PROLOG: Obstetrics, Eighth Edition (Assessment & Critique)

By American College of Obstetricians and Gynecologists

Each of the 6 units of PROLOG addresses a major area in obstetrics and gynecology and consists of two parts—an assessment book and a critique book. Put your knowledge to the test and earn 25 CME credits for this volume!

The obstetrician–gynecologist who completes Obstetrics, Eighth Edition, should be able to:

• Demonstrate an understanding of maternal and fetal physiology and pathophysiology and their impact on normal and complicated pregnancies
• Identify components of antepartum care that optimize maternal and perinatal outcomes in uncomplicated pregnancies, including education regarding normal pregnancy
• Diagnose and plan efficacious and cost-effective management of medical and obstetric conditions encountered during the antepartum period.
• Identify the risks and prognosis of selected complications of pregnancy and in the neonate
• Describe invasive and noninvasive methods of fetal assessment in the antepartum period and identify the risks, indications, predictive value, and physiologic basis for tests
• Diagnose problems and manage obstetric emergencies.
• Select appropriate management strategies for intrapartum care and delivery
• Consider medical-legal principles, risk management and office management guidelines in obstetric practice.

• Language: English
• Publisher: ACOG
• Release date: Jan 1, 2018
• ISBN: 9781948258159

Book preview

book coverCritique Title Page

ISBN 978-1-948258-15-9

Copyright 2018 by the American College of Obstetricians and Gynecologists. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, posted on the Internet, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission of the publisher.

2345/10

The American College of Obstetricians and Gynecologists

409 12th Street, SW

PO Box 96920

Washington, DC 20090-6920

In Memoriam

Michael Plevyak, MD

This eighth edition of PROLOG Obstetrics is published in memory of Michael Plevyak, MD, who passed away in August 2017. Michael served as a coeditor of this edition and wrote for the seventh edition of PROLOG Obstetrics. He practiced maternal–fetal medicine at Baystate Health in Springfield, Massachusetts, and served as the Associate Residency Program Director.

Michael was a superb clinician, highly regarded by referring physicians, faculty, residents, students, and support staff. He was a beloved mentor and teacher for medical students and residents and received several teaching awards. He saw every day as an opportunity to learn something new. During his time on PROLOG committees, Michael adeptly addressed complex topics, worked extensively with PROLOG authors, and displayed an impressive dedication to creating succinct and up-to-date critiques. His engaging and upbeat personality will be missed immensely by his colleagues at Baystate Health and the American College of Obstetricians and Gynecologists.

Photo kindly provided by Baystate Health

Contributors

PROLOG Editorial and Advisory Committee

CHAIR

Ronald T. Burkman Jr, MD

Professor of Obstetrics and Gynecology

University of Massachusetts Medical School–Baystate

Division of General Obstetrics and Gynecology

Baystate Medical Center

Springfield, Massachusetts

MEMBERS

Bernard Gonik, MD

Professor and Fann Srere Endowed Chair of Perinatal Medicine

Division of Maternal–Fetal Medicine

Department of Obstetrics and Gynecology

Wayne State University School of Medicine

Detroit, Michigan

John F. Greene Jr, MD

Vice President of Medical Affairs, Hartford Region

Hartford HealthCare

Professor of Obstetrics and Gynecology

University of Connecticut School of Medicine

Farmington, Connecticut

Roger P. Smith, MD

Assistant Dean for Graduate Medical Education

Professor of Clinical Biologic Sciences

Charles E. Schmidt College of Medicine

Florida Atlantic University

Boca Raton, Florida

PROLOG Task Force for Obstetrics, Eighth Edition

CO-CHAIRS

Donna D. Johnson, MD

Lawrence L. Hester Professor and Chair

Department of Obstetrics and Gynecology

Division of Maternal–Fetal Medicine

Medical University of South Carolina

Charleston, South Carolina

Michael Plevyak, MD

Assistant Professor of Obstetrics and Gynecology

University of Massachusetts Medical School

Division of Maternal–Fetal Medicine

Baystate Medical Center

Springfield, Massachusetts

MEMBERS

Nishath Athar Ali, MD

Assistant Professor Department of Obstetrics and Gynecology

Baylor College of Medicine

Houston, Texas

Ryan K. Brannon, MD

Assistant Professor Department of Obstetrics and Gynecology

Director, Obstetrics and Gynecology Clerkship and Pathway

Drexel University College of Medicine

Philadelphia, Pennsylvania

Amy G. Bryant, MD, MSCR

Assistant Professor of Obstetrics and Gynecology

Division of Family Planning

University of North Carolina School of Medicine

Chapel Hill, North Carolina

Deborah M. Feldman, MD

Associate Professor of Obstetrics and Gynecology

University of Connecticut School of Medicine

Farmington, Connecticut

Director, Division of Maternal–Fetal Medicine

Hartford HealthCare

Hartford, Connecticut

Elizabeth A. Ferries-Rowe, MD

Assistant Professor

Generalist Division of Obstetrics and Gynecology

Chief of Obstetrics and Gynecology

Eskenazi Health System

Vice Chair for Clinical Affairs

Indiana University School of Medicine

Indianapolis, Indiana

Susan E. Gerber, MD, MPH

Associate Professor

Residency Program Director

Division of Maternal–Fetal Medicine

Department of Obstetrics and Gynecology

Northwestern University Feinberg School of Medicine

Chicago, Illinois

Jeffrey A. Kuller, MD

Professor of Obstetrics and Gynecology

Division of Maternal–Fetal Medicine

Duke University Medical Center

Durham, North Carolina

A. Dhanya Mackeen, MD, MPH

Assistant Professor

Department of Epidemiology and Health Services Research

Division of Maternal–Fetal Medicine, Women’s Health Service Line

Director of Research

Maternal–Fetal Medicine Fellowship Director

Geisinger Health System

Danville, Pennsylvania

Keith H. Nelson, MD

Associate Professor

Department of Obstetrics and Gynecology

East Carolina University Brody School of Medicine

Greenville, North Carolina

Cheung Wong, MD, CPE

Vice Chair of Gynecology

Director of Gynecologic Oncology

Associate Dean of Continuing Medical Education

University of Vermont Medical Center

University of Vermont Larner College of Medicine

Burlington, Vermont

ACOG STAFF

Sandra A. Carson, MD

Vice President for Education

Erica Flynn, MBA, MS

Senior Director, Educational Development and Testing

Division of Education

Elizabeth Moran, MA

Editor

Division of Education

DISCLOSURE STATEMENT

The Accreditation Council for Continuing Medical Education (ACCME) requires that all faculty and planning committee members disclose any financial interests relative to topics within this edition of PROLOG. This information will be obtained in advance by staff via the American College of Obstetricians and Gynecologists’ (ACOG) online disclosure system. There must be ample time for resolution of all potential conflicts of interest. This information (with resolution of any conflicts of interest) should be on file before honoraria are paid.

DISCLOSURE OF FACULTY AND INDUSTRY RELATIONSHIPS

In accordance with ACOG’s policy, all faculty and planning committee members have signed a conflict of interest statement in which they have disclosed any financial interests or other relationships with industry relative to topics in this edition of PROLOG. Such disclosure allows for better evaluation of the objectivity of the information presented.

CONFLICT OF INTEREST DISCLOSURE

This PROLOG unit was developed under the direction of the PROLOG Advisory Committee and Task Force for Obstetrics, Eighth Edition. PROLOG is planned and produced in accordance with the Standards for Commercial Support of the ACCME. Any discussion of unapproved use of products is clearly cited in the appropriate critique.

Current guidelines state that continuing medical education (CME) health care providers must ensure that CME activities are free from the control of any commercial interest. The task force and advisory committee members declare that neither they nor any business associate nor any member of their immediate families has material interest, financial interest, or other relationships with any company manufacturing commercial products relative to the topics included in this publication or with any provider of commercial services discussed in the unit. All potential conflicts have been resolved through ACOG’s mechanism for resolving potential and real conflicts of interest.

Preface

Purpose

PROLOG (Personal Review of Learning in Obstetrics and Gynecology) is a voluntary, strictly confidential self-evaluation program. PROLOG was developed specifically as a personal study resource for the practicing obstetrician–gynecologist. It is presented as a self-assessment mechanism that, with its accompanying performance information, should assist the physician in designing a personal, self-directed, lifelong learning program. It may be used as a valuable study tool, a reference guide, and a means of attaining up-to-date information in the specialty. The content is carefully selected and presented in multiple-choice questions that are clinically oriented. The questions are designed to stimulate and challenge physicians in areas of medical care that they confront in their practices or when they work as consultant obstetrician–gynecologists.

PROLOG also provides the American College of Obstetricians and Gynecologists (ACOG) with one mechanism to identify the educational needs of the Fellows. Individual scores are reported only to the participant; however, cumulative performance data and evaluation comments obtained for each PROLOG unit help determine the direction for future educational programs offered by ACOG.

Process

The PROLOG series offers the most current information available in five areas of the specialty: 1) obstetrics; 2) gynecology and surgery; 3) reproductive endocrinology and infertility; 4) gynecologic oncology and critical care; and 5) patient management in the office. The series now includes a sixth volume for the subspecialty of female pelvic medicine and reconstructive surgery. A new PROLOG edition is produced annually, addressing one of those subject areas. Obstetrics, Eighth Edition, is the first unit in the eighth 5-year PROLOG series.

Each unit of PROLOG represents the efforts of a task force of subject experts under the supervision of an advisory committee. PROLOG sets forth current information as viewed by recognized authorities in the field of women’s health. This educational resource does not define a standard of care, nor is it intended to dictate an exclusive course of management. It presents recognized methods and techniques of clinical practice for consideration by obstetrician–gynecologists to incorporate in their practices. Variations of practice that take into account the needs of the individual patient, resources, and the limitations that are special to the institution or type of practice may be appropriate.

Each unit of PROLOG is presented as a two-part set, with performance information and cognate credit available to those who choose to submit their assessment for confidential scoring. The first part of the PROLOG set is the Assessment Book, which contains educational objectives for the unit and multiple-choice questions. The questions can be completed by taking an online assessment or submitting an answer sheet to return by mail. Participants can work through the unit at their own pace, choosing to use PROLOG as a closed- or open-book assessment. Submitting the assessment—online or on a paper answer sheet—is encouraged but voluntary.

The second part of PROLOG is the Critique Book, which reviews the educational objectives and questions set forth in the Assessment Book and contains a discussion or critique of each question. The critique provides the rationale for correct and incorrect options. Current, accessible references are listed for each question.

Continuing Medical Education Credit

ACCME Accreditation

The American College of Obstetricians and Gynecologists (ACOG) is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

AMA PRA Category 1 Credit(s)™

The American College of Obstetricians and Gynecologists designates this enduring material for a maximum of 25 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

ACOG Cognate Credit(s)

The American College of Obstetricians and Gynecologists designates this enduring material for a maximum of 25 Category 1 ACOG Cognate Credits. The American College of Obstetricians and Gynecologists has a reciprocity agreement with the American Medical Association that allows AMA PRA Category 1 Credits™ to be equivalent to ACOG Cognate Credits.

Participants who submit their assessment for scoring and receive a passing of 80% will be credited with 25 continuing medical education (CME) credits for this unit. Those who complete the assessment for CME credit will receive a performance report that provides a comparison of their scores with the scores of a sample group of physicians who have taken the unit as an examination. An individual may request credit only once for each edition. The credits are available immediately when a participant passes the online assessment. Allow 4–6 weeks to process paper answer sheets.

Credit for PROLOG Obstetrics, Eighth Edition, is initially available through December 2020. During that year, the unit will be reevaluated. If the content remains current, credit is extended for an additional 3 years, with credit for the unit automatically withdrawn after December 2023.

Conclusion

PROLOG was developed specifically as a personal study resource for the practicing obstetrician–gynecologist. It is presented as a self-assessment mechanism that, with its accompanying performance information, should assist the physician in designing a personal, self-directed learning program. The many quality resources developed by ACOG, as detailed each year in ACOG’s Publications and Educational Materials Catalog, are available to help fulfill the educational interests and needs that have been identified. PROLOG is not intended as a substitute for the certification or recertification programs of the American Board of Obstetrics and Gynecology.

Electronic Assessment for CME Credit

Participants have the option of taking this assessment electronically. Assessment results must be 80% or higher to achieve a passing score and attain CME credit. To access the online assessment, please visit https://prolog.acog.org. Test results and the CME certificate will be available upon completion of the examination.

If you purchased a print book, use the key code located on the inside front cover of the Critique Book and follow the directions provided. If you purchased an eBook, please follow the instructions online to purchase and access the assessment. To receive a paper answer sheet, please email [e-mail] or call 202-863-2405.

PROLOG Objectives

PROLOG is a voluntary, strictly confidential, personal continuing education resource that is designed to be stimulating and enjoyable. By participating in PROLOG, obstetrician–gynecologists will be able to do the following:

• Review and update clinical knowledge.

• Recognize areas of knowledge and practice in which they excel, be stimulated to explore other areas of the specialty, and identify areas requiring further study.

• Plan continuing education activities in light of identified strengths and deficiencies.

• Compare and relate present knowledge and skills with those of other participants.

• Obtain continuing medical education credit, if desired.

• Have complete personal control of the setting and of the pace of the experience.

The obstetrician–gynecologist who completes Obstetrics, Eighth Edition, will be able to

• demonstrate an understanding of maternal and fetal physiology and pathophysiology and the effect on normal and complicated pregnancies.

• identify components of antepartum care that optimize maternal and perinatal outcomes in uncomplicated pregnancies, including education regarding normal pregnancy.

• diagnose and plan efficacious and cost-effective management of medical and obstetric conditions encountered during the antepartum period.

• identify the risks and prognosis of selected complications of pregnancy and in the neonate.

• describe antenatal genetic screening and diagnostic test and identify the indications, risks, and predictive value for each.

• diagnose problems and manage obstetric emergencies.

• select appropriate management strategies for intrapartum care and delivery.

• consider medical–legal principles, risk management, and office management guidelines in obstetric practice.

Obstetrics, Eighth Edition, includes the following topics (item numbers appear in parentheses):

COUNSELING

Activity restriction (103)

Evaluation of fetal death (99)

Exercise in pregnancy (62)

Foods to avoid during pregnancy (22)

Obesity in a pregnant patient (69)

Peripartum cardiomyopathy and pregnancy planning (84)

Smoking cessation (117)

Timing of classical cesarean delivery (6)

Uterine leiomyomas (111)

EPIDEMIOLOGY AND BIOSTATISTICS

Epidural complications (23)

Human immunodeficiency virus testing in pregnant patient (86)

Neonatal encephalopathy (50)

Neonatal encephalopathy and neurologic injury (48)

Perinatal survival (72)

Teratogenic drugs (162–165)

ETHICAL AND LEGAL ISSUES

Contraception in a breastfeeding patient (11)

Maternal levels of care (139–143)

Neonatal intensive care unit levels of care (37)

Periviable birth (51)

Substance abuse in pregnancy (71)

Vaginal birth after multiple cesarean deliveries (115)

MEDICAL MANAGEMENT

Asthma medications (49)

Biophysical profile in a pregnant patient (90)

Brachial plexus injury (101)

Breast mass in pregnancy (81)

Cervical length (172–175)

Chorioamnionitis (45)

Hemolysis, elevated liver enzymes, and low platelet count syndrome (16)

Fetal death in a patient with prior cesarean delivery (87)

Group B streptococci (97)

Herpes simplex virus and preterm prelabor rupture of membranes management for patient in labor (83)

History of depression in pregnant patient (14)

Hypertension in pregnancy (7)

Hyperthyroidism in a pregnant patient (8)

Hypothyroidism in a pregnant patient (108)

Immunization in pregnancy (93)

Induction of labor (121–123)

Induction in patient undergoing trial of labor after cesarean delivery (106)

Intrahepatic cholestasis of pregnancy (46)

Intrauterine growth restriction (95)

Labor dystocia (60)

Labor induction methods (64)

Latent phase of labor (61)

Management of triplets (47)

Massive transfusion (76)

Mastitis and treatment of breast abscess (26)

Medically indicated preterm birth (30)

Migraine headaches (116)

Nausea and vomiting in pregnancy (74)

Oligohydramnios (24)

Peripartum anticoagulation (94)

Postpartum contraception (4)

Prevention of recurrent preterm delivery (80)

Prophylaxis for a patient with potential exposure to human immunodeficiency virus (63)

Pulmonary embolus (98)

Recurrent spontaneous abortion (44)

Seizure disorder medications (56)

Severe rhesus disease in pregnancy (43)

Shoulder dystocia (29)

Supplemental folic acid (107)

Syphilis (52)

Tocolytic agents (110)

Treatment of gestational diabetes mellitus (39)

Thrombocytopenia in pregnancy (78)

Use of steroids in late preterm pregnancy (18)

Uterine inversion (25)

Vulvar hematoma with alternate management (91)

PHYSIOLOGY

Drug metabolism (40)

Renal changes in pregnancy (3)

PREVENTION AND POPULATION HEALTH

Influenza exposure (70)

Influenza in pregnancy (102)

Vaccines in pregnancy (38)

SCREENING AND DIAGNOSIS

Acute right-sided abdominal pain (68)

Anemia (5)

Aneuploidy screening (158–161)

Antiphospholipid antibody syndrome (118)

Apgar score (155–157)

Autoimmune disorders and pregnancy (89)

Cell-free DNA (112)

Cell-free DNA screening for sex chromosome disorders (1)

Cerebral palsy (67)

Cervical insufficiency (27)

Chorioamnionitis complications (2)

Cystic fibrosis carrier screening (66)

Dermatologic conditions in pregnancy (144–147)

Diagnosis of congenital infection (124–128)

Differential diagnosis for postpartum fever (53)

Differential diagnosis of microcytic anemia (73)

Disseminated intravascular coagulation (19)

Electronic fetal heart rate monitoring (82)

Fetal acid–base assessment (114)

Gastric bypass surgery and nutritional deficiencies (41)

Gestational diabetes mellitus (35)

Gram-positive bacteria in pregnancy (58)

Headache during pregnancy (12)

Health care provider risk after exposure to needle stick (42)

Hepatitis B treatment (85)

Increased nuchal translucency measurement (33)

Inherited thrombophilias (113)

Intrapartum electronic fetal monitoring (166–171)

Macrosomia (15)

Maternal hemorrhage protocol (34)

Monochorionic twins (17)

Myasthenia gravis (36)

Peripartum cardiomyopathy (55)

Phenylketonuria (75)

Placenta previa (65)

Placental abruption (13)

Polyhydramnios (92)

Preeclampsia and preeclampsia imitators (135–138)

Serum markers and adverse pregnancy outcomes (31)

Severe preeclampsia and its imitators (77)

Sickle cell anemia in pregnant patient (32)

Thrombocytopenia (132–134)

Timing of chorionicity (100)

Tuberculosis in a pregnant patient (109)

Twin-to-twin transfusion syndrome (104)

Ultrasonography to estimate due date (54)

Ultrasound findings of common aneuploidy (129–131)

Ultrasound findings of early pregnancy loss (10)

Ultrasound markers for Down syndrome (96)

Urosepsis (79)

Vaginal birth after cesarean delivery (120)

Vitamin D deficiency (59)

Zika virus infections (150–154)

SURGICAL MANAGEMENT

Adnexal mass in pregnancy (20)

Gestational trophoblastic disease (88)

Operative complications in obesity (105)

Penicillin allergy (57)

Placenta accreta (28)

Postpartum hemorrhage (9)

Second-trimester abortion (148–149)

Successful external cephalic version (21)

Thromboprophylaxis (119)

A complete subject matter index appears at the end of the Critique Book.

1

Cell-free DNA screening for sex chromosome disorders

A 35-year-old woman, gravida 2, para 1, at 18 weeks of gestation presents for a prenatal appointment. She had a normal previous pregnancy with delivery of a healthy baby at term. She has an unremarkable family history for genetic disorders. She requested a cell-free DNA test that returned positive for Turner syndrome (45,X). The most appropriate next test to confirm the diagnosis of Turner syndrome is a(n)

*  (A) amniocentesis for karyotype analysis

(B) chorionic villus sampling

(C) fetal anatomic survey

(D) quadruple marker screen

(E) repeat cell-free DNA test

In 2011, noninvasive prenatal genetic testing using cell-free DNA circulating in the mother’s blood became commercially available for the first time. This screening test for aneuploidy has become widespread, but there are precautions that must be observed when interpreting the results to prevent inappropriate recommendations and potentially inappropriate pregnancy interruption on the basis of a suspected, but not confirmed, genetic abnormality. Currently, the Society for Maternal–Fetal Medicine recommends that cell-free DNA testing be limited to women at increased risk of fetal aneuploidy, such as patients with one of the following conditions:

• Advanced maternal age

• Fetal ultrasound findings concerning for aneuploidy

• History of pregnancy with trisomy 21, trisomy 18, or trisomy 13

• Positive screening tests for aneuploidy

• Known parental balanced Robertsonian translocation with risk of trisomy 13 or trisomy 21

In a recent clarification, the Society for Maternal–Fetal Medicine recognized the importance of patient autonomy and agreed that the option for cell-free DNA should be available to women who request it outside of the recommendations of professional societies. There is still concern about misinterpretation of screening results and the potentially adverse outcome of such misinterpretation.

Starting at 9 weeks or 10 weeks of gestation, cell-free DNA can be identified from maternal serum and usually accounts for 3–13% of the total circulating cell-free DNA. The source is thought to be placental. The fetal fraction, or that portion of cell-free DNA that is fetal in origin, is a critical component of the overall success of the screening test. Not all laboratories will report the fetal fraction. Some laboratories will require a minimum of 4% fetal fraction to report a result. The fetal fraction increases with gestational age and is decreased in obese patients. In one analysis of the effect of maternal characteristics on cell-free DNA screening, the proportion of pregnancies with a fetal fraction less than 4% (which would prompt a nonreportable result in some laboratories) increased with maternal weight, rising from less than 1% at 60 kg (132 lb) to greater than 50% at 160 kg (353 lb).

The risk that the cell-free DNA screening test will return with an uninterpretable result ranges from 1% to 8%. In patients who receive an uninterpretable result, whether as a result of low fetal fraction or other unknown factors, rates of aneuploidy may be as high as 23%. The other major concern in patients who receive an uninterpretable result is that repeat screening will still not be interpretable in 40–50% of cases. For these reasons, those patients who receive uninterpretable results for any reason should be counseled carefully and offered diagnostic testing. Repeat cell-free DNA screening may be performed, but the delay in diagnosis may affect a patient’s reproductive choices in pregnancy management. In most currently available formats, cell-free DNA can only test for trisomy 21, 18, and 13 and sex chromosomes. The test has not been validated in multiple gestations, partly because the cell-free DNA is a composite of the available DNA without the ability to differentiate between fetuses. Although some other genetic tests are available using cell-free DNA, their reliability has not been validated, so patients at risk of other genetic abnormalities should be offered conventional genetic testing.

Interpretation of cell-free DNA results, whether for trisomy or for disorders of the sex chromosomes, must be performed with careful attention to the prevalence of the disease of interest in the population being screened. For example, although cell-free DNA screening has a high sensitivity and specificity for trisomy 21 (greater than 99%), the prevalence of trisomy 21 in the screened population greatly affects the positive predictive value (PPV) (ie, percentage that a positive test is a true result). In a high-risk population screened by age, history of a pregnancy with trisomy 21, abnormal ultrasound findings, abnormal genetic screening, or known parental Robertsonian balanced translocation, the PPV of a cell-free DNA screen for trisomy 21 is 87%. In the general obstetric population (who have an a priori risk of 1:2,500), however, the same test result carries a PPV of only 33%. In other words, only one in three general obstetric patients who receives a positive cell-free DNA screen for trisomy 21 will in fact carry a child with Down syndrome. In populations where the a priori risk reaches 1:10,000, the PPV is as low as 11%. Health care providers unaware of this critical alteration in the screening test performance might erroneously counsel patients, and the patient might choose to terminate a pregnancy without confirming the presence of aneuploidy first.

The performance of cell-free DNA for screening for sex chromosome disorders is similarly poor depending on disease prevalence. The sensitivity and specificity of cell-free DNA screening are reported to be 91.0% and 99.6%, respectively, for abnormalities of the sex chromosomes, with a PPV ranging between 20% and 40% for most disorders. The prevalence of Turner syndrome in the general obstetric population is conservatively estimated to be 1:2,000 live births. The a priori risk of Turner syndrome is not affected by age, so applying the same modeling as described for trisomy 21 yields an estimated PPV of only 11%—that is, nearly 9 in 10 patients with a positive cell-free DNA screening for Turner syndrome will have a normal fetus. The performance of cell-free DNA screening in populations with a higher prevalence (eg, a group of patients whose first trimester ultrasonography has identified increased nuchal translucency or a cystic hygroma) would be expected to be better than in the general low-risk population. Screening with cell-free DNA alone for Turner syndrome also may miss patients who have a structurally abnormal X chromosome or who have mosaicism.

For the described patient, the appropriate next test for an abnormal screening test is a diagnostic test. Amniocentesis for karyotype is most appropriate based on gestational age compared with chorionic villus sampling. Although an anatomic survey is indicated, it is not a diagnostic test. The same may be said for a quad screen. Repeating the cell-free DNA test would not be appropriate given that a positive screening should prompt diagnostic testing. Repeat screening risks a false-negative test result. Repeat cell-free DNA testing is reasonable in patients whose initial test is not reportable (ie, a no-call result) as a result of low fetal fraction, but that is not the case for this patient.

Ashoor G, Syngelaki A, Poon LC, Rezende JC, Nicolaides KH. Fetal fraction in maternal plasma cell-free DNA at 11–13 weeks’ gestation: relation to maternal and fetal characteristics. Ultrasound Obstet Gynecol 2013;41:26–32.

Cell-free DNA screening for fetal aneuploidy. Committee Opinion No. 640. American College of Obstetricians and Gynecologists. Obstet Gynecol 2015;126:e31-7.

Prenatal aneuploidy screening using cell-free DNA. Society for Maternal–Fetal Medicine (SMFM) Publications Committee. Am J Obstet Gynecol 2015;212:711-6.

Screening for fetal aneuploidy. Practice Bulletin No. 163. American College of Obstetricians and Gynecologists. Obstet Gynecol 2016;127:e123-37.

Clarification of recommendations regarding cell-free DNA aneuploidy screening. Society for Maternal–Fetal Medicine (SMFM) Publications Committee. Am J Obstet Gynecol 2015;213:753–4.

Wax JR, Chard R, Cartin A, Litton C, Pinette MG, Lucas FL. Noninvasive prenatal testing: the importance of pretest trisomy risk and posttest predictive values. Am J Obstet Gynecol 2015;212:548–9.

* Indicates correct answer.

Note: See Appendix A for a table of normal values for laboratory tests.

2

Chorioamnionitis complications

A 22-year-old woman, gravida 2, para 1, at 40 weeks of gestation was admitted with prelabor rupture of membranes (also referred to as premature rupture of membranes) for labor augmentation. She received epidural analgesia for pain management. After 12 hours, the patient had a fever, an elevated white blood cell count, and fetal tachycardia. Parenteral antibiotics were given. The patient underwent vaginal delivery and repair of a second-degree perineal laceration. Immediately postpartum, this patient is at increased risk of

(A) amniotic fluid embolus

(B) preeclampsia

(C) postdural puncture headache

(D) postpartum depression

*  (E) postpartum hemorrhage

Chorioamnionitis refers to acute inflammation of the membranes and chorion of the placenta. It is most commonly an ascending polymicrobial bacterial infection in the setting of ruptured membranes, but it can occur before rupture of membranes and before the onset of labor—either as an ascending infection or as the result of hematogenous spread. Approximately 1–4% of all births in the United States are complicated by chorioamnionitis.

The diagnosis of chorioamnionitis is clinical and may be complicated by the recognized association between epidural anesthesia and fever; therefore, consideration of the entire clinical picture is helpful in making the diagnosis. Risk factors for the development of chorioamnionitis include prolonged labor, prolonged rupture of membranes, colonization of group B streptococci (GBS), genital tract infection, meconium-stained fluid, and multiple digital examinations. Although laboratory evaluation is not necessary to make the diagnosis, elevated white blood cell count and positive culture of amniotic fluid are typical. Histology of the placenta is often considered a supportive finding in the diagnosis after delivery. Box 2-1 provides the presumptive diagnostic criteria for chorioamnionitis.

Treatment of chorioamnionitis involves symptomatic treatment with antipyretics and antibiotic therapy directed toward the most common pathogens identified, including Mycoplasma, Enterobacteriaceae, GBS, Staphylococcus aureus, Gardnerella vaginalis, Neisseria gonorrhoeae, and Chlamydia trachomatis. Broad spectrum antibiotics, including penicillins or cephalosporins, aminoglycosides, and macrolides, are the mainstay of treatment.

Studies do not demonstrate improved outcomes with cesarean delivery based solely on a diagnosis of chorioamnionitis, and cesarean delivery should be undertaken based on obstetric indications. In the event of a cesarean delivery, the addition of clindamycin for anaerobic coverage has been demonstrated to reduce the incidence of postcesarean delivery endometritis. Studies suggest that a limited course of antibiotics (ie, one additional dose of scheduled antibiotics after delivery) is sufficient to prevent postpartum endometritis in virtually all patients.

Chorioamnionitis is associated with maternal and neonatal complications. Obstetric complications include dysfunctional labor, increased risk of cesarean delivery, postpartum hemorrhage, blood transfusion, and postpartum infection (eg, endomyometritis or abscess formation). Although 10% of women with chorioamnionitis will have bacteremia, incidences of septic shock, disseminated intravascular coagulation, adult respiratory distress syndrome, and maternal death are rare.

Neonatal complications of chorioamnionitis include neonatal sepsis, septic shock, pneumonia, intraventricular hemorrhage, cerebral white matter damage, long-term disability (including cerebral palsy), asphyxia, and perinatal death. Up to 40% of early-onset neonatal sepsis is associated with chorioamnionitis, and near-term or term infants are at a fourfold risk of cerebral palsy when delivery is complicated by chorioamnionitis. Given these significant complications for the neonate, in addition to the previously mentioned maternal complications, efforts to minimize risk factors for chorioamnionitis are an important component of labor management for all patients. Active management of prelabor rupture of membranes, GBS prophylaxis, and limiting the frequency of digital examinations are examples of efforts to minimize the morbidity and mortality associated with intrapartum chorioamnionitis.

BOX 2-1

Presumptive Diagnostic Criteria for Chorioamnionitis

Maternal fever of 39° or greater, or fever between 38.0°C (100.4°F) and 38.9°C on two occasions, and at least one of the following risk factors:

• Elevated maternal white blood cell count

• Fetal tachycardia

• Purulent material draining from cervix

Unlike postpartum hemorrhage, the risks of amniotic fluid embolus, preeclampsia, postdural puncture headache, and postpartum depression do not increase with chorioamnionitis. Prolonged induction for the indication of preeclampsia may increase the risk of chorioamnionitis, but the reverse is not true. Postdural headache is associated with difficult epidural placement, which was not a complication in the described patient. Postpartum depression is a relatively common condition with multiple associated risk factors, but chorioamnionitis is not among them.

Black LP, Hinson L, Duff P. Limited course of antibiotic treatment for chorioamnionitis. Obstet Gynecol 2012;119:1102–5.

Hauth JC, Gilstrap LC 3rd, Hankins GD, Connor KD. Term maternal and neonatal complications of acute chorioamnionitis. Obstet Gynecol 1985;66:59–62.

Intrapartum management of intraamniotic infection. Committee Opinion No. 712. American College of Obstetricians and Gynecologists. Obstet Gynecol 2017;130:e95–101.

Johnson CT, Farzin A, Burd I. Current management and long-term outcomes following chorioamnionitis. Obstet Gynecol Clin North Am 2014;41:649–69.

Tita AT, Szychowski JM, Boggess K, Saade G, Longo S, Clark E, et al. Adjunctive azithromycin prophylaxis for cesarean delivery. C/SOAP Trial Consortium. N Engl J Med 2016;375:1231–41.

Tita AT, Andrews WW. Diagnosis and management of clinical chorioamnionitis. Clin Perinatol 2010;37:339–54.

3

Renal changes in pregnancy

A 28-year-old woman, gravida 1, with a family history of adult polycystic kidney disease presents at 28 weeks of gestation with intermittent right-sided flank pain. Her urine dipstick shows trace protein but is otherwise negative. Renal ultrasonography shows slightly enlarged kidney size bilaterally (1 cm), moderate right hydronephrosis, and mild right ureteral dilation. Based on the findings, the patient’s most likely diagnosis is

(A) adult polycystic kidney disease

*  (B) normal renal changes in pregnancy

(C) pyelonephritis

(D) ureteral obstruction

Nearly all aspects of renal physiology are affected by pregnancy. As with other organ systems during pregnancy, kidney hemodynamics are marked by significant volume expansion and vasodilation. The glomerular filtration rate increases 50%, and renal plasma flow increases up to 80% compared with nonpregnant levels. The glomerular filtration rate can be measured by the creatinine clearance in a 24-hour urine collection.

The size of the kidneys increases during pregnancy because of fluid retention, and physiologic hydronephrosis is common, especially in the third trimester. The length of the kidneys also increases 1–1.5 cm during pregnancy and decreases within 6 months postpartum. Along with the increase in size, the volume of kidneys during pregnancy increases up to 30%. The growth most likely results from increased kidney vascular and interstitial volume rather than from changes in the number of nephrons.

The renal pelvis and calyceal systems dilate under compressive forces on the ureters from the growing uterus. In addition, there may be hormonal effects of progesterone reducing ureteral tone and peristalsis. Although the anteroposterior diameter of the renal pelvis also increases (especially in cases of hydronephrosis), the change is usually greater on the right side than the left side. Hydroureter is also common, typically on the right side. The described patient’s findings do not indicate an obstructive process.

Plasma osmolality is approximately 270 mOsm/kg, and serum sodium levels decrease 4–5 mEq/L. This drop in serum sodium likely is related to the occurrence of vasodilation and subsequent antidiuretic hormone release. Potassium excretion remains constant throughout pregnancy.

In a normal pregnancy, total urinary protein and albumin excretion increase, especially after 20 weeks of gestation. The increase in proteinuria during pregnancy often is attributed to the rise in glomerular filtration rate; however, the degree of increase is not as great as the increase in glomerular filtration rate. Abnormal proteinuria in pregnant women is defined as protein levels of 300 mg in 24 hours or greater, whereas normal mean levels of protein excretion generally do not exceed 200 mg in a 24-hour period. Although the use of urine protein and creatinine for quantification of proteinuria in pregnant and nonpregnant patients has become more routine and can be used to screen for presence or absence of proteinuria, the 24-hour urine collection is still the gold standard for quantification of proteinuria in pregnant patients.

For the described patient with a family history of adult polycystic kidney disease, a diagnosis of adult polycystic kidney disease would be suspected if the patient had three or more renal cysts noted on ultrasonography. The lack of cysts in a patient younger than age 30 years does not exclude adult polycystic kidney disease, and the patient should be followed accordingly.

The urinalysis does not show any evidence of pyelonephritis or urinary tract infection, such as white cells or leukocyte esterase. Although pyelonephritis should be considered in the differential of flank pain, this patient has no other clinical symptoms that make this the most likely diagnosis.

Cheung KL, Lafayette RA. Renal physiology of pregnancy. Adv Chronic Kidney Dis 2013;20:209–14.

Kuo VS, Koumantakis G, Gallery ED. Proteinuria and its assessment in normal and hypertensive pregnancy. Am J Obstet Gynecol 1992;167:723–8.

4

Postpartum contraception

A 25-year-old patient, gravida 2, para 1, comes to your office for prenatal care at 28 weeks of gestation. She finds it difficult to get to her appointments because she lives in a rural area 50 miles from the clinic and does not have reliable transportation. She is very concerned that she will not be able to return to the clinic easily for her postpartum visit and would like to know if there is a reliable method of contraception that she can receive before she leaves the hospital. She would like to have one more child but not for several years. The best option for this patient is

(A) oral contraceptive pills

(B) depot medroxyprogesterone acetate

*  (C) etonogestrel-releasing subdermal contraceptive implant

(D) levonorgestrel-releasing intrauterine device (IUD)

(E) partner vasectomy

The Centers for Disease Control and Prevention and the American College of Obstetricians and Gynecologists recommend an interpregnancy interval of at least 18 months to 2 years in order to achieve optimal maternal and infant health. Interpregnancy intervals of less than 18 months are associated with low birth weight, premature delivery, and other adverse outcomes. In the United States, almost one half of pregnancies are unplanned, and approximately 35% of women had interpregnancy intervals of less than 18 months. Effective methods for achieving these birth spacing intervals and for reducing unintended pregnancy are long-acting reversible contraceptives.

The etonogestrel-releasing subdermal contraceptive implant provides safe, effective, reversible contraception for up to 3 years. This contraceptive implant can be placed in the hospital immediately postpartum in women who desire it or will have difficulty returning to a clinic for follow-up care. The etonogestrel-releasing subdermal contraceptive implant has a very low failure rate (.05%) with little to no risk of expulsion. Because the described patient is seeking a contraceptive method immediately after delivery and cannot easily return to the clinic for follow-up care, this type of long-acting reversible contraceptive is the best option for her.

Women should be counseled carefully on the adverse effects of the contraceptive implant, which can cause more sustained irregular bleeding than other forms of progestin-only contraceptives. The contraceptive implant does not appear to impede breast milk production; however, studies investigating its effects on lactation have some limitations, and there may be some instances in which breast milk production is affected. Patients should be counseled regarding their intentions to breastfeed and the small possibility of an effect on lactation.

Intrauterine devices, including those that release levonorgestrel, also provide safe, effective, long-acting contraception and can be used in the postpartum period. The optimal timing of placement of an intrauterine device is within 10 minutes of delivery of the placenta for cesarean and vaginal deliveries. However, there is a higher risk of expulsion when placed immediately postpartum when compared with placement at the routine postpartum visit. Training is required to learn to place an IUD effectively. Transcesarean IUDs appear to have an expulsion rate of 5–10%, but after vaginal delivery, expulsion can be 20% or even higher. Overall, placing IUDs in the immediate postpartum time period may be cost effective, despite the high expulsion rate, as long as women are able to access another IUD if an expulsion occurs. Because the etonogestrel-releasing subdermal contraceptive implant does not require additional training to place in the postpartum period and can be placed without risk of expulsion, it is preferred to the levonorgestrel-releasing IUD in this patient.

Oral contraceptive pills and depot medroxyprogesterone acetate injections are not long-acting and require more frequent follow-up to remain effective. Combined oral contraceptive pills contain ethinyl estradiol and should not be given in the first 21 days postpartum because of the risk of venous thromboembolism. Depot medroxyprogesterone acetate requires return visits to clinic. Partner vasectomy is an effective and long-acting method for couples who desire permanent sterilization.

Goldthwaite LM, Shaw KA. Immediate postpartum provision of long–acting reversible contraception. Curr Opin Obstet Gynecol 2015;27:460–4.

Hatcher RA, Trussell J, Nelson AL, Cates W Jr, Kowal D, Policar MS. Contraceptive technology. 20th ed. New York (NY): Ardent Media; 2011.

Optimizing postpartum care. Committee Opinion No. 666. American College of Obstetricians and Gynecologists. Obstet Gynecol 2016;127:e187–92.

Peterson HB. Sterilization [published erratum appears in Obstet Gynecol 2011;117:989]. Obstet Gynecol 2008;111:189–203.

5

Anemia in pregnancy

A 38-year-old woman, gravida 2, para 1, returns to the office for a routine prenatal visit at 30 weeks of gestation. She reports eating 10 cups of ice daily and is found to have a hemoglobin level of 8.5 g/dL, hematocrit level of 26.5%, mean corpuscular volume of 77.3 fL, and a platelet count of 247,000/mm³. The laboratory test that has the highest sensitivity and specificity for diagnosing her anemia is

(A) hemoglobin electrophoresis

(B) iron level

*  (C) serum ferritin level

(D) total iron binding capacity

(E) transferrin saturation

Anemia is defined as a hemoglobin or hematocrit level less than the fifth percentile in a healthy reference population. The Centers for Disease Control and Prevention defines anemia in pregnancy as a hemoglobin value of 11 g/dL in the first and third trimesters and 10.5 g/dL in the second trimester. Pregnancy is associated with a physiologic decrease in hemoglobin concentration for a number of reasons. Failure to meet the increased iron requirement, a blood volume expansion of 50%, and disproportionate expansion of plasma volume compared with increased total red blood cell volume all result in the physiologic anemia seen in pregnancy.

Anemias are classified either as acquired or inherited (Box 5-1). Acquired anemias result from decreased red cell production, increased red cell destruction, or red cell loss. Decreased production may be the result of insufficient intake of nutrients, loss of nutrients because of malabsorption, or impaired bone marrow function. Inherited anemias such as sickle cell anemia or thalassemia refer to genetically inherited abnormalities in hemoglobin formation and are classified as hemoglobinopathies. Some but not all hemoglobinopathies may be detected with a hemoglobin electrophoresis.

Most pregnant women tolerate mild-to-moderate anemia without adverse fetal outcome. However, severe maternal anemia with maternal hemoglobin levels less than 6 g/dL is associated with abnormal fetal oxygenation, nonreassuring fetal heart rate patterns, reduced amniotic fluid volume, and fetal death.

The most common cause of anemia in pregnancy is iron deficiency. Iron deficiency in pregnancy is generally associated with a microcytic, hypochromic anemia with low iron stores, low plasma iron levels, high total iron binding capacity, low serum ferritin levels, and high levels of free erythrocyte protoporphyrin. A laboratory test of the described patient’s serum ferritin level would provide the highest sensitivity and specificity to establish a diagnosis of iron deficiency anemia. A serum ferritin level less than 10–15 mg/dL in a pregnant patient establishes this form of anemia.

Tests of iron levels, total iron binding capacity, and transferrin saturation may be suggestive of iron deficiency anemia but are not as sensitive or specific for this diagnosis. Hemoglobin electrophoresis is a test that differentiates types of hemoglobin and would be used to diagnose other forms of anemia such as sickle cell anemia.

First-line treatment for iron deficiency anemia in pregnancy is oral iron supplementation. For women who are unable to tolerate oral iron or in whom there is an insufficient response, treatment with parenteral iron may be considered. Anaphylactic reactions have been reported in approximately 1% of patients receiving parenteral iron, so caution should be exercised with this therapy. Studies looking at the use of erythropoietin therapy have demonstrated mixed results, so its role in the treatment of severe iron deficiency anemia during pregnancy is unclear. For severe anemia requiring immediate treatment, maternal transfusion should be considered.

BOX 5-1

Anemia Classification

Acquired

• Deficiency anemia (eg, iron, vitamin B12, folate)

• Hemorrhagic anemia

• Anemia of chronic disease

• Acquired hemolytic anemia

• Aplastic anemia

Inherited

• Thalassemias

• Sickle cell anemia

• Hemoglobinopathies (other than sickle cell anemia)

• Inherited hemolytic anemias

Anemia in pregnancy. ACOG Practice Bulletin No. 95. American College of Obstetricians and Gynecologists. Obstet Gynecol 2008;112:201–7.

Pica, the craving and purposeful consumption of nonfood items, has long been associated with pregnancy and is prevalent throughout the world, with descriptions of the condition dating to Hippocrates’ time. Typical nonnutritive substances consumed include soil, chalk, clay, starch, and ice. The etiology of pica is unknown, but it often is associated with iron deficiency anemia. What remains unclear is whether pica develops as a response to the anemia or whether it is causative of the anemia.

Anemia in pregnancy. ACOG Practice Bulletin No. 95. American College of Obstetricians and Gynecologists. Obstet Gynecol 2008;112:201–7.

Hemoglobinopathies in pregnancy. ACOG Practice Bulletin No. 78. American College of Obstetricians and Gynecologists. Obstet Gynecol 2007;109:229–37.

Cunningham FG, Leveno KJ, Bloom SL, Spong CY, Dashe JS, Hoffman BL, et al. In: Williams obstetrics. 24th ed. New York (NY): McGraw Hill Medical; 2014. p. 1101–24.

Fawcett EJ, Fawcett JM, Mazmanian D. A meta-analysis of the worldwide prevalence of pica during pregnancy and the postpartum period. Int J Gynaecol Obstet 2016;133:277–83.

6

Timing of classical cesarean delivery

A 35-year-old woman, gravida 2, para 1, at 37 weeks of gestation presented to triage for decreased fetal movement. Her obstetric history and antenatal course are significant only for a previous classical cesarean delivery. On external uterine monitoring, the patient has a reactive nonstress test and is found to be contracting every 5–7 minutes The cervix is soft, anterior, 2 cm dilated, 30% effaced, and –3 station. The fetus is in vertex presentation. The next best step in management is

(A) administer steroids

*  (B) cesarean delivery

(C) discharge home

(D) hospital observation

Classical cesarean delivery refers to a cesarean delivery with a vertical hysterotomy involving the contractile muscles in the uterine fundus. Included in this group for management purposes are previous T-incision and J-incision hysterotomies. Classical cesarean delivery is a rare occurrence in modern obstetrics but necessary at times for preterm breech deliveries and emergency maneuvers. In a subsequent pregnancy, the risk of uterine rupture in labor is significantly higher for women with a classical cesarean delivery (4–9%) versus a low transverse uterine delivery (less than 1%). Therefore, women with a previous classical cesarean delivery are advised to undergo scheduled repeat cesarean delivery before onset of labor.

Timing of the subsequent cesarean delivery is an important decision. The increased risk of uterine rupture must be balanced with the increased risks to the fetus with early term or late preterm delivery. Elective delivery before 39 weeks of gestation has been discouraged because evidence shows that neonatal morbidity is increased at this stage. An analysis of maternal and neonatal outcomes of all repeat cesarean deliveries during a 4-year span at 19 centers in the United States noted significant differences in outcomes based on gestational age. At 37 weeks of gestation, there were significantly higher maternal adverse outcomes, including the need for blood transfusion and occurrences of pneumonia. In addition, neonatal adverse events at 37 weeks of gestation were more frequent and included respiratory distress, transient tachypnea, and neonatal intensive care unit admissions. Thirty-nine weeks of gestation is the optimal time for elective delivery for the woman and neonate.

At times, waiting until 39 weeks of gestation for delivery risks the onset of labor with elevated risk of uterine rupture. This risk is particularly important for women with prior classical cesarean delivery in whom onset of labor is best avoided to decrease the risk of uterine rupture. Women with a history of low transverse uterine incision are more likely to rupture in active labor, whereas women with previous classical cesarean delivery run a risk of spontaneous uterine rupture without warning signs. This has led to an acceptance of delivery of women with prior classical cesarean delivery before 39 weeks of gestation.

Although the evidence is imprecise, the American College of Obstetricians and Gynecologists’ recommendation for managing women with previous classical cesarean delivery is to perform the repeat cesarean delivery at 36 weeks or 37 weeks of gestation. These patients are not offered a trial of labor. The optimal management of the described patient’s pregnancy is to proceed with repeat cesarean delivery because she is likely in early labor. Because this patient is in labor and at 37 weeks of gestation, steroids are not appropriate. Also, hospital observation and discharge home are not appropriate for this patient.

Chiossi G, Lai Y, Landon MB, Spong CY, Rouse DJ, Varner MW, et al. Timing of delivery and adverse outcomes in term singleton