Prenatal syphilis screening — can we always trust the result?

Authors

  • Caroline dos Reis Lopes General Pediatrics Department, Hospital Dona Estefânia, Unidade Local de Saúde de São José
  • Ana Pereira Lemos Pediatric Infectious Diseases Department, Hospital Dona Estefânia, Unidade Local de Saúde de São José https://orcid.org/0000-0002-0167-4280
  • Beatriz Costa General Pediatrics Department, Hospital Dona Estefânia, Unidade Local de Saúde de São José
  • Paula Kjöllerström Hematology Unit, Hospital Dona Estefânia, Unidade Local de Saúde de São José https://orcid.org/0000-0001-5526-5565
  • Vitória Matos Imunology Department, Unidade Local de Saúde de São José, Lisbon, Portugal https://orcid.org/0009-0000-8560-3027
  • Catarina Gouveia Pediatric Infectious Diseases Department, Hospital Dona Estefânia, Unidade Local de Saúde de São José https://orcid.org/0000-0002-4162-8473

DOI:

https://doi.org/10.25753/BirthGrowthMJ.v34.i4.36533

Keywords:

congenital syphilis, infant, Jarisch–Herxheimer reaction, prozone phenomenon

Abstract

Introduction: Congenital syphilis (CS) can be acquired by the fetus during pregnancy or delivery. When asymptomatic at birth, newborns usually present the first clinical signs by the age of three months.
Case report: We report the case of a three-month old infant presenting with severe anemia, hepatosplenomegaly, and vesicular rash with shedding palmoplantar erythema. The pregnancy was unremarkable. The blood work revealed severe non-immune hemolytic anemia, thrombocytopenia, and hepatitis. The initial rapid plasma reagin (RPR) screening for syphilis was negative. However, due to a high index of suspicion, a second RPR test was performed, with a positive result, which may be explained by the prozone phenomenon.
Conclusion: This case shows that a negative prenatal syphilis test does not rule out a diagnosis of CS. In the presence of compatible clinical findings and a high index of suspicion, extensive evaluation should be considered. We highlight the importance of serum dilution to overcome the prozone phenomenon.

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References

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Published

2025-12-23

How to Cite

1.
dos Reis Lopes C, Pereira Lemos A, Costa B, Kjöllerström P, Matos V, Gouveia C. Prenatal syphilis screening — can we always trust the result?. BGMJ [Internet]. 2025 Dec. 23 [cited 2025 Dec. 29];34(4):181-5. Available from: https://revistas.rcaap.pt/bgmj/article/view/36533

Issue

Vol. 34 No. 4 (2025)

Section

Clinical Case Reports

License

Copyright (c) 2025 Caroline dos Reis Lopes, Ana Pereira Lemos, Beatriz Costa, Paula Kjöllerström, Vitória Matos, Catarina Gouveia

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