Fetal blood sampling in addition to intrapartum ST-analysis of the fetal electrocardiogram: evaluation of the recommendations in the Dutch STAN® trial.

OBJECTIVES: To evaluate the recommendations for additional fetal blood sampling (FBS) when using ST-analysis of the fetal electrocardiogram. DESIGN: Prospective cohort study. SETTING: Three academic and six non-academic teaching hospitals in the Netherlands. POPULATION: Labouring women with a high-risk singleton pregnancy in cephalic position beyond 36 weeks of gestation. METHODS: In labouring women allocated to the STAN® arm of a previously published randomised controlled trial who underwent one or more FBS during delivery, we assessed whether FBS was performed according to the trial protocol and how fetal acidosis, defined as an FBS pH < 7.20, was related to ST-waveform analysis. MAIN OUTCOME MEASURES: The number of FBS showing fetal acidosis, related to the different STAN® criteria where additional FBS is recommended. RESULTS: Among 2827 women monitored with STAN®, 297 underwent FBS, of whom 171 (57.6%) were performed according to the predefined criteria and 126 were performed in absence of these criteria. In the first group, rates of fetal acidosis (pH < 7.20) were two of 18, none of nine, 12 of 111 and three of 33 when FBS was taken for abnormal cardiotocogram (CTG) at the start, intermediary CTG at the start, abnormal CTG >60 minutes, and poor electrocardiogram quality, respectively. When the predefined criteria were not met and ST-analysis showed no ST-events, only two incidents of fetal acidosis were seen. CONCLUSIONS: The performance of FBS is valuable in the advised STAN® criteria. When these criteria are not met, performance of FBS does not seem helpful in the detection of fetal acidosis.

Prediction of fetal lung immaturity using gestational age, patient characteristics and fetal lung maturity tests: a probabilistic approach.

OBJECTIVES: The lecithin/sphingomyelin (L/S) ratio and the lamellar body count (LBC) can be used to predict respiratory distress syndrome (RDS). DESIGN: We performed a retrospective cohort study among consecutive women who underwent amniotic fluid sampling for the assessment of fetal lung maturity. Logistic regression was used to construct models for the prediction of RDS in three gestational age categories, with models based on clinical characteristics only, clinical characteristics and the LBC, and on clinical characteristics and L/S ratio. RESULTS: When amniotic fluid was collected <30 weeks, the specificity of the LBC was 30% and the sensitivity 100%. Addition of the L/S ratio increased the specifity to 60%, for a sensitivity of 100%. When amniocentesis was performed between 30 and 33 weeks, addition of the L/S ratio only marginally improved the performance of the LBC. CONCLUSIONS: At a gestational age <30 weeks, the L/S ratio has additional value over the LBC. Above 30 weeks of gestation, single use of the LBC seems sufficient.

Lung maturation in small for gestational age fetuses from pregnancies complicated by placental insufficiency or maternal hypertension.

BACKGROUND: Clinical studies suggest that respiratory outcome of infants born preterm may be influenced by placental insufficiency and hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome. If so, one could expect to see differences in lung maturation indices (lecithin/sphingomyelin (L/S) ratio and lamellar body count (LBC)) in the amniotic fluid. The present study investigates lung maturation indices of preterm small for gestational age (SGA) fetuses with or without abnormal Doppler ultrasound examination and with or without maternal hypertension/HELLP syndrome. STUDY DESIGN: Retrospective cohort study of 76 neonates born in our center between 1997 and 2003 with gestational age (GA) <34 weeks, birth weight

Effect of antenatal glucocorticoid therapy on arterial and venous blood flow velocity waveforms in severely growth-restricted fetuses.

OBJECTIVE: To study the effects of antenatal glucocorticoid (betamethasone) therapy on blood flow velocity waveform patterns in the umbilical artery (UA), middle cerebral artery (MCA) and ductus venosus (DV) in severely intrauterine growth-restricted (IUGR) fetuses. METHODS: Fifty-five severely IUGR fetuses at 24-34 weeks of gestation were included in the study. The effect of antenatal glucocorticoid administration on Doppler findings in the UA, MCA and DV was studied using two statistical approaches, namely paired sample analysis and multilevel analysis. RESULTS: There were no effects of betamethasone on the pulsatility index (PI) of the vessels studied. The only changes noticed during the 14 days of observation were a gradual decrease of PI in the MCA, an increase in the UA-PI/MCA-PI ratio and an increase in the DV-PI. These changes with time may be explained by a progressive and gradual deterioration of the fetal condition. CONCLUSION: Antenatal glucocorticoids (betamethasone) do not affect fetal Doppler waveform patterns of the UA, MCA and DV in severely IUGR fetuses.

The effect of clinical characteristics on the lecithin/sphingomyelin ratio and lamellar body count: a cross-sectional study.

OBJECTIVES: To study the changes in the lecithin/sphingomyelin (L/S) ratio and lamellar body count (LBC) during pregnancy and to study the effect of clinical characteristics on these measurements. METHODS: We reviewed in retrospect the amniotic fluid samples for the assessment of fetal lung maturity of consecutive women between January 1996 and December 2000. We evaluated the effect of antenatal administration of glucocorticoids, the presence of diabetes, fetal growth restriction and the amount of amniotic fluid on the L/S ratio and LBC. We then constructed normal curves, by relating the L/S ratio and LBC to gestational age in the cases without respiratory distress syndrome (RDS). Data from the literature were added to these curves. RESULTS: From the 334 included women, 64 infants (19%) developed RDS. The LBC was lower in women with polyhydramnios (p = 0.04), and similar in women with oligohydramnios. Administration of glucocorticoids, the presence of maternal diabetes or fetal growth restriction did not affect the L/S ratio or the LBC. The median L/S ratio in cases without RDS showed a constant increase from a gestational age of 28 weeks onwards. The median LBC increased slowly between a gestational age of 28 weeks and 34 weeks, to increase more steeply thereafter. CONCLUSIONS: The amount of amniotic fluid affects the LBC, but not the L/S ratio. Since the L/S ratio and the LBC increase with gestation, differences in gestational age should be taken into account in the interpretation of these fetal lung maturity tests.

The accuracy of lamellar body count and lecithin/sphingomyelin ratio in the prediction of neonatal respiratory distress syndrome: a meta-analysis.

OBJECTIVE: To compare the performance of the lecithin/sphingomyelin ratio and the lamellar body count in the prediction of neonatal respiratory distress syndrome. DESIGN: Meta-analysis. SAMPLE: Six studies reporting on the performance of both the lecithin/sphingomyelin ratio and the lamellar body count published between January 1966 and August 1999. METHODS: We performed a computerised MEDLINE search to identify articles published on the subject. For the six selected studies, prevalence of respiratory distress syndrome and sensitivity and specificity of the tests in the prediction of respiratory distress syndrome were calculated, and overall performance was assessed by constructing summary receiver-operating characteristic curves. RESULTS: The constructed summary receiver-operating characteristic curves showed the lamellar body count to perform slightly better than the lecithin/sphingomyelin ratio in the prediction of respiratory distress syndrome (P= 0.13). CONCLUSIONS: Since the lamellar body count can be performed quickly and since it is less expensive than the lecithin/sphingomyelin ratio, we recommend the former as the test of first choice in the assessment of fetal lung maturity.

Nitric oxide production during the early neonatal period in small-for-gestational-age infants.

UNLABELLED: In a study of endogenous nitric oxide production in growth-retarded, very preterm newborns (<32 wk GA), urinary NOx/creatinine ratio and plasma guanosine 3',5'-cyclic monophosphate levels were determined during the early neonatal period. Newborns were divided into three groups: appropriate-for-gestational-age (AGA, n = 19), moderately small-for-gestational-age (SGA, n = 13) and severely SGA (n = 6) infants. Severely SGA infants showed significant higher values of nitric oxide derivatives during the first 24 h of life compared with the other groups. CONCLUSION: An increased NO production is found in SGA infants during the first 24 h after birth. This may reflect an increased intrauterine nitric oxide production in the feto-placental circulation found in cases with intrauterine growth retardation,

Learning in medicine: chorionic villus sampling.

Operator experience is considered to influence the safety and success of medical procedures. We performed a retrospective survey to assess learning curves in chorionic villus sampling (CVS). Data of 2081 consecutive women, in whom CVS was carried out in a tertiary care university hospital for prenatal diagnosis, were available for analysis. Endpoints of the analysis were fetal loss, failure of the procedure and need for several needle insertions. Frequencies of each endpoint were calculated and plotted for consecutive series of 50 samplings per operator. Logistic regression analysis was used to quantify the effect of operator experience. We observed a statistically significant learning effect for the unit as a whole as assessed by fetal loss figures and the same tendency for need to do several insertions. We did not observe a (collective) learning effect for failure of the procedure. Individual operators showed a significant learning profile for some endpoints. The individual learning profile predominantly depended on previous experience in amniocentesis. Our study substantiates the presence of a learning curve for CVS. This supports the view that centralization and restriction of CVS to a limited number of experienced operators within centres, is likely to have a positive influence on safety and success of the procedure.