The First Prenatal Visit—Setting the Stage for Optimal Pregnancy Care
Chloe M. Nielsen
Anna G. Euser
John C. Hobbins
Introduction
The initial prenatal visit can be one of the most important clinician-patient interactions during pregnancy. It may be a time of great anxiety and change for expectant parents and is often the beginning of a long and meaningful relationship with their obstetrician or midwife. Medically, the goal of prenatal care is to prevent complications and to reduce neonatal and maternal morbidity and mortality.1,2 This initial visit, which generally takes place prior to 12 weeks’ gestation, is also a time in which the clinician is tasked with assessing the patient’s medical, obstetric, surgical, family, and social histories. There are multiple laboratory tests—from initial prenatal laboratories, to genetic screenings, to patient-specific studies—that must be performed, and with those tests comes a significant counseling responsibility. This obstetrical visit is a pivotal opportunity to assess the patient’s overall health and evaluate patient-specific pregnancy risks. The following topics are meant as an overview of the many aspects of prenatal care and are not meant to be an exhaustive review, and many of the introduced topics are covered in more detail elsewhere in this textbook. The arc of obstetrical care will ultimately be guided by the issues and values most important to the patient.3
Before going further, we believe that it is important to determine the patient’s desires regarding pregnancy continuation. Approximately half of pregnancies in the United States are unintended,4 and although unintended may not be undesired, it is essential to determine if the patient wishes to continue the pregnancy. Prompt referral for termination services is associated with the ability to use either surgical or medical techniques for evacuation, both of which are associated with low complication rates.5 Generally speaking, first-trimester abortion is associated with a less than 1% rate of complications.6 As gestational age increases so do the risks of pregnancy termination—maternal mortality rates increase from 0.1 per 100,000 at 8 weeks to 8.9 deaths per 100,000 at 21 weeks or greater.7 This is particularly pertinent in women who may have diagnoses (eg, mechanical heart valves or prepregnancy renal failure) or an obstetric history (prior acute fatty liver of pregnancy or decompensated peripartum cardiomyopathy) that would make pregnancy continuation unadvisable.
Laboratory Screening
Prenatal laboratory tests should be obtained for every patient on initiation of obstetrical care. This panel of tests evaluates pregnancy risk associated with maternal alloimmunization, infectious disease, and anemia. The majority of these screening tests are recommended universally for all patients, and other tests should be considered based on individual patient characteristics (Table 13.1). There are additional laboratory tests that should be performed based on a woman’s obstetric and medical history, and these will be discussed later in this chapter.
Hematologic Screening
An ABO/Rh type and antibody screen evaluates for the presence or absence of the D (Rh) antigen on maternal red blood cells and also detects any other circulating antibodies that may affect pregnancy outcomes and fetal well-being (Chapter 22).8 A complete blood count is obtained to screen for underlying anemia, hemoglobinopathy, or thrombocytopenia (Chapters 23 and 38).9
Table 13.1 Panel of Common Laboratory Tests in Pregnancy | |||||||||||||||||||||||||||
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Infectious Disease Screening
Routine screening for maternal hepatitis B status is recommended using the hepatitis B surface antigen (Chapter 39).10,11,12 Although seroprevalence of hepatitis B is relatively low in the United States, vertical transmission can be decreased with third trimester treatment in patients with high viral loads and appropriate neonatal care.13 Testing for hepatitis C is recommended in women with risk factors, including incarceration, high-risk sexual behavior, or intravenous drug use, and allows for consideration for new curative treatment regimens in the postpartum period (Chapter 39).14 Human immunodeficiency virus (HIV) testing is recommended for all pregnant patients with each pregnancy confirmation and “opt-out” screening is favored.15 Appropriate HIV treatment during pregnancy and intrapartum decreases the risk of vertical transmission from 25% to <2% and allows for appropriate care for that woman’s future health.15,16,17,18 For patients at high risk of acute infection, it is prudent to obtain an HIV viral load as an additional test. Screening for syphilis by either rapid plasma regain or treponemal testing should performed due to the risk of congenital syphilis and the availability of treatment in pregnancy.19 Similarly, infectious disease testing should also include gonorrhea and chlamydia assessment, as well as urine evaluation for asymptomatic bacteriuria screening.20 Rubella immunoglobulin G is tested to determine the risk of maternal rubella infection in pregnancy and allow for immunization postpartum as needed. Consideration of tuberculosis testing in women who have recently emigrated from endemic areas or for women in close proximity to many others (such as those residing in shelters or who are incarcerated) is also prudent.21
There are several infectious diseases for which universal prenatal screening is not recommended. This includes cytomegalovirus, toxoplasmosis, parvovirus, genital herpes simplex virus, and bacterial vaginosis (see Chapter 10 for more details regarding congenital infections and testing indications).22,23,
General Health Screening
It is important to realize that for many women, pregnancy represents a period of time in which they have more contact with the healthcare system than they do outside of pregnancy. As such, it is prudent to make sure that all appropriate health screenings and interventions that can be safely administered during pregnancy are provided. The Women’s Preventative Services Initiative (WPSI) provides guidance that is updated annually with recommendations for well-woman care and includes prevention services recommendations for nonpregnant, pregnant, and postpartum women.24 Cervical cancer screening with cervical cytology and human papilloma virus testing should be performed if indicated per current guidelines (Chapter 42).25 All adults, pregnant or not, should be offered an influenza vaccine annually, and this is strongly recommended during pregnancy.26 Additionally, with increasing rates of obesity and sedentary
lifestyles, early screening for pregestational diabetes mellitus should also be considered based on risk factors (Chapters 30 and 32)27 Physical activity should be encouraged in all women, pregnant or not, with current recommendations for aerobic activity for at least 150 minutes per week in most women.28 Thyroid function testing should be performed based on personal history of thyroid disease or symptoms and is not universally recommended (Chapter 31).29
lifestyles, early screening for pregestational diabetes mellitus should also be considered based on risk factors (Chapters 30 and 32)27 Physical activity should be encouraged in all women, pregnant or not, with current recommendations for aerobic activity for at least 150 minutes per week in most women.28 Thyroid function testing should be performed based on personal history of thyroid disease or symptoms and is not universally recommended (Chapter 31).29
First-Trimester Ultrasound
Although there are no formal recommendations from professional organizations that all women receive an early ultrasound, first-trimester ultrasound can be useful to determine fetal viability, pregnancy location, and fetal number; establish dating; and review early fetal anatomy.30,31 This ultrasound can be either transabdominal or transvaginal and should also evaluate the uterus, cervix, and adnexa. In keeping with the ALARA (as low as reasonably achievable) principle, M-mode should be used for demonstration of fetal cardiac activity in the first trimester.32 These topics are covered in greater detail in Chapters 12, 19, and 20.
At least 10% of clinically recognized pregnancies result in miscarriage, and 80% of these pregnancy losses occur within the first trimester (Chapter 1).31,33 Thus, while ascertaining fetal viability is important at every visit, this is particularly important during the first trimester. There are commonly accepted diagnostic criteria for failed pregnancy, and prompt diagnosis allows for expeditious management (Chapter 4).34 The most accurate manner of establishing pregnancy dating is an ultrasound measurement of the crown-rump length, which can be measured up to 14 weeks.30,31 In addition, the rate of twin pregnancies (and higher order multiples) has been increasing over time, and first-trimester ultrasound assists diagnosis, chorionicity assignment, and guiding further prenatal care (see Chapter 5 for full discussion of multifetal pregnancies).
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