The effect of maternal oxygen inhalation upon fetal oxygenation.

In eight sheep, uterine and umbilical blood flows and oxygen uptakes, the transplacental flow-limited clearance of an inert molecule, pH values, and oxygen pressures, saturations, and capacities in the main placental vessels have been measured during maternal air breathing and oxygen inhalation. The mean +/-SEM percentage changes during oxygen inhalation were +4.6 +/-8.4 for the umbilical flow, +2.8 +/-8.7 for the uterine flow, and +4.6 +/-6.2 for the clearance. None of these changes are statistically significant. Oxygen uptake rose slightly in two cases and remained unchanged in the others. In all cases the oxygen pressures, saturations, and contents rose significantly in the uterine and umbilical vessels with oxygen inhalation.

Results of treatment of severe fetal hydrothorax with bilateral pleuroamniotic catheters.

Unusual antenatal treatment of a case of severe fetal hydrothorax with secondary polyhydramnios and preterm labor is presented and illustrated. Bilateral pleural drainage catheters were placed antenatally to decompress the fetal chest in an effort to prolong pregnancy because of immature pulmonary studies and poor prognosis. Catheter migration occurred and effective drainage ceased after three days, but with tocolysis and bilateral thoracentesis, delivery was delayed another 48 hours to allow steroid therapy. With ventilatory therapy and chest drainage the infant survived and is doing well at one year of age.

Birth-weight-for-gestational-age patterns by race, sex, and parity in the United States population.

OBJECTIVES: To describe birth-weight-for-gestational-age patterns by race, sex, and parity in the United States population, and to discuss the measurements of gestational age by different methods, the pitfalls of each method, and the potential effects of the errors on birth-weight-for-gestational-age curves. METHODS: We used the computerized certificates of live births from the entire population in 1989, consisting of more than four million infants born to residents of the United States. Gestational age was based on the date of the last menstrual period (LMP) modified by the clinical estimate in those situations in which normal distribution of birth weight does not apply. Birth weights for the tenth, 25th, 50th, 75th, and 90th percentiles were calculated by each gestational age and by race, sex, and parity. RESULTS: Eight sets of smoothed birth-weight-for-gestational-age curves were created for black-white, male-female, and primipara-multipara comparisons in sequence. Compared with previous major curves, our curves were closer to those in which the gestational age was derived from the LMP. There were marked differences observed between our curves and those in which the gestational age was based on ultrasound estimation. CONCLUSION: In the measurement of gestational age, the LMP may produce misclassification of gestational age, thereby elevating birth weight percentiles in preterm births and lowering birth weight percentiles in postterm births. However, ultrasound estimation is likely to create a differential misclassification of gestational age, which exerts the opposite effect of lowering birth weight percentiles early in gestation and increasing the percentiles late in gestation.

Amniotic fluid embolus-like syndrome presenting in the second trimester of pregnancy.

Two cases of sudden cardiopulmonary embarrassment and profound disseminated intravascular coagulation occurring in the second trimester of pregnancy are described and a third from the literature is reviewed. All 3 pregnancies were complicated by persistent uterine bleeding. With supportive care, all mothers survived with rapid and spontaneous resolution of the clotting abnormalities. It is speculated that the pathophysiology of this event involves an amniotic fluid embolus. At this time no specific recommendations for prevention or treatment can be made. Vigorous support of the mother appears to offer the best chance for a successful outcome.

Fetal versus maternal rights: medical and legal perspectives.

This report deals with a patient's refusal to undergo cesarean section, which was recommended when fetal distress occurred in labor. Faced with this conflict of maternal and fetal rights, the physicians, administrators, and attorneys of the hospital requested a hearing and decision on the issue by the juvenile court. As a result cesarean section was performed as ordered by the court to safeguard the life of the unborn infant in spite of the objections of the mother. This case, in part, illustrates the need for the administrative capability to deal with such a situation even on an emergency basis, and a possible solution when this situation arises.

Management of acute and subacute puerperal inversion of the uterus.

Eighteen cases of acute and subacute puerperal inversion were studied to identify important predisposing factors and to assess management and postpartum morbidity. The study patients did not differ from case-matched controls in age, parity, duration of labor, type of delivery, or management of the third stage. The most common signs noted were hemorrhage (94%) and shock (39%). All inversions were recognized immediately and manually replaced within 60 minutes. Shock was treated prior to repositioning in all cases. Calculated blood loss averaged 1775 ml. There was no mortality nor febrile morbidity. The average hospital stay of the study patients and their case-matched controls was 3 days. Immediate recognition of uterine inversion and prompt initiation of therapy will ensure a normal postpartum course.

Efficacy of external cephalic version: a review.

OBJECTIVE: To assess the efficacy of external cephalic version, including safety, cost-benefit analysis, and impact on the cesarean delivery rate. DATA SOURCES: A MEDLINE search was conducted to identify all articles published in English between 1980-1991 on external cephalic version. References were also cross-checked for all reports. METHODS OF STUDY SELECTION: We reviewed only those articles providing sufficiently detailed data to determine actual numbers of subjects. In cases of duplicate results, only the latest publication was used. Rates of successful version, cesarean delivery, and fetal and maternal complications were presented. DATA EXTRACTION AND SYNTHESIS: Among the United States trials, the success rate was approximately 65% (range 48-77%), and once version succeeded, almost all the fetuses stayed in the vertex position until birth. Among those in whom external version was performed, the mean cesarean delivery rate was 37%, compared with 83% in controls (P < .001). External version would also save 12.3% of the costs of delivering breech patients overall. CONCLUSION: External cephalic version is safe and cost-effective. It substantially reduces the cesarean delivery rate among breech presentations, decreases the risk related to breech delivery, and avoids cesarean delivery in subsequent pregnancies. However, external version will not have a major impact on the high overall cesarean birth rate.

Pulse oximetry: a review of the theory, accuracy, and clinical applications.

Pulse oximetry has emerged as a clinical tool in anesthesia and newborn monitoring within the last 7 years as a result of recent technological and theoretical advances. Oximeters measure the different absorption spectra of oxygenated and deoxygenated hemoglobin. Electronic measures of oxygenation at the peak of the pulse allow computation and display of oxygen saturation of the arterial blood almost instantly. Correlation coefficients between pulse oximetry and direct blood oxygen saturation measurement range from 0.77-0.99 when oxygen saturation is greater than 60%. The method is noninvasive (a clip or tape on a finger), simple to operate, and adaptable to various patient populations. Pulse oximetry monitors continuously and instantaneously, is responsive to change, and is accurate. Factors adversely affecting the accuracy of pulse oximeter output include transducer movement, peripheral vasoconstriction, a nonpulsating vascular bed, hypotension, anemia, changes in systemic vascular resistance, hypothermia, presence of intravascular dyes, and nail polish. Pulse oximetry has been used to monitor oxygen saturation intraoperatively in the adult and neonatal intensive care units and to monitor pregnant patients and their infants at delivery. Once the advantages and limitations of pulse oximetry are recognized, this monitoring technique can play an important role in the care of patients with cardiovascular and respiratory compromise.

Plasmapheresis during pregnancy.

Plasmapheresis, a process in which blood is withdrawn, the plasma removed, and the red cells reinfused after resuspension in a replacement solution, has been used for a variety of conditions during pregnancy, but is most useful in the treatment of pregnancy complicated by thrombotic thrombocytopenic purpura or persistent postpartum microangiopathic hemolytic disorders. A low risk of morbidity and fatalities associated with plasmapheresis has been reported, but the incidence of these complications does not seem to be affected by pregnancy.

Assessment of perineal floor function: electromyography with acrylic plug surface electrodes in nulliparous women.

A new technique using acrylic plug surface electrodes was employed to record electromyographic activity in the musculature surrounding the rectum and vagina. Forty-one asymptomatic nulliparous women were tested. The group had a wide range of normal values. When eight women were chosen at random for a second testing session, intra-class correlation coefficients to compare readings between the two sessions ranged from 0.76-0.97, indicating adequate reliability. No demographic factor correlated with the voltage generated in these women.

The Mueller-Hillis maneuver: can it be used to predict dystocia?

OBJECTIVE: To assess prospectively the utility of intrapartum Mueller-Hillis maneuvers in predicting labor abnormalities. METHODS: Patients underwent Mueller-Hillis maneuvers upon admission in active labor. Outcomes of each labor were assessed, and correlations were sought between the degree of descent and outcome. Labor curves were constructed for each patient, and labor abnormalities were described by an observer blinded to descent and outcome. The relationship of labor abnormality to outcome also was evaluated. RESULTS: One hundred six patients had Mueller-Hillis maneuvers performed. The distribution of results was as follows: no descent (N = 25) 23.6% one station (N = 33) 31.1%, two stations (N = 46) 43.4%, and three stations (N = 2) 1.9%. Lack of descent failed to indicate increased risk of abdominal delivery, operative vaginal delivery, need for oxytocin augmentation, prolonged second stage, or labor curve abnormality. Analysis of parity (nulliparous versus multiparous) did not alter these findings. CONCLUSION: We present normative data for the results of Mueller-Hillis maneuvers performed in active labor. To our knowledge, no such data exist. We also failed to find a relationship between dystocia and descent with the maneuver. Until this test is demonstrated to be useful, it should not be used to predict dystocia.

Does midline episiotomy increase the risk of third- and fourth-degree lacerations in operative vaginal deliveries?

OBJECTIVE: To explore the association between midline episiotomy and the risk of third- and fourth-degree lacerations during operative vaginal delivery with either vacuum extractor or forceps. METHODS: This retrospective cohort study analyzed all operative vaginal deliveries at a university hospital in 1989 and 1990. Univariate analysis of the relationships between perineal lacerations and obstetric variables was performed. Stratified analysis using the relevant variables was used to calculate relative risk (RR) estimates. RESULTS: Episiotomy, birth weight, and whether the index birth was the first vaginal birth were associated with third- and fourth-degree perineal lacerations. Stratified analysis demonstrated an RR of 2.4 with a 95% confidence interval of 1.7-3.5 for rectal injury with episiotomy, adjusting for parity and birth weight. CONCLUSION: Midline episiotomy is associated with an increased risk of third- and fourth-degree perineal lacerations in operative vaginal deliveries.

Selected use of midline episiotomy: effect on perineal trauma.

A prospective, nonrandomized controlled study was performed to determine the effect of using midline episiotomy only for mothers who experienced fetal distress and/or operative vaginal delivery. Such a policy resulted in a significant decline in third- and fourth-degree lacerations in nulliparous women. This reduction was most pronounced in nulliparous women delivering infants larger than 3400 g. No third- or fourth-degree laceration occurred without antecedent episiotomy in any woman. A policy of using episiotomy selectively appears to lower the incidence of perineal trauma.

Echogenic venous turbulence is a critical feature of successful intravascular intrauterine transfusion.

Late during the fifth intravascular intrauterine transfusion of a fetus with severe Rh isoimmunization, the loss of visible echogenic turbulence within the umbilical vein during injection preceded the development of unresolving fetal bradycardia. An umbilical cord hematoma was found at the time of emergency cesarean delivery. Although seldom described, echogenic turbulence is an important feature of the successful intravascular intrauterine transfusion, and deserves close surveillance. Disappearance of this visible turbulence suggests loss of proper needle location. Possible sources of needle tip displacement are discussed and preventive measures described.

Catecholamine levels in pregnant physicians and nurses: a pilot study of stress and pregnancy.

As a pilot study of occupational stress and pregnancy, we measured urinary catecholamine excretion in ten pregnant physicians and three intensive care nurses between 26-37 weeks' gestation, once during a work day and again during a non-work day. Urinary catecholamines were increased by 58% (P less than .03) during work periods compared with non-work periods. Catecholamine levels were also increased by 64% (P less than .025) over those of a working non-physician control group of similar gestational age. Urinary catecholamine levels are a direct reflection of plasma catecholamine levels. Catecholamine levels are known to increase with physical stress, such as standing, and with mental stress, such as difficult problem-solving. Catecholamines are also known to decrease uterine blood flow. Measurement of catecholamines may be a helpful marker in investigating the relationship between occupation and pregnancy outcome.

Twin delivery and neonatal and infant mortality: a population-based study.

OBJECTIVE: To examine the effect of mode of delivery on twin survival, especially among very premature twin births, in a population-based historical cohort study. METHODS: A total of 4428 pairs of live-born twins, birth weight 500 g or greater, were included based on data from vital records of the entire state of North Carolina for the period 1988-1991. The main outcome measures were Apgar score at 5 minutes (less than 7 versus 7 or greater), neonatal death, and infant death. RESULTS: After controlling for birth weight, twin order, fetal presentation, ethnicity, maternal age, marital status, and adequacy of prenatal care, we found that cesarean delivery was associated with reduced risks (by 50-60%) of low 5-minute Apgar score and neonatal and infant deaths among infants born weighing 500-749 g (P < .05). The cesarean delivery benefited the second twins more than the first twins. Among infants weighing more than 1000 g, the mode of delivery was not associated with either low Apgar score or neonatal and infant mortality. CONCLUSION: Our study suggests that cesarean delivery for twins with estimated fetal weights less than 1000 g together with a more liberal use of vaginal delivery for twins with estimated fetal weights more than 1000 g would have a net effect of increasing perinatal survival while lowering the overall cesarean delivery rate.

Team nursing coverage of prenatal-intrapartum patients at a university hospital. An innovation in obstetric nursing.

A unique approach in utilization of nursing personnel was instituted at the University of Colorado Medical Center to alleviate the following patient care problems: 1) lack of continuity of care of obstetric patients, 2) inadequate prenatal instruction, and 3) the unpredictability of patient census in the labor and delivery area. Half the nurses from the labor and delivery area were organized into four teams of two nurses each who acquired a case load of patients for antepartum care. When a patient was admitted to the hostpial in labor, the nurse from her team who was on call came in and provided all nursing care during the intrapartum period. The problems and benefits of this new approach to nursing care are discussed.

Antepartum and intrapartum events in women exposed in utero to diethylstilbestrol.

Using a retrospective cohort design, we analyzed the effects of intrauterine diethylstilbestrol (DES) exposure on various antepartum and intrapartum events. Gravidas exposed to DES had a higher likelihood of being delivered abdominally, undergoing manual removal of the placenta, and hemorrhaging in the postpartum period. The increased risk for these events remained after controlling for age, race, and parity. We also constructed labor curves in DES-exposed women by plotting cervical dilation against time. The curves were similar for nulliparous DES-exposed women and nulliparous controls, but DES-exposed parous women experienced prolonged labors. These findings suggest that, in addition to the well-known adverse effects of intrauterine DES exposure, the interaction between the uterus and placenta is altered in some DES-exposed patients.

Prenatal detection of intraamniotic bands: implications and management.

The prenatal diagnosis of intraamniotic bands with confirmation at delivery is presented, and the pertinent literature is reviewed. The significance of intrauterine membranes or bands detected during pregnancy is not known. Direct fetal involvement by these structures has been reported in only one instance, but malformations apparently unrelated to amniotic bands have been common among reported cases. Serial ultrasound examinations are recommended both to exclude pseudosac, extrachorionic hemorrhage, blighted twin, and other possible causes of membranous structures and to search for fetal abnormalities.