Obstetrics and Gynecology Prenatal Care Case File

Prenatal Care Case File

Eugene C. Toy, MD, Patti Jayne Ross, MD, Benton Baker III, MD, John C. Jennings, MD

CASE 28

A 35-year-old G2P1001 woman is seen for her first prenatal visit. Based on her last menstrual period, she is at 15 weeks’ gestation. She has no complaints and has no significant medical history. She denies dysuria or urinary urgency. Her surgical history is remarkable only for “ear tubes” as a child. Her last delivery was a vaginal delivery and was uncomplicated. She has had Pap smears each year which to her memory “have been normal.” On examination, she is a well-appearing white female in no distress. Her blood pressure is 100/65 mm Hg, heart rate is 90 beats per minute (bpm), respiratory rate is 12 breaths per minute, temperature is 98°F (36.6°C), and weight is 130 lb. Her general physical examination is normal. The breasts are nontender and without masses or skin changes. The heart reveals II/VI systolic ejection murmur. The lungs are clear. Her abdomen is nontender and her fundal height is at the level of the umbilicus. Fetal heart tones are 140 bpm. The pelvic examination reveals a normal external genitalia, normal-appearing vagina and cervix. The bimanual examination shows adequate pelvimetry, and nontender uterus without adnexal or other masses. The cervix is normal in consistency and without masses. Her extremities are without edema. Prenatal laboratories are obtained and reveal the following:

CBC: Hgb 10.0 g/dL, MCV 82 fLPlt, 150 000/mm3, WBC 8000/mm3

Rubella: nonimmune

Blood type: O, Rh-negative

HIV ELISA: negative

RPR: negative

Gonorrhea assay: negative

Hepatitis B surface antigen: positive

Indirect Coombs (antibody screen): negative

UC&S: 10 000 cfu/mL of group B streptococcus

Pap smear: ASC-US

Chlamydia assay: negative

» What items should be listed on the problem list?

» What is your next step for the problems listed?

» What other testing should be recommended to the patient?

ANSWER TO CASE 28:

Prenatal Care                                           

Summary: A 35-year-old G2P1001 white female at 15 weeks’ gestation whose prior delivery was normal. Her fundal height is at the umbilicus. Fetal heart tones are 140 bpm. Prenatal laboratory results indicate a hemoglobin level of 10.0 g/ dL with MCV 82 fL; hepatitis surface antigen positive; Rh-negative blood type, negative indirect Coombs; urine culture revealing 10 000 cfu/ mL of group B streptococcus; and a Pap smear showing ASC-US.

• Problem list:

1. Advanced maternal age (AMA)—age 35 or greater at estimated time of delivery.
2. Size greater than dates (fundal height at umbilicus corresponds to 20 weeks).
3. Mild microcytic anemia (Hgb < 10.5).
4. Hepatitis B surface antigen (HBsAg) positive.
5. Rh-negative blood type with negative indirect Coombs.
6. Urine culture with GBS 10 000 cfu/mL, asymptomatic.
7. Pap smear showing atypical squamous cells of undetermined significance (ASC-US).
8. Rubella nonimmune.

• Next steps:

1. AMA—genetic counseling and discuss invasive testing (amniocentesis) versus noninvasive prenatal testing.
2. Size/dates—fetal ultrasound to assess gestational age, multiple gestation, or cell-free fetal DNA testing (see Case 7).
3. Anemia—therapeutic trial of iron.
4. HBsAg positive—check liver function tests and hepatitis B serology to assess for active hepatitis versus chronic carrier status.
5. Rh-negative with indirect Coombs negative—RhoGAM at 28 weeks and at delivery if the baby proves to be Rh-positive.
6. Urine culture with GBS—treat with ampicillin and reculture urine, penicillin IV prophylaxis in labor.
7. Pap smear ASC-US—observe and repeat Pap smear postpartum.
8. Rubella status—vaccinate postpartum.

• Other testing: Cystic fibrosis screening; consider early diabetic screen.

ANALYSIS

Objectives

1. Describe the routine prenatal care and the key screening strategies.
2. Be able to understand the principle of developing a problem list and its importance.
3. Be able to describe the “next steps” with any abnormal finding and know its significance.

Considerations

This is a 35-year-old woman who is seen for her first prenatal visit. Since pregnancy and delivery is a normal physiological process, the purpose of the prenatal care is to educate and build rapport with the patient and family, establish gestational age, screen for possible conditions that may impact maternal or fetal health, and monitor the progress of the pregnancy. During the first visit, a fairly extensive process is used to screen for at-risk conditions using a detailed history, general physical examination, and laboratory panel. This patient has a variety of conditions that need addressing. The best way to ensure that each issue is dealt with in a systematic manner and until resolution is to use a “problem list.” Thus, numerous issues are written into the problem list, and investigation is performed until resolution of the problem. An understanding of the strategy and approach to addressing each issue is fundamental to the care of patients. Likewise, an understanding of the physiologic changes of pregnancy allows for interpretation of physical examination findings and impact of various diseases (see Table 28– 1).

For instance, this 35-year-old patient has an early systolic ejection murmur, very common in pregnancy due to the increased cardiac output. A diastolic murmur, however, would be abnormal. Although the American College of Obstetricians and Gynecologists recommends counseling to every pregnant patient about cystic fibrosis screening; Caucasian patients are at particular risk with gene frequency being about 1 in 40. Also for women over the age of 30, some practitioners will perform a glucose screen for gestational diabetes early (eg, 18 weeks), and if negative, then again at the time of universal screening, 26 to 28 weeks’ gestation.

APPROACH TO:

Prenatal Care                                               

DEFINITIONS

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

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 means an Rh-negative woman who develops anti-D (Rh factor) antibodies in response to exposure to Rh (D) antigen.

ASYMPTOMATIC BACTERIURIA: Urine culture of 100 000 cfu/mL or more of a pure pathogen of a midstream-voided specimen.

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 patients and their families with information about their condition or potential condition and help them make informed decisions.

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

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 and biophysical profile.

BASIC OBSTETRICAL ULTRASOUND: Sonographic examination focused on fetal biometry (dating and fetal weight), number of fetuses, fetal presentation, placental location, amniotic fluid volume, and limited fetal anatomical survey.

COMPREHENSIVE (OR TARGETED) ULTRASOUND: Detailed anatomical evaluation to assess a suspected structural anomaly.

CLINICAL APPROACH

Physiological Changes

Pregnancy is associated with numerous physiological changes. An understanding of these changes is critical in the interpretation of laboratory tests, or a rational awareness of how disease processes may impact the pregnant patient. Some “seemingly abnormal” findings will be normal in pregnancy such as glycosuria due to the increased glomerular filtration rate delivering more glucose to the kidneys. Other findings in pregnancy will appear to be normal, but are “worrisome” in pregnancy; for instance, when the PCO2 level is 40 mm H g (normal for nonpregnant), it indicates significant CO2 retention and possibly impending respiratory failure.

Dating

The priorities of prenatal care includes establishment of gestational age since all of the monitoring, assessments, and milestones are based on gestational age. History of the LMP, regularity of menses, medication use that may affect ovulation, physical examination, and early ultrasound help this determination. On examination, the fundal height in centimeters corresponds to the gestational age from 20 to 34 weeks. An ultrasound will be obtained when there is a discrepancy of 3 cm or more.

Prevention

Much of prenatal care involves educating the patient, screening for diseases or unsafe conditions (intimate partner violence), and preventive measures. Use of immunizations (influenza and RhoGAM), prenatal vitamin with folate, iron supplementation, and a balanced diet are recommended.

Screening for Conditions of Risk

Much of the time spent in caring for the pregnant patient is involved in trying to identify high-risk conditions and taking the proper steps to reduce the risk, or minimize complications (see Table 28– 2).

Because both maternal and fetal health are being considered, any high-risk condition must be balanced from both perspectives. Many of the cases involve antepartum, intrapartum, or postpartum complications (see Table 28– 3).

COMPREHENSION QUESTIONS

28.1 A 24-year-old woman G2P0010 had a pregnancy complicated by abruptio placentae leading to fetal death at 38 weeks’ gestation. There was no etiology found after a diligent search. Which of the following statements is most accurate regarding this pregnancy?

A. With no etiology found, the risk of abruption in this current pregnancy is the same as any other pregnant patient.

B. Antenatal testing with biophysical profile should be considered starting at 34 to 35 weeks’ gestation.

C. Induction of labor should be considered at 37 to 38 weeks’ gestation.

D. Weekly ultrasound examinations screening for retroplacental hemorrhage should be considered starting at 32 weeks’ gestation.

28.2 A 27-year-old G0P0 woman is contemplating becoming pregnant. In preparation, her obstetrician conducts a preconception counseling session, assesses rubella status, and prescribes supplemental folate. Which of the following is the best explanation of the purpose of the supplemental folate?

A. Avoidance of megaloblastic anemia

B. Decreasing fetal anomalies

C. Enhancing absorption of iron

D. Increasing maternal immune function

28.3 A 32-year-old G1P0 woman at 15 weeks’ gestation is a physiologist, and is questioning the physician about the adaptations that occur in pregnancy. Which of the following statements is most accurate regarding the changes in pregnancy?

A. Cardiac output is largely the same as the nonpregnant woman.

B. The plasma volume is increased by about 50%.

C. The systemic vascular resistance of a pregnant woman is slightly increased as compared to the nonpregnant woman.

D. The pregnant woman typically has a short diastolic murmur which is physiologic.

28.4 A 29-year-old G1P0 woman at 18 weeks’ gestation is noted to have a blood type of O, Rh-positive. Her antibody screen (indirect Coombs) is positive. Identification of the antibody is anti-Lewis. Which of the following is the most accurate statement regarding this patient?

A. This fetus is at significant risk for fetal erythroblastosis if she/ he is Lewis-positive.

B. The father of the baby’s Lewis antigen status should be evaluated.

C. Ultrasound for fetal hydrops should be performed.

D. Further testing is not indicated in this patient.

28.5 A 31-year-old G1P0 woman at 15 weeks’ gestation is noted to have a positive hepatitis B surface antigen. Which of the following would most significantly increase the risk of vertical transmission?

A. Presence of positive hepatitis E antigen

B. Presence of positive antihepatitis B surface antibody

C. Presence of positive antihepatitis B core antibody

D. Presence of elevated liver function tests

28.6 A 31-year-old G2 P1001 woman is at 30 weeks’ gestation and her obstetrician recommends that she receives the TdaP vaccine. The physician explains that this is to help prevent neonatal pertussis. The patient states that she received the vaccine after delivery of her first baby. Which of the following is the best next step?

A. If the patient received the TdaP vaccine within the last 5 years, no vaccine is needed.

B. If the patient received the TdaP vaccine at any time in her adult life, no vaccine is needed.

C. The vaccine should not be administered until postpartum.

D. The vaccine should be given regardless of whether has previously been given.

ANSWERS

28.1 C. A history of abruption that is unexplained confers an increased risk of abruption with subsequent pregnancies. Antenatal testing does not predict acute events such as abruption. Rather, fetal testing such as biophysical profile is designed to identify chronic uteroplacental insufficiency such as caused by chronic hypertension, renal insufficiency, or maternal lupus. Ultrasound has poor ability to identify retroplacental clots or abruption. Induction at or slightly before the time of abruption with the fetal loss, if at term, is a reasonable approach to avoid repeat abruption.

28.2 B. The main purpose of the supplemental folate prior to pregnancy is to help reduce fetal neural tube defects (NTDs). These conditions include anencephaly, a fatal anomaly where there are no cerebral hemispheres or fetal skull, or spina bifida which often leads to debilitation and inability to control bowel or bladder. Because the neural tube closes at 21 to 28 days embryonic age (5-6 weeks’ gestational age), by the time the patient realizes she is pregnant, the “die is cast” regarding the neural tube. Folate supplementation reduces the risk of neural tube defects by 50%; thus, every woman in the reproductive age should take sufficient folate to reduce the risk of fetal NTDs.

28.3 B. In pregnancy, the plasma volume is increased by about 50%. The cardiac output likewise increases by 50%, as does the glomerular filtration rate. Both the stroke volume and heart rate increase to account for this elevated CO. The mean arterial pressure is unchanged to slightly decreased, meaning that the systemic vascular resistance is markedly decreased as compared to the nonpregnant patient. An early systolic ejection murmur is physiologic, whereas a diastolic murmur usually indicates a pathological etiology.

28.4 D. No further testing is indicated in this patient, because anti-Lewis antibodies do not cause hemolytic disease of the newborn. This is because Lewis antibodies are IgM and do not cross the placenta, whereas anti-D (Rh) are IgG. Other worrisome antibodies include anti-Kell and anti-Duffy. “Lewis lives, Kell kills, Duffy dies.” This highlights the need to identify the antibody when the indirect Coombs (antibody screen) is positive. When a worrisome antibody is identified, the titer should be evaluated to assess the potential severity of the isoimmunization potential. In general, fetal risk is not great unless the titer is 1:8 or higher.

28.5 A. This patient has a positive hepatitis B surface antigen, meaning that the patient has been infected with hepatitis B virus and currently still infectious (virus actively replicating). Liver function tests would indicate whether this is a chronic carrier status (normal LFT) versus active hepatitis (elevated LFT). The hepatitis antibodies also will give a clue regarding acute versus chronic hepatitis. The presence of hepatitis Be antigen markedly increases the transmission. Regardless of whether E antigen is present, this baby when born should receive hepatitis B immune globulin to protect against immediate exposure, and then the active hepatitis B vaccine for lifelong immunity. Hepatitis B infections to the neonate often lead to cirrhosis and hepatocellular carcinoma.

28.6 D. The TdaP vaccine is a killed vaccine and is safe in pregnancy. It should be given between 28 and 36 weeks’ gestation regardless of whether it has been given in prior pregnancies. The reason is so that the patient will augment an IgG antibody response, which will result in passive transmission to the fetus. This is the mechanism for reducing the risk of neonatal pertussis. Other adults who will be near the newborn such as spouses, grandparents, older siblings, or babysitters should also be vaccinated to reduce the risk of their acquisition of pertussis.

    CLINICAL PEARLS    

» Pregnancy and delivery is a normal physiological process. The objective of prenatal care is to educate the patient, prevent complications, and screen for significant conditions that can affect maternal or fetal health. » Assessment of a pregnant woman depends on knowledge of the physiologic changes in pregnancy. » Human immunodeficiency virus (HIV), hepatitis B, and syphilis are three infectious diseases in which intervention can dramatically impact neonatal well being. » Identification and treatment of asymptomatic bacteriuria markedly decreases the risk of pyelonephritis in pregnancy. » The main objective in assessing for cervical dysplasia/neoplasia is to identify invasive cervical cancer since that finding would change the management in pregnancy and treatment of other lesser findings would be deferred until after pregnancy. » Advanced maternal age is defined as age of 35 or greater at the estimated date of delivery. These women are at increased risk for autosomal trisomies, and genetic counseling and genetic amniocentesis are usually offered. » Screening for hypertension and proteinuria by semiquantitative urine dipstick at each prenatal visit is performed to screen for gestational hypertension or preeclampsia. » Antepartum fetal testing is defined as 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 and biophysical profile. » Live-attenuated vaccines should be avoided in pregnancy, but killed vaccines are acceptable, and some, such as influenza vaccine, are indicated in pregnancy.

REFERENCES

Cunningham FG, Leveno KJ, Bloom SL, Hauth JC, Gilstrap LC III, Wenstrom KD. Prenatal care. In: Williams Obstetrics. 24th ed. New York, NY: McGraw-Hill; 2014:201-230. 

Lu MC, Williams III, J, Hobel CJ. Antepartum care: preconception and prenatal care, genetic evaluation and teratology, and antenatal fetal assessment. In: H acker NF, Gambone JC, Hobel CJ, eds. Essentials of Obstetrics and Gynecology. 5th ed. Philadelphia, PA: Saunders; 2009:71-90.

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