Prenatal Care: Screening, Immunizations, and Case Study Review

General Overview and Recommendations

• The American College of Obstetricians and Gynecologists (ACOG) provides guidelines for patient care in pregnancy.

• This presentation covers major topics from the Bates textbook, but it is recommended to read the relevant sections in Bates for full detail.

Health Promotion and Counseling

• Key Areas: Nutrition, weight gain, exercise, substance use, intimate partner violence (IPV), immunizations, perinatal depression, pregnancy planning/prevention, and laboratory/genetic/aneuploidy testing.

• These topics are aligned with recommendations found in the Bates textbook.

Immunizations in Pregnancy

• General Recommendations: It is crucial to recommend appropriate immunizations during pregnancy.

• Tdap Vaccine (Tetanus, Diphtheria, and Acellular Pertussis): Typically administered at $27$ to $36$ weeks of gestation.

• Influenza Vaccine: Regularly recommended.

• COVID-19 Vaccine: Updates and recommendations should be followed.

• RSV Vaccine (Respiratory Syncytial Virus): Recommended during the RSV season (September to January) for pregnant individuals between $32$ and $36$ weeks gestation.

Foods to Avoid During Pregnancy (Listeria Risk)

• Listeria is a significant concern during pregnancy.

• Foods to avoid include:

  • Unpasteurized milk and foods made with unpasteurized milk.

  • Raw and undercooked seafood, eggs, and meat.

  • Refrigerated pâté, meat spreads, and smoked salmon.

  • Hot dogs, luncheon meats, and cold cuts, unless served steaming hot.

General Prenatal Laboratory Screening

• Essential screenings include tests for:

  • Rh incompatibility

  • Hepatitis B

  • HIV (Human Immunodeficiency Virus)

  • Syphilis

  • Bacteriuria

  • Iron deficiency

  • Gestational diabetes

First Trimester Tests ($0-13$ Weeks)

• Rh Incompatibility Screening: To detect maternal blood type incompatibility, especially in Rh-negative mothers who may need RhoGAM to prevent hemolytic disease of the newborn.

• Complete Blood Count (CBC): Measures hemoglobin, hematocrit, and platelets.

  • Physiologic Anemia of Pregnancy: Caused by increased plasma volume leading to relative hemodilution. Requires monitoring for anemia, infections, or clotting disorders.

  • Iron supplementation is recommended for lower levels of anemia; low platelets require further evaluation.

• Infection Screenings: HIV, Syphilis, Hepatitis B surface antigen, Chlamydia, Gonorrhea.

  • Purpose: Detecting these infections can cause harm to both mother and fetus. Positive tests allow for early treatment to reduce maternal complications and vertical transmission.

• Rubella and Varicella Immunity: Assess prior immunization. If not immune, counsel on avoiding infection and offer vaccination postpartum (live vaccines are contraindicated during pregnancy).

• Urine Culture: Screens for asymptomatic bacteriuria, which, if untreated, can lead to pyelonephritis and preterm labor. Positive results are treated with pregnancy-safe antibiotics.

• Optional Additional Tests: Nuchal translucency and first-trimester screening at $11$ to $13$ weeks (further diagnostic imaging, such as ultrasound, to be discussed later).

Second Trimester Tests ($14-27$ Weeks)

• Quad/Quadruple Screen: Assesses risk for neural tube defects, Trisomy $21$ (Down syndrome), and Trisomy $18$.

• Anatomy Ultrasound: Checks fetal growth, anatomy, placental position, and amniotic fluid volume.

• Amniocentesis: If indicated, performed at $15$ to $20$ weeks for diagnostic genetic or chromosomal testing (not routinely performed).

Third Trimester Tests ($28-40$ Weeks)

• Repeat CBC: Screens again for anemia.

• Glucose Challenge Test: Screens for gestational diabetes.

• Antibody Screen: Performed at $28$ weeks if the mother is Rh-negative. Confirms no sensitization and determines the timing for RhoGAM administration.

• Group B Strep (GBS) Cultures: Collected at $35$ to $37$ weeks to prevent neonatal infection.

• Nonstress Test (NST): Performed after $32$ weeks if the patient is high-risk, to assess fetal well-being and oxygenation.

• Tdap Vaccine: Ideally administered at $27$ through $36$ weeks gestation.

Case Study: Early Pregnancy Management

• Patient Presentation: A $23$ y/o G1P0 presents with $2$ months of amenorrhea, breast tenderness, morning nausea, positive home and office pregnancy tests. Last menstrual period (LMP) was $11/3$. No bleeding or pain, but has constipation. History of oligomenorrhea. Physical exam shows a bluish cervix (Chadwick sign), no palpable fetal heart tones (FHT) on Doppler, and a bimanual exam suggesting a $14$-week sized uterus, despite LMP suggesting $8$ weeks.

• Differential Diagnoses (Initial):

  • Missed abortion (positive pregnancy test, absent FHT).

  • Normal pregnancy with incorrect dates (due to oligomenorrhea, patient may have conceived later than LMP suggests; BMI may also make FHT difficult to detect).

  • Ectopic pregnancy (urgent consideration given absent FHT).

  • Fibroid uterus (could cause an enlarged uterus).

  • Molar pregnancy (often presents with an enlarged uterus and no heartbeat; ultrasound may show a "snowstorm pattern").

  • Multiples (twins/triplets can result in a larger-than-expected uterus and difficulty finding FHT).

• Cervical Color: The bluish discoloration of the cervix is a normal physiological change in early pregnancy, known as Chadwick's sign, caused by increased venous flow; it is not a concern.

• Next Step: An ultrasound is crucial to:

  • Rule out an ectopic pregnancy (a medical emergency).

  • Determine if there is a molar pregnancy or miscarriage.

  • Confirm fetal viability (presence of FHT).

  • Bate the pregnancy accurately, especially with an unreliable LMP, thereby estimating the gestational duration and estimated delivery date (EDD).

• Ultrasound Report ($1/3$): Revealed a single fetus with an estimated gestational age of $8$ weeks, a $4$ cm posterior fibroid, and a $4$ cm clear simple cyst on the left ovary.

• Estimating Delivery Date (EDD):

  • Naegele's rule (based on LMP, but unreliable with oligomenorrhea).

  • Date of conception (if known).

  • Ultrasound (most effective).

  • Fetal heart Doppler (typically audible by $10$ weeks).

  • Early pelvic exam.

  • Quickening (patient's perception of fetal movement): Occurs at $18-20$ weeks for primigravid patients and $16-18$ weeks for multigravid patients.

• Pregnancy Trimester: Based on the ultrasound, the patient is $8$ weeks, placing her in the first trimester.

• Ovarian Cyst Management: A $4$ cm clear simple cyst on the ovary is likely a corpus luteum cyst, which is common in early pregnancy and supplies progesterone until the placenta takes over around $12$ weeks. If asymptomatic, it can be followed with another ultrasound at $14-16$ weeks.

• Patient Education and Labs: For a first-trimester patient, health promotion and counseling (referencing Bates) are important, including dietary advice (foods to avoid) and the general first-trimester lab tests discussed previously in the lecture.