A 32-year-old G5 delivers a stillborn fetus at 34 weeks. The placenta is noted to be much larger than normal. The fetus appeared hydropic and had petechiae over much of the skin. What is the most likely causative agent?

1. A

   Parvovirus

2. B

   Treponema pallidum (syphilis)

3. C

   Herpes simplex virus

4. D

   Rubella

Appeared in: NORCERT 8 Mains-2025

Explanation

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• The clinical triad of hydrops fetalis (fetal swelling), placentomegaly (abnormally large placenta), and petechiae (small red/purple spots) in a stillborn is highly characteristic of congenital syphilis.
• Treponema pallidum spirochetes cross the placenta, causing widespread inflammation and damage to fetal organs like the liver and heart.
• This leads to severe anemia, heart failure, and fluid accumulation (hydrops), while placental inflammation (placentitis) causes it to become large, pale, and boggy.
• The petechiae are a result of thrombocytopenia (low platelets) and vasculitis caused by the infection.

Why Other Options Were Wrong

• Option A: While Parvovirus B19 is a major cause of non-immune hydrops fetalis due to severe anemia, it is not typically associated with petechial rashes. The primary finding is profound anemia.
• Option C: Congenital Herpes Simplex Virus (HSV) infection typically presents with skin vesicles, ulcers, or scarring, and central nervous system issues like microcephaly. Significant hydrops and placentomegaly are not characteristic features.
• Option D: Although congenital rubella can cause a "blueberry muffin" rash (which includes petechiae), it is classically associated with a normal or small placenta, not a large one. The triad of cataracts, deafness, and cardiac defects is more specific.

Related Visual

• Visual 1: Image: Gross specimen of a placenta in congenital syphilis, showing its large, pale, and thickened appearance (placentomegaly).
• Visual 2: Image: Fetus with hydrops fetalis, illustrating the generalized edema, ascites, and skin swelling.
• Visual 3: Chart: Comparison of TORCH infections (Toxoplasmosis, Other/Syphilis, Rubella, Cytomegalovirus, Herpes) and their effects on the fetus and placenta.

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Differential diagnosis of congenital infections causing stillbirth and hydrops fetalis as background academic context rather than a clinical decision trigger.
• Routine screening for syphilis (VDRL or RPR test) is a critical part of antenatal care to prevent congenital syphilis.
• Early detection and treatment of maternal syphilis with penicillin can effectively prevent fetal transmission and its devastating consequences, including stillbirth.
• A nurse attending a delivery with these findings should anticipate the need for neonatal resuscitation, diagnostic workup for infection, and careful handling of the placenta for pathologic examination.

How to Approach the Question

• First, identify the key clinical findings presented in the scenario: 1) stillbirth, 2) large placenta, 3) hydropic fetus, and 4) petechiae.
• Recognize that this question is asking for the differential diagnosis of a congenital infection, often grouped under the TORCH acronym.
• Systematically evaluate each option against the constellation of symptoms provided.
• Consider Parvovirus: It causes hydrops but not typically petechiae.
• Consider Rubella: It causes petechiae (blueberry muffin rash) but is not associated with a large placenta.
• Consider Herpes: It has a different presentation, usually involving skin vesicles.

Concept Tested & Keywords

• Concept Tested: Differential diagnosis of congenital infections causing stillbirth and hydrops fetalis.
• Stem keywords: stillborn, 34 weeks, large placenta, hydropic fetus, petechiae
• Lead-in keywords: most likely
• Clinical cues: The combination of a large placenta (placentomegaly), fetal swelling (hydrops), and skin petechiae is a classic triad.
• Clinical cues: The presence of all three findings strongly points to a specific infectious cause over others.

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