Prenatal infection screening (TORCH, HIV, STIs)

Prenatal infection screening (TORCH, HIV, STIs)

Prenatal infection screening (TORCH, HIV, STIs)

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Prenatal Infection Screening - Proactive Protection

  • Universal 1st prenatal visit screening is critical to prevent vertical transmission.
  • Core Panel:
    • HIV-1/2 antigen/antibody assay
    • Syphilis: RPR or VDRL
    • Hepatitis B: HBsAg
    • Rubella: IgG antibody
    • Chlamydia/Gonorrhea: NAAT
  • TORCH Infections: Toxoplasmosis, Other (Syphilis, VZV, Parvo B19), Rubella, CMV, Herpes.
    • Screening is risk-based, not universal (except Rubella).

Parvovirus B19 is the most common cause of fetal hydrops (hydrops fetalis) from congenital infection.

TORCH Infections - Classic Congenital Threats

📌 TORCH: Toxoplasmosis, Other (Syphilis, VZV, Parvo B19), Rubella, CMV, HSV.

  • Toxoplasmosis
    • Classic Triad: Chorioretinitis, hydrocephalus, diffuse intracranial calcifications.
    • Source: Raw meat, cat feces.
  • Rubella
    • Classic Triad: Sensorineural deafness, cataracts, patent ductus arteriosus (PDA).
    • "Blueberry muffin" rash.
  • Cytomegalovirus (CMV)
    • Most common congenital infection.
    • Features: Periventricular calcifications, hearing loss, petechial rash.
  • Herpes Simplex Virus (HSV-2)
    • Transmission: Perinatal (passage through birth canal).
    • Triad: Vesicular skin lesions, eye disease (e.g., keratitis), encephalitis.
  • Other Agents
    • Syphilis: Saber shins, Hutchinson teeth, saddle nose.
    • VZV: Limb hypoplasia, cutaneous scars (cicatricial lesions).

⭐ CMV is the most common TORCH infection. Differentiate its periventricular calcifications from the diffuse intracranial calcifications seen in Toxoplasmosis.

HIV & STI Screening - The Standard Panel

  • HIV: Universal opt-out screening at 1st prenatal visit.

    • Test: HIV-1/HIV-2 antigen/antibody immunoassay.
    • Repeat in 3rd trimester for high-risk individuals or in high-prevalence areas.
  • Syphilis (Treponema pallidum): Universal screening at 1st visit.

    • Tests: Nontreponemal (RPR, VDRL); confirm with treponemal (FTA-ABS).
    • Repeat in 3rd trimester & at delivery for high-risk patients.
  • Chlamydia & Gonorrhea:

    • Test: Nucleic Acid Amplification Test (NAAT).
    • Screen all women <25 years & older women with risk factors at 1st visit.
  • Hepatitis B Virus (HBV):

    • Test: HBsAg at the first prenatal visit.

⭐ Penicillin G is the only effective agent for treating syphilis in pregnancy to prevent congenital transmission. Allergic patients must undergo desensitization followed by penicillin therapy.

Other Key Infections - GBS, Parvo & More

  • Group B Strep (GBS): Universal screen at 36-38 wks (rectovaginal culture). Prophylaxis with IV Penicillin G during labor prevents neonatal sepsis.
  • Parvovirus B19: Can cause severe fetal anemia, leading to hydrops fetalis (fetal CHF).
  • Hepatitis B/C: Screen all for HBsAg at 1st visit. If mom HBsAg+, neonate needs HBIG + vaccine. HCV screening for high-risk; risk of vertical transmission.

Ultrasound: Fetal ascites in hydrops fetalis

⭐ For GBS+ mothers with a penicillin allergy, use Cefazolin (low-risk for anaphylaxis) or Clindamycin (if susceptible). Vancomycin is reserved for high-risk anaphylaxis or clindamycin resistance.

High‑Yield Points - ⚡ Biggest Takeaways

  • Universal 1st-trimester screening includes HIV, RPR (syphilis), and HBsAg.
  • Congenital toxoplasmosis triad: chorioretinitis, hydrocephalus, and intracranial calcifications.
  • CMV is the most common congenital infection, often from an asymptomatic mother.
  • Congenital rubella triad: cataracts, deafness, and heart defects (PDA). The live vaccine is contraindicated.
  • Maternal Parvovirus B19 can cause fetal hydrops fetalis.
  • Give acyclovir prophylaxis from 36 weeks for recurrent genital herpes to prevent neonatal transmission.

Practice Questions: Prenatal infection screening (TORCH, HIV, STIs)

Test your understanding with these related questions

A 40-year-old pregnant woman, G4 P3, visits your office at week 30 of gestation. She is very excited about her pregnancy and wants to be the healthiest she can be in preparation for labor and for her baby. What vaccination should she receive at this visit?

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Flashcards: Prenatal infection screening (TORCH, HIV, STIs)

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Anencephaly is characterized by _____ levels of AFP in utero

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Anencephaly is characterized by _____ levels of AFP in utero

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