Severe early-onset Fetal Growth Restriction (<20 weeks).
Clinical Ref: Routine "Panel" testing is discouraged by FIGO/RCOG due to high false-positive rates. Testing should be serial and pathogen-specific based on clinical suspicion.
Guidelines & Evidence
Clinical Details
Section 1
When to Use
When to Use
Differential diagnosis for symmetric Intrauterine Growth Restriction (IUGR).
Evaluation of fetal anomalies on ultrasound (e.g., intracranial calcifications, microcephaly, hydrops).
Screening pregnant patients with concerning exposures or viral prodromes (fever, lymphadenopathy, rash).
Workup for unexplained stillbirth or neonatal jaundice/thrombocytopenia.
Exclusion Criteria
The TORCH framework is a screening heuristic. It is not a single "test" but a diagnostic approach. Routine universal TORCH screening in asymptomatic patients is not cost-effective and is generally discouraged by ACOG.
Section 2
Formula & Logic
The Acronym Breakdown
T
Toxoplasmosis (T. gondii)
O
Other (Syphilis, Parvovirus B19, VZV, Zika, HIV)
R
Rubella
C
Cytomegalovirus (CMV)
H
Herpes Simplex Virus (HSV)
Pathophysiology
These agents share the ability to cross the placenta (hematogenous spread) or infect the fetus via the birth canal (ascending/contact spread). The severity of fetal impact is generally inversely proportional to the gestational age at the time of primary maternal infection.
Section 3
Pearls/Pitfalls
Diagnostic Pearls
CMV: The most common congenital infection; look for periventricular calcifications on US.
Toxoplasmosis: Classically presents with the triad of chorioretinitis, hydrocephalus, and intracranial calcifications (diffuse, unlike CMV).
Syphilis: Rising incidence; check RPR/VDRL at first visit and again at 28 weeks in high-risk areas.
HSV: Risk of transmission is highest (30–50%) during a primary outbreak at the time of delivery; recurrent outbreaks carry <1% risk.
Serology Pitfalls
IgM false positives are common; always confirm with IgG avidity testing if available.
Low IgG avidity suggests a primary infection within the last 3–4 months.
Do not wait for seroconversion in HSV; if lesions are present, treat empirically and consider C-section.
Common US Findings
Intracranial Calcifications
CMV (Periventricular) or Toxoplasmosis (Diffuse)
Hydrops Fetalis
Parvovirus B19, Syphilis, CMV
Limb Hypoplasia
Varicella (VZV)
Hepatomegaly
Syphilis, CMV
Section 4
Next Steps
Next Steps for Positive Maternal Serology
01
Determine timing of infection via IgG avidity or serial titers.
02
Refer to Maternal-Fetal Medicine (MFM) for detailed anatomy ultrasound.
03
Consider amniocentesis for PCR (wait at least 6-8 weeks post-infection and after 21 weeks gestation for CMV).
04
Initiate pathogen-specific therapy (e.g., Spiramycin/Pyrimethamine for Toxo, Penicillin for Syphilis).
Delivery Considerations
Active HSV lesions or prodromal symptoms at the time of labor are an absolute indication for Cesarean delivery to prevent neonatal HSV.
Section 5
Evidence Appraisal
Key Citations
Practice Bulletin No. 151: Cytomegalovirus, Parvovirus B19, Varicella Zoster, and Toxoplasmosis in Pregnancy.
ACOG • Obstetrics & Gynecology. 2015;Reaffirmed 2023. The definitive guidance for managing the "non-O" components of TORCH.
Congenital cytomegalovirus infection: antenatal and postnatal considerations.
Kimberlin DW et al. • Clinical Microbiology Reviews. 2013;Comprehensive review of the leading cause of non-genetic sensorineural hearing loss.
Section 6
Literature
History of the Acronym
The acronym was coined in 1971 by André Nahmias to group infections that presented with similar clinical features in the neonate. While the "Other" category has expanded significantly, the framework remains the primary teaching tool for perinatal infectious diseases.
