川上 穣, 日高 庸博, 原 枝美子, 佐藤 由佳, 近藤 有希子, 村田 将春, 藤田 恭之, 加藤 聖子

Minoru KAWAKAMI, Nobuhiro HIDAKA, Emiko HARA, Yuka SATO, Yukiko KONDO, Masaharu MURATA, Yasuyuki FUJITA, Kiyoko KATO

九州大学病院産科婦人科

Department of Obstetrics and Gynecology, Kyushu University Hospital

キーワード : cytomegalovirus, congenital infection, pregnancy, maternal IgM antibody, intrauterine fetal death

妊娠中のサイトメガロウイルス（CMV）感染は児に不良な予後をもたらしうる重大な感染症であり，診断には母体の血清CMV-IgMが用いられることが多い．症例は29歳の初産婦．妊娠24週の超音波検査で胎児の発育不全，腹水，腸管高輝度像を認めた．胎児中大脳動脈最高血流速度が2.5 MoMと高値であり臍帯穿刺を行ったが，臍帯血の血色素量は9.2 g/dlと貧血は軽度で，一方で血小板数が2.8万/μlと著明低値であった．母体血清よりTORCHスクリーニングを行ったが，CMV-IgMをはじめ全て陰性であった．しかし諸所見からCMV感染を強く疑い，羊水でのCMV-PCR検査を行ったところ，陽性であり先天感染の診断に至った．妊娠26週に胎児機能不全と診断したが急速墜娩を選択されず，子宮内胎児死亡となった．死産後の胎盤病理検査で巨細胞封入体を認め，免疫染色で抗CMV抗体が陽性であった．先天性CMV感染は母体のCMV-IgMが陰性であることをもって必ずしも否定されず，諸所見で感染を強く疑えば羊水PCR検査を考慮すべきである．

Cytomegalovirus (CMV) infection is the most common intrauterine infection worldwide, and the clinical manifestations are potentially severe. Typically, the diagnosis of acute CMV infection in pregnancy is based on positive results for maternal IgM. Herein, we present a case of a fetal CMV infection in which maternal CMV-specific IgM antibodies were negative. The patient was a 29-year-old primipara. At 24 weeks’ gestation, fetal ascites, growth restriction (-2.3 SD), and a hyperechoic bowel were detected by ultrasound scan. Fetal anemia was strongly suspected based on the markedly elevated fetal middle cerebral artery peak systolic velocity value at 84.6 cm/s (2.5 MoM). We performed umbilical cord sampling; fetal anemia was mild, but marked thrombocytopenia was noted (hemoglobin level: 9.2 g/dL, platelet count: 28,000/mm³). Maternal blood tests for IgM against TORCH revealed negative results. Nevertheless, we strongly suspected congenital CMV infection based on the sonographic and cord blood examination findings. PCR using amniotic fluid drained at 25 weeks and 3 days revealed CMV-DNA, at which point a definitive diagnosis of congenital CMV infection was made. The condition of the fetus deteriorated, and at 26 weeks and 2 days, fetal death was noted. Pathological examination of the placenta after stillbirth revealed CMV placentitis. This case suggests that maternal CMV-specific IgM antibodies are not reliable for excluding CMV infection in cases of fetal infection with characteristic sonographic findings.