Joseph V. Collea

Magnetic resonance imaging of vasa praevia

A 34 year old primigravid woman had an ultrasound examination at 20 weeks of gestation that showed a complete placenta praevia. Follow up transvaginal sonography at 24 weeks of gestation revealed echolucent linear structures overlying the cervix, suggesting a vasa praevia. The placenta appeared to have two lobes, with vessels running over the cervix between them. Pulsed Doppler demonstrated a fetal pulse rate of 140 beats per minute in these vessels. We decided to perform magnetic resonance imaging on the patient in order to determine whether vasa praevia could be diagnosed using magnetic resonance imaging, and also to see whether magnetic resonance imaging could add any further information beyond that which we already had with ultrasound and Doppler. We obtained approval from our Institutional Review Board to perform a magnetic resonance imaging on the patient for further evaluation of the vasa praevia. The patient was counselled, and informed consent was obtained. T2-weighted magnetic resonance imaging revealed three areas of signal void overlying the cervix (Fig. 1). Using two-dimensional time-of-flight sequences, flow was demonstrated through these structures. There was flow through two vessels in one direction (Fig. 2A), and flow through the third vessel in the opposite direction (Fig. 2B), consistent with the expected directions of flow in the umbilical arteries and the vein. The placenta was shown to have an accessory lobe, and these vessels ran between the lobes. The woman was hospitalised in the third trimester and was delivered by elective caesarean section at 351⁄2 weeks of gestation. The diagnosis of vasa praevia was confirmed at delivery; the placenta had two lobes, with communicating vessels running over the cervix between them. The live male infant had Apgar scores of 8 and 9, and was discharged home eight days later. The infant is doing well at 10 months of age.

The effect of propofol on isolated human pregnant uterine muscle

Background Propofol is an alternative to thiopental as an intravenous induction agent for cesarean section. Because it has relaxant effects on vascular and other smooth muscles, the authors set out to determine whether propofol has any effect on pregnant human uterine smooth muscle in an isolated preparation. Methods Myometrial specimens were excised from 10 parturients undergoing elective cesarean section. The muscle strips were suspended in tissue baths and isometric tension was recorded. After establishment of rhythmic contractions in the buffer solution as a control, propofol (0.5 to 10 [micro sign]g/ml) in fat emulsion was applied cumulatively to the bath. The effect of the fat emulsion at equivalent concentrations was also examined. Results Propofol concentrations of 2.7 x 10‐6 M (0.5 [micro sign]g/ml) and 1.1 x 10‐5 M (2 [micro sign]g/ml) had no significant effect on the active tension developed by muscle contraction. However, propofol at concentration of 5.5 x 10‐5 M (10 [micro sign]g/ml) reduced the active tension by 45% (P < 0.02) compared with the control value. The fat emulsion had no effects on the active tension. Conclusions These results imply that the decline in the active tension of muscle contraction was most likely caused by propofol and not by the fat emulsion. However, the propofol concentrations needed to produce a significant reduction in the uterine muscle tension appear to be much greater than the free propofol concentrations reported by others during cesarean section.

Predictive value of transvaginal cervical length in triplet pregnancies for spontaneous preterm delivery at ≤ 32 weeks

Objective: To establish whether cervical length is a predictor of spontaneous preterm delivery at ≤ 32 weeks in triplet pregnancies. Methods: This was a case-control study of all triplet pregnancies followed with more than three sonographic assessments of cervical length at 4-week intervals from 1995 to 2000. Cervical length in women delivered spontaneously at ≤ 32 weeks (cases) was compared with that of the remaining women (controls). Statistical analysis included Fishers exact test, χ2 test, one-way analysis of variance, logistic regression and receiver operating characteristic (ROC) curve to determine optimal cervical length thresholds for spontaneous preterm delivery at ≤ 32 weeks. Results: Of the 58 women included in the study, 17 (29%) delivered spontaneously at ≤ 32 weeks. The preterm delivery group had similar demographic and obstetric variables, but a higher rate of cerclage placement (65% vs 17%, p < 0.001) than controls. Mean ± standard deviation cervical length was significantly shorter among cases than controls at 16-20.0 weeks (3.0 ± 1.2 vs. 3.9 ± 0.8 cm, p = 0.01), but not at 20.1-24.0 weeks (3.5 ± 1.1 vs. 3.8 ± 1.0 cm, p = 0.76). Logistic regression analysis determined that cervical length at 16-20 weeks had an odds ratio of 0.43 (95% CI = 0.23, 0.80) for the prediction of spontaneous preterm delivery at ≤ 32 weeks. ROC curve analysis identified a cervical length of ≤ 2.6 cm as the optimal threshold for the prediction of spontaneous preterm delivery at ≤ 32 weeks (sensitivity 41%, specificity 92%). Conclusions: In a population of triplet gestations with a 29% rate of preterm delivery, cervical length at 16-20.0 weeks, but not at 20.1-24.0 weeks, was inversely correlated with the probability of preterm delivery at ≤ 32 weeks.

Risk Factors for Pulmonary Edema in Triplet Pregnancies

OBJECTIVE: Multiple gestations are known to be at increased risk for pulmonary edema. Our objective was to characterize this morbidity in a cohort of triplet pregnancies.STUDY DESIGN: Charts from triplet pregnancies managed by the Georgetown University Hospital Maternal–Fetal Medicine service were abstracted for demographic information and complications. Cases who developed pulmonary edema were compared with those who did not using Fisher exact test, χ2 and Students t-test with p<0.05 considered significant.RESULTS: Of 66 triplet pregnancies with complete records, 15 (22.7%) were complicated by pulmonary edema. Patients developing this condition were more likely to be receiving magnesium sulfate therapy than those who did not [14/15 (93.3%) vs 32/51 (62.7%) p=0.049]. There was no difference between patients developing pulmonary edema and those who did not in terms of maternal age (mean±SD: 34.5±6.8 vs 34±4.3 years, p=0.8) or gestational age at delivery (33.3±2.3 vs 32.8±3.5 weeks, p=0.6), but the former group had smaller babies than the latter (1739± 369 vs 1891±538 g, p=0.04). Among the patients treated with magnesium sulfate, those who developed the more severe form of pulmonary edema were more likely than those who did not to have been treated for pre-eclampsia than preterm labor (6/10 (60%) vs 7/33 (21.2%), p=0.04).CONCLUSIONS: Pulmonary edema is a common complication of triplet pregnancy. Patients receiving magnesium sulfate, having pre-eclampsia or fetal growth restriction are at increased risk for pulmonary edema, particularly in its worst clinical presentation.

Breath pentane concentrations during labor and the effect of epidural analgesia on the pentane concentration

Increased lipid peroxidation has been observed in pregnancy and particularly in preeclampsia. Pentane, a by-product of lipid peroxidation, can be measured in exhaled breath, and its measurement is considered a non-invasive method of assessing lipid peroxidation in vivo. We measured pentane levels in the breath of 36 healthy parturient women and examined the effect of epidural analgesia on the pentane level. Single-expiratory breath samples were analyzed by gas chromatography. The breath pentane level was higher during labor (4.88 parts per billion [p.p.b.], 95% confidence interval 3.25-6.51 p.p.b.) than before the induction of labor (3.10 p.p.b., 95% confidence interval 2.01-4.19 p.p.b.). There was a significant decrease in the pentane level after the institution of epidural analgesia (2.27 p.p.b., 95% confidence interval 1.43-3.11 p.p.b.). Our results suggest that labor may be accompanied by an increase in lipid peroxidation, and epidural analgesia reverses this increase.

The effect of glucagon on spontaneous contractility of isolated pregnant uterine muscle

Objective To determine whether glucagon has relaxant effects on the spontaneous contractions of term pregnant human uterine smooth muscle in an isolated preparation. Methods Myometrial specimens were excised from the upper incisional surface of the lower uterine segment in seven women during elective cesarean delivery. The muscle strips were suspended in tissue baths and isometric tension was recorded. After establishing rhythmic spontaneous contractions, glucagon reconstituted with distilled water or the accompanying diluent was added directly to the bath in a cumulative manner. In the second phase of the study, the effect of the diluent (1.6% glycerin with 0.2% phenol) alone on muscle contractility was evaluated. Results Glucagon had no effect on uterine muscle concentrations when reconstituted with distilled water. However, glucagon reconstituted with the diluent decreased the contractile amplitude by 27 ± 11% (mean ± standard deviation, P <.01) and the frequency by 13 ± 10% (P <.05) at a concentration of 20 μg/mL. At a cumulative concentration of 40 μg/mL, the reductions in amplitude and frequency were 65 ± 13% (P <.001) and 18 ± 14% (P <.01), respectively. The diluent at equivalent concentrations exerted relaxation similar to that produced by glucagon when reconstituted with the diluent. The relaxant effects were not different between the two solutions (P >.2, power 90%, a = .05). Conclusion These results suggest that relaxation of contractions was likely caused by the diluent rather than by glucagon. We conclude that glucagon does not have a direct relaxant effect on spontaneous contraction of isolated uterine muscle obtained from term pregnant uteri.

Effect of dantrolene sodium on contractility of isolated human uterine muscle

Summary The administration of intravenous dantrolene in a parturient susceptible to malignant hyperthermia has been associated with post partum uterine atony. We examined the effect of dantrolene sodium for injection (Dantrium Intravenous) on spontaneous contractility of uterine smooth muscle from women in term pregnancy in an isolated preparation. Dantrolene sodium for injection at 5 μg/ml and 10 μg/ml had no effect on the spontaneous contractility of the uterine muscle preparations. At a cumulative concentration of 20 μg/ml, a mild depression (16 ± 14%) in the frequency of spontaneous contractions was noted. However, a similar depression in the muscle preparations treated with mannitol suggests that the depression observed with the dantrolene was likely due to the mannitol that was included in the dantrolene formulation rather than to dantrolene sodium itself. We conclude that dantrolene sodium has no effect on the spontaneous contractility of uterine smooth muscle. The depression of uterine muscle activity observed with dantrolene for injection appears attributable to the mannitol.

Complications and Management of Breech Presentation

The increased risk of perinatal morbidity and mortality associated with vaginal delivery of the fetus in breech presentation has attracted the attention of obstetricians and midwives for centuries. From the Dark Ages to well into the nineteenth century, the perinatal morbidity and mortality from birth anoxia, injuries, and congenital malformations instilled in the superstitious and the uneducated the belief that breech presentation was an evil omen.1 Primitive African tribes believed that breech presentation foretold the death of the child’s parents,2 while noble attendants to the crowned heads of Europe whispered in birthing rooms that “children brought forth by their feet are cursed—they are born as monsters, crippled in mind and body, and destined to bring misfortune into the world. It would be better if they were not born.”3

Effect of Dantrolene Sodium on Contractility of Isolated Human Uterine Muscle

The administration of intravenous dantrolene in a parturient susceptible to malignant hyperthermia has been associated with post partum uterine atony. We examined the effect of dantrolene sodium for injection (Dantrium Intravenous) on spontaneous contractility of uterine smooth muscle from women in term pregnancy in an isolated preparation. Dantrolene sodium for injection at 5 microg/ml and 10 microg/ml had no effect on the spontaneous contractility of the uterine muscle preparations. At a cumulative concentration of 20 microg/ml, a mild depression (16 +/- 14%) in the frequency of spontaneous contractions was noted. However, a similar depression in the muscle preparations treated with mannitol suggests that the depression observed with the dantrolene was likely due to the mannitol that was included in the dantrolene formulation rather than to dantrolene sodium itself. We conclude that dantrolene sodium has no effect on the spontaneous contractility of uterine smooth muscle. The depression of uterine muscle activity observed with dantrolene for injection appears attributable to the mannitol.