What is Torch (Toxoplasmosis, Rubella, Cytomegalovirus (CMV), and Herpes simplex virus (HSV)) infection and its relationship with abortion?

TORCH Infections and Their Relationship with Abortion

TORCH is an acronym representing a group of congenital infections—Toxoplasmosis, Other agents, Rubella, Cytomegalovirus (CMV), and Herpes simplex virus (HSV)—that cause asymptomatic or mild maternal disease but can result in spontaneous abortion, stillbirth, and severe fetal malformations when acquired during pregnancy. 1, 2

What TORCH Infections Are

TORCH represents specific pathogens that cross the placental barrier and cause congenital disease:

• Toxoplasmosis (caused by Toxoplasma gondii) 1
• Other agents including syphilis, varicella-zoster virus, parvovirus B19, and other emerging pathogens 3, 2
• Rubella virus 1
• Cytomegalovirus (CMV) 1
• Herpes simplex virus (HSV) 1

These pathogens have evolved mechanisms to bypass placental defenses that normally protect against vertical transmission. 1

Direct Relationship with Abortion and Adverse Pregnancy Outcomes

Spontaneous Abortion Risk

TORCH infections are a significant cause of spontaneous abortion, with studies showing abortion rates of 31.8% among infected pregnant women. 4 The mechanism involves direct fetal damage, placental insufficiency, or severe congenital malformations incompatible with continued pregnancy. 2, 4

In a large prospective Chinese study of 1,863 pregnant women, TORCH-infected participants experienced:

• Spontaneous abortions: 31.8% (27/85 infected cases) 4
• Stillbirths: 9.4% (8/85 infected cases) 4
• Premature births: 8.2% (7/85 infected cases) 4

Bad Obstetric History Association

Women with bad obstetric history (recurrent pregnancy loss, stillbirths, previous congenital malformations) show significantly higher TORCH seropositivity rates. 5, 6 In South Indian populations, 75% of high-risk pregnancy cases had bad obstetric history, with total seropositivity reaching 36% for toxoplasma, 84% for rubella, 97% for CMV, and 65% for HSV. 5

Specific Pathogen Risks During Pregnancy

Toxoplasmosis

• Transmission risk increases with gestational age: 15% at 13 weeks, rising to 44% at 26 weeks and 71% at 37 weeks 7
• Severity is inversely related to gestational age: Earlier infections cause more severe disease (15% symptomatic at 13 weeks vs. 71% at 37 weeks) 7
• Early treatment within 3 weeks of maternal seroconversion reduces transmission by 52% 7
• Congenital manifestations include chorioretinitis (92%), intracranial calcifications (80%), and hydrocephaly (68%) 7

Rubella

• Rubella is a significant infectious agent for high-risk pregnancy, with 84-97% seropositivity in affected populations 5
• Confers predisposing risk toward fetal congenital malformation in current pregnancy 5
• Preconception screening for rubella seronegativity and vaccination if indicated is essential 3

Cytomegalovirus (CMV)

• CMV is the most common TORCH infection, with seropositivity rates of 91-97% in high-risk pregnancies 5, 6
• CMV infection rate of 3.15% represents the highest among TORCH agents 4
• Fetal infection manifests as echogenic bowel on ultrasound, with 2-10% incidence of congenital infection in affected fetuses 3
• Amniocentesis with PCR for CMV DNA is the best diagnostic test, most sensitive when performed after 21 weeks gestation and >6 weeks from maternal infection 3
• Symptomatic neonatal infection is usually related to primary maternal infection during pregnancy 3

Herpes Simplex Virus (HSV)

• HSV seropositivity of 61-65% in high-risk pregnancies represents the highest prevalence reported in India 5
• Approximately 70% of HIV-infected persons are HSV-2 seropositive, indicating high background prevalence 3
• Neonatal herpes transmission risk is primarily from genital lesions during delivery rather than in utero transmission 3

Clinical Approach to TORCH Screening

Who Should Be Screened

Routine TORCH screening of asymptomatic pregnant women is NOT recommended. 3, 8 However, targeted screening is indicated for:

• Pregnant women with bad obstetric history (recurrent pregnancy loss, previous stillbirths, prior congenital malformations) 6
• Women with upper respiratory tract infection during pregnancy (14.6% TORCH positivity rate) 4
• Pregnant women with unexplained fever, meningitis, encephalitis, or acute flaccid paralysis in areas with ongoing transmission 3
• Women with fetal ultrasound abnormalities suggestive of congenital infection 3, 7

Diagnostic Testing

Test for IgM and IgG antibodies by ELISA or chemiluminescence immunoassay to distinguish acute from past infection. 5, 4, 6

• IgM positive = acute/recent infection requiring immediate intervention 6
• IgG positive alone = past infection with immunity (except for CMV and HSV which can reactivate) 6
• For CMV specifically, IgG avidity testing helps determine timing: low avidity suggests recent infection 3

Fetal Evaluation When Maternal Infection Confirmed

Perform detailed fetal ultrasound 2-4 weeks after onset of maternal illness to evaluate for structural abnormalities. 3, 8 Look specifically for:

• Ventriculomegaly or hydrocephaly 7
• Intracranial calcifications 3, 7
• Echogenic bowel 3
• Hydrops fetalis 3
• Ascites 3
• Intrauterine growth restriction 3

Consider amniocentesis for pathogen-specific PCR testing, though sensitivity and specificity vary by pathogen and gestational age. 3, 8 For CMV, amniocentesis is most accurate after 21 weeks and >6 weeks from maternal infection. 3

Management During Pregnancy

Treatment Limitations

No specific antiviral treatment exists for most TORCH infections during pregnancy, making prevention the primary strategy. 3, 8

• Toxoplasmosis: Early treatment reduces transmission by 52% but requires prompt initiation within 3 weeks of seroconversion 7
• Rubella: No treatment available; prevention through preconception vaccination is essential 3
• CMV: Ganciclovir or valganciclovir may be considered but are pregnancy category C with limited safety data 3
• HSV: Acyclovir for symptomatic disease; chronic suppressive therapy for frequent recurrences 3

Prevention Strategies

All women of reproductive age should receive preconception counseling about TORCH prevention. 3

• Rubella vaccination for seronegative women before pregnancy (contraindicated during pregnancy) 3
• Avoid exposure to toxoplasmosis through proper food handling and cat litter avoidance 3
• Use latex condoms to reduce HSV transmission risk 3
• Insect repellent and protective clothing in areas with vector-borne disease transmission 8

Critical Pitfalls to Avoid

• Do not screen asymptomatic pregnant women routinely—this leads to unnecessary anxiety and interventions without proven benefit 3, 8
• Do not assume IgG positivity alone indicates acute infection—it usually represents past immunity 6
• Do not perform amniocentesis for CMV before 21 weeks or within 6 weeks of maternal infection—sensitivity is inadequate 3
• Do not delay toxoplasmosis treatment—efficacy drops dramatically after 3 weeks from seroconversion 7
• Do not ignore bad obstetric history—these women warrant targeted TORCH screening 5, 6

Outcomes and Prognosis

Congenital malformations occur in 12.9% of TORCH-infected pregnancies, significantly higher than the 1.1% rate in uninfected pregnancies. 4 Among infected women, 70-90% of infected newborns are asymptomatic at birth but may develop late sequelae including chorioretinitis, hearing loss, and developmental delays. 7, 2

In cases of miscarriage or induced abortion, test all products of conception (placenta, umbilical cord) for evidence of TORCH infection to document effects on pregnancy outcome and guide future pregnancy planning. 3, 8