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Biomedical subjects

G A Macones

Publications and source records attributed to G A Macones.

34 records · Page 2Linked to original sources
PubMed1998

Optimising maternal-fetal outcomes in preterm labour: a decision analysis.

OBJECTIVE: To compare, using decision analytic techniques, maternal and fetal risk and benefits of three strategies for the management of preterm labour after 32 weeks. These strategies are empiric tocolysis, no tocolysis, or amniocentesis for fetal maturity testing. DATA SOURCES: Published medical literature provided the probabilities, including those for tocolysis efficacy, maternal and neonatal outcomes, and steroid efficacy. DATA: Synthesis Separate decision trees were created for hypothetical cohorts of patients presenting with preterm labour at 32, 34, and 36 weeks of gestation to compare strategies. The primary outcome was the total number of expected adverse maternal and neonatal events for each strategy at each gestational age. RESULTS: At 32 weeks tocolysis yielded the lowest total number of adverse maternal and neonatal events. At 34 weeks, both tocolysis and no tocolysis yielded similar overall outcomes. At 36 weeks most clinical outcomes were good regardless of strategy. CONCLUSIONS: This analysis supports the empiric use of tocolytics at 32 weeks. At 34 weeks, either tocolysis or no tocolysis appear to be reasonable alternatives. At 36 weeks no tocolysis is probably preferred. This analysis also suggests that amniocentesis should not be employed in the management of preterm labour at these gestational ages.

Amniocentesis↗
PubMed1997

Predictive factors for neonatal morbidity in neonates with an umbilical arterial cord pH less than 7.00.

OBJECTIVE: Fewer than 50% of neonates with an umbilical arterial pH < 7.00 have neonatal complications. Our objective was to identify clinical predictive factors for adverse outcomes in this group of neonates. STUDY DESIGN: In this case-control study both cases and controls had an umbilical arterial cord pH < 7.00. Cases were defined as those neonates who had seizures, grade 3 to 4 intraventricular hemorrhage, gastrointestinal dysfunction, respiratory distress syndrome requiring intubation, sepsis, or death. Controls had an umbilical arterial cord pH < 7.00 and no complications. A multivariable prediction model was created, with variables having an association with adverse outcome by bivariate analyses, attempting to predict which neonates in this umbilical arterial pH range are at greatest risk for adverse outcomes. RESULTS: We identified 73 of 10,705 neonates born between July 1992 and October 1996 with an umbilical arterial cord pH < 7.00. Thirty-five neonates met our case definition, and the remaining 38 composed the control group. Cases had significantly lower arterial pH values and 1- and 5-minute Apgar scores, greater arterial base deficit values, and a higher incidence of abruptio placentae and maternal cocaine use. More cases were delivered before 34 weeks. There were three neonatal deaths, two cases of grade 3 or 4 intraventricular hemorrhage, five cases of gastrointestinal dysfunction, and four cases of neonatal seizures. In our predictive model for adverse neonatal outcome, an arterial base deficit > or = 16 mmol/L and a 5-minute Apgar score < 7 had a sensitivity and a specificity of 79% and 80.8%, respectively. CONCLUSION: Neonatal morbidity in neonates with an umbilical arterial cord pH < 7.00 can be predicted by a high arterial base deficit value and low 5-minute Apgar score.

Acidosis↗
PubMed1997

The association between maternal cocaine use and placenta previa.

OBJECTIVE: Our aim was to determine whether maternal cocaine exposure is a risk factor for placenta previa. STUDY DESIGN: In this case-control study, cases of placenta previa confirmed at delivery (ascertained by International Classification of Diseases, ninth revision, Clinical Modification, code-based search, N = 40) were compared with a random sample of patients without placenta previa (N = 80) in a ratio of two controls per case. Data on antecedent maternal cocaine use, as well as other potential risk factors for placenta previa, were obtained from a review of the prenatal chart and the hospital record. Categorization of cocaine use was based on either patient self-report or urine toxicologic testing, or both. Multiple logistic regression was performed to assess the association between cocaine and placenta previa while we controlled for other variables. RESULTS: After the effects of other variables were adjusted for, maternal cocaine use was an independent risk factor for placenta previa (adjusted odds ratio = 4.39, 95% confidence interval 1.17 to 16.4). Other significant risk factors included a history of cesarean section and prior elective abortion. CONCLUSION: These results suggest that cocaine use, as well as prior cesarean section, prior elective abortion, and parity, are associated with placenta previa.

Adult↗
PubMed1997

Is there justification for using indomethacin in preterm labor? An analysis of neonatal risks and benefits.

OBJECTIVE: Recent reports have suggested that the use of indomethacin for tocolysis may independently increase the risk for major adverse neonatal events such as intraventricular hemorrhage and necrotizing enterocolitis. The objective of this study was to determine whether this potential risk of indomethacin is outweighed by the benefit of delivery delay at gestational ages < 32 weeks. STUDY DESIGN: We constructed separate decision trees to compare strategies of tocolysis with indomethacin versus no tocolysis for hypothetic cohorts of patients with idiopathic preterm labor at 24, 26, 28, 30, and 32 weeks' gestation. Probabilities for these decision models, including estimates of indomethacin efficacy and the potential for increase in adverse neonatal events with indomethacin, were obtained from the medical literature. The primary outcome was the number of expected adverse neonatal events per 1000 women for each strategy at each gestational age. RESULTS: In the base case analysis tocolysis with indomethacin was a more favorable strategy than no tocolysis across all gestational ages that we studied. As expected, the difference in the number of events between the two strategies declined with advancing gestational age because of a decreasing baseline risk for adverse neonatal events as gestational age increased. The models at 26, 28, 30, or 32 weeks were not sensitive to our estimates of indomethacin efficacy, nor to our estimates of baseline neonatal morbidity or steroid efficacy, or to the relative increase in some neonatal morbidities with indomethacin use. CONCLUSIONS: On the basis of current estimates, the benefits of indomethacin outweigh the potential risks to the neonate at gestational ages < or = 32 weeks. Thus the use of indomethacin for tocolysis at these ages is a reasonable strategy.

Cerebral Hemorrhage↗
PubMed1997

Prenatal screening for toxoplasmosis.

OBJECTIVE: To evaluate the merits of screening for toxoplasmosis in all pregnant women. METHODS: We used decision analysis to compare three strategies for the antepartum management of congenital toxoplasmosis: 1) no testing for congenital toxoplasmosis; 2) current practice, which is to perform targeted screening in cases of incidental abnormalities noted on ultrasound; and 3) universal serologic screening of pregnant women followed by amniocentesis to diagnose fetal infection in cases of maternal seroconversion. For each of the three strategies, we considered the two available treatment options: intrauterine antiparasitic treatment or pregnancy termination. RESULTS: Universal screening reduced the total number of cases of congenital toxoplasmosis compared with no testing or targeted screening. However, compared with no testing, universal screening with medical treatment resulted in 18.5 additional pregnancy losses for each case of toxoplasmosis avoided. If infected pregnancies underwent termination, universal screening resulted in 12.1 additional pregnancy losses for each case avoided. CONCLUSION: Maternal screening reduces the number of cases of disease, but at a substantial clinical cost. The rarity of the disease and limitations in diagnosis and therapy limit the effectiveness of screening strategies. The risks associated with amniocentesis are particularly important. Universal maternal screening for congenital toxoplasmosis should not be performed.

Decision Support Techniques↗
PubMed1997

Evidence for magnesium sulfate as a tocolytic agent.

The objective of our study is to quantitatively examine the available evidence regarding the efficacy and side effects of magnesium sulfate for acute tocolysis (from randomized trials) compared with placebo and beta-agonist agents. Randomized trials comparing magnesium sulfate with placebo or beta-agonists for tocolysis were identified with a MEDLINE-based search and was supplemented by a search of obstetrical textbooks and bibliographies. Trials underwent quality evaluation and data abstraction by two independent, blinded investigators. Outcomes evaluated included delivery delay of various durations as well as the frequency of major and minor side effects. Summary odds ratios and 95 percent confidence intervals for dichotomous outcomes were calculated using a random effects model. Interstudy heterogeneity for these outcomes was assessed with a Q statistic. We identified 12 randomized controlled trials of magnesium sulfate for acute tocolysis. Four studies were excluded because of either lack of comparison of magnesium sulfate to either placebo or beta-agonists or lack of reporting clinical outcomes of interest. The eight remaining randomized trials comparing magnesium sulfate with placebo or beta-agonists were included in this analysis. There was no significant difference between MgSO4 and placebo for any of the measured outcomes for delay in delivery. Comparing magnesium sulfate to ritodrine or beta-agonists did not demonstrate any differences between the agents in achieving clinically significant tocolysis. There was a significant difference between MgSO4 and beta-agonists in the frequency of medication discontinuation because of side effects, but not in the frequency of major adverse drug events. There are few data comparing magnesium sulfate with a placebo for acute tocolysis. Magnesium sulfate seems to be comparable to ritodrine and beta-agonists, although the available data are not sufficient for a rational choice between these agents.

Adrenergic beta-Agonists↗
PubMed1997

Costs, true costs, and whose costs in economic analyses in medicine?

Cost-effectiveness analyses of clinical practices are becoming more common in the development of health policy. However, such analyses can be based on misconceptions and flawed assumptions, leading to flawed policies. We argue that such is the case with the recent recommendations for routine measurement of umbilical cord gases at delivery, a policy based on the assumption that this clinical strategy will pay for itself by reduced malpractice awards. As we demonstrate, this argument reflects the physician's perspective, not that of society or of patients. It also ignores the fact that malpractice awards are largely transfer payments, not cost of healthcare.

Blood Gas Analysis↗
PubMed1996

Intrauterine onset of a mononeuropathy: peroneal neuropathy in a newborn with electromyographic findings at age one day compatible with prenatal onset.

Mononeuropathies are unusual at birth, and electromyographic (EMG) definition the first day of life has not been reported previously. Although neonatal mononeuropathies may be related to obstetric complications, prenatal mechanisms also merit consideration. We report an infant, born with a peroneal neuropathy, whose EMG was performed 18 h after birth. An isolated peroneal nerve lesion with lack of compound muscle action potential and the presence of fibrillation potentials, confined to the tibialis anterior muscle, suggested a primary intrauterine mechanism for this mononeuropathy. Because of an infant's small size, the temporal profile used in adults for appearance of EMG signs of wallerian degeneration may not apply. Inaccurate conclusions may result if the EMG standards for timing adult nerve injury are applied to newborns. To our knowledge, previous published cases of neonatal mononeuropathies have not included babies whose first EMG was performed before age 4 days. Therefore, an EMG study shortly after birth needed to be accomplished if strong support for the hypothesis of a prenatal onset were to be generated. Our findings are compatible with an intrauterine onset of this baby's peroneal neuropathy.

Electromyography↗
PubMed1996

Prolongation of pregnancy and survival of remaining fetuses after operative evacuation of one triplet at 18 weeks' gestation.

BACKGROUND: Successful delay of aftercoming siblings is an infrequent event in obstetrics. No case of second-trimester operative vaginal evacuation of a fetus followed by delayed delivery of the remaining siblings has been described previously. CASE: A triplet pregnancy was complicated by preterm rupture of membranes at 17 weeks' gestation, followed by cord prolapse and subsequent fetal arm prolapse at 18 weeks' gestation. Operative evacuation of triplet A was performed under ultrasound guidance, with the placenta left undisturbed. Antibiotics and tocolytics were used perioperatively and the pregnancy was prolonged for another 16 weeks. Onset of active labor at 34 weeks' gestation resulted in the vaginal delivery of viable twin males weighing 2810 and 2680 g. CONCLUSION: In cases of multiple gestations with second-trimester rupture of the lower sac, selective fetal evacuation can be performed safely and may allow successful continuation of the remaining pregnancy.

Adult↗
PubMed1996

Multifetal pregnancy reduction: evaluation of fetal growth in the remaining twins.

OBJECTIVE: Our purpose was to study fetal growth after reduction of high-order multiple gestations to twins. STUDY DESIGN: Birth weight and gestational age data were collected for 236 triplet and greater multiple pregnancies reduced to twins (113 triplets, 89 quadruplets, and 34 quintuplets or above) and was compared with those of a control group of unreduced twins. RESULTS: Rates of intrauterine growth restriction per pregnancy were significantly different between the nonreduced and all categories of reduced multifetal pregnancies. The incidence of intrauterine growth restriction was 19.4% in the nonreduced twins, 36.3% in pregnancies reduced from triplets, 41.6% in pregnancies reduced from quadruplets, and 50% from higher-order multiple gestations. There was a statistically significant trend toward increasing frequency of intrauterine growth restriction with increasing starting fetal number (p = 0.04). The increase in intrauterine growth restriction was primarily accounted for by twin pairs with only one growth-restricted newborn. CONCLUSION: Multifetal pregnancy reduction does not reduce the incidence of intrauterine growth restriction in the remaining fetuses to that of nonreduced twins.

Birth Weight↗
PubMed1996

Does station of the fetal head at epidural placement affect the position of the fetal vertex at delivery?

OBJECTIVE: The objective study was to determine whether epidural placement before engagement of the fetal head is associated with an increase in the incidence of malposition at delivery. STUDY DESIGN: We performed a retrospective cohort study to ascertain the relation between station at epidural placement and malposition. Three hundred fifty-seven patient records were reviewed; 320 records of patients in spontaneous or induced labor who received epidural analgesia were included in the analysis. Patients with a contraindication to labor, antepartum fetal death, or twins were excluded. Maternal demographics, cervical examination at epidural placement, epidural medication characteristics, and labor and delivery data were abstracted from medical records. Station was characterized as high if the fetal vertex was above the level of the maternal ischial spines or low if the vertex was at or below the level of the ischial spines at the time of epidural placement. RESULTS: The relative risk of occiput malposition was significantly increased with epidural placement at high station. This risk remained after we controlled for age and birth weight. Cervical dilatation was not independently associated with occiput position at delivery. CONCLUSIONS: Epidural placement before engagement of the fetal head is associated with an increased incidence of malposition at delivery. This finding may provide an insight into the empiric observation that operative delivery is variably increased for patients laboring under epidural anesthesia.

Adult↗
PubMed1995

Efficacy of oral beta-agonist maintenance therapy in preterm labor: a meta-analysis.

OBJECTIVE: To analyze the available data on the efficacy of oral beta-agonist maintenance therapy in delaying delivery and in decreasing the incidence of preterm birth and its complications. DATA SOURCES: A computer search of English-language abstracts using MEDLINE (medical subject heading terms: labor, premature and beta-adrenergic receptor agonist, therapeutic use) was supplemented with a review of the bibliographies of obstetric texts to identify randomized trials of oral beta-agonist maintenance therapy. METHODS OF STUDY SELECTION: Six trials were identified, of which four met our inclusion criteria for the meta-analysis. DATA EXTRACTION AND SYNTHESIS: Trials to be included in this meta-analysis underwent trial quality evaluation and data abstraction independently by two blinded investigators. An estimate of the odds ratio (OR) and risk difference was calculated for the dichotomous outcomes using both a random effects model and a fixed effects model. Continuous outcomes were pooled using a simple weighted average of the within-study difference in means. The pooled OR for preventing preterm delivery was 1.09 (95% confidence interval [CI] 0.60-1.99) and the OR for preventing recurrent preterm labor was 1.05 (95% CI 0.53-2.05). The pooled difference in the mean interval to delivery was -0.22 days (95% CI -2.5 to +1.99). CONCLUSIONS: The available data do not support a role for beta-agonist maintenance therapy after resolution of an acute episode of preterm labor in reducing the incidence of preterm delivery, increasing the interval to delivery, or reducing the incidence of recurrent preterm labor.

Administration, Oral↗
PubMed1993

Multifetal reduction of triplets to twins improves perinatal outcome.

OBJECTIVE: Our purpose was to compare the perinatal outcome of triplet pregnancies reduced to twins with the outcomes of continuing triplet pregnancies and twin pregnancies. STUDY DESIGN: Pregnancy outcomes of triplet pregnancies reduced to twins delivered between July 1988 and July 1992 were compared with pregnancy outcomes of continuing triplet and twin pregnancies delivered over the same time period. RESULTS: The mean gestational age at delivery for the reduced triplets was 35.6 weeks, compared with 31.2 weeks in the nonreduced triplets (p = 0.002). The perinatal mortality rate was 30 per 1000 births in the reduction group and 210 per 1000 births in the nonreduced triplets (p < 0.0001). There were no statistically significant differences between the reduced and nonreduced twins. CONCLUSION: Multifetal pregnancy reduction of triplets to twins yields an improved perinatal outcome compared with nonreduced triplets and a similar outcome compared with nonreduced twins.

Abortion, Therapeutic↗
PubMedDate not supplied

Does cesarean section decrease the incidence of major birth trauma?

OBJECTIVE: To determine whether the increase in frequency of cesarean section is associated with a decreased incidence of major birth trauma. STUDY DESIGN: A retrospective cohort study was performed evaluating all neonatal cases of major birth trauma from January 1989 to December 1994. Major birth trauma was defined as peripheral plexus or nerve injuries, fractures, or lacerations. The data were grouped into two mutually exclusive periods (January 1989 to December 1990 vs January 1991 to December 1994) in which a significant difference in the cesarean section rate was known. RESULTS: Of 17,957 deliveries during the period, 141 cases of birth trauma occurred. One hundred thirty-seven of the 141 medical records were available for review, and 116 were classified as having had major birth trauma and were included in the study. The overall incidence of major birth trauma was 6.5/1000 deliveries. During the two-year period (January 1989 to December 1990), 18.3% of deliveries were by cesarean section and the major birth trauma rate was 8.4/1000 deliveries. During the following 4 years, the cesarean section rate was 22.3% and the major birth trauma rate was 5.3/1000 deliveries. Significant differences in the birth trauma chi(2) = 6.12, p = 0.013) and cesarean section (chi(2) = 40.80, p < 0.001) rates were observed. Controlling for the mode of delivery lessened the association between time period and birth trauma incidence (chi(2)MH = 3.28, p = 0.07). A significant decrease in the occurrence of major birth trauma in neonates delivered by cesarean section in the later period was discovered (relative risk = 0.46, 95% confidence interval 0.22 to 0.97). This decrease appeared to be mediated by a decrease in total lacerations between the periods (chi(2) = 11.76, p < 0.001), because the rates of other types of major birth trauma did not differ in neonates delivered by cesarean section or the vaginal route. CONCLUSIONS: With a 4% increase in rate of cesarean section at our institution, a significant decrease in the occurrence of major birth trauma was observed. This finding cannot be explained by a decreased risk of neonatal trauma in patients delivering vaginally, but rather by a decreased risk of neonatal trauma at cesarean section during the latter period.

Birth Injuries↗