Korean J Obstet Gynecol.  1998 Feb;41(2):399-414.

Prenatal Diagnosis of Congenital Rubella by Polymerase Chain Reaction in Korean Pregnant Women

• Ryu HM
• Moon IG
• Cho DH
• Kim MY
• Kim ES
• Han HW
• Lee SH
• Yoo HK

Abstract

Objectives
; Rubella viral infection in pregnant women is frequently transmitted to the fetus, resulting in the fetal damage. Fetal rubella infection have been diagnosed by detection of rubella specific IgM in fetal blood. However this has been limited because the fetal IgM is not developed before 22 weeks of gestation. The purpose of this study was to determine accuracy of PCR for rubella virus to diagnose congenital rubella infection. Methods; In this study, 85 amnionic fluid and 30 fetal blood samples were obtained from 85 pregnant women, whose serum rubella IgM were positive. Viral RNA from clinical specimens was reverse transcribed and the produced cDNA was amplified by nested polymerase chain reaction (nested PCR)using a set of primers, the outer primer pair defining a 591 bp sequence and the inner primer pair defining a 321 bp sequence within the former one. RESULTS: A reverse transcription nested PCR by detection of RNA extracted from 10-1 50% tissure culture infective dose of live attenuated rubella vaccine was sensitive method. The identity of PCR product were verified by direct sequencing using fluorescent dideoxy-termination to confirm the target sequence. RT-PCR detected rubella virus RNA in bloods from 4 children who were confirmed rubella infection serologically. Rubella virus was detected from 2 of 15 products of conceptus which was obtained from pregnant women with rubella specific IgM. Among 85 pregnant women, there were typical skin rashes in 15 cases (18%). In only one case of 55 amnionic fluid obtained in 13~19 weeks of gestation from pregnant women with rubella specific IgM, rubella PCR was positive. Rubella virus was detected by RT-PCR in only 1 case among 30 fetal blood obtained by cordocentesis from another pregnant women with rubella specific IgM. But, in one case, the results were not concordent, that is, PCR was negative and rubella specific IgM was positive in fetal blood obtained in 22 weeks of gestation. There was no statistical significance between maternal clinical symptoms, such as rashes, and incidence of fetal infection. Among delivered 56 neonates whose prenatal rubella PCR and IgM results were negative, 3 neonates showed positive for postnatal rubella specific IgM, but showed no congenital rubella up to 8~9 months follow up. Among total 85 cases, presently 19 were ongoing pregnancy, 56 went to term and resulted in healthy babies except 2 anomaly with unrelated congenital rubella infection, while 19 pregnancies are progressing normally and 4 were failed to follow up and one was preterm birth and 5 were electively terminated. Incidence of congenital rubella infection which was diagnosed prenatally or postnatally was relatively low, 7% (6/85). Coclusion; PCR for rubella virus was earlier, faster and more accurate method for detection of fetal rubella infection in amnionic fluid and/or fetal blood than rubella specific IgM in fetal blood, when rubella specific IgM was positive in early pregnant women. Appropriate detection for fetal rubella infection should be carried out by direct etiologic diagnosis such as PCR. This method will become an valuable approach to provide prenatal counselling following rubella virus infection for prevention of unnecessary termination of pregnancy.

MeSH Terms

Amnion
Child
Cordocentesis
Diagnosis
DNA, Complementary
Exanthema
Female
Fetal Blood
Fetus
Follow-Up Studies
Humans
Immunoglobulin M
Incidence
Infant, Newborn
Polymerase Chain Reaction*
Pregnancy
Pregnant Women*
Premature Birth
Prenatal Diagnosis*
Reverse Transcription
RNA
RNA, Viral
Rubella Vaccine
Rubella virus
Rubella*
DNA, Complementary
Immunoglobulin M
RNA
RNA, Viral
Rubella Vaccine