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Obstetric Clinical Algorithms

Second Edition

Errol R. Norwitz, M.D., Ph.D., M.B.A.

Louis E. Phaneuf Professor of Obstetrics & Gynecology
Tufts University School of Medicine
Chairman., Department of Obstetrics & Gynecology
Tufts Medical Center
Boston, USA

George R. Saade, M.D.

University of Texas Medical Branch
Galveston, TX, USA

Hugh Miller, M.D.

Department of Obstetrics and Gynecology
University of Arizona
Tuscon, AZ, USA

Christina M. Davidson, M.D.

Baylor College of Medicine
Ben Taub Hospital
Houston, TX, USA

 

 

 

 

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Preface

Recent advances in obstetrical practice and research have resulted in significant improvements in maternal and perinatal outcome. Such improvements carry with them added responsibility for the obstetric care provider. The decision to embark on a particular course of management simply because “that’s the way we did it when I was in training” or because “it worked the last time I tried it” is no longer acceptable. Clinical decisions should, wherever possible, be evidence‐based. Evidence‐based medicine can be defined as “the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients” [1]. In practice, evidence‐based medicine requires expertise in retrieving, interpreting, and applying the results of scientific studies and in effectively communicating the risks and benefits of different courses of action to patients. This daunting task is compounded by the fact that the volume of medical literature is doubling every 10–15 years. Even within the relatively narrow field of Obstetrics & Gynecology, there are more than five major publications each month containing an excess of 100 original articles and 35 editorials. How then does a busy practitioner maintain a solid foundation of up‐to‐date knowledge and synthesize these data into individual management plans? New information can be gleaned from a variety of sources: the advice of colleagues and consultants, textbooks, lectures and continuing medical education courses, original research and review articles, and from published clinical guidelines and consensus statements. The internet has created an additional virtual dimension by allowing instant access to the medical literature to both providers and patients. It is with this background in mind that we have written Obstetric Clinical Algorithms: Management and Evidence, 2nd edition.

Standardization of management reduces medical errors and improves patient safety and obstetrical outcomes [2,3]. In this text, we have developed a series of obstetric algorithms based on best practice to mimic the decision‐making processes that go on in our brains when faced with a vexing clinical problem. To further facilitate decision‐making, we have superimposed “levels of evidence” as defined by the report of the US Preventive Services Task Force (USPSTF) of the Agency for Healthcare Research Quality, an independent panel of experts appointed and funded by the US government to systematically review evidence of effectiveness and develop recommendations for clinical preventive services [4]. The table below summarizes the ‘levels of evidence’ used in this text.

‘Levels of Evidence’ used in Obstetric Clinical Algorithms: Management and Evidence, 2nd edition:

Color keyLevels of evidence available on which to base recommendations*Recommendation/suggestions for practice
Red boldLevel I/II‐1Definitely offer or provide this service
Red regularLevel II‐1/II‐2Consider offering or providing this service
Red italicsLevel II‐2/II‐3/IIIDiscuss this service, but insufficient evidence to strongly recommend it
Black regularLevel II‐3/IIIInsufficient evidence to recommend this service, but may be a reasonable option

* Levels of evidence are based on the ‘hierarchy of research design’ used in the report of the 2nd US Preventive Services Task Force:

Level I: Evidence obtained from at least one properly powered and conducted randomized controlled trial (RCT); also includes well‐conducted systematic review or meta‐analysis of homogeneous RCTs.

Level II‐1: Evidence obtained from well‐designed controlled trials without randomization.

Level II‐2: Evidence obtained from well‐designed cohort or case‐control analytic studies, preferably from more than one center or research group.

Level II‐3: Evidence obtained from multiple time series with or without the intervention; dramatic results from uncontrolled trials might also be regarded as this type of evidence.

Level III: Opinions of respected authorities, based on clinical experience; descriptive studies or case reports; or reports of expert committees.

Obstetric care providers can be broadly divided into two philosophical camps: those who believe that everything possible should be offered in a given clinical setting in the hope that something may help (also called the “we don’t have all the information we need” or “might as well give it, it won’t do any harm” group) and those who hold out until there is consistent and compelling scientific evidence that an individual course of action is beneficial and has a favorable risk‐to‐benefit ratio (sometimes referred to as “therapeutic nihilists”). As protagonists of the latter camp, we argue that substantial harm can be done—both to individual patients and to society as a whole—by implementing management plans that have not been the subject of rigorous scientific investigation followed by thoughtful introduction into clinical practice. In Obstetric Clinical Algorithms: Management and Evidence, 2nd edition, we provide evidence‐based management recommendations for common obstetrical conditions. It is the sincere hope of the authors that the reader will find this book both practical and informative. However, individual clinical decisions should not be based on medical algorithms alone, but should be guided also by provider experience and judgment.

Errol R. Norwitz
George R. Saade
Hugh Miller
Christina M. Davidson

  1. 1. Sackett DL, Rosenberg WM, Gray JA et al. Evidence based medicine: what it is and what it isn’t. BMJ 1996;312:71–72.
  2. 2. Pettker CM, Thung SF, Norwitz ER et al. Impact of a comprehensive patient safety strategy on obstetric adverse events. Am J Obstet Gynecol 2009;200:492 (e1‐8).
  3. 3. Clark SL, Belfort MA, Byrum SL et al. Improved outcomes, fewer cesarean deliveries, and reduced litigation: results of a new paradigm in patient safety. Am J Obstet Gynecol 2008;199:105 (e1‐7).
  4. 4. Report of the US Preventive Services Task Force (USPSTF). Available at http://www.ahrq.gov/clinic/uspstfix.htm (last accessed on 19 February 2016).

List of Abbreviations

ABG
arterial blood gas
AC
abdominal circumference
ACA
anticardiolipin antibody
ACE
angiotensin‐converting enzyme
ACIP
Advisory Committee on Immunization Practices
ACOG
American College of Obstetricians and Gynecologists
AED
antiepileptic drug
AED
automated external defibrillator
AFE
amniotic fluid embolism
AFI
Amniotic Fluid Index
AGA
appropriate for gestational age
AGC
atypical glandular cells
AHA
American Heart Association
AIDS
acquired immune deficiency syndrome
AIS
adenocarcinoma in situ
AMA
advanced maternal age
ANA
antinuclear antibodies
APLAS
antiphospholipid antibody syndrome
ARB
angiotensin receptor blockers
ARDS
acute respiratory distress syndrome
ART
assisted reproductive technology
ART
antiretroviral therapy
ARV
antiretroviral
ASCUS
atypical squamous cells of undetermined significance
ATP
alloimmune thrombocytopenia
AZT
azidothymidine
BCG
Bacillus Calmette‐Guérin
BMI
body mass index
BP
blood pressure
BPD
biparietal diameter
BPP
biophysical profile
BUN
blood urea nitrogen
BV
bacterial vaginosis
CAOS
chronic abruption‐oligohydramnios sequence
CBC
complete blood count
CDC
Centers for Disease Control and Prevention in the U.S.
CFU
colony‐forming units
CI
cervical insufficiency
CL
cervical length
CMV
cytomegalovirus
CO
cardiac output
CPD
cephalopelvic disproportion
CST
contraction stress test
CT
computed tomography
CTG
cardiotocography
CVS
chorionic villous sampling
CXR
chest radiograph
DCIS
ductal carcinoma in situ
DES
diethylstilbestrol
DIC
disseminated intravascular coagulopathy
DKA
diabetic ketoacidosis
DVT
deep vein thrombosis
ECC
endocervical curettage
ECG
electrocardiography
ECT
electroconvulsant therapy
ECV
external cephalic version
EDD
estimated date of delivery
EFM
electronic fetal monitoring
EFW
estimated fetal weight
ELISA
enzyme‐linked immunosorbant assay
EMB
endometrial biopsy
FEV1
forced expiratory volume in one second
fFN
fetal fibronectin
FFP
fresh frozen plasma
FL
femur length
FSE
fetal scalp electrode
FTA‐ABS
fluorescent treponemal antibody absorption
FVC
forced vital capacity
GBS
Group B β‐hemolytic streptococcus
GCT
glucose challenge test
GDM
gestational diabetes mellitus
GFR
glomerular filtration rate
GLT
glucose load test
GTT
glucose tolerance test
HBsAb
anti‐hepatitis B surface antibodies
HBsAg
hepatitis B surface antigen
HBIg
hepatitis B immunoglobulin
HBV
hepatitis B virus
HC
head circumference
hCG
human chorionic gonadotropin
HEG
hyperemesis gravidarum
HELLP
hemolysis, elevated liver enzymes, low platelets
HGSIL
high‐grade squamous intraepithelial lesions
HIE
hypoxic ischemic encephalopathy
HIV
human immunodeficiency virus
HPV
human papilloma virus
HSV
herpes simplex virus
IAI
intraamniotic infection
ICP
intrahepatic cholestasis of pregnancy
ICU
intensive care unit
IgA
immunoglobulin A
IgG
immunoglobulin G
IGRA
interferon gamma release assay
INH
isoniazid
IOL
induction of labor
IOM
Institute of Medicine
ITP
immune thrombocytopenic purpura
IUFD
intrauterine fetal demise
IUGR
intrauterine growth restriction
IUPC
intrauterine pressure catheter
IV
intravenous
IVIG
intravenous immune globulin
LAC
lupus anticoagulant
LEEP
loop electrosurgical excision procedure
LFT
liver function test
LGA
large‐for‐gestational age
LGSIL
low‐grade squamous intraepithelial lesions
LMP
last menstrual period
LMWH
low molecular weight heparin
LTL
laparoscopic tubal ligation
MCA
middle cerebral artery
MDI
metered dose inhaler
MFM
maternal‐fetal medicine
MFPR
multifetal pregnancy reduction
MHA‐TP
microhemagglutination assay for antibodies to T. pallidum
MoM
multiples of the median
MRCP MR
cholangiopancreatography
MRI
magnetic resonance imaging
MS‐AFP
maternal serum α‐fetoprotein
MTX
methotrexate
NIDDM
non‐insulin‐dependent diabetes mellitus
NIPT
noninvasive prenatal testing
NR‐NST
non‐reactive NST
NSAIDs
non‐steroidal anti‐inflammatory drugs
NST
non‐stress testing
NT
nuchal translucency
NTD
neural tube defect
NVP
nausea and vomiting in pregnancy
OCT
oxytocin challenge test
OST
oxytocin stimulation test
PCOS
polycystic ovarian syndrome
PCP
pneumocystis carinii pneumonia
PCR
polymerase chain reaction
PE
pulmonary embolism
PEFR
peak expiratory flow rate
PKU
phenylketonuria
po
per os (orally)
POC
products of conception
PPD
purified protein derivative
PPH
postpartum hemorrhage
pPROM
preterm PROM
PRBC
packed red blood cell
PROM
premature rupture of membranes
PTT
partial thromboplastin time
PTU
propylthiouracil
PUBS
percutaneous umbilical blood sampling
q
every
QFT‐GIT
QuantiFERON®‐TB Gold In‐Tube test
RhoGAM
anti‐Rh[D]‐immunoglobulin
R‐NST
reactive NST
RPL
recurrent pregnancy loss
RPR
rapid plasma reagin
SC
subcuticular
SGA
small for gestational age
SIADH
syndrome of inappropriate ADH secretion
SLE
systemic lupus erythematosus
SMA
spinal muscular atrophy
SSI
surgical site infection
STI
sexually transmitted infection
TB
tuberculosis
TBG
thyroxine‐binding globulin
TFT
thyroid function test
TORCH
toxoplasmosis, rubella, cytomegalovirus, herpes
TPPA
T. pallidum particle agglutination assay
TRAP
twin reverse arterial perfusion
TST
tuberculin skin testing
TTP/HUS
thrombotic thrombocytopenic purpura/hemolytic uremic syndrome
TTTS
twin‐to‐twin transfusion syndrome
UA C&S
urine culture and sensitivity
UDCA
ursodeoxycholic acid
UFH
unfractionated heparin
UTI
urinary tract infection
VAS
vibroacoustic stimulation
VBAC
vaginal birth after cesarean
VDRL
Venereal Disease Research Laboratory
VL
viral load
V/Q
ventilation‐perfusion
VTE
venous thromboembolism
ZDV
zidovudine

SECTION 1
Preventative Health

 

 

 

 

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1
Abnormal Pap Smear in Pregnancy

Algorithm from determining screening frequency to checking of Pap smear for normal, unsatisfactory, and abnormal cytologies.
  1. Recommendations for screening and management of abnormal cervical cytology in pregnancy follow from the general guidelines for screening onset and frequency that were updated in 2012 to reflect the recommendations of the American Cancer Society ACOG, and U.S. Preventive Services Task Force for detection of cervical cancer. Routine pap screening should not be collected until age 21 regardless of first vaginal intercourse. The risk of severe dysplasia or cancer is very low among adolescents, but they should be encouraged to receive human papilloma virus (HPV) vaccination and counseled about safe sex practices to limit exposure to sexually transmitted infections. Women between the age of 21–29 years should be screened with cervical cytology alone. Women >30 years of age should be screened with cytology and HPV testing every 5 years (or with cytology alone every 3 years). Women with a history of cervical cancer, HIV or other risk factors (such as immunocompromise) should continue annual screening. These guidelines and the associated algorithm are based on a large database of patients including adolescents who were managed using former criteria in the Kaiser Healthcare system. The American Society of Colposcopy and Cervical Pathology (ASCCP) has developed an updated free App that can assist with the current recommendations.
  2. Women who have risk factors for cervical/vaginal cancer (such as a history of in utero diethylstilbestrol (DES) exposure, HIV, women who are immunocompromised, or those on chronic steroids) should be screened annually.
  3. Women aged 21–29 with normal cytology but absent or insufficient endocervical–transformation zone elements can continue regular screening, which should not include HPV testing. In women >30 years with a similar cytology result, HPV testing is recommended. Positive HPV results should prompt repeat co‐testing in one year, unless the HPV genotype is known to be 16 or 18, in which case, immediate colposcopy is recommended. A negative HPV result in a woman >30 years means that she can go back to routine screening.
  4. Unsatisfactory cytology is less common in current practice with the use of liquid‐based media for cervical screening. Insufficient squamous cells to detect epithelial abnormalities generally arise from blood or inflammation that obscures the result. Repeat cytology is recommended in 2–4 months. Colposcopy can be considered in women >30 years with positive HPV, and is recommended in those women who have had two consecutive unsatisfactory cytology test results.
  5. Women should always be informed of an abnormal Pap result by her physician or another healthcare professional who can answer basic questions and allay anxiety. Verbal notification should be followed with written information and clear recommendations for follow‐up. Additionally, if there is evidence of infection along with cellular abnormalities, the infection should be treated.
  6. The 2012 criteria substantially clarify the management of ASCUS, which is guided by HPV test results whether obtained reflexively or as a co‐test. The management in pregnancy differs only in that colposcopy and endocervical curettage (ECC) should be deferred until 6 weeks postpartum unless a CIN 2+ lesion is suspected. Women >25 years old with a negative HPV test should be returned to a regular three‐year follow‐up cycle. Following pregnancy colposcopy is recommended in women who are HPV+ with annual co‐test follow‐up. Similarly, an endocervical curettage (ECC) should be obtained whenever possible and excisional procedures should be avoided to prevent over‐treatment. In women 21–24 years old, cytology should be repeated in one year. A positive HPV result does not change the recommended follow‐up, but a negative result should return the woman to a three‐year follow‐up cycle.
  7. Atypical squamous cells cannot exclude high‐grade squamous intraepithelial lesions (HSIL) (ASC‐H), which is associated with a higher risk of CIN 3+ regardless of patient age and a five‐year invasive cancer risk of 2% regardless of HPV status. That said, HPV is highly correlated with ASC‐H, but the cancer risk demands that all women receive immediate colposcopy, including those 21–24 years of age. Colposcopy with directed biopsies of any area that might be concerning for micro invasion should be done by a highly trained clinician. Treatment should be dictated by histologic evaluation of the biopsied lesions.
  8. Atypical glandular cells (AGC) or adenocarcinoma in situ (AIS) warrant aggressive investigation and close follow‐up. Although the risk of cancer is lower in younger age groups, women >30 years have a 9% risk of CIN3+ and 2% risk of invasive cancer. All such women of all ages should have antenatal colposcopy with 6‐weeks postpartum follow‐up to include colposcopy, ECC and endometrial biopsy (EMB). Subsequent treatment and follow‐up are dictated by the biopsy results, maternal age, and the histologic evaluation of the glandular elements.
  9. Approximately 60% of low‐grade squamous intraepithelial lesions (LGSIL) will regress spontaneously without treatment depending on the age of the patient, HPV status, and HPV genotype. For women >25 years old in whom HPV testing is negative, repeat co‐testing in ome year is preferred but colposcopy is acceptable. However, if the HPV is positive, then colposcopy is preferred. If colposcopy is not part of the initial evaluation, subsequent co‐testing needs to be entirely normal to allow patients to return to three‐year follow‐up. Any abnormality at the one‐year follow‐up visit should result in colposcopy. In women 21–24 years old, annual repeat cytology without HPV testing is preferred and colposcopy should be avoided unless the results recur for two consecutive years or if one of the following lesions is detected: ASC‐H, AGC, or HSIL. Pregnant women >25 years old with low‐grade squamous intraepithelial lesions should undergo immediate colposcopy without ECC, while those 21–24 years old should be evaluated postpartum.
  10. High‐grade squamous intraepithelial lesions (HGSIL) are associated with a 60% risk of CIN2+ and a 2% risk of invasive cervical cancer. Immediate colposcopy with directed biopsies of any area that might be concerning for micro invasion is recommended, regardless of maternal age. The antepartum diagnosed of HGSIL should prompt a 6‐weeks postpartum follow‐up colposcopy with ECC and treatment as dictated by the biopsy results. If diagnosed early in pregnancy, colposcopy can be repeated every 12 weeks. Treatment during pregnancy should be reserved for invasive carcinoma and should be managed in concert with a gynecologic oncologist.

2
Immunization

Algorithm illustrating the immunization in women of childbearing age, with three categories for non-pregnant, pregnant, travelling women.
  1. Immunization can be active (vaccines, toxoid) or passive (immunoglobulin, antiserum/antitoxin). In active immunity, the immune response is induced by wild infection or vaccination, which is generally robust and long‐lasting. As such, subsequent exposure to the vaccine‐preventable infection will result in the release of antibodies and the prevention of illness. In passive immunity, antibodies are acquired passively through maternal transfer across the placenta or breast milk or through the receipt of exogenous immunoglobulins. Protection is temporary and fades within a few weeks to months. The immune system of the recipient is therefore not programmed, and subsequent exposure to vaccine‐preventable infections can lead to active infection.
  2. Vaccination works by inducing antibodies in recipients that protects them against infection after future exposure to specific disease‐causing microbes. The level of protection varies according to the strength and durability of the immune response induced by the vaccine as well as the virulence, prevalence, and ease of transmission of the infection itself. Vaccination programs may have different goals: (i) to protect at‐risk individuals (e.g., meningococcal disease); (ii) to establish control by minimizing the overall prevalence of the infection (e.g., measles, varicella); or (iii) to attain global elimination of an infection (e.g., neonatal tetanus, polio).
  3. Vaccination in pregnancy is of benefit and at times poses concern relative to the increased vulnerability of the mother and fetus. Inactivated vaccines are approved for use in pregnancy. The inactivated influenza vaccine should be given to all pregnant women during the influenza season (October through May in the northern hemisphere), regardless of gestational age. It is clear that there are significant maternal benefits including fewer cases of fever and respiratory illness and substantial neonatal protection through the transplacental passage of antibodies that provide months of protection at a time when the infant is vulnerable and could not be directly vaccinated. However, live‐attenuated vaccines (including rubella, MMR, varicella) are not recommended for pregnant women despite the fact that no cases of congenital anomalies have been documented. Exceptions include yellow fever and polio, which can be given to pregnant women when traveling to high prevalence areas. In addition, women should be advised not to get pregnant within 1 month of receiving a live‐attenuated vaccine. The live‐attenuated influenza vaccine is available as an intranasal spray, which is considered safe in the postpartum period. Vaccines considered safe in pregnancy include tetanus, diphtheria, hepatitis B, and influenza. Tetanus immunization during pregnancy is a common strategy used in the developing world to combat neonatal tetanus
  4. Risk factors for specific vaccine‐preventable illnesses include:
    • illicit drug users (hepatitis A and B, tetanus)
    • men who have sex with men (hepatitis A) or >1 sexual partner in the past 6 months (hepatitis A, human papilloma virus)
    • travel to or immigration from areas where infection is endemic (hepatitis A and B, measles, meningococcus, rubella, tetanus, varicella)
    • healthcare workers (hepatitis B, influenza, varicella)
    • nursing home residents (meningococcus, pneumococcus, varicella) or ≥50 years of age (influenza)
    • chronic medical diseases: diabetes, asthma, HIV, liver disease and/or renal disease (hepatitis A, influenza, pneumococcus)
    • adults who have had their spleens removed (meningococcus, pneumococcus)
    • accidental or intentional puncture wounds (tetanus)
  5. One of the ongoing controversies about vaccination in pregnancy is whether vaccines containing thimerosal pose a risk to the fetus. Thimerosal is a mercury‐containing preservative that has been used in multidose vaccines since the 1930s. Although there has been concern about the cumulative levels of mercury, the current scientific evidence does not consider thimerosal to be associated with adverse outcomes in children exposed in utero. The Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP) does not recommend avoiding thimerosal containing vaccines. Although the ACIP does not recommend any specific formulation, there are newer trivalent and quadrivalent influenza vaccines (containing two A and two B influenza strains) that are available for use. The following adult vaccines are thimerosal‐free: Tdap (but not Td), Recombivax hepatitis B vaccine (but not Engerix‐B), and some influenza vaccines (Fluzone with no thimerosal).
  6. Tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine (Tdap) may be given at any time of pregnancy or the postpartum period but ideally is administered between 27–36 weeks to confer the best passive immunity through the transfer of antibodies to the fetus. This recommendation has developed to address the significant impact of pertussis disease in the newborn.

3
Preconception Care

Algorithm illustrating the annual heath assessment of women of childbearing age through history, physical examination, and laboratory testing, and then by assessment of risk/recommendations.
  1. Fetal organogenesis occurs before most women are aware that they are pregnant. As such, the ideal time for addressing primary prevention of reproductive health risks is in the preconception period. Since approximately half of all pregnancies in the United States are unplanned, all women of reproductive age should be considered candidates for discussion of these issues.
  2. Discuss social, financial, and psychological issues in preparation for pregnancy.
  3. Maternal alcohol use is the leading known cause of congenital mental retardation and is the leading preventable cause of birth defects in the Western world. An accurate drinking history is best elicited using a tool that employs standardized screening questions (such as the CAGE questionnaire). The adverse effects of alcohol may be compounded with abuse of other drugs. Cigarette smoking, cocaine, and other drug use should be included in the history. Patients at risk should be provided education, contraceptive counselling, and referral for treatment as necessary.
  4. Screen for domestic violence. Be aware of available state and local resources and state laws regarding mandatory reporting. Risk increases with pregnancy. Domestic violence is not isolated to any particular risk group in pregnancy; it cuts across socio‐economic and ethnic lines.
  5. Take an occupational history that will allow assessment of workplace risks to the pregnancy. Elicit information about any exposures to hazardous materials or biologic hazards (HIV, cytomegalovirus (CMV), toxoplasmosis) and review the use of safety equipment. Talk to patients about the appropriate and correct use of seat belts while in a moving vehicle.
  6. Counsel patients with a history of preeclampsia, placental abruption, unexplained fetal death, or severe intrauterine growth restriction (IUGR) about the risks of recurrence. Low‐dose aspirin starting at the end of the first trimester is recommended to prevent recurrent preeclampsia. The use of low‐dose aspirin, calcium supplementation, and/or anticoagulation for women with documented inherited thrombophilias to prevent adverse pregnancy outcome is controversial, and cannot be routinely recommended.
  7. Personal and family histories should be examined for evidence of genetic diseases. Genetic testing is available to determine a patient’s carrier status for some autosomal recessive conditions such as Tay–Sachs, Canavan disease, sickle cell disease, and the thalassemias. Consider referral for further genetic counselling if patients are at high risk. ACOG currently recommends that all couples be offered prenatal testing for cystic fibrosis. ACMG (but not ACOG) recommends that all couples also be offered genetic testing for spinal muscular atrophy (SMA).
  8. Emphasize the importance of nutrition. Assess appropriateness of patient’s weight for height, special diets and nutrition patterns such as vegetarianism, fasting, pica, bulimia, and vitamin supplementation. Recommend folic acid supplementation as necessary: 0.4 mg per day for all pregnant women or women considering pregnancy, 4.0 mg per day if the woman has a personal/family history of a child with a neural tube defect or is on anticonvulsant medications (especially valproic acid). Counsel to avoid oversupplementation (such as vitamin A). Review the recommendations on dietary fish ingestion (<12 ounces per week of cooked fish) to minimize mercury intake, and steps for prevention of listeriosis (avoiding raw or undercooked meat/fish, unpasteurized milk and soft cheeses, unwashed fruit and vegetables) and toxoplasmosis (exposure to cat feces).
  9. A thorough immunization history should be obtained that addresses vaccination. Women should be tested for immunity to rubella and vaccinated prior to pregnancy if not immune. Women without a history of chickenpox (varicella) should be tested and offered vaccination prior to pregnancy. Hepatitis B vaccination should be offered to all women at high risk, and screening for other sexually transmitted infections should be offered as needed. The U.S. Centers for Disease Control and Prevention (CDC) recommends that pregnancy be delayed for at least 1 month after receiving a live‐attenuated vaccine (such as MMR, varicella, live‐attenuated influenza, BCG).
  10. Discuss birth spacing and the options available for postpartum contraception.
  11. Effects of the pregnancy on any medical conditions for both mother and fetus should be discussed. Pregnancy outcomes can be improved by optimizing control of chronic medical conditions prior to pregnancy (such as glycemic control in patients with diabetes and blood pressure control in patients with hypertension). Medications should be reviewed, and patients counselled regarding alternatives that may be safer in pregnancy. Close communication with the patient’s primary care and subspecialty physicians should always be maintained.

4
Prenatal Care1

Algorithm of initial prenatal visit for low-risk pregnancy and high-risk pregnancy. Low-risk pregnancy is followed by regular follow-up prenatal visits while high-risk is followed by maternal and fetal tests.
  1. The goal of prenatal care is to promote the health and well‐being of the pregnant woman, fetus, infant, and family up to 1 year after birth. To achieve these aims, prenatal care must be available and accessible. The three major components are: (i) early and continuing risk assessment, including preconception assessment (see Chapter 3, Preconception Care); (ii) continued health promotion; and (iii) both medical and psychosocial assessment and intervention.
  2. Routine prenatal tests that should be completed for all pregnant women include complete blood count (CBC), blood group type and screen (Rh status), rubella serology, HIV, hepatitis B, syphilis serology (VDRL/RPR), Pap smear, cystic fibrosis (CF) carrier status, chlamydia/gonorrhea cultures, and urine culture and sensitivity (UA C&S).
  3. Approximately 20% (1 in 5) of pregnancies are considered high risk. Risk factors for adverse pregnancy outcome may exist prior to pregnancy or develop during pregnancy or even during labor (examples are listed below, although this list should not be regarded as comprehensive).
  4. The frequency and timing of prenatal visits will vary depending on the risk status of the pregnant woman and her fetus. In low‐risk women, prenatal visits are typically recommended q 4 weeks to 28 weeks, q 2 weeks to 36 weeks, and then weekly until delivery.
  5. See Chapter 12 (Preeclampsia).
  6. See Chapter 53 (Prenatal diagnosis).
  7. See Chapter 10 (Gestational diabetes mellitus)
  8. See Chapter 24 (GBS)
  9. See Chapter 55 (Screening for preterm birth)

High‐Risk Pregnancies

Maternal factors
  • Pre‐existing medical conditions (diabetes, chronic hypertension, cardiac disease, renal disease, pulmonary disease)
  • Preeclampsia
  • Gestational diabetes
  • Morbid obesity
  • Extremes of maternal age
  • Active venous thromboembolic disease
  • Poor obstetric history (prior preterm birth, preterm PROM, stillbirth, IUGR, placental abruption, preeclampsia, recurrent miscarriage)
Fetal factors
  • Fetal structural or chromosomal anomaly
  • History of a prior baby with a structural or chromosomal anomaly
  • Family or personal history of a genetic syndrome
  • Toxic exposure (to environmental toxins, medications, illicit drugs)
  • IUGR
  • Fetal macrosomia
  • Multiple pregnancy (esp. if monochorionic)
  • Isoimmunization
  • Intra‐amniotic infection (chorioamnionitis)
  • Nonreassuring fetal testing
Uteroplacental factors
  • Preterm premature rupture of membranes
  • Unexplained oligohydramnios
  • Large uterine fibroids (esp. if submucosal)
  • Prior cervical insufficiency
  • Prior uterine surgery (especially prior “classic” hysterotomy)
  • Placental abruption
  • Placenta previa
  • Uterine anomaly (didelphys, septate)
  • Abnormal placentation (placenta accreta, increta or percreta)
  • Vasa previa

SECTION 2
Maternal Disorders

 

 

 

 

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5
Antiphospholipid Antibody Syndrome

Algorithm of antiphospholipid antibody syndrome, from confirmation of diagnosis with two branches for 2 elements (correct clinical setting and confirmatory serologic testing) leading to 3 different treatments.
  1. Antiphospholipid antibody syndrome (APLAS) is an autoimmune disease characterized by the presence in the maternal circulation of one or more autoantibodies against membrane phospholipid as well as one or more specific clinical syndromes. It is an acquired rather than an inherited condition. As such, it cannot explain a family history of venous thromboembolism (VTE). A significant family history of VTE should prompt testing to exclude inherited thrombophilias, including factor V Leiden mutation, prothrombin gene mutation, and protein S, protein C, and antithrombin deficiency.
  2. The diagnosis of APLAS requires two distinct elements: (i) the correct clinical setting; and (ii) confirmatory serologic testing. Approximately 2–4% of healthy pregnant women will have circulating antiphospholipid antibodies in the absence of any clinical symptoms. As such, routine screening for these antibodies in all pregnant women is strongly discouraged.
  3. Clinical manifestations of APLAS include: (i) recurrent pregnancy loss (defined as  ≥ 3 unexplained first‐trimester pregnancy losses or  ≥ 1 unexplained second‐trimester pregnancy loss); (ii) unexplained thrombosis (venous, arterial, cerebrovascular accident or myocardial infarction); and/or (iii) autoimmune thrombocytopenia (platelets <100,000/mm3). Recent consensus opinions suggest that such clinical conditions as unexplained intrauterine growth restriction (IUGR), massive placental abruption, and recurrent early‐onset severe pre‐eclampsia be included.
  4. At least one of three serologic tests confirming the presence of circulating antiphospholipid antibodies (below) is required to make the diagnosis of APLAS. Moreover, the diagnosis requires the persistence of such antibodies as confirmed by two or more positive tests at least 12 weeks apart.
    • Lupus anticoagulant (LAC) is an unidentified antiphospholipid antibody (or antibodies) that causes prolongation of phospholipid‐dependent coagulation tests in vitro by binding to the prothrombin–activator complex. Examples of tests that can confirm the presence of LAC include the activated PTT test, dilute Russel viper venom test, kaolin clotting time, and recalcification time. In vivo, however, LAC causes thrombosis. LAC results are reported as present or absent (no titers are given). The term LAC is a misnomer: it is not specific to lupus (SLE) and it acts in vivo as a procoagulant and not an anticoagulant.
    • Antibodies against specific phospholipids as measured by enzyme‐linked immunosorbant assay (ELISA). These high‐avidity IgG antibodies have anticoagulant activity in vitro, but procoagulant activity in vivo. The most commonly used ELISA test is the anticardiolipin antibody (ACA). Cardiolipin is a negatively charged phospholipid isolated from ox heart. ACA ELISA is at best semi‐quantitative. Results have traditionally been reported as low, medium or high titers. More recently, standardization of the phospholipid extract has allowed for standard units to be developed (GPL units for IgG, MPL units for IgM). ACA IgM alone, IgA alone, and/or low‐positive IgG may be a nonspecific (incidental) finding since they are present in 2–4% of asymptomatic pregnant women. As such, moderate‐to‐high levels of ACA IgG (>40 GPL units) are required to make the diagnosis of APLAS.
    • The presence of anti‐β2‐glycoprotein I antibodies.
  5. A number of additional antiphospholipid antibodies are described, including antiphosphatidylserine, antiphosphatidylethanolamine, antiphosphatidylcholine, anti‐Ro, and anti‐La, but these are not sufficient to make the diagnosis. A false‐positive test for syphilis (defined as a positive rapid plasma reagin (RPR) or Venereal Disease Research Laboratory (VDRL) test, but negative definitive test for syphilis) is another common finding in women with APLAS, but is nonspecific and is not sufficient to confirm the diagnosis. Antinuclear antibodies (ANA) are not antiphospholipid antibodies, and may suggest the diagnosis of SLE but not APLAS.
  6. Treatment for APLAS depends on the clinical features:
    • For women with thrombosis (such as stroke or pulmonary embolism), therapeutic anticoagulation is indicated with either unfractionated heparin (UFH) or low molecular weight heparin (LMWH) during pregnancy followed by oral anticoagulation (coumadin) postpartum because of a 5–15% risk of recurrence. In pregnancy, regular blood tests are required 4 hours after administration of the drug to ensure that anticoagulation is therapeutic: the PTT should be 1.5‐ to 2.5‐fold normal and anti‐Xa activity levels should be 0.6–1.0 U/mL. Side‐effects include hemorrhage, thrombocytopenia, and osteopenia and fractures. Such women may need lifelong treatment.
    • For women with recurrent pregnancy loss, treatment should include prophylactic UFH (5000–10,000 units sc bid) or LMWH (enoxaparin (Lovenox) 30–40 mg sc daily or dalteparin (Fragmin) 2500–5000 U sc daily) starting in the first trimester of pregnancy. Although prophylactic dosing does not change PTT, it will increase anti‐Xa activity to 0.1–0.2 U/mL. However, it is not necessary to follow serial anti‐Xa activity in such patients. The goal of this treatment is to prevent pregnancy loss and to prevent VTE, which is possible in women with APLAS in pregnancy even if they have not had a VTE in the past. Therefore, anticoagulation should be administered throughout pregnancy and typically for 6–12 weeks after delivery.
    • For women with autoimmune thrombocytopenia or a history of severe pre‐eclampsia, IUGR or placental abruption, the optimal treatment is unknown. Consider treating as for recurrent pregnancy loss. Postpartum anticoagulation is probably not necessary.