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Evaluation of the Obstetric Patient

by Haywood L. Brown, MD

Ideally, women who are planning to become pregnant should see a physician before conception; then they can learn about pregnancy risks and ways to reduce risks. As part of preconception care, primary care clinicians should advise all women of reproductive age to take a vitamin that contains folate 400 mcg (0.4 mg) once/day. Folate reduces risk of neural tube defects. If women have had a fetus or infant with a neural tube defect, the recommended daily dose is 4000 mcg (4 mg).

Once pregnant, women require routine prenatal care to help safeguard their health and the health of the fetus. Also, evaluation is often required for symptoms and signs of illness. Common symptoms that are often pregnancy-related include vaginal bleeding, pelvic pain, vomiting, and lower-extremity edema (for specific obstetric disorders, see Abnormalities of Pregnancy; for nonobstetric disorders in pregnant women, see Pregnancy Complicated by Disease).

The initial routine prenatal visit should occur between 6 and 8 wk gestation. Follow-up visits should occur at about 4-wk intervals until 28 wk, at 2-wk intervals from 28 to 36 wk, and weekly thereafter until delivery. Prenatal care includes screening for disorders, taking measures to reduce fetal and maternal risks, and counseling.

History

During the initial visit, clinicians should obtain a full medical history, including

  • Previous and current disorders

  • Drug use (therapeutic, social, and illicit)

  • Risk factors for complications of pregnancy ( Pregnancy Risk Assessment)

  • Obstetric history, with the outcome of all previous pregnancies, including maternal and fetal complications (eg, gestational diabetes, preeclampsia, congenital malformations, stillbirth)

Family history should include all chronic disorders in family members to identify possible hereditary disorders (see Genetic Evaluation).

During subsequent visits, queries focus on interim developments, particularly vaginal bleeding or fluid discharge, headache, changes in vision, edema of face or fingers, and changes in frequency or intensity of fetal movement.

Gravidity and parity

Gravidity is the number of confirmed pregnancies; a pregnant woman is a gravida. Parity is the number of deliveries after 20 wk. Multifetal pregnancy is counted as one in terms of gravidity and parity. Abortus is the number of pregnancy losses (abortions) before 20 wk regardless of cause (eg, spontaneous, therapeutic, or elective abortion; ectopic pregnancy). Sum of parity and abortus equals gravidity.

Parity is often recorded as 4 numbers:

  • Number of term deliveries (after 37 wk)

  • Number of premature deliveries (> 20 and < 37 wk)

  • Number of abortions

  • Number of living children

Thus, a woman who is pregnant and has had one term delivery, one set of twins born at 32 wk, and 2 abortions is gravida 5, para 1-1-2-3.

Physical Examination

A full general examination, including height and weight, is done first. BMI should be calculated and recorded.

In the initial obstetric examination, speculum and bimanual pelvic examination is done

  • To check for lesions or discharge

  • To note the color and consistency of the cervix

  • To obtain cervical samples for testing

Also, fetal heart rate and, in patients presenting later in pregnancy, lie of the fetus are assessed (see Figure: Leopold maneuver.).

Pelvic capacity can be estimated clinically by evaluating various measurements with the middle finger during bimanual examination. If the distance from the underside of the pubic symphysis to the sacral promontory is > 11.5 cm, the pelvic inlet is almost certainly adequate. Normally, distance between the ischial spines is 9 cm, length of the sacrospinous ligaments is 4 to 5 cm, and the subpubic arch is 90°.

During subsequent visits, BP and weight assessment is important. Obstetric examination focuses on uterine size, fundal height (in cm above the symphysis pubis), fetal heart rate and activity, and maternal diet, weight gain, and overall well-being. Speculum and bimanual examination is usually not needed unless vaginal discharge or bleeding, leakage of fluid, or pain is present.

Testing

Laboratory testing

For diagnosis of pregnancy, see Physiology of Pregnancy : Diagnosis. Initial laboratory evaluation is thorough; some components are repeated during follow-up visits ( Components of Routine Prenatal Evaluation).

Components of Routine Prenatal Evaluation

Type

Initial Visit

Follow-up Visits

Physical examination

Height measurement

Weight and BP measurement

X

Examination of thyroid, heart, lungs, breasts, abdomen, extremities, and optic fundus

Examination of ankles for edema

X

Complete pelvic examination

Examination to determine pelvic capacity

Examination of uterus to determine size and fetal position a

X

Evaluation for fetal heart sounds a

X

Blood tests b

CBC c

Blood typing and Rh 0 (D) antibody levels d

Hepatitis B serologic test (see )

Human immunodeficiency virus (HIV)

Rubella and varicella immunity e

Serologic test for syphilis

Cervical tests

Cervical cultures for gonorrhea and chlamydial infection f

Cervical Papanicolaou (Pap) test

Urine tests

Urine culture

Urine protein and glucose determination

X

Other tests

Screening for TB (if at risk)

Genetic screening ( Genetic Evaluation), including 1st-trimester screening for aneuploidy

Pelvic ultrasonography g

a Component may not be detectable depending on the stage of pregnancy at presentation.

b Diabetes screening is done only once—routinely at 24–28 wk but earlier in women at risk.

c Hct is repeated in the 3rd trimester.

d The test is repeated at 26–28 wk in Rh-negative women.

e Rubella and varicella titers are measured unless women have been vaccinated or have had a documented previous infection, thus confirming immunity.

f For women at high risk, the test is repeated at 36 wk.

g Ideally, the test is done in the 2nd trimester, between 16 and 20 wk; it is not obtained routinely by all practitioners.

X = repeated at follow-up visits.

If a woman has Rh-negative blood, she may be at risk of developing Rh 0 (D) antibodies, and the fetus may be at risk of developing erythroblastosis fetalis. Rh 0 (D) antibody levels should be measured in pregnant women at 18 to 20 wk and again at about 26 to 28 wk. Additional measures may be necessary to prevent development of maternal Rh antibodies (see Erythroblastosis Fetalis).

Generally, women are routinely screened for gestational diabetes between 24 and 28 wk using a 50-g, 1-h glucose tolerance test (see Diabetes). However, if women have significant risk factors for gestational diabetes, they are screened during the 1st trimester. These risk factors include

  • Gestational diabetes or a macrosomic neonate (weight > 4500 g at birth in a previous pregnancy

  • Unexplained fetal losses

  • A strong family history of diabetes in 1st-degree relatives

  • A history of persistent glucosuria

  • Body mass index (BMI) > 30 kg/m 2

  • olycystic ovary syndrome with insulin resistance

If the 1st-trimester test is normal, the 50-g test should repeated at 24 to 28 wk, followed, if abnormal, by a 3-h test. Abnormal results on both tests confirms the diagnosis of gestational diabetes.

Ultrasonography

Most obstetricians recommend at least one ultrasound examination during each pregnancy, ideally between 16 and 20 wk, when estimated delivery date (EDD) can still be confirmed fairly accurately and when placental location and fetal anatomy can be evaluated. Estimates of gestational age are based on measurements of fetal head circumference, biparietal diameter, abdominal circumference, and femur length. Measurement of fetal crown-rump length during the 1st trimester is particularly accurate in predicting EDD: to within about 5 days when measurements are made at < 12 wk gestation and to within about 7 days at 12 to 15 wk. Ultrasonography during the 3rd trimester is accurate for predicting EDD to within about 2 to 3 wk.

Specific indications for ultrasonography include

  • Investigation of abnormalities during the 1st trimester (eg, indicated by abnormal results of noninvasive maternal screening tests)

  • Need for detailed assessment of fetal anatomy (usually at about 16 to 20 wk), possibly including fetal echocardiography at 20 wk if risk of congenital heart defects is high (eg, in women who have type 1 diabetes or have had a child with a congenital heart defect)

  • Detection of multifetal pregnancy, hydatidiform mole, polyhydramnios, placenta previa, or ectopic pregnancy

  • Determination of placental location, fetal position and size, and size of the uterus in relation to given gestational dates (too small or too large)

Ultrasonography is also used for needle guidance during chorionic villus sampling, amniocentesis, and fetal transfusion. High-resolution ultrasonography includes techniques that maximize sensitivity for detecting fetal malformations.

If ultrasonography is needed during the 1st trimester (eg, to evaluate pain, bleeding, or viability of pregnancy), use of an endovaginal transducer maximizes diagnostic accuracy; evidence of an intrauterine pregnancy (gestational sac or fetal pole) can be seen as early as 4 to 5 wk and is seen at 7 to 8 wk in > 95% of cases. With real-time ultrasonography, fetal movements and heart motion can be directly observed as early as 5 to 6 wk.

Other imaging

Conventional x-rays can induce spontaneous abortion or congenital malformations, particularly during early pregnancy. Risk is remote (up to about 1/million) with each x-ray of an extremity or of the neck, head, or chest if the uterus is shielded. Risk is higher with abdominal, pelvic, and lower back x-rays. Thus, for all women of childbearing age, an imaging test with less ionizing radiation (eg, ultrasonography) should be substituted when possible, or if x-rays are needed, the uterus should be shielded (because pregnancy is possible). Medically necessary x-rays or other imaging should not be postponed because of pregnancy. However, elective x-rays are postponed until after pregnancy.

Treatment

Problems identified during evaluation are managed. Women are counseled about exercise and diet, and nutritional supplements are prescribed. What to avoid, what to expect, and when to obtain further evaluation are explained. Couples are encouraged to attend childbirth classes.

Diet and supplements

To provide nutrition for the fetus, most women require about 250 kcal extra daily; most calories should come from protein. If maternal weight gain is excessive (> 1.4 kg/mo during the early months) or inadequate (< 0.9 kg/mo), diet must be modified further. Weight-loss dieting during pregnancy is not recommended, even for morbidly obese women.

Most pregnant women need a daily oral iron supplement of ferrous sulfate 300 mg or ferrous gluconate 450 mg, which may be better tolerated. Woman with anemia should take the supplements bid. All women should be given oral prenatal vitamins that contain folate 400 mcg (0.4 mg), taken once/day; folate reduces risk of neural tube defects. For women who have had a fetus or infant with a neural tube defect, the recommended daily dose is 4000 mcg (4 mg).

Physical activity

Pregnant women can continue to do moderate physical activities and exercise but should take care not to injure the abdomen. Sexual intercourse can be continued throughout pregnancy unless vaginal bleeding, pain, leakage of amniotic fluid, or uterine contractions occur.

Travel

The safest time to travel during pregnancy is between 14 and 28 wk, but there is no absolute contraindication to travel at any time during pregnancy. Pregnant women should wear seat belts regardless of gestational age and type of vehicle.

Travel on airplanes is safe until 36 wk gestation. The primary reason for this restriction is the risk of labor and delivery in an unfamiliar environment.

During any kind of travel, pregnant women should stretch and straighten their legs and ankles periodically to prevent venous stasis and the possibility of thrombosis. For example, on long flights, they should walk or stretch every 2 to 3 h. In some cases, the clinician may recommend thromboprophylaxis for prolonged travel.

Immunizations

Vaccines for measles, mumps, rubella, and varicella should not be used during pregnancy (see Drugs in Pregnancy : Vaccines). The hepatitis B vaccine can be safely used if indicated, and the influenza vaccine is strongly recommended for women who are pregnant or postpartum during influenza season. Booster immunization for diphtheria, tetanus, and pertussis (Tdap) after 20 wk gestation or postpartum is recommended, even if women have been fully vaccinated.

Because pregnant women with Rh-negative blood are at risk of developing Rh 0 (D) antibodies, they are given Rh 0 (D) immune globulin 300 mcg IM in any of the following situations:

  • After any significant vaginal bleeding or other sign of placental hemorrhage or separation (abruptio placentae)

  • After a spontaneous or therapeutic abortion

  • After amniocentesis or chorionic villus sampling

  • Prophylactically at 28 wk,

  • If the neonate has Rh 0 (D)-positive blood, after delivery

Modifiable risk factors

Women should not use alcohol and tobacco and should avoid exposure to secondhand smoke. They should also avoid exposure to chemicals or paint fumes, direct handling of cat litter (due to risk of toxoplasmosis), prolonged temperature elevation (eg, in a hot tub or sauna), and exposure to people with active viral infections (eg, rubella, parvovirus infection [fifth disease], varicella).

Women with substance abuse problems should be monitored by a specialist in high-risk pregnancy. Women should be screened for domestic violence (see History) and depression.

Drugs and vitamins that are not medically indicated should be discouraged (see Drugs in Pregnancy).

Symptoms requiring evaluation

Women should be advised to seek evaluation for unusual headaches, visual disturbances, pelvic pain or cramping, vaginal bleeding, rupture of membranes, extreme swelling of the hands or face, diminished urine volume, any prolonged illness or infection, or persistent symptoms of labor. Multiparous women with a history of rapid labor should notify the physician at the first symptom of labor.

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