Obstetric Literature Research Articles

The design, execution, and interpretation of genetic association studies to decipher complex diseases

Genetic association studies are becoming increasingly frequent in the obstetric and gynecologic literature and they are considered central to the deciphering of the genetic basis of complex disease. The purpose, design, execution, analysis, and interpretation of genetic association studies in reproduction are discussed. Frequently used terms are defined (eg, genotype, haplotype, polymorphism, single nucleotide polymorphism, linkage disequilibrium). Guidelines are proposed for the evaluation of reports of genetic association studies (including selection of polymorphisms for study, study design, assay characteristics, sample size, multiple testing, and multivariable analysis). The potential value of this type of investigation in elucidating the mechanisms of disease in reproduction is illustrated. (Am J Obstet Gynecol 2002;187:1299-312.)

Vaginal birth after cesarean birth: a national survey of U.S. midwifery practice

Midwives have been providing care for women choosing vaginal birth after cesarean birth (VBAC) for over 20 years. The 1999 American College of Obstetrician Gynecologist (ACOG) guidelines and recent studies questioning the relative safety of VBAC have raised concerns about continuing to offer this option. As part of an effort to understand VBAC care provided by midwives, this study used a national survey sample to examine practices, scope, and recent changes in the provision of VBAC care. The survey, which included demographic and practice items was mailed in late 2000 to a purposeful sample of 325 midwifery practices. The return rate was 62%. Nearly all (94%) of the responding practices were providing VBAC care, and almost half of them (43%) stated that their ability to do so had changed within the past 2 years secondary to recent studies in the obstetric literature, the 1999 ACOG statement, and concerns from third-party payers. Criteria for offering VBAC are stricter, and consent forms are more extensive. Other changes included the need for additional or more intensive support services, in-house anesthesia, and surgery backup. Midwives continue to provide VBAC care, although with some increased restrictions. This study provides background for future research that will determine how midwifery care affects the rate of successful VBACs.

Myomectomy during cesarean section

Obstetricians are often confronted with large fibroids while performing cesarean sections. Pedunculated fibroids can easily be removed and hemostasis secured at that time without endangering the life of the mother. Yet, myomectomy during cesarean section was practically absent from the obstetric literature until the last decade and the current teaching still is to deliver the baby and perform myomectomy later, perhaps before the next pregnancy. When the fibroids are located in the lower segment of the uterus, many obstetricians prefer to choose this classical route. To deliver the baby, however, they are sometimes faced with the emergency decision of either removing fibroids, or incising through them and leaving them behind for a later myomectomy. In a prospective clinical trial conducted between April 2000 and January 2001 at the Korle Bu Teaching Hospital and Family Health Hospital in Accra, Ghana, a myomectomy performed during

Calcium channel blockers as tocolytics

This article reviews the clinical and basic science investigations regarding the safety and efficacy of calcium channel blockers as tocolytic agents. The authors reviewed the English language literature on the pharmacology and clinical applications of calcium antagonists in obstetrics. A MEDLINE (1966-2000) search was performed with the terms "calcium channel blockers," "randomized controlled trial," "preterm labor," "calcium antagonist," "tocolysis," and "nifedipine." References from these data sources were then used to find additional studies. Animal data and clinical trials in humans were included. The safety of these agents was researched in published data from the nonobstetric as well as obstetric literature. The calcium channel blockers most commonly used as tocolytics are nifedipine and nicardipine. These agents act to inhibit calcium influx across cell membranes, thereby decreasing tone in the smooth muscle of the vasculature. They act as profound vasodilatory agents and have minimal effect on the cardiac conduction system. Numerous randomized clinical trials have shown them to be as effective as beta-mimetics and magnesium in achieving tocolysis. When used for tocolysis, calcium antagonists have fewer maternal side effects than other tocolytics and have no adverse effect on fetal outcome.

Labor analgesia for the 21st century

T HE GREATEST ADVANCES in analgesia and anesthesia for labor and childbirth in the 20 th century have been (1) the discovery and development of today's safe and efficacious analgesic techniques; (2) the social acceptance that it is unnecessary for parturients . . . to bring forth children in pain and sorrow; 1 (3) the development of organizations dedicated to teaching and training in this highly specialized field; and (4) the wider availability of obstetric care, including modern analgesia and anesthesia. These events have been less than 150 years in the making and have gone hand-in-hand with a dramatic reduction in maternal mortality in developed countries. Anesthesia is usually accorded its due place in this chronicle, 2 but analgesia is still regarded as an intervention that hampers 'natural childbirth,' prolonging labor and increasing the incidence of operative delivery. Hopefully the weight of evidence now accrued will settle the arguments about a causal relationship between analgesia and mode of delivery) Unfortunately there are still instances of the 'them and us' attitude. A recent report in the obstetric literature is typical of the lack of cooperation and coordinated understanding so necessary for the future. 4 Obstetric analgesia is now as much a part of our (Western) culture as air travel, the mobile phone, and the personal computer. Humankind's conquest of pain should have been achieved, in obstetrics at least. But has it? Sadly, modern, safe, and effective obstetric analgesia is still unavailable to most women worldwide. Moreover, the provision of safe pain relief services is restricted by bureaucratic and political conflict in some of the world's most economically developed societies, such as the

Uterine prolapse associated with bladder exstrophy: Surgical management and subsequent pregnancy

Congenital bladder exstrophy affects 1 in 125,000 to 250,000 females. Consisting of absence of the anterior abdominal wall with exposure of the ureteral orifices, failure of pubic symphysis fusion, and deficient anterior pelvic diaphragm musculature, bladder exstrophy is frequently associated with genital prolapse. Pregnancy may be complicated by recurrent urinary tract infections, preterm labor, mild procidentia, and malpresentation. Due to the rarity of the condition, there is a corresponding scarcity of obstetric literature regarding management during pregnancy. We report the case of a young woman with surgically repaired bladder exstrophy who developed genital prolapse. The uterus was suspended using a sacral colpopexy utilizing a Gore-Tex graft. Subsequently, the patient became pregnant and delivered a healthy male infant at 35 weeks' gestation via cesarean section (without recurrence of the genital prolapse postpartum). Sacral colpopexy to correct genital prolapse associated with bladder exstrophy may preserve fertility in young patients. J. Matern.-Fetal Med. 2000;9:150–152. © 2000 Wiley-Liss, Inc.

Uterine Prolapse Associated with Bladder Exstrophy: Surgical Management and Subsequent Pregnancy

Congenital bladder exstrophy affects 1 in 125,000 to 250,000 females. Consisting of absence of the anterior abdominal wall with exposure of the ureteral orifices, failure of pubic symphysis fusion, and deficient anterior pelvic diaphragm musculature, bladder exstrophy is frequently associated with genital prolapse. Pregnancy may be complicated by recurrent urinary tract infections, preterm labor, mild procidentia, and malpresentation. Due to the rarity of the condition, there is a corresponding scarcity of obstetric literature regarding management during pregnancy. We report the case of a young woman with surgically repaired bladder exstrophy who developed genital prolapse. The uterus was suspended using a sacral colpopexy utilizing a Gore-Tex graft. Subsequently, the patient became pregnant and delivered a healthy male infant at 35 weeks' gestation via cesarean section (without recurrence of the genital prolapse postpartum). Sacral colpopexy to correct genital prolapse associated with bladder exstrophy may preserve fertility in young patients.

Clinical uses of intravenous immunoglobulin in pregnancy.

The obstetric literature contains numerous reports of IVIG therapy for various conditions encountered during pregnancy. The mechanisms of action of IVIG are uncertain and may vary depending on the specific disorder. Immunoglobulin G infusions appear to be well tolerated by the parturient. The occurrence of major and minor side effects is uncommon, and infectious morbidity is low. Further research will be necessary to elucidate the specific mechanisms of action of IVIG in certain disease states. Determining the exact "therapeutic agent" in IVIG for each specific disease state may allow for a more tailored approach to treatment (i.e., isolation or production of the particular antibody). Outcome assessment, long-term positive and negative effects, cost-benefit analysis, and effects on fetal and neonatal immune function require further study through randomized trials.

Logistic Regression Models in Obstetrics and Gynecology Literature

In Brief Objective To evaluate the reporting of multivariable logistic regression analyses and assess variations in quality over time in the obstetrics and gynecology literature. Methods Methodologic criteria for reporting logistic regression analyses were developed to identify problems affecting accuracy, precision, and interpretation of this approach to multivariable statistical analysis. These criteria were applied to 193 articles that reported multivariable logistic regression in the issues of four generic obstetrics and gynecology journals in 1985, 1990, and 1995. Rates of compliance with the methodologic criteria and their time trends were analyzed. Results The proportion of articles using logistic regression analysis increased over time: 1.7% in 1985, 2.8% in 1990, and 6.5% in 1995 (P < .001 for trend). Violations and omissions of methodologic criteria for reporting logistic models were common. The research question, in terms of dependent and independent variables, was not clearly reported in 32.1%. The process of variable selection was inadequately described in 51.8% of the articles. Among articles with ranked independent variables, 85.1% did not report assessment of conformity to linear gradient. Tests for goodness of fit were not given in 93.2% of articles. The contribution of the independent variables could not be evaluated in 36.2% of the articles because of a lack of coding of the variables. Interactions between variables were not assessed in 86.4% of articles. Analysis of variations in the quality of logistic regression analyses over time showed no increase in reporting of the criteria concerning variable selection and goodness of fit. However, the proportion of articles reporting one quality criterion concerning interpretation of the substantive significance of independent variables showed a trend toward improvement: 42.3% in 1985, 73.6% in 1990, and 75.4% in 1995 (P = .004 for trend). Conclusion The reporting of multivariable logistic regression models in the obstetrics and gynecology literature is poor, and the time trends of improvement in quality of reporting are not particularly encouraging. The reporting of multivariable logistic regression analyses in obstetrics and gynecology literature is of poor quality.

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. (Am J Obstet Gynecol 1999;180:1303-7.)

Preeclampsia-associated hepatic hemorrhage and rupture: mode of management related to maternal and perinatal outcome.

This article is a critical review of the obstetric literature concerning preeclampsia-associated hepatic hemorrhage to develop guidelines conducive to optimal maternal and perinatal outcomes. An English literature search was performed for reports of hepatic hemorrhage or hepatic rupture in pregnancy during 1960 to 1997. Data were analyzed by Statmost packages using ANOVA, Chi-square, and Fisher's exact tests. One hundred forty-one patients with hepatic rupture/hemorrhage were reported. The three most common presenting findings were epigastric pain, hypertension, and shock. With rare exception, patients had evidence of preeclampsia. Diagnosis was elusive and most frequently accomplished at laparotomy. When utilized, ultrasound and computed tomography (CT) were helpful diagnostic modalities. Maternal survival was highest in the arterial embolization treatment group. Maternal and perinatal survival improved considerably during the study interval. Route of delivery did not seem to impact survival rates. It was concluded that the application of ultrasound and CT for diagnosis and the use of hepatic artery embolization for treatment of hepatic hemorrhage/rupture seem to be beneficial management options for this rare event.

HELLP AND THE LIVER DISEASES OF PREECLAMPSIA

Hemolysis , abnormal liver function tests , and thrombocytopenia have been recognized as complications of preeclampsia-eclampsia for many years. 8 , 9 , 14 , 26 According to Chesley, 8 some of these components had been reported in the obstetric literature for more than a century (coagulation defects and microthrombi were first described by Schmorl in 1893). In 1982, Weinstein described 29 cases of severe preeclampsia-eclampsia complicated by thrombocytopenia, abnormal peripheral smear, and abnormal liver function tests. 41 He suggested that this collection of signs and symptoms constituted an entity separate from severe preeclampsia and coined the term HELLP syndrome ( H = hemolysis; EL = elevated liver enzymes ; and LP = low platelets). Since then, numerous articles and case reports describing this syndrome have appeared in the literature. In addition, the presence of this syndrome has become a major cause of litigation against obstetricians, involving cases of alleged misdiagnosed preeclampsia, particularly in those patients complicated by severe liver involvement of their disease. This article reviews the diagnosis, hepatic manifestations, and current management recommendations for pregnancies complicated by HELLP syndrome.

SOAP 30th Annual Meeting

SOAP 30th Annual Meeting

Comment on “compromised birth outcomes and infant mortality among racial and ethnic groups”

Frisbie, Forbes, and Pullum (1996) show that it is meaningful to account for low birth weight, preterm delivery, and intrauterine growth-retardation when analyzing differences in compromised birth outcomes and infant mortality among racial and ethnic groups. I compare their findings for the 1987 U.S. birth cohort with findings for the 1988 U.S. birth cohort, using linked birth and infant death vital statistics from the National Center for Health Statistics. I focus on their calculation of fetal growth curves, which are highly at odds with the curves commonly used in the obstetric and pediatric literature. I compare birth outcome distributions and infant death probabilities using Frisbie et al.'s method and other standards. I conclude that Frisbie et al.'s method is not suited for the study of intrauterine growth-retardation at the population level because of the major flaws in gestational age measurement that exist in the type of data they use. An appropriate alternative is to apply a standard of normal intrauterine growth derived from antenatal estimation of fetal weight-for-gestational-age to the vital statistics data.

Acute intentional iron overdose in pregnancy

Background: Although iron is the second most common overdose agent in pregnancy, the obstetric literature does not reflect current management of this emergency. Case: A 27-year-old woman, para 0-3-4-3, at 27 weeks’ gestation ingested 24 mg/kg of elemental iron in a suicide attempt. Therapy with crystalloid hydration, gastric lavage, and intravenous deferoxamine chelation treated the overdose without maternal or fetal complications. Conclusion: Pregnancy should not alter therapy for acute iron overdose. Deferoxamine administered in the third trimester is not associated with perinatal complications and is potentially life saving.

ACUTE INTENTIONAL IRON OVERDOSE IN PREGNANCY

Background Although iron is the second most common overdose agent in pregnancy, the obstetric literature does not reflect current management of this emergency. Case A 27-year-old woman, para 0-3-4-3, at 27 weeks' gestation ingested 24 mg/kg of elemental iron in a suicide attempt. Therapy with crystalloid hydration, gastric lavage, and intravenous deferoxamine chelation treated the overdose without maternal or fetal complications. Conclusion Pregnancy should not alter therapy for acute iron overdose. Deferoxamine administered in the third trimester is not associated with perinatal complications and is potentially life saving.

A Short History of Clinical Midwifery: The Development of Ideas in the Professional Management of Childbirth (review)

Reviewed by: A Short History of Clinical Midwifery: The Development of Ideas in the Professional Management of Childbirth Ronald Elmer Batt Philip Rhodes. A Short History of Clinical Midwifery: The Development of Ideas in the Professional Management of Childbirth. Cheshire, England: Books for Midwives Press, 1995. vii + 200 pp. Ill. £17.95 (paperbound). British emeritus professor and consultant Philip Rhodes wrote this book, in his retirement, for “midwives” and “ordinary men and women” (p. vii). The work comes from the perspective and bias of a clinician, not a professional historian. Though the bibliography consists mainly of secondary sources, this is an “insider’s” history, written by a master physician with intimate knowledge of twentieth-century scientific obstetrical literature. The central theme is progress in the management of difficult labor and the obstetrical complications that for centuries claimed the lives of pregnant women and their babies. There appears to be very little about the actual practice of midwifery, despite the title and the innumerable mentions of midwifery throughout the text. This reviewer automatically substituted obstetrics for the word midwifery during the reading. Perhaps this is the bias of an American clinician, but a more appropriate title might be “A Short History of Clinical Obstetrics.” [End Page 549] Starting in ancient Mesopotamia, the story skims to the seventeenth century in twenty-two pages. The chapters on the seventeenth, eighteenth, and nineteenth centuries read like miniature biographies and annotated bibliographies interspersed with very interesting commentary. Chapters 10, 11, and 12, the second half of the book, deal with the twentieth century. Here the story gains from the personal experience of a master clinician conversant with the clinical problems and with some of the major obstetricians from that era. The strength of the book for graduate students in history would seem to be the authoritative interpretation of practical clinical obstetrics by a knowledgeable British consultant who trained and practiced during the transitional eras: from heroic obstetrics, characterized by spontaneous deliveries, destructive operations on the fetus, and internal podalic version and extraction; to the specialty of obstetrics and gynecology, characterized by low forceps and episiotomy, and the conservative use of cesarean section; to the postmodern era of spontaneous delivery, liberal use of cesarean section, and the subspecialty of fetal and maternal medicine. The work is generally applicable to American obstetrics. Obstetrical residents and nurse midwives trained in the philosophy of normal vaginal delivery and cesarean section, as well as young mothers and fathers with the expectation of normal outcome—healthy mothers and babies—will appreciate reading of the long struggle to achieve the present state of the art. Ronald Elmer Batt State University of New York at Buffalo Copyright © 1997 The Johns Hopkins University Press

The case for trial of labor in the patient with a prior low-segment vertical cesarean incision

OBJECTIVE: Our purpose was to review recent obstetric literature detailing the subsequent delivery experience of patients with a prior low-segment vertical cesarean incision and to derive recommendations for practice on the basis of this information. STUDY DESIGN: Ten studies that included information about pregnancy outcome in patients with prior low-segment vertical cesarean operations were retrieved and reviewed from the American obstetric literature since 1981 and from a review of all abstracts presented annually since 1981 to the Society of Perinatal Obstetricians. RESULTS: Altogether, information about subsequent pregnancy outcome for 382 patients with prior low-segment vertical cesarean delivery was available for analysis. Among the 372 patients with complete patient population information, vaginal delivery was safely accomplished in 306 (82%). Four uterine ruptures (1.05%) have been reported, only one of which occurred after a single prior unextended low-segment vertical cesarean incision. Two ruptures occurred elsewhere on the lateral or posterior aspect of the uterus in subsequent pregnancies, and the fourth rupture occurred at the juncture of prior low vertical and transverse incisions. No perinatal mortality or permanent perinatal morbidity was encountered with these pregnancies. CONCLUSIONS: In the otherwise uncomplicated pregnancy the patient with one previous nonextended low-segment vertical cesarean incision should be considered to have a prior low-segment scar and as such be a candidate for trial of labor in her current singleton pregnancy. The same care, counseling, and caution should be exercised for this patient as for one with a prior low-segment transverse incision.(Am J Obstet Gynecol 1997;177:144-8)

Anesthetic management of a parturient with an incompletely resected cerebral arteriovenous malformation

The anesthetic, neurosurgical, and obstetric literature regarding management of parturients with intracranial arteriovenous malformations is relatively sparse. A case report is given of a parturient, with a recent subtotal resection of a cerebral arteriovenous malformation, who presented for delivery of a viable male fetus. The patient was scheduled for an elective labor induction, with early epidural analgesia advocated as a strategy to minimize the cardiovascular changes of labor and prevent involuntary Valsalva maneuvers. An elective instrumental delivery was planned when the fetal head had descended appropriately. Epidural analgesia was initiated when the patient reached 3 cm cervical dilation and provided excellent labor analgesia. After a passive fetal descent during the second stage of labor, Luikart-Simpson forceps were used to facilitate this stage. The newborn Apgar score was 9 at both 1 and 5 minutes after delivery. Both the patient and the infant have done well. The available obstetric and neurosurgical literature does not offer firm recommendations for the optimal route of fetal delivery or the timing of neurosurgical resection of an arteriovenous malformation in the parturient. Anesthetic management is predicated on the principles of minimizing the cardiovascular changes of labor and preventing involuntary Valsalva maneuvers during the second stage of labor. Both of these goals are readily accomplished with epidural anesthesia.

Anesthetic Management of a Parturient With an Incompletely Resected Cerebral Arteriovenous Malformation

Background and ObjectivesThe anesthetic, neurosurgical, and obstetric literature regarding management of parturients with intracranial arteriovenous malformations is relatively sparse. A case report is given of a parturient, with a recent subtotal resection of a cerebral arteriovenous malformation, who presented for delivery of a viable male fetus.MethodsThe patient was scheduled for an elective labor induction, with early epidural analgesia advocated as a strategy to minimize the cardiovascular changes of labor and prevent involuntary Valsalva maneuvers. An elective instrumental delivery was planned when the fetal head had descended appropriately.ResultsEpidural analgesia was initiated when the patient reached 3 cm cervical dilation and provided excellent labor analgesia. After a passive fetal descent during the second stage of labor, Luikart-Simpson forceps were used to facilitate this stage. The newborn Apgar score was 9 at both 1 and 5 minutes after delivery. Both the patient and the infant have done well.ConclusionsThe available obstetric and neurosurgical literature does not offer firm recommendations for the optimal route of fetal delivery or the timing of neurosurgical resection of an arteriovenous malformation in the parturient. Anesthetic management is predicated on the principles of minimizing the cardiovascular changes of labor and preventing involuntary Valsalva maneuvers during the second stage of labor. Both of these goals are readily accomplished with epidural anesthesia.