Biomedical subjects

S N MacGregor

Publications and source records attributed to S N MacGregor.

45 records · Page 3Linked to original sources

PubMed1988

Cordocentesis: an appraisal of risks.

Fetal blood sampling via cordocentesis is being used with increasing frequency. Between March 1986 and February 1988, we performed 58 intravascular transfusions (64 attempts) and 27 fetal blood samplings (28 attempts) guided by ultrasonography. The complication rates for intravascular transfusion and fetal blood sampling were 9.4% (6 of 64) and 7.1% (2 of 28), respectively. The procedure-related mortality rates were 4.7% (3 of 64) and 0%. We caution that the potential complications be seriously considered when appropriate patients are selected for cordocentesis. Additionally, we recommend that cordocentesis be performed only in tertiary care centers by personnel skilled in both ultrasonography and prenatal diagnosis.

Blood Specimen Collection↗

PubMed1988

Fetal heart rate changes after fetal intravascular treatment with pancuronium bromide.

Because of recurrent needle dislodgement secondary to fetal movement, we have altered our intravascular transfusion technique by replacing maternal premedication (meperidine and diazepam [group 1]) with fetal intravascular infusion of pancuronium bromide (Pavulon [group 2]), a nondepolarizing neuromuscular blocking agent. Baseline fetal heart rate, number of accelerations, and variability were assessed before and after transfusion in both groups. Whereas there were no changes after transfusion in the former group, those fetuses who received pancuronium bromide demonstrated a dramatic abolishment of accelerations and decrease in variability, with the heart rate pattern often appearing "sinusoidal-like." These alterations in fetal heart rate were temporary changes that reverted to normal once the fetus "awakened" from the neuromuscular blockade. We speculate that these changes in fetal heart rate are secondary to the interaction of the reported hypertensive and vagolytic effects of pancuronium bromide.

Blood Transfusion, Intrauterine↗

PubMed1988

Fetal acidosis in prolonged pregnancy cannot be attributed to cord compression alone.

Fetal heart rate abnormalities associated with prolonged pregnancy have been attributed to umbilical cord vulnerability rather than placental insufficiency. Although intrapartum fetal heart rate patterns indicative of umbilical cord compression are common beyond 41 weeks' gestation, fetal intolerance to labor develops only in a subset of such patients. To test the hypothesis that suboptimal placental function contributes to reduced amniotic fluid volume and, ultimately, to fetal intolerance to labor, we prospectively collected biochemical and clinical data on 112 prolonged pregnancies. Data analysis was blinded to outcome and included cord blood acid-base measurements and intrapartum fetal heart rate interpretation. We observed a high incidence of umbilical cord compression (46.4%), but this finding was not predictive of emergent delivery in 32 of 52 cases (61.5%). Fetal acidosis (arterial pH less than 7.20) occurred more often in patients with cord compression, but the anticipated increase in carbon dioxide tension was not observed. Instead, a primary metabolic or combined acidosis was encountered in those fetuses delivered emergently. The additional findings of lower amniotic fluid volume and diminished birth weight in those patients delivered for fetal intolerance to labor suggest a direct role for suboptimal placental function in selected patients with prolonged pregnancy.

Acidosis↗

PubMed1988

Differing fetal growth patterns in pregnancies complicated by preterm labor.

Previous studies have demonstrated diminished ultrasonic fetal growth parameters in women delivering preterm. In this study, we tested the following hypothesis: In pregnancies complicated by spontaneous preterm labor, 1) unsuccessful tocolysis is likely to be associated with diminished fetal growth, and 2) successful tocolysis is likely to occur when fetal growth is normal. Ultrasound examinations were performed in 78 pregnancies complicated by preterm labor before 35 weeks' gestation. Tocolysis was attempted unless contraindicated or unless cervical dilatation was advanced (4 cm or greater). Pregnancies delivering before 36 weeks' gestation were compared with those delivering after this gestational age. Among the 48 pregnancies delivered before 36 weeks' gestation, a significantly greater proportion had ultrasonic growth parameters lower than normal values at corresponding gestational ages. In contrast, those pregnancies that had successful tocolysis and delivered near term demonstrated a normal distribution of ultrasound growth parameters. In pregnancies complicated by preterm labor, ultrasonic documentation of diminished fetal growth may identify the subgroup at increased risk for preterm delivery.

Adult↗

PubMed1987

Cocaine use during pregnancy: adverse perinatal outcome.

Cocaine use has increased dramatically in the United States during the past decade. The life-threatening cardiovascular and central nervous system complications of cocaine have been well documented; however, few studies have examined the risks of cocaine use during pregnancy. In this report the perinatal outcome data of 70 women receiving care at the Perinatal Center for Chemical Dependence of Northwestern University, whose pregnancies were complicated by cocaine abuse, were compared with those of matched control subjects. The use of cocaine during pregnancy was associated with lower gestational age at delivery, an increase in preterm labor and delivery, lower birth weights, and delivery of small for gestational age infants.

Adult↗

PubMed1987

Percutaneous umbilical transfusion in severe rhesus isoimmunization: resolution of fetal hydrops.

The rhesus-sensitized fetus with the worst prognosis is one with early onset of hydropic changes. Percutaneous umbilical blood sampling now enables access to the fetal circulation and thereby allows more precise evaluation of fetal anemia and direct intravascular transfusion. A variation of this technique was used in three pregnancies complicated by fetal pericardial effusion, scalp edema, and abdominal ascites before 26 weeks' gestation. Twelve ultrasound-guided percutaneous transfusions of 30 to 85 ml packed red blood cells were administered into the umbilical cord at its placental insertion. In each fetus the hydropic changes completely resolved and pregnancy outcome was successful. Neither adjunctive therapy with digoxin or Lasix nor exchange transfusions were used. Percutaneous umbilical transfusions appear to have the potential to improve the prognosis for the severely isoimmunized fetus.

Adult↗

PubMed1987

Ultrasonic prediction of birth weight in preterm fetuses: which formula is best?

Data from previous studies have suggested that birth weight prediction was enhanced by using formulas specifically derived from preterm fetuses. However, no prospective comparison of different formulas was performed. We obtained ultrasonic data on 61 pregnancies at risk for preterm delivery with a gestational age of 29.0 +/- 3.0 weeks (mean +/- SD). In all women birth weight was predicted within 7 days of delivery. Of the 61 pregnancies, 49 (80%), 41 (67%), 30 (49%), and 17 (28%) weighed less than 1750, 1500, 1250, and 1000 gm, respectively; 14 published formulas were compared for accuracy in predicting birth weight in these four categories. The formulas with the smallest absolute mean percent errors incorporated head and abdominal circumferences and femur length. The formula of Weiner et al., derived from low birth weight infants, produced the smallest absolute mean percent error and SD, 10.9% +/- 7.9%; this error was further reduced to 7.7% +/- 6.5% in infants weighing less than 750 gm. These findings suggest that birth weight in the preterm fetus is best predicted by a formula targeted to such a population.

Birth Weight↗

PubMed1987

Underestimation of gestational age by conventional crown-rump length dating curves.

Inaccuracies in gestational age assignment based on published crown-rump length data were noted in patients with known ovulation dates. In this study, we tested the hypothesis that crown-rump length data derived from pregnancies with known ovulation dates differ from those of menstrually timed pregnancies. Seventy-two previously infertile women with known dates of ovulation had crown-rump length measurements from 35-79 days postovulation. We transformed the data to menstrual age (gestational age) by adding 14 days to the date of ovulation and compared our crown-rump length values with those of two previous reports. At corresponding crown-rump length values, the gestational ages from our data differed from those in the previous studies. We suggest using crown-rump length dating curves based on ovulation-timed pregnancies because crown-rump length data derived from menstrually dated pregnancies underestimate true gestational age.

Embryonic and Fetal Development↗

PubMedDate not supplied

Comparison of active phase labor between triplet, twin, and singleton gestations.

OBJECTIVE: To characterize the active phase of labor in triplet pregnancies and compare it with gestational age-matched twins and singletons. METHODS: Active phase rates were calculated beginning at 5 cm of dilation for women with triplet gestations longer than 24 weeks who labored and reached the second stage. Twin and singleton cohorts that also completed the first stage of labor were matched for gestational age at delivery (+/-1 week), parity, and epidural use. Intrapartum variables included oxytocin use (induction or augmentation, duration of infusion, and maximum dosage), cervical dilation at membrane rupture, and active phase dilation rate. RESULTS: Thirty-two triplet pregnancies met inclusion criteria between January 1994 and September 1998 and were each compared with twin and singleton cases in a 1:2 ratio. Triplet and twin active phase rates, while similar (1.8 versus 1.7 cm/hour, respectively), were significantly lower than the mean singleton dilation rate (2.3 cm/hour, P =.02). No other intrapartum variables differed between the three groups. Despite controlling for gestational age at delivery, mean birth weights were significantly higher in singletons and correspondingly lower in twins and triplets (2,493 versus 2,112 and 1,968 g, respectively; P =.001). An analysis of active phase dilation rates as a function of the cumulative birth weight per pregnancy demonstrated an inverse correlation, with slower progress in active labor associated with increasing total fetal weight (R = -.24; P =.002). CONCLUSIONS: Triplet and twin active phase dilation proceeds at a slower rate than that observed in singleton pregnancies. The rate of active phase dilation is inversely correlated to total fetal weight.

Birth Weight↗