Background: Cytomegalovirus (CMV) infection is one of the most common congenital infections and the most frequent cause of mental retardation and non-genetically cause of deafness. The risk of fetal transmission is above 40%. The objectives of this study were to review and improve the CMV diagnosis in pregnancy.
Method: 50 pregnant women took part in the study. They were taken in evidence at the virology counseling office. The reason for the need of viral diagnosis came from the fact that the result of previous routine serological testing came out positive for CMV IgM antibodies (Ab). Based on the test result, the gynecologist may normally indicate the termination of the pregnancy.
Results: In the virology counseling office the results for CMV IgM Ab test turn out negative in 48 of the 50 (96%) referred pregnant women. In two women CMV IgM Ab test turn out positive. These women also tested positive for CMV IgG Ab test. The pregnant women were also tested for pp65 antigenemia. They presented a four times raise in CMV IgG Ab titer. All the rest were negative for pp65 antigemenia.
Conclusion: From the 50 women only two needed to terminate their pregnancies. It is important to test for CMV infection in pregnancy along with other viral, bacterial or parasitic infections, but the indication of pregnancy termination must be taken only after a thorough examination and testing. It would be helpful if CMV tests, as well as all the TORCH tests were supported by the health insurance system.
CMV infection, pregnancy termination, CMV IgM Ab
Introducere: Infecția cu CMV este una dintre cele mai frecvente infecții congenitale și cea mai frecventă cauză de retard mintal și surditate de etiologie non-genetică. Riscul transmiterii materno-fetale este peste 40%. Obiectivele acestui studiu sunt revizuirea și îmbunătățirea algoritmului de diagnostic în infecția cu CMV din sarcină.
Metode: La studiu au participat 50 de gravide. Au fost luate în evidență la cabinetul de consiliere asociat diagnosticului virusologic. Diagnosticul era necesar – pentru că testul de detecție a anticorpilor anti‑CMV IgM la testarea de rutină din sarcină a fost pozitiv. Acest rezultat poate duce la indicație de avort terapeutic.
Rezultate: În cabinetul de consiliere, după diagnosticul virusologic, rezultatul la testul de detecție a anticorpilor anti‑CMV IgM a fost negativ la 96% dintre femeile testate (48 din 50). Două femei au prezentat testul pozitiv. În cazul acestora s-au detectat și anticorpi anti‑CMV IgG, în dinamică titrul crescând de patru ori. Testele au fost pozitive și pentru Ag pp65.
Concluzii: Dintre cele 50 de femei, doar două aveau indicație de avort terapeutic. Este important să efectuăm testarea prezenței anticorpilor anti‑CMV IgM în sarcină împreună cu alte teste pentru infecții virale, bacteriene sau parazitare, dar indicația de avort terapeutic trebuie făcută numai în urma unor investigații complexe. Ar fi folositor dacă testările în cadrul infecției cu CMV sau a celorlalte teste din cadrul panelului TORCH ar intra în lista testărilor decontate de casa de asigurări.
Cytomegalovirus (CMV) a member of the Herpesviridae family affects any category of age. CMV causes a latent infection, frequently asymptomatic. The first contact with CMV could be during childhood. It will persist all life in a latent state, without replication, but with possible reactivation. It is estimated that more than 80% of the adult population is infected with CMV until the age of 40. Humans represent the natural source of the infection(1,2). The transmission rate is high in schools and kindergartens with a high excretion rate.
CMV infection is one of the most common congenital infections and the most frequent cause of mental retardation and non-genetically cause of deafness. Besides mother to child transmission, the transmission is possible by respiratory or sexual route, through saliva droplets, breast feeding, urine, transfusions and organ transplant. According to CDC Atlanta in US about 50% of the women are CMV infected and 1-4 women not previously infected are CMV infected for the first time during pregnancy. The risk of fetal transmission is above 40%(3).
The highest risk of maternal fetal transmission is in the third trimester of pregnancy but the children bear no symptoms at birth or later. The lowest risk of maternal fetal transmission is in the first trimester of pregnancy but the children have symptoms that often are incompatible with survival(4,5).
The outcome is severe for symptomatic newborns: the mortality ranges up to 80% and the survivors have severe sequellae: deafness, ocular impairment, mental and physical retardation(6).
The risk of CMV transmission ranges also according to the level of child development at birth: it is higher for premature babies than for term delivered babies: 2.1% vs. 1.8%(7). More recent studies have revealed even a higher risk of mother to child transmission: 3.8% up to 4.1%(8,9).
In Romania there is no recent published data on healthy population regarding CMV prevalence but the older studies have revealed a high CMV prevalence(10,11).
The objectives of this study were to review and improve the CMV diagnosis in pregnancy in order to decrease unnecessary abortion/pregnancy termination when CMV IgM Ab are detected in a pregnant woman. The serological diagnosis is based on serological tests that are routinely recommended by general practitioners or specialists in pregnancy. If the patient and the practitioner understand correctly the outcome of the testing, an unnecessary abortion may be avoided.
Fifty pregnant women took part in the study. They were taken in evidence at the virology counseling office as they presented themselves or as they were referred by specialists. The pregnant women were in the first and second pregnancy trimester, the average gestation age was of 13.2±6.8 weeks, limits between 6 to 28 weeks of pregnancy. We split the pregnant women into two groups according to the pregnancy trimester:
70% were in the first pregnancy trimester
30% were in the second pregnancy trimester.
All pregnant women came to the virology counseling office for CMV diagnosis in pregnancy. The reason for viral diagnosis (confirmation) was the result of previous routine serological testing - positive for CMV IgM antibodies. Based on the test result, the gynecologist would indicate the termination of the pregnancy. The women refused the initial indication and seek for more precise CMV diagnosis.
Routine testing in pregnancy includes serological testing for detection of CMV IgM Ab and CMV IgG Ab.
All included women were previously tested for CMV IgM Ab in different laboratories across Romania, with positive results as mentioned above. 32 (64%) were tested also for CMV IgG Ab with different results, but 18 (36%) of them were not tested for CMV IgG Ab, so for these 18 ladies, the CMV status was not known at all at the moment of counseling and testing.
At the virology counseling office two samples of blood were collected from the patients: one with EDTA for pp65 Ag detection and one without anticoagulant for serology (CMV IgM Ab detection and antibody titer detection of CMV IgG Ab). After 14 days from initial collection another blood sample without anticoagulant was collected for serology: for antibody titer detection in dynamics. The testing was realized from serum from the venopuncture using commercial kits. The testing was performed within 24 hours of sample collection; the samples were kept at 2-8ºC.
For CMV IgM Ab detection capture ELISA technique was used. The results were evaluated according to possible cross reactivity in patients with other herpes viral infections such as Epstein‑Barr Virus infection or Varicella Zoster Virus infection that may generate false positive results. A CMV infection without CMV IgM Ab was taken into account.
For CMV IgG Ab titer detection indirect ELISA technique was performed (two blood samples were tested, at 14 days distance, in order to establish the dynamics of antibody titers).
For Antigen detection and evaluation of the replicative viral status of CMV infection a pp65 Antigenemia Immunofluorescence Assay was used. The presence or absence of matrix pp65 protein was evaluated in the lymphocytes of the tested pregnant women.
All pregnant women referred to the virology counseling office for CMV diagnosis had a positive CMV IgM Ab test result obtained from different laboratories in the country (result given within the last 48 hours). 32 (64%) of them presented a CMV IgG Ab positive test result, also with the avidity test result calculated. The interpretation of these results conducted toward a possible first infection with CMV in the last 3 months in these 32 pregnant women.
In the counseling office the results for CMV IgM Ab test turned out negative in 48 of the 50 (96%) referred pregnant women.
Also in 8 of 50 (16%) referred pregnant women the result for CMV IgG Ab was negative, along with CMV IgM Ab that was also negative (Table 1).
These 8 women were excluded from the risk of having CMV infection during the pregnancy.
There were only two women in which CMV IgM Ab test turned out positive. These women also tested positive for CMV IgG Ab test. They were interviewed and they admitted previous contact within the family (smaller children) with chickenpox. One woman was in the first trimester of pregnancy and the other in the second.
For the 42 (84%) of the women who tested positive for CMV IgG Ab test a titer of antibodies was determined. The average value of the titer of CMV IgG Ab for the 42 women was 6.5±2.94 IU/ml; limits 2.01-11.7 IU/ml.
In order to avoid the underdiagnosis of an eventual recurrence to a prior CMV infection in patients with an old CMV infection, the possibility of titer increase was evaluated in dynamics. So, for the 42 women which tested positive for CMV IgG Ab at the first, test a second CMV IgG Ab test was performed at two weeks distance at the same location with the same assay kit. From these 42 women only two presented a raised titer of CMV IgG Ab at the second test. The raise was significant and the obtained value was four times higher in both cases.
An average value of the titer for CMV IgG Ab was calculated at the second testing for all 42 women. It was 5.8±2.7IU/ml; limits 2-10.0IUi/ml, almost one unit less from the initial testing.
In order to establish a more precise diagnosis the pregnant women were tested also for pp65 antigenemia. The pp65 Ag was detected only in the cases of the pregnant women who presented the four‑times raise in CMV IgG Ab titer.
CMV infection diagnosis in pregnant women is based on an initial serological screening for CMV antibodies. Both types, IgM and IgG antibodies could be detected. The presence of CMV IgM Ab together with the absence of CMV IgG Ab allows for the assumption that the woman is infected with CMV for the first time in her life. If CMV IgG Ab are detected the CMV infection is older but the test alone cannot establish the onset of CMV infection. Additional precise information for establishing the exact stage of CMV infection and viral replication may be given by detecting CMV viral load or pp65 Ag. Another method, not very specific, is the detection of the avidity of CMV IgG Ab. This method has 80% specificity and is used in order to obtain more information about the onset of CMV infection. Also, for establishing a retrospective diagnosis, 2 tests for CMV IgG Ab titer detection are recommended at two weeks distance in order to follow the dynamics of CMV Ab titer.
An ideal case is to detect CMV IgG Ab titer before conceiving the baby, and if the result is negative, the third trimester of pregnancy must be strictly monitored. The following testing is recommended according to the result of the first testing using the proposed algorithm (Figure 1).
In the studied group there were only two women who presented risk for CMV infection and possible mother to child transmission. They presented CMV IgM Ab and CMV IgG Ab. At these two women the initial moment of CMV infection was unclear. One of them was in the second trimester of pregnancy and there was a high possibility that first CMV infection occurred in the first trimester of pregnancy. These women were those who had prior contact within their families with VZV, their smaller children developed chicken pox.
The pregnant woman that was in the second trimester of pregnancy was already given two ultrasounds for the fetus, both ended up within the normal range.
The other pregnant woman who was in the first trimester of pregnancy had a recent possible first CMV infection.
Both women tested positive for pp65 antigenemia and were recommended detection of CMVADN from amniotic fluid. Both refused the CMVADN detection test because they were afraid of losing their pregnancies. None agreed for the end of pregnancy, that was also recommended. The virology counseling cabinet could not follow‑up the outcome of their pregnancies. The women were lost from evidence.
Taking into account that an initial number of 50 women were referred to the virology counseling cabinet, it is important to notice that from the 50 women only two needed to terminate their pregnancies and the rest presented no need for pregnancy termination.
It is important to test for CMV infection in pregnancy along with other viral, bacteria or parasite infection, but the indication of pregnancy termination must be taken only after a thorough examination and testing. The fact that all these tests are not supported by the health insurance system is an impairment in CMV diagnosis in ambulatory cases and leads to the indication of pregnancy termination more easily. It would be helpful if those tests, as well as all the TORCH tests were supported by the health insurance system. n
Conflict of interests: The authors declare no conflict of interests.
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