Williams Obstetrics MCGH420_FM_pi-xviii.indd 1 13/12/21 1:28 PM NOtice Medicine is an ever-changing science. As new research and clinical experience broaden our knowl- edge, changes in treatment and drug therapy are required. he authors and the publisher o this work have checked with sources believed to be reliable in their eorts to provide inormation that is complete and generally in accord with the standards accepted at the time o publication. However, in view o the possibility o human error or changes in medical sciences, neither the authors nor the publisher nor any other party who has been involved in the preparation or publication o this work warrants that the inormation contained herein is in every respect accurate or complete, and they disclaim all responsibility or any errors or omissions or or the results obtained rom use o the inormation contained in this work. Readers are encouraged to conirm the inormation contained herein with other sources. For example and in particular, readers are advised to check the product inormation sheet included in the package o each drug they plan to administer to be certain that the inormation contained in this work is accurate and that changes have not been made in the recom- mended dose or in the contraindications or administration. his recommendation is o particular importance in connection with new or inrequently used drugs. MCGH420_FM_pi-xviii.indd 2 13/12/21 1:28 PM Williams Obstetrics 2 6 t h e d i t i O N F. Gay cunnngam Knn J. Lvno Jo s. da baaa L. hoffman can Y. spong ban M. cay New York Chicago San Francisco Lisbon London Madrid Mexico City Milan New Delhi San Juan Seoul Singapore Sydney oronto MCGH420_FM_pi-xviii.indd 3 13/12/21 1:28 PM Copyright © 2022 by McGraw Hill. All rights reserved. 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Under no circumstances shall McGraw-Hill Education and/or its licensors be liable for any indirect, incidental, special, punitive, consequential or similar damages that result from the use of or inability to use the work, even if any of them has been advised of the possibility of such damages. This limitation of liability shall apply to any claim or cause whatsoever whether such claim or cause arises in contract, tort or otherwise. Editors F. Gay Cnnngham, Md Babaa L. Hffman, Md Proessor, Department o Obstetrics and Gynecology Distinguished Proessor in Obstetrics and Gynecology, University o exas Southwestern Medical Center in Honor o F. Gary Cunningham, M.D. Parkland Health and Hospital System University o exas Southwestern Medical Center Dallas, exas Parkland Health and Hospital System Dallas, exas Kenneh J. Leven, Md Proessor, Department o Obstetrics and Gynecology Cahene Y. spng, Md University o exas Southwestern Medical Center Paul C. MacDonald Distinguished Chair in Obstetrics and Parkland Health and Hospital System Gynecology Dallas, exas Proessor and Chair, Department o Obstetrics and Gynecology Chie, Division o Maternal-Fetal Medicine J s. dahe, Md University o exas Southwestern Medical Center Proessor, Department o Obstetrics and Gynecology Parkland Health and Hospital System University o exas Southwestern Medical Center Dallas, exas Medical Director o Prenatal Diagnosis Parkland Health and Hospital System Ban M. Caey, Md Dallas, exas Proessor, Department o Obstetrics and Gynecology Vice Chair, Obstetrics Director, Division o Maternal-Fetal Medicine University o Alabama at Birmingham v MCGH420_FM_pi-xviii.indd 5 13/12/21 1:28 PM DR. F. GARY CUNNINGHAM Williams Obstetrics Editor of 18th through 26th Editions In the early 1970s, as I was nishing my residency at Charity Ater publication o the 17th edition, these mentors asked me Hospital o New Orleans, the 14th edition oWilliams Obstet- to assume the senior editor role. I was immediately struck by rics was published. Te residents in our program were totally the awesome responsibility o shepherding the book that many enamored with the textbook because it was a clinical manual people called “the bible o obstetrics.” derived rom the editors’ personal experiences and rom con- Over the years, and now as we publish this 26th edition, temporary, evidence-based literature. I refect on the evolution o obstetrics, and hence the com- During my last year, my chairman, Dr. Abe Mickal, invited plexity o sustaining a textbook designed to cover the breadth me to attend a national meeting where I rst met our obste- o obstetrics. As essential elds such as sonography, genetics, tricians who would have an immeasurable impact on my and etal medicine were developed, we enlisted the help o lie—Drs. Jack Pritchard, Paul MacDonald, Norman Gant, extremely talented leaders in their respective elds to ensure and Peggy Whalley. Following that, I was invited to Dallas to that the book adequately presented these innovations. As or spend time at the University o exas Southwestern and Park- my role in this and other editions, I can only promise the read- land Hospital. As I ollowed Dr. Pritchard through Labor & ers that the quality o the book has been oremost in my mind Delivery and his clinical research laboratory, I became hooked and led me to spend literally tens o thousands o hours to on “Parkland Obstetrics” and later that year began a ellowship help prepare the past nine editions. o this end, the editors that was the nascent subspecialty o Maternal–Fetal Medicine. have always strived to put the best product orward because o It also began a lielong riendship with Jack Pritchard that I will the tremendous responsibility that we shoulder regarding the always treasure. care o women and their unborn children. Te textbook has Beginning with the 15th edition o Williams Obstetrics, the been one o the great passions in my lie, and I will miss the author-editors were Drs. Pritchard, MacDonald, and Gant. challenge. v MCGH420_FM_pi-xviii.indd 6 13/12/21 1:28 PM dEdiCAtioN KENNETH LEVENO, MD 1941–2020 Dr. Kenneth Leveno was a vocal and stalwart deender o evi- Indeed, his contributions to these programs were reverently dence-based obstetrics. Sadly, he passed away in May 2020. reerred to by us asParkland Obstetrics. Ken joined the Department o Obstetrics & Gynecology Ken Leveno’s leadership extended well beyond the hospital at the University o exas Southwestern ater completing a that he loved. He was a leader in American obstetrics by his Maternal–Fetal Medicine ellowship in 1978. In 1984, he was dening o clinical research. Trough his hundreds o peer- appointed Chie o Obstetrics at Parkland Memorial Hospi- reviewed publications, his clinical opinions, and his willingness tal—a role in which he served or the next 20 years. During to engage in national debates, he helped shape obstetrical prac- that time and aterwards, he worked tirelessly to achieve a level tices worldwide. In 1993, Ken began serving as an editor or o excellence in obstetrical care or indigent women o Dallas Williams Obstetrics—a task that he regarded as a privilege and County. His inspiring leadership and innovations raised the a responsibility. He co-authored the 19th through the current quality o care at the community obstetrics clinics, the high- 26th editions. Last and importantly, he mentored the careers risk prenatal clinics at Parkland, and the inpatient units, which o many Maternal–Fetal Medicine ellows and young aculty include the Obstetrical riage Unit, Labor & Delivery, post- who have gone on to achieve national reputations in the care o partum wards, and the High-Risk Pregnancy Unit. Early on, women. Ken will be greatly missed. he also designed a computerized database to measure quality Te Editors indicators and provide an underpinning or clinical research. v MCGH420_FM_pi-xviii.indd 7 13/12/21 1:28 PM AssoCiAtE Editors Mala s. Mahen, Phd shvan Pael, Md Proessor, Department o Obstetrics and Gynecology and Associate Proessor, Department o Obstetrics and Gynecology Green Center or Reproductive Biological Sciences University o exas Southwestern Medical Center University o exas Southwestern Medical Center Assistant Quality Oicer, Health Systems Aairs Dallas, exas Medical Director o Obstetrics, William P. Clements Jr. University Hospital dav B. Neln, Md Parkland Health and Hospital System Dedman Family Scholar in Clinical Care Dallas, exas Associate Proessor, Department o Obstetrics and Gynecology dane M. twckle, Md, FACr University o exas Southwestern Medical Center Dr. Fred Bonte Proessorship in Radiology Chie o Obstetrics Proessor, Department o Radiology and o Obstetrics and Parkland Health and Hospital System Gynecology Dallas, exas Vice Chairman at Large or Radiology University o exas Southwestern Medical Center Medical Director o Obstetrics and Gynecology Ultrasonography Parkland Health and Hospital System Dallas, exas CoNtriButiNG AutHors Emly H. Ahka, Md Weke ta, Md Assistant Proessor, Department o Obstetrics and Gynecology Proessor, Department o Anesthesiology and Pain Management University o exas Southwestern Medical Center University o exas Southwestern Medical Center Medical Director o Perinatal Inectious Diseases Parkland Health and Hospital System Parkland Hospital and Hospital System Dallas, exas Dallas, exas C. Ewa Well, Md dnal d. Mcine, Phd Proessor, Department o Obstetrics and Gynecology Biostatistician University o exas Southwestern Medical Center Proessor, Department o Obstetrics and Gynecology Parkland Health and Hospital System University o exas Southwestern Medical Center Dallas, exas Dallas, exas Mya H. Wyckff, Md Wlme Men, Md Proessor, Department o Pediatrics Assistant Proessor, Department o Obstetrics and Gynecology University o exas Southwestern Medical Center University o exas Southwestern Medical Center Director, Newborn Resuscitation Services Parkland Health and Hospital System Parkland Health and Hospital System Dallas, exas Dallas, exas dav M. owen, Md, Phd Assistant Proessor, Department o Obstetrics and Gynecology University o exas Southwestern Medical Center Parkland Health and Hospital System Dallas, exas v MCGH420_FM_pi-xviii.indd 8 13/12/21 1:28 PM PrEFACE Over its 26 editions, Williams Obstetrics has aimed to serve o accomplish our teaching goals, the text has been practicing obstetricians and midwives in the bedside care o updated with more than 3000 new literature citations through their patients. With its detailed explanations o disease patho- 2021. Many o the nearly 900 igures are new, and these physiology and treatment undamentals, it provides a bedrock graphs, sonograms, magnetic resonance images, photographs, text or residents who are training in Obstetrics or in Family photomicrographs, and data graphs are all in vivid color. Medicine specialties. Fellows in Maternal–Fetal Medicine will Much o the original artwork was rendered by our own medi- beneit rom its additional discussions o complicated pathology cal illustrators. and management. Last, Williams Obstetrics can aid specialists As beore, we continue to incorporate contemporaneous who act as consultants or gravidas with non-pregnancy-related guidelines rom proessional and academic organizations such disorders. Speciically, each chapter in Section 12 ocuses on a as the American College o Obstetricians and Gynecologists, speciic organ system, the normal physiological changes and the Society or Maternal–Fetal Medicine, the Centers or requent disorders o that system in pregnancy, and suitable Disease Control and Prevention, the National Institutes o treatment options. Health, and other authoritative sources. Many o these data are For this 26th edition, we continue to present the detailed distilled into nearly 100 tables, in which inormation has been staples o basic obstetrics such as maternal anatomy and physi- arranged in an easy read-and-use ormat. In addition, several ology, preconceptional and prenatal care, labor, delivery, and diagnostic and management algorithms are available to quickly the puerperium. hese accompany detailed discussions o guide practitioners. Although we strive to cite numerous obstetrical complications exempliied by preterm labor, hemor- sources and provide multiple evidence-based options or such rhage, hypertension, and many more. o emphasize the “M” in management schemes, we also include our own clinical experi- Maternal–Fetal Medicine, we continue to instruct on the many ences drawn rom the large obstetrical service at Parkland medical and surgical disorders that can complicate pregnancy. Hospital. We are convinced that these are disciplined examples And, our second patient—the etus—has accrued especial o evidence-based obstetrics but quickly acknowledge that they attention with an entire section devoted to diagnosis and treat- do not constitute the sole method o management. ment o etal disorders. For all o these, we once again empha- size the science-based practice o clinical obstetrics. Expert F. Gary Cunningham clinical pearls add depth to these discussions and are written or Kenneth J. Leveno busy practitioners—those “in the trenches.” o integrate all Jodi S. Dashe our content, the reader o one chapter may be reerred to a di- Barbara L. Homan erent chapter that contains complementary content. his Catherine Y. Spong oers a more global understanding o a given topic. Brian M. Casey x MCGH420_FM_pi-xviii.indd 13 13/12/21 1:28 PM