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Journal of Clinical Microbiology, March 2003, p. 1329-1331, Vol. 41, No. 3
0095-1137/03/$08.00+0 DOI: 10.1128/JCM.41.3.1329-1331.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.
| CASE REPORT |
Section of Microbiology, Department of Clinical and Experimental Medicine,1 Section of Anatomic Pathology, Department of Oncology,2 Department of Preventive Pediatrics and Neonatology,3 Department of Obstetrics and Gynecology, University of Bologna, Bologna, Italy4
Received 9 August 2002/ Returned for modification 14 September 2002/ Accepted 16 November 2002
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Routine ultrasound examinations showed normal growth of both fetuses throughout gestation and vertex presentation at the end of pregnancy. Cesarean section was performed at the 36th week, and two female infants were delivered. Both neonates were healthy and vigorous: the Apgar scores at 1 and 5 min were 9 in both determinations for the left-side twin, the first born (weight, 2,670 g), and 7 and 9, respectively, for the right-side twin (weight, 2,400 g).
In contrast to prenatal diagnosis (4), diagnosis of congenital CMV infection of both twins was done by a positive virus isolation from saliva and urine collected 1 day after birth. While the left-side twin was antigenemia negative and had a low viral DNAemia (7.8 x 102 copies/105 PMNL), the right-side twin had 2 pp65-positive cells/2 x 105 PMNL and a DNAemia of 2.5 x 103 copies/105 PMNL, suggesting an infection of the left-side twin after the time of amniocentesis.
Further clinical studies revealed no cranial ultrasonography abnormalities and no evidence of chorioretinitis. However, auditory brain stem-evoked responses were absent at 80 dB in the right-side twin, indicating a severe hearing impairment caused by infection early in pregnancy. The other infant had normal auditory brain stem-evoked responses.
Interestingly, placenta examination showed a fused placenta (Fig. 1a). In the portion separating the two amniotic sacs (dividing membranes), one amnion on either side and two chorions in the middle, separated by a thin trophoblastic rim, were histologically identified, thus indicating the diamniotic-dichorionic (DiDi) nature of the placenta (Fig. 1b). At submacroscopic examination, performed with a stereomicroscope (Fig. 1c) and by assessment of histology (Fig. 1d), blood vessels crossing the two placentas were detected. Both placentas were CMV positive, as detected by in situ hybridization (ISH) (Fig. 1e and f).
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FIG. 1. Placenta examination. (a) Macroscopic view of DiDi twin placenta, with the two sacs separated by the dividing membranes. Note the close approximation of the two placental disks with a partial fusion. (b) At histology, the membrane dividing the two placental sacs was composed of two layers of fetal membranes separated by a thin rim of trophoblastic tissue (hematoxylin and eosin stain). Magnification, x225. (c) A stereomicroscopic examination of the DiDi fused placenta demonstrated anastomosing vascular channels at the point of fusion. Magnification, x3.6. (d) Histology confirmed the presence of communicating blood vessels between the two placental disks at the point of fusion (hematoxylin and eosin stain). Magnification, x36. (e) Right-side placenta. CMV positivity was detected in stromal cells by ISH (arrow). Magnification, x225. (f) Left-side placenta. The arrow indicates an endothelial cell showing nuclear positivity for CMV (ISH). Magnification, x112.5.
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This report provides plausible evidence of horizontal in utero transmission of CMV. The possibility that our findings are due to a late intrauterine viral transmission from the mother to the second fetus is very unlikely for the following reasons. (i) The route of CMV transfer from mother to fetus is presumed to be hematogenous, with placenta infection following maternal viremia, and the viremia phase in immunocompetent subjects is short (less than 30 days) (5). (ii) In our case, at the time of amniocentesis, maternal DNAemia was CMV negative. (iii) Third-trimester trophoblasts are much more resistant to CMV infection than are early pregnancy trophoblasts (3). (iv) Under our experimental conditions, a negative result in prenatal diagnosis indicates the absence of an infection of the fetus or newborn (4).
Anne Collins edited the English text.
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