The term “TORCH” in the context of TORCH screening in pregnancy was first coined in 1971 by immunologist Andre Nahmia of Emory University, U.S.A. Nahmia combined a complex of perinatal infections called TORCH, toxoplasma (To), rubella (R), cytomegalovirus (C), herpes simplex virus type 1 or 2 (H). Herpes simplex virus type 1 or type 2 (H). It has been almost half a century since the concept of TORCH was introduced. Should screening tests for antibodies to the 4 pathogenic microorganisms be performed during pregnancy? How should it be done? This is still a controversial issue in the medical community.
In 2011, the Obstetrics and Gynecology Group of the Chinese Society of Obstetrics and Gynecology: A Guide to Preconception and Pregnancy Care, 1st edition, listed TORCH screening as the preferred screening test in the first trimester of pregnancy.
In recent years, with the advancement of prenatal diagnostic techniques, especially fetal ultrasound and the introduction of MRI, more and more fetal congenital malformations have been found to be associated with TORCH infection. Since 2008, some countries in Europe and North America have issued guidelines for the screening and diagnosis of cytomegalovirus, rubella virus, herpes simplex virus and toxoplasmosis during pregnancy, approved by the government and obstetrics and gynecology associations.
In order to meet the needs of eugenics and maternal and child health care, the National Professional Committee on Family Planning and Eugenics decided to compile a TORCH screening guideline suitable for Chinese conditions. Due to the lack of standardized testing methods and limited research data in China, especially the lack of evidence from large sample randomized controlled trials (RCTs), this guideline is based on the European and Canadian guidelines issued in recent years, following the principles of “based on national conditions, evidence-based, realistic and new, and resource sharing”, and combined with the current situation of eugenic work. Many of the ideas recommended in the guideline are preliminary and need to be supported by more and stronger evidence.
Recommended recommendations
I. Misconceptions about TORCH screening
1, TORCH screening in pregnancy should be based on the characteristics of the pathogenic microorganisms being screened to determine the timing of screening, and the test request form should indicate the week of gestation (head-rump length in early pregnancy and biparietal diameter in mid-pregnancy to determine the week of gestation). (II-2A)
2, TORCH screening should be conducted using quantitative analysis methods. (II-2A)
Cytomegalovirus screening
1. Routine cytomegalovirus screening of pregnant women using serological methods and quantitative urine CMV-DNA assays. (III-B)
2. Consider cytomegalovirus serologic testing for pregnant women with influenza-like symptoms or ultrasonographic findings of suspected cytomegalovirus infection during pregnancy. (III-B)
3. Health care workers and caregivers who are seronegative (IgG negative) should be monitored serologically during pregnancy. Serologic surveillance should also be performed for pregnant women (IgG negative) who are at risk of exposure to infant urine and saliva. (III-B)
4. The diagnosis of initial maternal giant cell infection during pregnancy should be based on the new appearance of virus-specific IgG antibodies in the serum of pregnant women (who were previously seronegative) or the finding of specific IgM antibodies accompanied by a decrease in IgG antibody affinity. (II-2A)
5. The diagnosis of recurrent infection should be based on a pregnant woman who has previously tested positive for IgG antibodies, a significant increase in the current IgG antibody titer (4-fold increase in quantitative testing), with or without the presence of IgM antibodies, and a high affinity for IgG (≤ 16 weeks); a positive saliva or throat swab specimen or other human tissue culture for cytomegalovirus; or a quantitative PCR test for cytomegalovirus from urine, saliva or throat swab specimens or other human tissue. High cytomegalovirus copy number by quantitative PCR. (III-C)
The risk of intrauterine vertical transmission and fetal infection is 30%-40% for first-time infected pregnant women, and if the fetus is infected, the risk of postnatal sequelae is 20%-25%. (II-2A)
7. Pregnant women with recurrent infection should also be informed that the risk of intrauterine vertical transmission and fetal infection is 1% for both partners and that the risk of postnatal sequelae is 20%-25% if the fetus is infected. (II-2A)
The prenatal diagnosis of fetal cytomegalovirus infection should be based on amniocentesis. Amniocentesis should be performed after 21 weeks of gestation and after at least 7 weeks of presumed maternal infection. This time interval is important because it takes 5-7 weeks for the virus to replicate in the kidney after fetal infection before the amount of virus secreted into the amniotic fluid can be detected. (II-2A)
9. Amniocentesis may be considered for recurrent cytomegalovirus infection in pregnant women, but the corresponding risk-benefit ratio is not high due to the low rate of vertical transmission. (III-C)
Once fetal cytomegalovirus infection has been diagnosed, pregnant women should undergo a series of ultrasound examinations every 2-4 weeks to detect sonographic abnormalities. This sonographic abnormality can help us to predict the prognosis of the fetus, but it should be recognized that the absence of sonographic abnormalities does not ensure a normal fetus. (II-2B)
11. Quantification of cytomegalovirus-DNA in amniotic fluid can help predict fetal outcome. (II-2B)
Rubella virus screening
1. Women who are planning to become pregnant are advised to undergo counseling to determine antibody status and, if necessary, to receive rubella vaccination. (I-A)
2. Since the risk of congenital rubella syndrome varies with the week of gestation at the time of infection, it is essential to know the exact week of gestation, which is critical for counseling. (II-3A)
3. Primary maternal infection should be diagnosed by serologic testing. (II-2A)
4. Pregnant women who have been exposed to rubella or are symptomatic should have serologic testing to determine immune status and risk of congenital rubella syndrome. (III-A)
5. Rubella vaccination should not be given during pregnancy, but is safe after delivery. (III-B)
6. Careless vaccination in early pregnancy or pregnancy immediately after vaccination is safe for pregnant women because no cases of congenital rubella syndrome have been reported in that setting. (III-B)
7. Screening for rubella virus during pregnancy should IgG and IgM antibody testing at the same time. (II-2B)
IV. Toxoplasma screening
1. All women who are pregnant or planning to become pregnant should be informed in detail about the prevention of Toxoplasma gondii infection during pregnancy. (III-C)
2. Routine universal screening should not be performed in low-risk pregnant women. Serologic screening should be offered to pregnant women considered to be at high risk for initial Toxoplasma gondii infection. (II-3E)
3. Pregnant women with suspected recent infection should be tested in a reference laboratory prior to interventional diagnosis, and the test must reflect the infection as accurately as possible and be interpretable. (II-2B)
To confirm Toxoplasma gondii infection, PCR should be used to detect Toxoplasma gondii DNA in amniotic fluid in the following cases.
(1) a maternal diagnosis of initial infection; (2) serologic assays that do not confirm or exclude acute infection; (3) abnormal ultrasound findings (intracranial calcification, microcephaly, hydrocephalus, ascites
hepatosplenomegaly, or severe intrauterine growth restriction). (II-2B)
5. Amniocentesis should be performed at >18 weeks and after 4 weeks of suspected maternal infection to reduce the incidence of false negative results. (II-2D)
6. Suspected maternal toxoplasma infection should be screened with ultrasound to see if ultrasound findings are consistent with TORCH (toxoplasma, rubella, cytomegalovirus, herpesvirus, and others) findings. These include, but are not limited to, intracranial calcifications, microcephaly, hydrocephalus, ascites, hepatosplenomegaly, or severe intrauterine growth restriction of the fetus. (II-2B)
7. If acute infection is suspected, repeat testing should be performed within 2-3 weeks, taking into account the immediate initiation of treatment with acetylcholine, without waiting for repeat test results. (II-2B)
8. If maternal infection is confirmed but it is not known at this time whether the fetus is infected, acetylspiramycin should be given for prophylaxis of the fetus (to prevent vertical transmission). (I-B)
9. Pregnant women with confirmed or highly suspected fetal infection (positive amniotic fluid PCR) should be treated with a combination of acetaminophen, sulfadiazine, and formyltetrahydrofolate. (I-B)
10. Pregnant women who have been previously infected with Toxoplasma gondii and have been immunized do not need anti-Toxoplasma treatment. (I-E)
11. Every suspected case of Toxoplasma infection should be discussed with a specialist. (III-B)
12. Immunosuppressed or HIV-positive women should be screened because of the risk of toxoplasma activation and toxoplasmic encephalitis. (I-A)
13. Women diagnosed with acute Toxoplasma infection who are not pregnant should wait 6 months before becoming pregnant and should consult a specialist in each case. (III-B)
V. Herpes simplex virus screening
1. Women should be screened for genital herpes (HSV) infection as early as possible during pregnancy. (III-A)
2. Women presenting with recurrent episodes of HSV simplex should be informed of the risk of possible transmission of the virus to the newborn during delivery. (III-A)
3. In women with primary HSV in late pregnancy, the probability of HSV transmission to the newborn is very high and the clinician should advise the pregnant woman to have a cesarean section to reduce the risk of infection. (II-3B)
4. If HSV infection recurs during labor and delivery, cesarean delivery should be performed for women with prodromal symptoms or when there is suspicion of pre-existing functional impairment related to HSV. (II-2A)
5. For recurrent HSV during pregnancy, acyclovir and valacyclovir should be given at week 36 to inhibit viral replication, reduce the probability of lesions, reduce viral transmission, and reduce the rate of cesarean delivery. (I-A)
6. If a pregnant woman is planning to become pregnant or has no history of HSV infection but has a partner with genital HSV infection, serologic testing should be performed to confirm the diagnosis of HSV infection before or as early as possible during pregnancy and should be repeated during the 32nd to 34th week of pregnancy. (III-B)