Labor and Delivery Flashcards
- A 24 year old G1P0 at 39 weeks gestation with spontaneous labor is at 6 cm and has recurrent variable decelerations. Which resuscitative measure will MOST likely decrease the likelihood of cesarean delivery for non-reassuring fetal heart tracing?
A. Oxygenation
B. Terbutaline
C. Amnioinfusion
D. Ephedrine
Answer:
C.In 2011, one in three women who gave birth in the United States did so by cesarean delivery. Recently SMFM and ACOG published an obstetric care consensus to safely prevent the first cesarean delivery (1). According to the document, the two leading indications for primary cesarean delivery are labor arrest (34%) and non-reassuring fetal heart rate tracing (23%). Variable decelerations are abrupt (from the onset of the deceleration to the beginning of the FHR nadir of less than 30 seconds) decreases in fetal heart rate (FHR). The decrease in FHR is 15 beats per minute or greater, lasting 15 seconds or greater, and less than 2 minutes in duration. Both the ACOG Practice Bulletin on the topic (2) and the consensus report (1) recommend use of amnioinfusion for recurrent variable deceleration (Strong recommendation; high-quality evidence). The recommendation was based on a meta-analysis of 12 randomized trials that allocated women to transcervical amnioinfusion vs. no treatment. The analysis noted that the placement of fluid in the uterine cavity significantly decreased the rate of decelerations and cesarean delivery for non-reassuring fetal heart rate (RR 0.35; 95% CI 0.24- 0.52). During amnioinfusion, the fluid can be placed as a bolus or continuously. and both techniques have a similar ability to abolish recurrent variable decelerations (2). Although supplemental maternal oxygen is used frequently for the management of abnormal FHR patterns, there is a paucity of data on its efficacy and safety (2). Tocolytics should be used with tachysystole and abnormalities of FHR tracing; ephedrine is recommended if the category II FHR pattern occurs in conjunction with maternal hypotension (2).
- In a term newborn with neonatal encephalopathy, which of the following MOST STRONGLY suggests that acute hypoxia-ischemia in the peripartum or intrapartum period was contributor?
A. Multisystem organ failure
B. Category II tracing with absent variability on admission
C. Umbilical artery pH of 7.1
D. APgar score of 7 at 5 minutes
E. Spastic diplegia cerebral palsy
A. Neonatal encephalopathy is a clinically defined syndrome of disturbed neurologic function in the earliest days of life in an infant born at or beyond 35 weeks of gestation. In order to determine the likelihood that an acute peripartum or intrapartum hypoxic-ischemic event contributed to the diagnosis, a comprehensive assessment of neonatal status and obstetric factors needs to be undertaken. Neonatal encephalopathy that is due to acute hypoxia-ischemia will be accompanied by abnormal neonatal signs and associated with etiologic events in close temporal proximity to delivery. The ability of fetal heart rate tracings to predict adverse neurodevelopmental outcomes is limited since the tests have poor positive predictive value. A persistent category II fetal heart rate pattern (as defined by the Eunice Kennedy Shriver NICHD guidelines) with absent variability that is identified on initial presentation is suggestive of a previously compromised or injured fetus. A tracing that deteriorates during observation is more concerning for acute intrapartum hypoxia-ischemia. For example, a category I fetal heart rate pattern that converts to category III is most suggestive of a hypoxic-ischemic event. Low Apgar scores at 5 and 10 minutes (<7) are associated with an increased risk of neonatal encephalopathy and cerebral palsy. However, there are many causes for low Apgar scores, and most infants with low scores will have normal subsequent neurodevelopment. If the Apgar score at 5 minutes is ≥7, it is unlikely that peripartum hypoxia-ischemia contributed to neonatal encephalopathy. Fetal umbilical artery pH <7.0 or base deficit ≥12 mmol/L increases the probability of neonatal encephalopathy. However, even in the presence of significant acidemia, most newborns will be neurologically normal. Less severe cord gas abnormalities are unlikely to be associated with neonatal encephalopathy. Cord arterial gases >7.2 are not consistent with intrapartum hypoxia. The cord gas of 7.1 in this case is very unlikely to be associated with neonatal encephalopathy. It is important to remember that, even when present, metabolic academia does not define the timing of onset of a hypoxic-ischemic event. Multisystem organ failure can include renal injury, hepatic injury, hematologic abnormalities, cardiac dysfunction, metabolic derangements, and gastrointestinal injury. The presence of multi-organ failure increases the chances of hypoxic-ischemic injury as an explanation for neonatal encephalopathy. This finding has the strongest association with hypoxic-ischemic encephalopathy of the options presented. However, it alone is insufficient for the diagnosis. In addition to the above considerations, sentinel obstetric events occurring immediately before or during labor and delivery increase the chance of hypoxic-ischemia contributing to neonatal encephalopathy. Examples include uterine rupture, placental abruption, umbilical cord prolapse, amniotic fluid embolus, and hemorrhage associated with vasa previa. While these events support an intrapartum or peripartum timing of neonatal encephalopathy, they are not sufficient for the diagnosis. Spastic quadriplegia and dyskinetic cerebral palsy are associated with acute hypoxic-ischemic events. Other types of cerebral palsy, such as spastic diplegia, are much less likely to be associated with acute hypoxic-ischemic injury.
. When counseling a patient with an uncomplicated dichorionic twin pregnancy at 36 weeks gestation with Twin A in the cephalic presentation, which of the following statements regarding mode of delivery is TRUE?
A. Planned vaginal delivery and planned cesarean delivery have similar risk of adverse neonatal outcomes
B. Planned vaginal delivery is associated with the lowest risk of adverse neonatal outcomes
C. Scheduled cesarean delivery is associated with the lowest risk of adverse neonatal outcomes
D. Planned cesarean delivery is associated with the lowest risk of adverse neonatal outcomes, but only if Twin B is non-cephalic
A. Twins now represent 3.3% of all US live births. The rate of cesarean delivery of twins has increased from 53% in 1995 to 75% in 2008 in the United States. The increase was seen both in vertex and breech twins. Part of the reason for the increase in cesarean delivery of twins is the thought that cesarean delivery is associated with lower neonatal morbidity, particularly if the second twin was non-vertex. Several large retrospective observational studies show conflicting results, with some studies showing an association between cesarean delivery and improved neonatal outcomes and other studies showing no improvement in outcomes based on the mode of delivery in twins. These differences are likely due to confounding factors that could not be controlled for in the retrospective analyses. In 2013, results of a large randomized clinical trial (RCT) on the safety of vaginal delivery of twins were published. This trial included 1398 women with a twin pregnancy at 32 0/7 to 38 6/7 weeks of gestation and a first twin in cephalic presentation. The participants were randomized to planned vaginal delivery or planned cesarean section. Elective delivery was planned between 37 5/7 and 38 6/7 weeks of gestation. The inclusion criteria for the RCT were both twins alive, the first twin cephalic presentation, and an estimated fetal weight 1500 g to 4000 g confirmed within 7 days of randomization. The exclusion criteria were monoamniotic twins, fetal reduction at 13 or more weeks, lethal fetal anomaly, or a contraindication to labor or vaginal delivery. All participating obstetricians were required to have experience in vaginal twin delivery and all patients had continuous fetal heart rate monitoring in labor. There was no difference between the two groups in regards to the primary outcome of composite neonatal death or serious neonatal morbidity, nor in any of the individual secondary outcomes measured. Based mostly on the RCT, a recent ACOG-SMFM consensus statement concluded that “Perinatal outcomes for twin gestations in which the first twin is in cephalic presentation are not improved by cesarean delivery. Thus, women with either cephalic/cephalic-presenting twins or cephalic/noncephalic-presenting twins should be counseled to attempt vaginal delivery.” (Grade of recommendation = 1B).
Barrett JF, Hannah ME, Hutton EK, et al. Twin Birth Study Collaborative Group. A randomized trial of planned cesarean or vaginal delivery for twin pregnancy. N Engl J Med. 2013;369:1295-305
American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine, Caughey AB, Cahill AG, Guise JM, Rouse DJ. Safe prevention of the primary cesarean delivery. Am J Obstet Gynecol. 2014 ;210:179-93
Recognizing that hospitals, departments, and specific obstetric care providers may vary considerably in their expertise and capabilities, the Society for Maternal-Fetal Medicine (SMFM) has described several practice models for MFM subspecialists in the ongoing care of high-risk obstetric patients. Which of the following is NOT one of these models?
A. Consultation-only model in which the MFM subspecialists sees the patient for a 1-time consultation and makes recommendations for evaluation and/or care
B. Consultation with ongoing care model in which the MFM subspecialist becomes responsible for the care of the patient’s high risk conditions, but referring physician remains in charge of general obstetric care
C. Laborist model in which the MFM subspecialist is responsible for intrapartum management of patients on labor and delivery, typically during an assigned shift and with no other clinical responsibilities
D. Transfer-of-care model in which the MFM subspecialist assumes complete responsibility for the care of the patient, either outpatient only or outpatient and inpatient, including delivery and postpartum care
C. The SMFM special report on the role of MFM subspecialists within a health care system notes that the MFM physician can provide many different services for high-risk obstetric patients. The report recommends that local or regional obstetric care providers should understand the nature of the services available from their MFM subspecialists. Further, the special report notes that high-risk obstetric patients may require a team approach to care, and clear delineation and communication of the responsibilities of the providers involved is crucial. The three care models for high-risk obstetric patients recognized by SMFM include the consultation only, consultation with ongoing care, and transfer-of-care models. MFM physicians may, of course, function as laborists, but this is not one of the high-risk obstetric care models unique to MFM, in part because the laborist typically functions in the management of labor per se (rather than high-risk conditions of the mother or fetus) and is involved in the care of many low-risk pregnancy patients. The obstetric-gynecologic hospitalist, or laborist, is an evolving model of medical care with its own professional society. Society for Maternal-Fetal Medicine (SMFM). Society for Maternal-Fetal Medicine (SMFM) special report: the maternal-fetal medicine subspecialists’ role within a health care system. Am J Obstet Gynecol 2014; 211:607-16.
- What is the incidence of a stillbirth per thousand (corrected for anomalies and unpredictable causes) within 1 week of a normal modified biophysical profile?
A. 0.3
B. 0.8
C. 1.9
D. 2.4
B.
The following is a list of antenatal surveillance test modalities and their associated incidence of stillbirth per thousand, within 1 week of testing: nonstress test – 1.9, biophysical profile – 0.8, modified biophysical profile – 0.8, contraction stress test – 0.3.
Practice Bulletin #145, Antepartum Fetal Surveillance.
- Which of the following statements about activity restriction in pregnancy is true?
A. Activity restriction is associated with an increased risk of anxiety and depression
Which of the following has the best positive predictive value for subsequent development of preeclampsia?
A. First trimester uterine artery doppler
B. Pregnancy associated plasma protein A (PAPP-A) level in the first trimester
C. Second trimester maternal serum alpha fetoprotein (AFP) level
D. Clinical risk factor assessment
C. Activity restriction can result in decreased bone density, but does not have an effect on muscle mass
D. Due to lack of power, the majority of published studies fail to show an association between activity restriction and an increased risk of thrombosis
A.
Activity restriction is commonly recommended to pregnant patients, frequently without sufficient evidence demonstrating benefit. This is potentially concerning given the potential risks of activity restriction. Several large studies found a significant association between activity restriction in pregnant patients and an increased risk of thrombosis. Activity restriction in pregnant patients is associated both with decreased bone density, as well as decreased muscle mass. Physiological changes associated with activity restriction can be seen in as soon as 2–3 days, not 2–3 weeks. Along with the potential physical harms of activity restriction, there is also an increased incidence of maternal anxiety and depression, loss of income, and adverse psychological effects on the family.
SMFM Consult. Activity Restriction.
- Which of the following statements about activity restriction in pregnancy is true?
A. Activity restriction is associated with an increased risk of anxiety and depression
B. The physiologic changes associated with activity restriction will not develop until after 2-3 weeks of activity restriction
C. Activity restriction can result in decreased bone density, but does not have an effect on muscle mass
D. Due to lack of power, the majority of published studies fail to show an association between activity restriction and an increased risk of thrombosis
A.
Activity restriction is commonly recommended to pregnant patients, frequently without sufficient evidence demonstrating benefit. This is potentially concerning given the potential risks of activity restriction. Several large studies found a significant association between activity restriction in pregnant patients and an increased risk of thrombosis. Activity restriction in pregnant patients is associated both with decreased bone density, as well as decreased muscle mass. Physiological changes associated with activity restriction can be seen in as soon as 2–3 days, not 2–3 weeks. Along with the potential physical harms of activity restriction, there is also an increased incidence of maternal anxiety and depression, loss of income, and adverse psychological effects on the family.
SMFM Consult. Activity Restriction.
Which of the following has the best positive predictive value for subsequent development of preeclampsia?
A. First trimester uterine artery doppler
B. Pregnancy associated plasma protein A (PAPP-A) level in the first trimester
C. Second trimester maternal serum alpha fetoprotein (AFP) level
D. Clinical risk factor assessment
D.
The correct answer is: clinical risk factor assessment. Although there have been several trials demonstrating promising new techniques for early prediction of pre-eclampsia, individually these have not demonstrated sufficiently high positive predictive values to warrant incorporation into routine practice. There have been other studies assessing combinations of screening methods and clinical factors. With currently available testing, many women will have a positive screening test without developing subsequent disease, leading to unnecessary testing with its associated costs, and worry on the part of the patient. For example, in a 2009 study by Poon et al, 7797 women were screened using a model that incorporated both biochemical markers, ultrasound, and clinical risk factors. Of those, 476 screened positive for early onset pre-eclampsia, but only 32 developed disease – a positive predictive value of 7%. Hypertensive disorders of pregnancy are a serious source of morbidity and mortality in pregnancy, and studies are ongoing to establish better screening algorithms and corresponding therapy to prevent onset once at-risk individuals are identified. Studies suggest that low dose aspirin may slightly ameliorate the risk of pregnancy-induced hypertension in high-risk women.
ACOG Committee Opinion #638, First-Trimester Risk Assessment for Early-Onset Preeclampsia, September 2015.
Poon LC, Kametas NA, Maiz N, et al. First-trimester prediction of hypertensive disorders in pregnancy. Hypertension. 2009;53:812-818.
Your patient reports a history of severe unexplained neonatal thrombocytopenia with her first baby. She is pregnant with her second child. What is the recommended diagnostic approach for neonatal alloimmune thrombocytopenia (NAIT)?
A. NAIT is a diagnosis of exclusion
B. Assess ADAMTS13 activity
C. Perform fetal cordocentesis for platelet antigen status
D. Evaluate for fetal antiplatelet antibodies
E. Determine maternal and paternal platelet antigen status
E.
Several polymorphic, diallelic platelet antigen systems are responsible for neonatal alloimmune thrombocytopenia (NAIT). The most common cause of NAIT among Caucasians is sensitization to human platelet antigen 1a (HPA-1a), in which the mother lacks the HPA-1a antigen and forms antibodies to HPA-1a. In most cases, the diagnosis of NAIT can be determined by testing the parents. Parents should undergo platelet antigen typing, either serologically or with genotyping. The genes for HPAs associated with NAIT have been well characterized. Typically, maternal and paternal human platelet antigen testing is performed simultaneously, looking for potential antigen incompatibility. In addition to determining parental platelet antigen incompatibility, maternal serum should be screened for HPA antibodies. When maternal and paternal platelet incompatibility and maternal anti-HPA antibodies have been demonstrated, paternal zygosity should be determined (if not already known by genotyping) to determine the fetus’ risk of NAIT. In general, fetal blood sampling is avoided in pregnancies affected by NAIT due to the risk of bleeding associated with severe thrombocytopenia. Current treatment algorithms advocate avoiding fetal blood sampling unless platelet count must be known because vaginal delivery is desired. Cordocentesis for fetal HPA status is therefore avoided. Instead, amniocytes obtained by amniocentesis can be used for fetal HPA genotyping if the father has heterozygous antigen status. Evaluation for fetal antiplatelet antibodies would not be helpful; it is maternal antibodies that are relevant to the pathophysiology.
The diagnosis of primary immune thrombocytopenia (also known as idiopathic thrombocytopenic purpura, or ITP), not NAIT, is primarily one of exclusion. Reduced ADAMTS13 activity, an enzyme that cleaves von Willebrand factor (vWF) multimers, is a risk factor for thrombotic thrombocytopenic purpura (TTP), in which larger than average vWF multimers appear to contribute to the pathophysiology.
Creasy and Resnik, Chapter 53, Coagulation Disorders in Pregnancy, 7th ed. pp 896-898.
Pacheco LD, et al. Fetal and neonatal alloimmune thrombocytopenia: a management algorithm based on risk stratification. Obstet Gynecol. 2011;118(5):1157-1163.
Your patient was diagnosed with neonatal alloimmune thrombocytopenia (NAIT) after her first baby was born with intracranial hemorrhage and severe neonatal thrombocytopenia. She is now pregnant again. Which of the following is the most consistently effective antenatal therapy for NAIT?
A. Maternal prednisone
B. Fetal intravenous immunoglobulin (IVIG)
C. Maternal dexamethasone
D. Maternal intravenous immunoglobulin (IVIG)
E. Fetal platelet transfusion
D.
The goal of obstetric management of pregnancies at risk for neonatal alloimmune thrombocytopenia (NAIT) is to prevent intracranial hemorrhage and associated neonatal complications. Recurrence may be prevented by implementation of timely therapy during pregnancy. Optimal management is uncertain, and there are few randomized trials available to guide therapy. Proposed therapies include maternal steroids, maternal intravenous immunoglobulin (IVIG), fetal IVIG, and fetal platelet transfusions. No therapy is effective in all cases. There is little data on direct fetal administration of IVIG and the available literature suggests that it does not consistently raise fetal platelet counts. Platelet transfusions are effective, but transfused platelets have a short half-life and serial (generally weekly) procedures are necessary. The risk associated with platelet transfusion in a thrombocytopenic fetus limits the use of this approach. Maternal IVIG is the most consistently effective antenatal therapy in clinical trials. Maternal IVIG is typically infused weekly at a dose of 1 g/kg maternal weight. The majority of fetuses responded to this therapy in observational and randomized trials and intracranial hemorrhage is rare among treated pregnancies. The mechanism of action is uncertain, but may be related to placental Fc receptor blockade, preventing active transport of antiplatelet antibodies across the placenta. Therapeutic addition of maternal prednisone, but not dexamethasone, to IVIG regimens has been shown to further increase fetal platelets, particularly in fetuses with severe thrombocytopenia (<20,000 platelets/microliter). It has been recommended that the treatment regimen (IVIG +/- prednisone) be individualized with stratification by level of risk for NAIT. This risk-stratified approach to therapy, with IVIG as the therapeutic cornerstone, has become a common approach to NAIT treatment.
Creasy and Resnik. Chapter 53. Coagulation Disorders in Pregnancy, 7th ed. pp 896-898.
Pacheco LD, et al. Fetal and neonatal alloimmune thrombocytopenia: a management algorithm based on risk stratification. Obstet Gynecol. 2011;118(5):1157-1163.
