Joseph G. Ouzounian

Physiologic Changes During Normal Pregnancy and Delivery

The major adaptations of the maternal cardiovascular system that progress throughout gestation may unmask previously unrecognized heart disease and result in significant morbidity and mortality. Most of these changes are almost fully reversed in the weeks and months after delivery. Hemodynamic changes during pregnancy include increased blood volume, cardiac output (CO), and maternal heart rate; decreased arterial blood pressure; decreased systemic vascular resistance. CO increases up to 30% in the first stage of labor, primarily because of increased stroke volume; maternal pushing efforts in the second stage of labor can increase CO by as much as 50%.

Brachial plexus palsy: An in utero injury?

Acquired brachial plexus injury historically has been linked with excessive lateral traction applied to the fetal head, usually in association with shoulder dystocia. Recent reports in the obstetric literature, however, have suggested that in utero forces may underlie a significant portion of these injuries. Brachial plexus palsies may therefore precede the delivery itself and may occur independent of the actions of the accoucheur. Thus we propose that the long-held notions of a traction-mediated pathophysiologic mechanism for all brachial plexus injuries warrant critical reappraisal.

Disseminated intravascular coagulation and antithrombin III depression in acute fatty liver of pregnancy

OBJECTIVE Acute fatty liver of pregnancy has been associated with a syndrome of marked depression of antithrombin III and disseminated intravascular coagulation. We sought to identify the clinical importance of this accelerated coagulation. STUDY DESIGN The medical records of patients with acute fatty liver of pregnancy identified during the period of 1982 to 1994 were retrospectively reviewed. RESULTS Twenty-eight patients with acute fatty liver of pregnancy were identified for an incidence of 1:6692 births. Laboratory evidence of persistent disseminated intravascular coagulation was found in all patients tested. Six patients had clinical bleeding, all associated with genital tract injury. Twenty-three of twenty-three patients tested had markedly decreased antithrombin III levels (average 11%, normal range 80% to 100%). Seven patients received antithrombin III transfusions, which was associated with a significant transient rise in the plasma level. Compared with patients not transfused, however, there was a similar clinical outcome. CONCLUSION Profoundly depressed antithrombin III levels and laboratory evidence of disseminated intravascular coagulation were present in all cases of acute fatty liver of pregnancy but rarely influenced clinical outcome unless there was concomitant genital tract injury. Antithrombin III transfusions increased plasma levels, but no definite clinical benefit was established in this series because of the small number of cases.

Brachial plexus palsy associated with cesarean section: an in utero injury?

OBJECTIVE Brachial plexus injury may be unrelated to manipulations performed at the time of delivery, occurring in the absence of shoulder dystocia and in the posterior arm of infants with anterior shoulder dystocia. To further support the hypothesis that some of these nerve injuries appear to be of intrauterine origin, we present a series of brachial plexus palsies associated with atraumatic cesarean delivery among fetuses presenting in the vertex position. STUDY DESIGN We performed a computerized search of all deliveries from 1991 to 1995 for the discharge diagnoses of brachial plexus injury and cesarean section. Inclusion criteria included cephalic presentation at the time of delivery and the absence of traumatic delivery. RESULTS We noted six cases of Erbs palsy, with four palsies in the anterior shoulder and two in the posterior arm. Among those five patients undergoing cesarean section because of labor abnormalities, two had uterine cavity abnormalities whereas one had a prolonged second stage of labor. One brachial plexus palsy occurred in the absence of active labor. All nerve injuries were persistent at age 1 year. CONCLUSIONS Brachial plexus palsy can be associated with cesarean delivery. Such palsies appear to be of intrauterine origin and are more likely to persist.

Permanent Erb palsy: A traction-related injury?

Historically, the primary risk factor attributed to brachial plexus injury during birth has been excessive traction applied at delivery to an entrapped anterior shoulder. However, recent evidence has suggested that not all cases of brachial plexus palsy are attributable to traction. We have encountered several cases of permanent Erb palsy associated with birth that were not attributable to traction applied at delivery. We reviewed cases of neonates with documented permanent Erb palsy that occurred either in the absence of shoulder dystocia or in the neonates posterior arm in the presence of anterior shoulder dystocia. We identified four cases that occurred in the absence of shoulder dystocia and four cases that occurred in the posterior arm of infants with anterior shoulder dystocia. These data further support the notion that the etiology of permanent brachial plexus palsy associated with birth may not be related to traction.

Measurement of cardiac output in pregnancy by thoracic electrical bioimpedance and thermodilution: A preliminary report

Thoracic electrical bioimpedance is a noninvasive, continuous method of obtaining cardiac output that requires no operator skill. However, the most recent thoracic electrical bioimpedance technology has not been validated in pregnancy. We therefore compared two methods of measuring cardiac output in pregnancy, thoracic electrical bioimpedance and thermodilution. We studied 11 patients who required pulmonary artery catheterization for peripartum management and measured cardiac output simultaneously by thoracic electrical bioimpedance and thermodilution. Among eight of nine patients, there was agreement (within +/- 20%) between the two methods. Bivariate linear regression with these nine cases showed excellent correlation (r = 0.91, p less than 0.001) with a slope of 1.04, which indicated a one-to-one relationship between thoracic electrical bioimpedance and thermodilution. The remaining two cases were removed from analysis because of septic shock in one case (which invalidates thoracic electrical bioimpedance) and 4+ tricuspid regurgitation in another case (which invalidates thermodilution). These data support that thoracic electrical bioimpedance measurement of cardiac output may be valid in most peripartum patients.

Clinical significance of prenatal ultrasonographic intestinal dilatation in fetuses with gastroschisis

OBJECTIVE Our purpose was to evaluate the clinical significance of intestinal dilatation detected by prenatal ultrasonographic examination in fetuses with gastroschisis. STUDY DESIGN A retrospective chart review was performed of all patients cared for at Los Angeles County/University of Southern California Womens and Childrens Hospital with the prenatal diagnosis of gastroschisis over a 7-year period (1988 through 1995). Patients were divided into two groups on the basis of the presence or absence of ultrasonographically measured fetal bowel diameter of > or = 17 mm. Neonatal outcomes of the two groups were compared. RESULTS Twenty-one patients met the entry criteria during the study period. Fetuses with maximal bowel diameter of > or = 17 mm did not have a longer time to full oral feeding, a longer initial hospital stay, or a greater need for bowel resection when compared with fetuses with a bowel diameter < 17 mm. Two newborns underwent bowel resection because of intestinal atresia. Prenatal ultrasonographic examination failed to show significant bowel dilatation in either infant. CONCLUSION Our data suggest that prenatal evidence of intestinal dilatation in fetuses with gastroschisis does not predict immediate neonatal outcome. Thus this finding is not an appropriate indication for preterm delivery in the absence of other evidence of fetal compromise.

A comparison of shoulder dystocia-associated transient and permanent brachial plexus palsies ☆

OBJECTIVE To estimate differences between shoulder dystocia-associated transient and permanent brachial plexus palsies. METHODS We performed a retrospective case-control analysis from national birth injury and shoulder dystocia databases. Study patients had permanent brachial plexus palsy and had been entered into a national birth injury registry. Cases of Erb or Klumpke palsy with documented neonatal neuromuscular deficits persisting beyond at least 1 year of life were classified as permanent. Cases of transient brachial plexus palsy were obtained from a shoulder dystocia database. Non-shoulder dystocia–related cases of brachial plexus palsy were excluded from analysis. Cases of permanent brachial plexus palsy (n = 49) were matched 1:1 with cases of transient brachial plexus palsy. RESULTS Transient brachial plexus palsy cases had a higher incidence of diabetes mellitus than those with permanent brachial plexus palsy (34.7% versus 10.2%, odds ratio [OR] 4.68, 95% confidence interval [CI] 1.42, 16.32). Patients with permanent brachial plexus palsies had a higher mean birth weight (4519 ± 94.3 g versus 4143.6 ± 56.5 g, P < .001) and a greater frequency of birth weight greater than 4500 grams (38.8% versus 16.3%, OR, 0.31, 95% CI 0.11, 0.87). There were, however, no statistically significant differences between the two groups with respect to multiple antepartum, intrapartum, and delivery outcome measures. CONCLUSION Transient and permanent brachial plexus palsies are not associated with significant differences for most antepartum and intrapartum characteristics.

The accuracy of intrapartum ultrasonographic fetal weight estimation in diabetic pregnancies

OBJECTIVE Our purpose was to compare the accuracy of ultrasonographic fetal weight estimation in pregnant diabetic women with that of matched nondiabetic controls. STUDY DESIGN We performed a case-control study of pregnant patients who underwent ultrasonographic fetal weight estimation within 3 days of delivery. The study group consisted of pregnant diabetic women and nondiabetic controls matched for maternal body mass index and neonatal birth weight. Fetal weight estimates were calculated with use of Hadlocks and Shepards formulas. The difference between ultrasonographic fetal weight estimation and actual birth weight (absolute percent error) was analyzed with respect to maternal diabetic status and actual birth weight. RESULTS A total of 450 patients were studied (225 patients in each group). The mean (+/- SD) gestational age at delivery was 39.0 +/- 1.5 weeks versus 39.9 +/- 1.7 weeks for the diabetic and nondiabetic patients, respectively. There was no statistically significant difference between the two groups with respect to the mean (+/- SD) time interval between the ultrasonographic examination and delivery (0.9 +/- 1.8 days vs 0.8 +/- 2.1 days) or the mean (+/- SD) absolute percent error (9.0% +/- 7.1% vs 8.4% +/- 6.3%). The mean (+/- SD) absolute percent error of fetal weight estimates among subjects with macrosomic fetuses (birth weight > or = 4500 gm) was significantly greater than that observed in fetuses with birth weights < 4500 gm (12.6% +/- 8.4% vs 8.4% +/- 6.5, p = 0.001). This difference was observed irrespective of maternal diabetic status. CONCLUSION When matched for maternal body mass index and birth weight, the accuracy of ultrasonographic fetal weight estimation was similar among diabetic and nondiabetic women. Birth weights > or = 4500 gm rather than maternal diabetes seem to be associated with less accurate ultrasonographic fetal weight estimates.

Pre-pregnancy weight and excess weight gain are risk factors for macrosomia in women with gestational diabetes

Objective:To determine whether women with gestational diabetes mellitus (GDM) whose weight gain exceeded the 2009 Institute of Medicine (IOM) recommendations were more likely to have macrosomia.Study Design:Retrospective cohort study of the association of weight gain in women with Class A1 GDM, with term (⩾37 weeks) singleton liveborns and macrosomia (birthweight ⩾4000 g). Multivariate logistic regression models were used to adjust for covariates and test for interactions.Result:Of 1502 women studied, pre-pregnancy body mass index (BMI) categories were: normal (39.6%), overweight (28.5%) and obese (31.9%). The mean (±standard deviation ) weight gain (lbs) for these groups was: 27.6±10.9, 24.2±13.0 and 18.8±16.3 (P<0.0001), whereas the occurrence of macrosomia was 7.4, 11.4 and 19.0%, respectively. Women with an obese BMI were twice as likely to have a macrosomic infant compared with women in the normal BMI group (odds ratio, OR 2.0; 95% CI 1.4–3.0; P=0.0005). Independently, women who exceeded the IOM guidelines were three times more likely to have a macrosomic infant (OR 3.0, 95% CI 2.2–4.2, P<0.0001).Conclusion:Maternal pre-pregnancy weight and weight gain during pregnancy appear to be significant and independent risk factors for macrosomia in women with GDM.