Abstract & Commentary
Cytomegalovirus in Pregnancy
By John C. Hobbins, MD, Professor, Department of Obstetrics and Gynecology, University of Colorado Health Sciences Center, Denver
This story ran previously in the January 2012 issue of OB/GYN Clinical Alert and was peer reviewed by Catherine Leclair, MD. Dr. Hobbins reports no financial relationships relevant to this field of study.
Synopsis: In 528 women who were infected with CMV at various times before and during pregnancy, fetal transmission was the least in the preconception and periconception period.
Source: Feldman B, et al. Pregestional, perigestional, and gestational primary maternal CMV infection: Prenatal diagnosis in 508 pregnancies. Am J Obstet Gynecol 2011; 205:342 e1-6.
Dealing with cytomegalovirus (CMV) can be vexing for everybody involved, but a recent paper may help with the management and counseling of patients infected with this virus at different times before and during pregnancy. Feldman et al studied 580 pregnant patients who were diagnosed with seriologic evidence of CMV infection. Patients were broken up into five groups depending on when the infection occurred: preconception (before 8 weeks prior to conception), periconception (within 8 weeks prior to and 6 weeks after conception), first trimester, second trimester, and third trimester. There were 16 twin pregnancies included in the study, bringing the total number of fetuses to 524. Specifically, there were 97, 130, 152, 100, and 29 patients in the above chronological categories, respectively.
Amniocenteses were performed in all women after 21 weeks and after at least 7 weeks post sero-conversion. The amniotic fluids were tested for CMV by polymerase chain reaction (PCR). All pregnancies were monitored with ultrasound and all newborns were carefully evaluated for signs of sequelae.
There was no transmission of the virus in the pre-conception group, only 4.6% in the peri-conception group, 34.8% in the first trimester, 42% in second trimester, and 58% in the third trimester groups. There were 45 infected infants born alive, none were symptomatic at birth. In the third trimester group, there were no ultrasound signs of CNS involvement before birth, and all infants appeared normal at 18 months of age.
The authors concluded that CMV infection prior to 8 weeks of conception does not result in transmission of the virus and that peri-conception infection up until 6 weeks of gestation had less than a 5% chance of fetal transmission. First and second trimester exposure could have an effect on the 30-40% of fetuses in whom the virus was found. However, although there was a high transmission rate in the third trimester, none of the infants appeared to be affected by the CMV.
Commentary
The emergence of this paper coincided with a counseling dilemma we had regarding a patient who appeared in the second trimester with an elevated sequential screen for Down syndrome. At 21 weeks, the fetus was noted to be small for dates and had a few soft markers for Down syndrome, including echogenic bowel. When the amniocentesis was productive of normal chromosomes, we screened her for cystic fibrosis—which was negative. At the time of her follow-up ultrasound examination, the fetus showed adequate growth, but the bowel remained weakly echogenic. Reaching a bit, we did an infectious workup. The CMV IgG was strongly positive and the IgM was at the laboratory's threshold of normal. We repeated the titer and the IgM was then solidly negative. We resurrected the frozen amniotic fluid sample and tested the supernatant for CMV with PCR. This was negative. We also did avidity testing on the patient's blood, which returned as "high," suggesting a non-recent infection.
The above paper helped us to counsel this couple that the likelihood of their baby being affected by CMV was remote based on the premise that the time of exposure was pre- or, at worst, peri-conception.
The finding that triggered this diagnostic saga was echogenic bowel. In the vast majority of cases, this is a normal variant and commonly occurs when fetuses swallow particulate material in the amniotic fluid that light up the bowel. Sometimes they are heme pigments which can be linked to an episode of first or second trimester vaginal bleeding. However, it can be a marker for aneuploidy, cystic fibrosis, or even early IUGR (especially when coupled with high hCG or inhibin-A). A lesser possibility is CMV, and, in this case, I think the finding was unassociated with this condition. In fact, isolated echogenic bowel is so common and, in our experience, so rarely associated with CMV, that we often will not test for it.
Dealing with cytomegalovirus (CMV) can be vexing for everybody involved, but a recent paper may help with the management and counseling of patients infected with this virus at different times before and during pregnancy.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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