% meconium solution and the meconium-stained sample was then run in tandem with the patient’s sample used in clinical management. Pure meconium samples without amniotic fluid were also run through the cell counter for analysis.

Results: Following meconium contamination, the lamellar body count value increased in 67% of the cases, decreased in 23% and remained the same in 10%. There were 13 test results that had “immature” values in the uncontaminated patient management sample group and nine of these (69%) became elevated to a “mature” level (a false elevation) following the addition of meconium. All of the 10 pure liquid meconium samples devoid of amniotic fluid processed by the cell counter identified and quantified some particle the size of platelets.

Conclusions: The lamellar body count test result is not reliable in meconium-stained amniotic fluid specimens. There is some unknown particle found in meconium that is the size of platelets/lamellar bodies that can falsely elevate the test result. Currently, the only reliable fetal lung maturity test in meconium-stained amniotic fluid is the presence of phosphatidylglycerol.     

Bacteria and endotoxin in meconium-stained amniotic fluid at term: could intra-amniotic infection cause meconium passage?

Abstract

Background: Meconium-stained amniotic fluid (MSAF) is a common occurrence among women in spontaneous labor at term, and has been associated with adverse outcomes in both mother and neonate. MSAF is a risk factor for microbial invasion of the amniotic cavity (MIAC) and preterm birth among women with preterm labor and intact membranes. We now report the frequency of MIAC and the presence of bacterial endotoxin in the amniotic fluid of patients with MSAF at term.

Materials and methods: We conducted a cross-sectional study including women in presumed preterm labor because of uncertain dates who underwent amniocentesis, and were later determined to be at term (n?=?108). Patients were allocated into two groups: (1) MSAF (n?=?66) and (2) clear amniotic fluid (n?=?42). The presence of bacteria was determined by microbiologic techniques, and endotoxin was detected using the Limulus amebocyte lysate (LAL) gel clot assay. Statistical analyses were performed to test for normality and bivariate comparisons.

Results: Bacteria were more frequently present in patients with MSAF compared to those with clear amniotic fluid [19.6% (13/66) versus 4.7% (2/42); p?<?0.05]. The microorganisms were Gram-negative rods (n?=?7), Ureaplasma urealyticum (n?=?4), Gram-positive rods (n?=?2) and Mycoplasma hominis (n?=?1). The LAL gel clot assay was positive in 46.9% (31/66) of patients with MSAF, and in 4.7% (2/42) of those with clear amniotic fluid (p?<?0.001). After heat treatment, the frequency of a positive LAL gel clot assay remained higher in the MSAF group [18.1% (12/66) versus 2.3% (1/42), p?<?0.05]. Median amniotic fluid IL-6 concentration (ng/mL) was higher [1.3 (0.7–1.9) versus 0.6 (0.3–1.2), p?=?0.04], and median amniotic fluid glucose concentration (mg/dL) was lower [6 (0–8.9) versus 9 (7.4–12.6), p?<?0.001] in the MSAF group, than in those with clear amniotic fluid.

Conclusion: MSAF at term was associated with an increased incidence of MIAC. The index of suspicion for an infection-related process in postpartum women and their neonates should be increased in the presence of MSAF.     

Delivery room risk factors for meconium aspiration syndrome

The objective of this study is to identify risk factors for meconium aspiration syndrome (MAS) in newborns born through meconium-stained amniotic fluid (MSAF). From May 27, 1994 to June 9, 1997 maternal and neonatal data were prospectively collected on all infants born through MSAF. Development of MAS was the primary outcome. Using bivariate and logistic regression analysis we identified risk factors for MAS. There were 8,967 births during this period: 7.9% (708 of 8,967) were delivered through MSAF. Respiratory symptoms developed in 6.8% (48 of 708) of births. Of these, 50% (24 of 48) were excluded due to the diagnosis of transient tachypnea of the newborn (17), respiratory distress syndrome (4), group B streptococcus pneumonia (1), congenital cytomegalic inclusion disease (1), and supraventricular tachycardia (1). Of the 24 infants with respiratory symptoms consistent with MAS, 45.8% (11 of 24) required ventilatory support, one required extracorporeal-membrane oxygenation. Bivariate analysis identified six risk factors ( p <0.05): Apgar <7 at 1 minute, Apgar <7 at 5 minutes, thick meconium, fetal distress, suction of infant's stomach by delivery room team at <5 minutes of age, and need for resuscitation. Tracheal meconium was very prevalent in our population at 74% of all intubated infants, and was not significantly associated with MAS. Logistic regression analysis identified four independent risk factors. Looking at multiple prediction models, an infant with fetal distress, Apgar <7 at 1 and 5 minutes and thick meconium has a 79.8% probability of developing respiratory symptoms. If these risk factors are not present, there is a 0.8% risk. In our cohort, this group had 16.7% positive predictive value (4 of 24) and 99.6% negative predictive value (657 of 660). In meconium deliveries, infants with thick meconium, fetal distress, and Apgar scores <7 at 1 and 5 minutes are at high risk for development of respiratory symptoms. Infants delivered in the absence of all of these risk factors are at low risk for development of MAS.     

L-arginine pathway in neonates with meconium-stained amniotic fluid

Objective

To study the arginase, nitric oxide synthase and nitric oxide pathways associated with passage of meconium.

Study design

Cord blood samples were collected from 20 newborns with meconium-stained amniotic fluid (MSAF) and from 23 newborns with clear amniotic fluid. Cord blood pH, arginase, nitric oxide synthase and nitric oxide levels were compared between the groups.

Result

The differences between the arginase and nitric oxide measurements of the newborns with MSAF and those with clear amniotic fluid were significant. In the MSAF group arginase levels were significantly lower (p = 0.007) and nitric oxide levels were significantly higher (p = 0.032) than the clear amniotic fluid group.

Conclusion

Hypoxia may be involved in the pathogenesis of meconium passage due to decreased arginase and increased nitric oxide levels.