"Doing something" about the cesarean delivery rate.

There is a general consensus that the cesarean delivery rate in the United States is too high, and that practice patterns of obstetricians are largely to blame for this situation. In reality, the US cesarean delivery rate is the result of 3 forces largely beyond the control of the practicing clinician: patient expectations and misconceptions regarding the safety of labor, the medical-legal system, and limitations in technology. Efforts to "do something" about the cesarean delivery rate by promulgating practice directives that are marginally evidence-based or influenced by social pressures are both ineffective and potentially harmful. We examine both the recent American Congress of Obstetricians and Gynecologists (ACOG)/Society for Maternal-Fetal Medicine Care Consensus Statement "Safe Prevention of Primary Cesarean Delivery" document and the various iterations of the ACOG guidelines for vaginal birth after cesarean delivery in this context. Adherence to arbitrary time limits for active phase or second-stage arrest without incorporating other clinical factors into the decision-making process is unwise. In a similar manner, ever-changing practice standards for vaginal birth after cesarean driven by factors other than changing data are unlikely to be effective in lowering the cesarean delivery rate. Whether too high or too low, the current US cesarean delivery rate is the expected result of the unique demographic, geographic, and social forces driving it and is unlikely to change significantly given the limitations of current technology to otherwise satisfy the demands of these forces.

Fetal heart rate patterns at 20 to 24 weeks gestation as recorded by fetal electrocardiography.

INTRODUCTION: With advancing technology it has become possible to accurately record and assess fetal heart rate (FHR) patterns from gestations as early as 20 weeks. The aim of our study was to describe early patterns of FHR, as recorded by transabdominal fetal electrocardiogram according to the Dawes-Redman criteria. Accordingly, short-term variability, basal heart rate, accelerations and decelerations were quantified at 20-24 weeks gestation among women with uncomplicated pregnancies. METHODS: This study was conducted in a subset of participants enrolled in a large prospective pregnancy cohort study. Our final data set consisted of 281 recordings of women with good perinatal outcomes who had undergone fetal electrocardiographic assessment as part of the Safe Passage Study. RESULTS: The success rate of the recordings was 95.4%. The mean frequency of small and large accelerations was 0.5 and 0.1 per 10 min, respectively and that of small and large decelerations 0.3 and 0.008 per 10 min, respectively. The mean and basal heart rates were both equal to 148.0 bpm at a median gestation of 161 days. The mean short term variation was 6.2 (SD 1.4) ms and mean minute range 35.1 (SD 7.1) ms. CONCLUSION: The 20-24-week fetus demonstrates FHR patterns with more accelerations and decelerations, as well as higher baseline variability than was anticipated. Information from this study provides an important foundation for further, more detailed, studies of early FHR patterns.

Reconsidering the switch from low-molecular-weight heparin to unfractionated heparin during pregnancy.

Venous thromboembolic disease accounts for 9% of all maternal deaths in the United States. In patients at risk for thrombosis, common practice is to start prophylactic doses of low-molecular-weight heparin and transition to unfractionated heparin during the third trimester, with the perception that administration of neuraxial anesthesia will be safer while on unfractionated heparin, as spinal/epidural hematomas have been associated with recent use of low-molecular-weight heparin. In patients receiving prophylactic doses of unfractionated heparin, neuraxial anesthesia may be placed, provided the dose used is 5,000 units twice a day. The American Society of Regional Anesthesia and Pain Medicine guidelines recognize that the safety of neuraxial anesthesia in patients receiving more than 10,000 units per day or more than 2 doses per day is unknown, limiting the theoretical benefit of unfractionated heparin at doses higher than 5,000 units twice a day.

Fetal sex-related dysregulation in testosterone production and their receptor expression in the human placenta with preeclampsia.

OBJECTIVE: To determine the effects of fetal sex on aromatase and androgen receptor (AR) expression in the placenta of normal and preeclamptic pregnancies. STUDY DESIGN: Placentae from preeclamptic (five female and six male fetuses) and healthy pregnancies (seven female and seven male fetuses) were examined by immunofluorescence, western blotting and quantitative reverse transcriptase PCR. RESULT: Placental AR levels were significantly higher (P<0.05) in placentae of both male and female fetuses compared with their respective sexes in normal pregnancies. The placental aromatase levels varied depending on fetal sex. If the fetus was female, aromatase levels were substantially higher (P<0.05) in preeclamptic than in normal placentae. If the fetus was male, the aromatase levels were significantly lower (P<0.05) in preeclamptic than in normal placentae. Placental aromatase levels were significantly higher (P<0.05) in male- than in female-bearing normal placentae. CONCLUSION: Dysregulation in androgen production and signaling in preeclamptic placentae may contribute to placental abnormalities, increasing the frequency of maternal-fetal complications associated with preeclampsia.

Defining cerebral palsy: pathogenesis, pathophysiology and new intervention.

Cerebral palsy (CP) affects 2/1 000 live-born children. There are several antenatal factors, including preterm delivery, low birth weight, infection/inflammation, multiple gestations, and other pregnancy complications, that have been associated with CP in both the preterm and term infant, with birth asphyxia playing a minor role. Due to the increasing survival of the very preterm and very low birth weight infant secondary to improvements in neonatal and obstetric care, the incidence of CP may be increasing. The topics of neonatal encephalopathy and CP, as well as hypoxic-ischemic encephalopathy, are of vital importance to anyone who ventures to deliver infants. Criteria sufficient to define an acute intrapartum hypoxic event as sufficient to cause CP have been advanced previously by both the American College of Obstetricians and Gynecologists and the International Cerebral Palsy Task Force. This review will cover the progression toward defining the pathogenesis and pathophysiology of cerebral palsy. Four essential criteria were advanced as prerequisites if one is to propose that an intrapartum hypoxic-ischemic insult has caused a moderate to severe neonatal encephalopathy that subsequently results in CP. Importantly, all four criteria must be met: 1) evidence of metabolic acidosis (pH <7.0 and base deficit of 12 mmol/L or more); 2) early onset of severe or moderate neonatal encephalopathy in infants born at 34 or more weeks' gestation; 3) CP of the spastic quadriplegic or dyskinetic type, and 4) exclusion of other identifiable etiologies, such as trauma, coagulation disorders, infectious conditions, or genetic disorders. Other criteria that together suggest intrapartum timing are also discussed. The focus of this paper is to explore antenatal antecedents as etiologies of CP and the impact of obstetric care on the prevention of CP.

Are we optimizing gestational diabetes treatment with glyburide? The pharmacologic basis for better clinical practice.

Glyburide's pharmacokinetics (PK) and pharmacodynamics have not been studied in women with gestational diabetes mellitus (GDM). The objective of this study was to assess steady-state PK of glyburide, as well as insulin sensitivity, beta-cell responsivity, and overall disposition indices after a mixed-meal tolerance test (MMTT) in women with GDM (n = 40), nonpregnant women with type 2 diabetes mellitus (T2DM) (n = 26), and healthy pregnant women (n = 40, MMTT only). At equivalent doses, glyburide plasma concentrations were approximately 50% lower in pregnant women than in nonpregnant subjects. The average umbilical cord/maternal plasma glyburide concentration ratio at the time of delivery was 0.7 +/- 0.4. Insulin sensitivity was approximately fivefold lower in women with GDM as compared with healthy pregnant women. Despite comparable beta-cell responsivity indices, the average beta-cell function corrected for insulin resistance was more than 3.5-fold lower in women with glyburide-treated GDM than in healthy pregnant women. Women with GDM in whom glyburide treatment has failed may benefit from alternative medication or dosage escalation; however, fetal safety should be kept in mind.

Calcitonin gene-related peptide stimulates human villous trophoblast cell differentiation in vitro.

Calcitonin gene-related peptide (CGRP) is a multifunctional peptide present in both maternal and fetal circulations in pregnancy. Its receptors have been identified on human trophoblast cells, but the role of CGRP in trophoblast differentiation remains unknown. This study was designed to determine the effect of CGRP on the differentiation of villous trophoblasts isolated from normal human term placentae. The morphological and functional differentiation of the trophoblast cells were assessed by desmosomal protein immunofluorescent staining and the quantification of hCG, estrogen and progesterone secretion. Results showed that (i) exposure of villous trophoblast cells to CGRP led to a dose-dependent increase in intracellular cyclic adenosine monophosphate (cAMP) accumulation; (ii) immunofluorescent staining with antidesmosomal antibody was identified at the boundaries between aggregated cytotrophoblast cells, and these stainings disappeared when cells fused to form syncytiotrophoblast cells; (iii) the formation of multinucleated syncytiums in primary cultured cytotrophoblasts was stimulated by CGRP as evidenced by the changes in antidesmosomal staining; (iv) CGRP increases trophoblast hCG secretion in a time- and dose-dependent manner, and this secretion was blocked by CGRP antagonist, CGRP(8-37), and (v) both 17beta-estradiol (E(2)) and progesterone concentrations in the culture medium were increased by CGRP, and these increases were dose dependent. These observations suggest that CGRP may be involved in the morphological and functional differentiation of trophoblast cells, and these actions might be attributed to CGRP-induced intracellular cAMP accumulation.

Contrast sonography, video densitometry and intervillous blood flow: a pilot project.

PURPOSE: To examine the feasibility of constructing time-intensity (TI) curves from the intervillous space with an intravascular ultrasound contrast agent and computer assisted video densitometry. STUDY DESIGN: We sedated nine pregnant baboons, optimized the grey scale and color Doppler images of their placentas, and then fixed the transducers in place. For each injection of contrast, we recorded images on videotape without changing the ultrasound image processing functions. Video images were captured using a Macintosh personal computer equipped with a video-capture board using image analysis software (Image 1.4, W Rasband, NIH). For each injection, we sampled digitized images of a fixed region of interest at regular intervals. After computing the mean video density of each image, we used the sampling frequency to construct TI curves depicting any change over time as the contrast agents washed into and out of the intervillous space. RESULTS: Three of four agents tested produced changes in the video density of the placenta. TI curves were established using both grey scale and color Doppler signal augmentation. As expected, intra-arterial agents produced rapid accumulation and decay. Intravenous agents produced more protracted effects secondary to bolus dilution and transit through the right heart and pulmonary vascular bed. CONCLUSION: TI curves may be generated from the intervillous space with the use of a transpulmonary ultrasound contrast agent and video densitometry. If validated by further study, this may allow investigators to apply ultrasound and indicator-dilution theory to intervillous blood flow.

Stillbirth in obstetric practice: report of survey findings.

OBJECTIVE: Stillbirth affects a large portion of the population and results in mortality rates comparable to those of preterm delivery and sudden infant death syndrome combined. Despite the large burden, little information is available to offer patients regarding etiology, treatment or prevention for a subsequent pregnancy. METHODS: We surveyed a sample of Fellows of the American College of Obstetricians and Gynecologists to determine the practice patterns in the management of stillbirth. RESULTS: The majority of Fellows agreed on the definition of stillbirth; however, their approach to treatment and prevention varied. A majority of Fellows believed that research on understanding stillbirth was of national importance. CONCLUSIONS: A comprehensive educational effort to include current knowledge regarding causes and management, standardized diagnostic procedures, death registration and case review is recommended to improve obstetric care of those with a stillbirth.

Postpartum hemorrhagic shock resulting in thrombotic thrombocytopenic purpura-hemolytic uremic syndrome.

Thrombotic microangiopathies may be initiated by a number of antecedent events. When presented with postpartum hemorrhage and unexplained thrombocytopenia, it is prudent to consider microangiopathic hemolytic anemia in the differential diagnosis. A 25-year-old woman, gravida 2, para 1, had an uncomplicated repeat Cesarean delivery at 38 weeks' gestation. She subsequently had an exploratory laparotomy for hemoperitoneum resulting from a left uterine artery laceration. On postoperative day 3, she developed thrombotic chrombocytopenic purpura-hemolytic uremic syndrome and was treated with plasma exchange therapy and dialysis. It is critical that clinicians consider this potentially fatal disease in the differential diagnosis when hemorrhagic shock is associated with unexplained thrombocytopenia, so that appropriate and early treatment may lead to a favorable outcome.

Effects of L-type Ca(2+)-channel blockade, K(+)(ATP)-channel opening and nitric oxide on human uterine contractility in relation to gestational age and labour.

Relative uterine inactivity during pregnancy changes to vigorous rhythmic contractility during labour. We hypothesized that mechanisms involved in the regulation of uterine quiescence and contractility differ between term and preterm myometrium and in labour and non-labour states. Myometrial strips, prepared from biopsies taken at Caesarean section from labouring and non-labouring women preterm and at term, were mounted in organ chambers for isometric tension recording. Oxytocin (10(-9) mol/l) was added to maintain stable contractions, and effects of various inhibitors of uterine contractility were studied. The inhibitory effects of L-type Ca(2+)-channel blocker nifedipine and ATP-sensitive K(+)-channel opener pinacidil were greater in myometrium from the non-labour versus the labour group, both preterm and at term. In addition, pinacidil's effect was greater at term compared with preterm in the non-labour group. Mg(2+) and the nitric oxide donor sodium nitroprusside significantly inhibited contractility in all groups without significant differences with regard to labour or gestational age. Decreased inhibition of human uterine contractility by L-type Ca(2+)-channel blockers and K(+)(ATP)-channel openers in preterm and term labour may reflect changes in expression and activity of these channels. Effects of nitric oxide and Mg(2+) are not affected by gestational age or labour.

Cardiac disease and pregnancy.

The pregnant state imposes a supraphysiologic strain on the pregnant woman's cardiac performance through complex biochemical, electric, and physiologic changes affecting the blood volume, myocardial contractility, and resistance of the vascular bed. In the presence of underlying heart disease, these changes can compromise the woman's hemodynamic balance, her life, and that of her unborn child. Cardiac pathology represents a heterogeneous group of disorders, each with its own hemodynamic, genetic, obstetric, and social implications. Physicians caring for these women should actively address the issue of reproduction. Ideally, pregnancy should be planned to occur after optimization of cardiac performance by medical or surgical means. Once pregnancy is achieved, the concerted effort of a multidisciplinary team of obstetricians, cardiologists, anesthesiologists, nursing, social, and other services provides the best opportunity to carry the pregnancy to a successful outcome.

Teaching the Laufe-Piper forceps technique at cesarean delivery.

OBJECTIVE: To present a method of teaching forceps technique during cesarean delivery of breech-presenting infants using Laufe-Piper forceps and to evaluate its usefulness. STUDY DESIGN: For several years, residents at the University of Texas Medical Branch, Galveston, have learned and practiced Piper forceps technique during cesarean delivery. To assess their experience with this method, we mailed questionnaires to third- and fourth-year residents and recent graduates of the Galveston program. The same surveys were mailed to a control group of residents and recent graduates of two other programs where this teaching exercise is not practiced routinely. RESULTS: Responses were received from 32 (74%) study subjects and 63 (71%) controls. Demographic characteristics and experience with vaginal breech delivery were similar between the two groups. Respondents from the Galveston program noted greater annual use of forceps for vaginal delivery of cephalic-presenting infants (P = .012). They also rated themselves as more comfortable (P = .023) and more skilled (P = .006) with Piper forceps than controls. Of 53 respondents who had had previous experience with this teaching method, 47 noted that it provided a great or moderate educational benefit, and 36 strongly or moderately believed it gave them more confidence in using Piper forceps during vaginal breech delivery. Using multiple regression analysis, sex, overall level of experience, Piper forceps experience during vaginal delivery and overall forceps use were stronger determinants of self-rated comfort and skill than was experience with Laufe-Piper forceps during cesarean. CONCLUSION: Laufe-Piper forceps can be used for cesarean delivery of breech-presenting infants. This practice promotes confidence and skill for their use at vaginal delivery.

Prospective study of IgM to Toxoplasma gondii on Beckman Coulter's Access(TM) immunoassay system and comparison with Zeus ELISA and gull IFA assays.

We compared a new assay for Toxoplasma IgM on the Access analyzer (Beckman Coulter, Inc., Chaska, MN, USA), a random access instrument based on the principle of paramagnetic particle enzyme immunoassay with an enzyme-linked immunosorbent assay (ELISA) (Zeus Scientific, Inc., Raritan, NJ, USA) and an immunofluorescent assay (IFA) (Gull Laboratories, Inc., Salt Lake City, UT, USA). Four hundred fresh, unfrozen clinical samples from pregnant women (n = 154), HIV positive patients (n = 41), and patients in whom infection with Toxoplasma gondii was suspected (n = 200) were collected and assayed over a three month period. The specificity of the Access assay was compared to the consensus results. Results that were discrepant between the ELISA and IFA were resolved using a third IFA (Zeus). Once resolved, the specificity for the Access assay, the Zeus ELISA and the Gull IFA were 99.22%, 97.91%, and 99.45%, respectively. We conclude that the Access assay specificity is comparable to consensus results, minimizing false positive results; and because it is a random access instrument, it may be preferable over batch methods.

Embryonic hemoglobins are expressed in definitive cells.

Human embryonic zeta and epsilon globin chains are synthesized in yolk sac-derived primitive erythroid cells, and decrease rapidly during definitive erythropoiesis. Examination of zeta and epsilon globin expression at the cellular level using dual-color immunofluorescence staining with specific monoclonal antibodies showed that embryonic globin proteins are present in definitive erythroid cells. More than half of fetal erythrocytes were positive for zeta and approximately 5% for epsilon globin. Approximately one third of newborn red blood cells were zeta-positive and less than 1% epsilon-positive. Adult erythrocytes did not have embryonic globins. Erythroblasts that developed in liquid cultures also contained embryonic globin in amounts which declined with ontogenic age, and the proportion of positive cells in vitro was less than in the comparable erythrocytes that developed in vivo. Thus, embryonic globin chains are synthesized in definitive erythroid cells and decrease with ontogeny. Modulation of embryonic globin gene expression is not solely due to a switch from primitive to definitive erythropoiesis.

Forceps and vacuum delivery: expectations of residency and fellowship training program directors.

The objective of this study is to compare current forceps training practices in North American obstetrical residency training programs with that in maternal-fetal medicine fellowship programs. We sent a survey to all obstetrics and gynecology residency training programs and to all maternal-fetal medicine fellowship programs in North America. After sending out 354 questionnaires, 219 were returned for a response rate of 62%. The response rate for fellowship programs (52 of 59; 88%) was significantly greater than that of residency training programs (167 of 295; 56.6%) (p < 0.05). All fellowship training programs were using the 1988 ACOG forceps classification system, as were 98% of the residency training programs. Eighty-five percent of fellowship directors and 80% of residency directors felt the same system should be used for vacuum deliveries. All residency and fellowship directors expected proficiency with both instruments for outlet deliveries. For low deliveries requiring < or =45 degrees of rotation, at least 92% expected proficiency with both instruments. For low-forceps deliveries with >45 degrees of rotation, 82% of fellowship directors and 80% of residency directors expected proficiency. For low-vacuum deliveries with >45 degrees of rotation, 80% of fellowship directors and 76% of residency directors expected proficiency. Significantly more fellowship directors expected midforceps proficiency (47%) than did residency program directors (38%) (p < 0.05). Midvacuum proficiency was expected by 73% of fellowship directors and 69% of residency directors. The ACOG 1988 forceps classification system has now achieved wide acceptance and is taught by both residency and fellowship program directors. Most program directors favor using the same classification system for vacuum extraction deliveries. In general, the expectations of the residency program directors mirror those of maternal-fetal medicine fellowship directors. While outlet and low operations with < or =45 degrees of rotation are taught and proficiency is expected, most programs no longer expect proficiency in midforceps delivery, but do expect proficiency in midvacuum delivery. Proficiency in low operations with rotations < or =45 degrees is still expected.

Electronic fetal monitoring. Are we meeting documentation standards?

OBJECTIVE: To test whether fetal heart rate documentation requirements for high-risk pregnancies are too stringent to achieve compliance, especially during the second stage of labor. STUDY DESIGN: Random retrospective chart and monitor strip review of deliveries occurring one year earlier were reviewed. Thirty-four low-risk and 34 high-risk pregnancies were selected and assessed for compliance with nationally accepted documentation guidelines. RESULTS: All monitor strips and charts were successfully retrieved from medical records. Charted documentation of the strips met national requirements in the active phase of the first stage of labor in 97% of cases, as did documentation during the second stage. For high-risk pregnancies, compliance during the active phase of the first stage of labor was 65% as compared to 35% in the second stage. All infants had normal five-minute Apgar scores, and none had umbilical arterial acidemia. CONCLUSION: Given current resources, we cannot reliably meet established documentation standards for high-risk pregnancies. Such overly stringent documentation standards pose a significant risk in cases going to litigation. A standard should be developed that is based on outcome data.

Maternal oxygen transport variables during the third trimester of normal pregnancy.

OBJECTIVE: The aim of this study was to measure and calculate oxygen transport variables in uncomplicated term pregnancies. STUDY DESIGN: Ten normotensive primiparous women between 36 and 38 weeks' gestation underwent pulmonary and radial arterial catheterization as part of a larger study. Seven women had studies repeated at approximately 12 weeks post partum. Measurements were made with patients in the left lateral recumbent position after a 30-minute stabilization period. Cardiac output was measured with the thermodilution technique. Blood samples were obtained simultaneously from the pulmonary and radial arteries and analyzed in duplicate for oxygen content with a blood gas analyzer. RESULTS: The oxygen contents of both arterial and mixed venous blood are significantly lower (P <.05) in the third trimester of pregnancy (15.96 and 11.97 mL/dL, respectively) than in the postpartum period (18.00 and 13.54 mL/dL). The fall in oxygen content during pregnancy prevents any significant increase in oxygen delivery in the third trimester (867. 59 mL/min) relative to the postpartum period (806.50 mL/min, P not significant). CONCLUSION: This is the first report of directly measured oxygen transport variables in healthy pregnant women.

The effect of amniotic fluid on the human omental artery in vitro.

OBJECTIVE: The aim of the study was to determine the effect of amniotic fluid on the in vitro contractility of the human omental artery. STUDY DESIGN: Amniotic fluid and a segment of omentum were obtained from each of 5 patients at the time of planned cesarean delivery at normal term gestation for the indication of previous cesarean delivery. The omental artery was cleaned and cut into 3-mm rings, which were placed in 10-mL organ chambers for isometric tension recording. The chambers were filled with Krebs-Henseleit solution bubbled with 5% carbon dioxide in air and maintained at 37 C, pH 7.4. The rings were then equilibrated at 1 g passive tension for 90 minutes. The amniotic fluid was centrifuged for 10 minutes at 3000 rpm to remove all debris. Increasing volumes of supernatant (10-2000 microL) were added to the omental artery rings at baseline tone or after contraction with U46619 (10(-7) mol/L) or potassium chloride (60 mmol/L) to detect contractile and relaxant effects, respectively. Time-solvent control preparations were also run in parallel. RESULTS: Amniotic fluid had no effect on the basal tone of omental artery rings. Amniotic fluid had no effect on the tension in rings previously contracted with either U46619 or potassium chloride. CONCLUSIONS: Amniotic fluid has no direct effect on isolated human omental artery. The catastrophic hemodynamic changes associated with the syndrome of amniotic fluid embolism are not due to a direct effect of circulating amniotic fluid on vascular tone but rather may be due to secondary responses

The role of forceps rotation in maternal and neonatal injury.

OBJECTIVE: Our purpose was to assess the impact of forceps rotation on maternal and neonatal injury. STUDY DESIGN: In this retrospective case-controlled study performed at the University of Texas Medical Branch at Galveston all forceps deliveries with a rotation of >/=90 degrees performed between July 1992 and September 1995 were identified (n = 113). For controls 167 forceps deliveries with rotations of /=90 degrees accounted for 0.8% of all deliveries. A major fetal injury, defined as a skull fracture, subdural hematoma, brachial plexus or a sixth or seventh cranial nerve injury, occurred in 10.2% of deliveries with rotations of /=90 degrees. The only permanent injury was a brachial plexus palsy that occurred with a forceps rotation of 45 degrees. Rotations of >/=90 degrees were not associated with umbilical arterial acidemia below 7.0 or 7.1 compared with rotations of /=90 degrees were associated with longer maternal hospital stays (P =.009). Neither lacerations of the birth canal, third- or fourth-degree episiotomies, or fall in the maternal hematocrit correlated with the degree of forceps rotation. CONCLUSIONS: Advanced degrees of forceps rotations do not result in any clinically significant increase in infant or maternal morbidity relative to that encountered with lesser degrees of forceps rotation.