Access Medicine Clinical Rotation Cases Files Gynecologic, Obstetric & Breast Conditions, Case Study - Prenatal Care

Question

A 22-year-old woman who has never been pregnant presents to the office after having a positive home pregnancy test. She has no significant medical history. Upon further questioning, she states that she is unsure of the date of her last menstrual period (LMP). She denies any symptoms and is worried as she has not felt the baby move thus far. She is also concerned because she recently had dental x-rays taken prior to discovering that she was pregnant. She denies the use of any drugs, alcohol, or tobacco. She inquires about when she can get an ultrasound and a genetic test to rule out Down syndrome.

When is an ultrasound indicated in prenatal care?

What laboratory studies are routinely indicated at an initial prenatal visit?

What is the risk to the pregnancy based on the radiation exposure that the patient has encountered?

When is the optimal time for a trisomy screen test?

Answers to Case 4: Prenatal Care

Summary:

A 22-year-old woman presents with Primigravida status and desire for initial prenatal care visit with unknown LMP

No significant past medical history

Numerous questions regarding her care

• Recent history of dental x-rays

Indications for an ultrasound in pregnancy: According to the American College of Obstetricians and Gynecologists (ACOG), an ultrasound is not mandatory in routine, low-risk prenatal care. An ultrasound is indicated for the evaluation of uncertain gestational age, size/date discrepancies, vaginal bleeding, multiple gestations, or other high-risk situations.

Laboratory studies recommended at the initial prenatal visit: Confirm pregnancy with urine pregnancy test. If positive, then complete blood count (CBC), hepatitis B surface antigen (HBsAg), HIV testing, syphilis screening with a rapid plasma reagin (RPR), urinalysis and urine culture, rubella antibody, blood type and Rh status with antibody screen, Papanicolaou (Pap) smear, and cervical swab for gonorrhea and Chlamydia. A urine drug screen is also considered and often performed at the first prenatal visit.

Risk to the pregnancy based on the radiation exposure from dental x-rays: Risk for the baby is increased once the radiation exposure is greater than 5 rad or 50 mGy; the radiation exposure from routine dental x-rays is 0.0005 rad. ACOG states that dental x-rays are safe in pregnancy when the thyroid and the abdomen are adequately shielded.

Optimal time for the trisomy screen: Considerations for trisomy screening include

• First trimester testing for nuchal translucency (NT) via ultrasound or a combined test of NT and serum markers human chorionic gonadotropin (hCG) and pregnancy-associated plasma protein A (PAPP-A) testing between 10 and 13 weeks.
• Second-trimester triple (alpha-fetoprotein [AFP], hCG, estriol) or quadruple (triple screen and inhibin-A) screen between 16- and 18-weeks’ gestation; however, it may be performed between 15- and 20-weeks’ gestation, if necessary.
• Emerging evidence shows that combining results of first- and second-trimester screening tests improves the trisomy detection rate; consequently, the optimal time for screening should be discussed at the initial prenatal visit.
• Concerning results from the tests mentioned may warrant more invasive testing to confirm chromosomal abnormalities. These tests include chorionic villous sampling at 11 to 13 weeks or amniocentesis at or after 15 weeks.

Analysis

Objectives

1. Learn the components of the preconception counseling and the initial prenatal visit. (EPA 12)
2. Know the recommended screening tests and visit intervals in routine prenatal care. (EPA 3, 11, 12)
3. Learn the relevant psychosocial aspects of providing prenatal care, including important counseling issues. (EPA 12)

Considerations

Prenatal, or antenatal, care affords the opportunity to both perform appropriate medical testing and provide counseling and anticipatory guidance. Pregnancy can be a time of anxiety, and patients frequently have many questions. One of the goals of prenatal care is to provide appropriate education to reduce anxiety and help women to be active participants in their own care.

·         ADVANCED MATERNAL AGE: Pregnant woman who will be 35 years or beyond at the estimated date of delivery (EDD).

·         ANTENATAL TESTING: A procedure that attempts to identify whether the fetus is at risk for uteroplacental insufficiency and perinatal death. Some of these tests include nonstress test (NST) and biophysical profile (BPP).

·         ASYMPTOMATIC BACTERIURIA (ASB): ASB is assessed as 100,000 colony-forming units per milliliter (cfu/mL) or more of a pure pathogen of a midstream voided specimen without clinical symptoms. ASB in pregnant women increases risk of acute pyelonephritis, preterm delivery, and low birth weight; therefore, early detection is paramount, and treatment is mandated.

·         GENETIC COUNSELING: An educational process provided by a health care professional for individuals and families who have a genetic disease or who are at risk for such a disease. It is designed to provide information about their condition or potential condition and help them make informed decisions.

·         ISOIMMUNIZATION: The development of specific antibodies as a result of antigenic stimulation by material from the red blood cells of another individual. For example, Rh isoimmunization occurs when an Rh-negative woman develops anti-D (Rh factor) antibodies in response to exposure to Rh (D) antigen.

·         VERTICAL TRANSMISSION: Infectious passage of infection from mother to fetus, whether in utero, during labor and delivery, or postpartum.

Preconception Care

In the United States, the first visit for prenatal care frequently is at 8 weeks of gestation or later, and yet it is the time preceding this that poses the greatest risk to fetal development. A preconception visit is an ideal opportunity for the patient to discuss with her provider any issue related to possible pregnancy or contraception occurring within 1 year of pregnancy. Providers may also take this opportunity to do counseling for inheritable conditions. The preconception visit can be included during visits for many reasons, including fertility problems, contraception, periodic health assessment, recent amenorrhea, or specifically for preconception counseling. Roughly one-half of patients with a negative pregnancy test may have some risk that could adversely affect a future pregnancy. Because approximately 50% of pregnancies are unplanned or unintended, clinicians should consider the potential of pregnancy when writing each prescription. The primary care provider should ask women of reproductive age about their intention to become pregnant. Contraceptive counseling should be given based on the patient’s intentions. Women who intend to become pregnant should be advised to avoid, whenever possible, potentially harmful agents such as radiation, drugs, alcohol, tobacco, over-the-counter (OTC) medications, herbs, and other environmental agents.

Radiation. Radiation exposure greater than 5 rad is associated with fetal harm. Most commonly performed x-ray procedures, including dental, chest, and extremity x-rays, expose a fetus to only very small fractions of this amount of radiation. Fetuses are particularly sensitive to radiation during the early stages of development, between 2 and 15 weeks after conception. Whenever possible, the abdomen and pelvis should be shielded and x-rays performed only when the benefit outweighs the potential risk. Imaging procedures not associated with ionizing radiation, including ultrasound or magnetic resonance imaging, should be considered as alternatives to x-ray during pregnancy when appropriate.

OTC Preparations. Women should refrain from OTC medicines, herbs, vitamins, minerals, and nutritional products until cleared by their obstetric provider. The US Public Health Service and Centers for Disease Control and Prevention (CDC) recommend that all women of childbearing age take folic acid daily, and women considering conception should start a folic acid supplement at least 1 month prior to attempting to conceive. For low-risk women, a dose of 400 to 800 micrograms of folic acid daily is recommended to reduce the risk of neural tube defects. Higher doses are recommended in the presence of certain risk factors. For women with diabetes mellitus or epilepsy, 1 mg of folic acid a day is recommended. A woman who has had a child with a neural tube defect should take 4 mg of folic acid daily.

Genetic Screening. Women from certain ethnic backgrounds may be offered specific genetic screening. African and African American women may be offered sickle cell trait screening. A French Canadian or Ashkenazi Jewish background is an indication to consider screening for a Tay-Sachs carrier state. Southeast Asian and Middle Eastern women may be offered screening for thalassemia. Ashkenazi Jews and Caucasian women may be offered screening for cystic fibrosis.

Age-Related Risk. Women who will be 35 years old or older at the anticipated time of delivery should be educated about age-related risk, particularly the increased risk of Down syndrome. They should be counseled about the available screening and diagnostic testing available, along with the appropriate time frame in which each test may be performed. Although invasive in nature, chorionic villous sampling or amniocentesis are recommended to be offered to women who are 35 years of age or greater during the time of pregnancy. In practice, however, screening laboratory tests usually precede invasive testing for general risk identification.

Comorbidities. Women with medical conditions such as diabetes, asthma, thyroid disease, hypertension, lupus, thromboembolism, and seizures should be referred to providers with experience in managing high-risk pregnancies. Women with psychiatric disorders should be comanaged with a psychiatrist and counselor/therapist so that the patient can benefit from pharmacologic and behavioral therapy. These patients may require more frequent visits.

Lifestyle Counseling. Pregnant women and those looking to become pregnant should be screened for tobacco use. Patients who have drug, tobacco, or alcohol dependence should be educated about the risks and referred to rehab/treatment centers to quit the drug prior to conception. Women should also be educated about proper nutrition and exercise during pregnancy. Preconception counseling may also address issues such as financial readiness, social support during pregnancy and the postpartum period, and issues of domestic violence.

Initial Prenatal Visit

The initial visit should address all the concepts in the preconception visit if no preconception counseling was done. Ideally, the initial visit should be in the first trimester. A detailed history and physical examination, initial obstetric laboratory tests, and counseling regarding the logistics for prenatal care should be done at this visit.

Last Menstrual Period. The history should begin with an assessment of the LMP and its reliability. One of the most crucial pieces of information is the accuracy of the dating. The first day of the LMP is used to obtain the EDD using Naegele’s rule (from the first day of the LMP subtract 3 months and add 7 days). The LMP is considered reliable if the following criteria are met: the date is certain, the LMP was normal, there has been no contraceptive use in the past 1 year, the patient has had no bleeding since the LMP, and her menses are regular. If these criteria are not met, an ultrasound should be performed. The ACOG has established further criteria that can be used to ensure that a fetus is mature at the time of delivery, which include criteria such as early sonography and the timing of the positive pregnancy test.

History Components. History should also be obtained with particular attention to medical history, prior pregnancies, delivery outcomes, pregnancy complications, neonatal complications, and birth weights. Gynecologic history should focus on the menstrual history, contraceptive use, and history of sexually transmitted infections. Allergies, current medications—both prescription and OTC—and substance use should also be investigated. Social history should consider whether the pregnancy was planned, unplanned, or unintentional. A discussion of social supports for the patient during the prenatal and postpartum period is also warranted. Genetic history should be obtained for the patient and partner’s family, if known.

Physical Examination. The initial examination should be thorough and should include height, weight, body mass index, blood pressure, thyroid, breast, and general physical and pelvic examinations. Pregnancy-specific examinations, including an estimation of gestational age by uterine size or fundal height measurement and an attempt to hear fetal heart tones by Doppler fetoscope, should be performed. Heart tones should be obtainable by 10 weeks’ gestation using a handheld Doppler fetoscope. Pelvimetry has been removed as a recommended intervention, but it may be useful to have a subjective assessment for risks of problems during delivery.

Laboratory Screening. The initial laboratory screen (Table 4–1) should include blood type and Rh status antibody screen, rubella status, HIV, HBsAg, RPR, urinalysis, urine culture, Pap smear, cervical swab for gonorrhea and Chlamydia, and a CBC. The inactivated influenza vaccination should be offered to all pregnant women during flu season.

SUMMARY OF PRENATAL LABORATORIES, RAMIFICATIONS, AND EVALUATION

Table 4–1SUMMARY OF PRENATAL LABORATORIES, RAMIFICATIONS, AND EVALUATION

View Table||Download (.pdf)

Prenatal Visit Scheduling. The logistics of the prenatal visits should be addressed. A typical protocol includes follow-up visits every 4 weeks until 28 weeks’ gestation, every 2 weeks from 28 to 36 weeks’ gestation, and every week from 36 weeks’ gestation until delivery. More frequent visits should be performed if any problems arise or if not all issues are addressed in the scheduled visits.

Ultrasound. The ACOG does not stipulate routine ultrasonography in patients without complications. Ultrasound is considered accurate for establishing gestational age, fetal number, viability, and placental location. Therefore, ultrasonography should be performed in patients without reliable dating criteria, with a discrepancy between the measured and expected uterine growth, and, in the case of a postdated pregnancy, suspicion for twin gestation, placental issues, chromosomal abnormalities, or other problems. For gestational age estimations, ultrasonography is accurate to within 1 week if performed in the first trimester, 2 weeks in the second trimester, and 3 weeks in the third trimester. If the ultrasound dates and LMP are off by more than the aforementioned intervals, the due date should be recalculated based on the ultrasound findings.

Other Concerns. The visit should end with an adequate explanation of all patient/partner concerns. Women should be counseled that sexual activity is not associated with any harm during an uncomplicated pregnancy, although there may be conditions that arise during the course of a pregnancy that would make sexual activity inadvisable. A follow-up visit should be scheduled prior to her leaving the office. She should also be educated about preterm labor precautions, signs of ectopic pregnancy, and situations in which to call the provider or go to the obstetrics triage unit for evaluation.

Subsequent Prenatal Visits

Assessing for Complications. At follow-up prenatal visits, concerns or questions brought up by the patient should be addressed. The examiner should ask questions specifically targeted at symptoms suggestive of complications, including gestational hypertension, preeclampsia, infections (urinary tract, vaginal, etc), fetal compromise, placenta previa/abruption, and preterm labor or premature rupture of membranes. At each visit, the patient should be asked about vaginal bleeding, loss of fluid, headaches, visual changes, abdominal pain, dysuria, facial or upper extremity edema, vaginal discharge, and subjective sensation of fetal movements.

The examination on each subsequent visit should include weight, blood pressure, fundal height measurement, and fetal heart tones by handheld Doppler. In addition, a urinalysis should be performed at every visit to assess for protein, glucose, or nitrates/leukoesterase.

Prenatal Screening and Laboratory Studies

Triple and Quad Screens. At 15 to 20 weeks’ gestation (preferably between 16 and 18 weeks’ gestation), a multiple-marker test, which screens for trisomy 21, trisomy 18, and neural tube defects, should be offered to patients. The two most common modalities of screening the fetus for these anomalies are the triple screen and the quad screen. The triple screen tests for serum hCG, unconjugated estriol, and AFP; the quad screen tests for those three plus inhibin-A. The triple screen has a sensitivity of approximately 65% to 69% and specificity of 95% for detecting aneuploidy. The quad screen increases sensitivity to approximately 80% without reducing specificity. The most common cause for a false-positive serum screen is incorrect gestational age dating. During the first trimester, fetal NT can be measured by ultrasonography combined with maternal serum analyte levels (ie, free hCG and PAPP-A). This testing can be performed at 10 to 14 weeks’ gestation. Sensitivity and specificity of these tests are determined by the risk cutoff used (eg, for trisomy 21, sensitivity is 85.2% when specificity is 90.6%; at 95% specificity, the sensitivity is 78.7%). Women should be counseled about the limited sensitivity and specificity of the tests, the psychological implications of a positive test, the potential impact of delivering a child with Down syndrome, the risks associated with prenatal diagnosis and second-trimester abortion, and the delays inherent in the process. More advanced testing is also available to look for fetal DNA fragments that are present in maternal blood. These tests are high tech and not invasive, but they are expensive and insurance coverage varies.

Amniocentesis and Chorionic Villus Sampling. Women at increased risk of aneuploidy should be offered prenatal diagnosis by amniocentesis or chorionic villus sampling (CVS). Persons at increased risk include women with singleton pregnancies who will be older than 35 years at delivery, or those with twin pregnancies who will be older than 32 years at delivery; women carrying a fetus with a major structural anomaly identified by ultrasonography; women with ultrasound markers of aneuploidy (including increased nuchal thickness); women with a previously affected pregnancy; couples with a known translocation, chromosome inversion, or aneuploidy; and women with a positive maternal serum screen. Amniocentesis may be performed after 15 weeks’ gestation and is associated with a 0.5% risk of spontaneous abortion. CVS is performed at 10- to 12-weeks’ gestation and has a 1% to 1.5% risk of spontaneous abortion. CVS may be associated with transverse limb defects (0.3 to 1 per 1000 fetuses). Women undergoing CVS also should be offered maternal serum AFP testing for neural tube defects. Women older than age 35 years at time of delivery may opt for serum screening and ultrasonography before deciding whether to proceed with amniocentesis. Although the risk for trisomy 21 increases with maternal age, an estimated 75% of affected fetuses are born to mothers younger than age 35 years at time of delivery.

Gestational Diabetes. The United States Preventive Services Task Force recommends screening for gestational diabetes in asymptomatic pregnant women after 24 weeks of gestation (grade B). At 24 to 28 weeks’ gestation, patients should be screened for gestational diabetes with a 1-hour, 50-g glucose challenge test. When the screening test is positive, a 3-hour glucose tolerance test (GTT) should be performed (after an overnight fast) by giving the patient a 100-g glucose load and obtaining fasting, 1-hour, 2-hour, and 3-hour postload serum glucose samples; two out of four positive values generally establish the diagnosis of gestational diabetes. A diagnosis of gestational diabetes not only impacts the pregnancy, but it also increases the risk of type 2 diabetes in the patient throughout her life. Women diagnosed with gestational diabetes should be screened for type 2 diabetes at 12 weeks’ postpartum.

Laboratory Tests at 28 Weeks. At 28 weeks’ gestation, repeat RPR, HIV, and hemoglobin/hematocrit tests should be obtained in those at risk. In addition, a patient who is Rh negative should receive Rho(D) immune globulin (RhoGAM) at this time. An Rh-negative patient should also receive RhoGAM at delivery and in any instance of trauma. Nonsensitized, Rh-negative women also should be offered a dose of RhoGAM after spontaneous or induced abortion, ectopic pregnancy termination, CVS, amniocentesis, cordocentesis, external cephalic version, abdominal trauma, and second- or third-trimester bleeding. Administration of RhoGAM can be considered before 12 weeks’ gestation in women with a threatened abortion and live embryo, but Rh alloimmunization is rare.

Group B Streptococcus Screening. The CDC and ACOG recommend that all women be offered group B Streptococcus (GBS) screening by vaginorectal culture at 35 to 37 weeks’ gestation, and that colonized women be treated with intravenous antibiotics at the time of labor or rupture of membranes in order to reduce the risk of neonatal GBS infection. The proper method of collection is to swab the lower vagina, perineal area, and rectum. Of tested women, 10% to 30% will test positive for GBS colonization. Because GBS bacteriuria indicates heavy maternal colonization, women with GBS bacteriuria at any time during their pregnancy should be offered intrapartum antibiotics and do not require a vaginorectal culture. Similarly, women with a previous infant who was diagnosed with a GBS infection should be offered intrapartum antibiotics.

Preterm and Late Term Pregnancies

Birth before 37 weeks’ gestation is considered preterm. To decrease the risk of neonatal morbidity and mortality, it is important to distinguish women with a history of preterm delivery and premature rupture of membranes. Women with either of these known risk factors should be given progesterone injections weekly from 16 to 37 weeks’ gestation. Women diagnosed with a short cervix have an increased risk of preterm labor. Placing a cervical cerclage may reduce this risk, but current evidence is not definitive.

Late-term pregnancy is from 41 weeks, 0 days to 41 weeks, 6 days. Postterm pregnancy is defined as a pregnancy that has extended beyond 42 weeks or 294 days. Several studies found that induction of labor at 41 weeks reduced the need for cesarean delivery and reduced neonatal mortality and morbidity. Women who deliver postterm are at greater risk for maternal complications such as postpartum hemorrhage, dystocia, and maternal infection.

Vaccinations During Pregnancy

All pregnant women should receive the influenza vaccination at their initial prenatal visit. The influenza vaccine is safe in any stage of pregnancy provided there is no allergy to any of its components. Tetanus toxoid, diphtheria, and acellular pertussis vaccination (Tdap) should be administered between 27 and 36 weeks’ gestation of each pregnancy, regardless of prior vaccination status. Varicella, rubella, and the live attenuated intranasal influenza vaccinations are not advised during pregnancy. For pregnant mothers with a rubella nonimmune status, a rubella vaccination should be given after delivery of the infant. During the first prenatal visit, the mother’s history of varicella should be documented. Women with a negative varicella history should undergo serologic testing to confirm immunoglobulin G. Those not immunized to varicella should be advised to avoid exposure during pregnancy and should be offered the vaccine postpartum.

·         See also Case 11 (Health Maintenance in Women), Case 28 (Family Planning—Contraceptives), and Case 29 (Adolescent Health Maintenance).

Clinical Pearls

·         The initial prenatal visit often is scheduled after fetal organogenesis has occurred. For this reason, a preconception visit can be very beneficial.

·         When prescribing medications, clinicians must consider the possibility that any woman of reproductive age may become pregnant.

·         Genetic counseling should be offered to any woman who will be 35 years old or older at her estimated date of confinement (EDD).

·         Folic acid supplementation is important for every woman, and the recommended daily dose is based on individual risk factors such as anticonvulsant therapy or a previous pregnancy with a neural tube defect.

·         If all criteria are met, Naegele’s rule can be used to determine the EDD (subtract 3 months, add 7 days). If there is any uncertainty, the dating should be confirmed by ultrasound, preferably in the first trimester.

 Quiz

Question 1: Correct

A 24-year-old woman presents for an initial prenatal visit. She is at 9 weeks’ gestation based on her LMP, but on further questioning, she is not certain of the first day of her LMP. Which of the following would be the most accurate estimate of her gestational age?

A Using her LMP if her uterine size is consistent

B A first-trimester ultrasound

C A second-trimester ultrasound

D A quantitative serum hCG level

The correct answer is B. You answered B.

Explanation:

A first-trimester ultrasound is accurate to within ± 1 week for gestational dating and would be the most accurate assessment of gestational age of the options listed. The further into the pregnancy the ultrasound is performed, the less accurate the gestational dating is; therefore, a second-trimester ultrasound (answer C) would not be as accurate as a first-trimester ultrasound. When LMP is in question (answer A), an ultrasound is a more reliable method of gestational dating. Answer D (quantitative hCG level) does not correlate to the gestational age as accurately, and there is significant overlap among various gestational ages

 Question 2: Correct

A 38-year-old pregnant woman presents for initial visit at 12 weeks’ gestation. She requests a “genetic screen” because she is concerned about her advanced maternal age. She does not want any invasive testing that may cause a potential miscarriage but does want the test that would have the highest detection rate.

Which of the following is most appropriate to offer this patient?

A If no prior personal or family history of genetic defects, no screen is needed.

B Draw and send blood for the triple or quad screen as patient has advanced maternal age.

C Nuchal translucency screening and hCG and PAPP-A testing.

D Offer the patient CVS.

E Discuss cell-free DNA testing.

The correct answer is E. You answered E.

 Explanation:

Cell-free DNA testing (looking for fetal cells within the maternal serum) has the highest sensitivity in detecting a chromosomal abnormality (aneuploidy). For example, the sensitivity in detecting Down syndrome is in the 99% range, trisomy 18 in the 96% range, and trisomy 13 in the 90% range. This modality can be performed from 10 weeks’ gestation onward. Answer C (biochemical screening and NT) is performed between 10 and 13 weeks’ gestational age; first-trimester trisomy screening may be performed by NT, serum hCG, and PAPP-A; the sensitivity for detecting Down syndrome is about 85% to 90%. CVS (answer D) is more invasive and is not the initial screening of choice. Not performing the screening due to a lack of personal or family history of genetic defects (answer A) would not be appropriate, especially since the patient is requesting screening.

 Question 3: Correct

A 28-year-old woman with a history of epilepsy presents to the office for a preconception consultation visit. Her seizures are well controlled on medication. Which of the following is the most important advice to give to this patient?

A Diabetes screening prior to pregnancy.

B Electroencephalogram (EEG) reading that is normal prior to conception.

C Preconception folate supplementation.

D Stop epilepsy medication prior to pregnancy and through the first trimester.

The correct answer is C. You answered C.

 Explanation:

Women with a history of epilepsy should receive 1 mg of folic acid supplementation daily to help prevent neural tube defects. In general, epilepsy medications should be continued (not stopped, as in answer D), although the type of medication may be changed. For instance, valproic acid has a relatively high rate of neural tube defects associated with its use, and if possible, another medication should be used. Answer A (diabetes screening before pregnancy) is indicated if a patient has significant risk factors or symptoms that are suggestive. Answer B (EEG reading) is not relevant to pregnancy considerations as long as her seizures are under control.

Question 4: Correct

A 28-year-old gravida 1, para 0 woman at 16 weeks’ gestation is noted to be Rh negative. She denies any previous blood transfusion or pregnancy. Which of the following is the most appropriate next step for this patient?

A  Administer RhoGAM at this time.

B Check the patient’s antibody screen (indirect Coombs).

C Schedule the patient for amniocentesis to assess for isoimmunization.

D Counsel the patient to terminate the pregnancy.

The correct answer is B. You answered B.

Explanation:

For women who are Rh negative, the next step is to assess the antibody screen or indirect Coombs test. Even though this patient is unaware of prior transfusion or miscarriage, there is some risk of the development of alloantibodies (against red blood cell antigens)—for example, an early miscarriage when she did not suspect she was pregnant. If the antibody screen is negative, there is no isoimmunization, and RhoGAM is given at 28 weeks’ gestation and again at delivery if the baby is confirmed as Rh positive. The RhoGAM is given to prevent isoimmunization. This patient is at 16 weeks’ gestation, so RhoGAM would not be given at this time (answer A). If the antibody screen is positive and the identity of the antibody is confirmed as Rh (anti-D), then assessment of its titer will assist in knowing the probability of fetal effect. A low titer can be observed, whereas a high titer should initiate further testing such as ultrasound and possibly amniocentesis (answer C). Answer D (counseling the patient to terminate the pregnancy) is not appropriate.