Prenatal diagnosis of trisomy 18: report of 30 cases.
OBJECTIVE
To review the detection rate of the prenatal screening tests used for the diagnosis of the trisomy 18.


METHODS
From 1 October 1998 to 31 December 2001, we reviewed the database and medical records of 30 cases of trisomy 18. All were singletons and trisomy 18 was confirmed by amniocentesis in 19 cases, by cordocentesis in 6 cases, by chorionic villi sampling in 2 cases and by skin biopsy in 3 cases.


RESULTS
Of the 30 study cases, 23 cases (77%) were offered genetic study due to abnormal ultrasound (US) findings. Twelve (40%) out of the 23 cases were due to abnormal US findings detected before the triple test and 11 (37%) were due to abnormal US findings after the normal triple test. Six cases (20%) were offered genetic study because of an abnormal triple test, and one case was offered genetic study due to advanced maternal age only. Including the second targeted ultrasonogram, one or more abnormal US findings were found in all 30 fetuses.


CONCLUSIONS
Abnormal US finding is the most sensitive screening test for trisomy 18. The most sensitive ultrasonographic finding for trisomy 18 at under 16 weeks of gestation is increased nuchal translucency (75%) and, after 16 weeks, is cardiac defect (83%).
Yang
Jae Hyug
JH
Department of Obstetrics and Gynecology, Samsung Cheil General Hospital and Women's Healthcare Center, Sungkyunkwan University School of Medicine, Seoul, Korea. jhy60408@yahoo.co.kr
Chung
Jin Hoon
JH
Shin
Joong Sik
JS
Choi
June Seek
JS
Ryu
Hyun Mi
HM
Kim
Moon Young
MY
D000328:Adult; D000649:Amniocentesis; D002887:Chromosomes, Human, Pair 18; D005260:Female; D006801:Humans; D007723:Korea / Q000453:epidemiology; D008499:Medical Records; D011237:Predictive Value of Tests; D011247:Pregnancy; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014314:Trisomy; D016216:Ultrasonography, Prenatal