Australian and New Zealand Journal of Obstetrics and Gynaecology 2003; 43: 16–26 16 Blackwell Science, Ltd Original Article Sonographic markers for aneuploidy Prospective ranking of the sonographic markers for aneuploidy: Data of 2143 prenatal cytogenetic diagnoses referred for abnormalities on ultrasound Art DANIEL, 1 Neil ATHAYDE, 2 Robert OGLE, 3 Alice M. GEORGE, 4 Jonathan MICHAEL, 5 Mark D PERTILE, 6 Jennifer BRYAN, 7 Vapinder JAMMU 8 and Brian J. TRUDINGER 2 1 Department of Cytogenetics, Western Sydney Genetics Program, Children’s Hospital at Westmead, 2 Maternal Fetal Medicine,Westmead Hospital, Sydney, 3 Feto-Maternal Unit, Liverpool Health Service, Sydney, 4 Cytogenetics Department, Auckland Hospital, Grafton, Auckland, New Zealand, 5 Department of Cytogenetics, Melbourne Pathology, Collingwood, Melbourne, 6 Cytogenetics Laboratory, Royal Women’s Hospital, Carlton, Melbourne, 7 Cytogenetics Division Mater Health Services, South Brisbane, Brisbane and 8 Cytogenetics Unit,Woden Valley Hospital, Canberra, Australia Abstract Objective: To design a scheme to rank sonographic anomalies as indicators of aneuploidy and record the distribu- tion of data from 2143 prenatal amniotic fluid/chorionic villous sample diagnoses referred for karyotyping because of fetal anomalies detected with ultrasound. Methods: In all cases the records of sonographic anomalies were obtained prior to karyotyping. A cascade of seven prospective categories of ultrasound anomalies was chosen and the data were included in the highest compatible sonography category. The categories were in descending order: (I) combined central nervous system (CNS)/cranial shape and cardiac anomalies (excluding spina bifida and anencephaly); (II) key anomaly present (exomphalos/ intrauterine growth restriction/duodenal atresia/cystic hygroma/fetal hydrops/talipes – with other multiple anomalies); (III) CNS ± other abnormality (excluding choroid plexus cyst, spina bifida, anencephaly); (IVa) increased nuchal translucency – first trimester ± other abnormality; (IVb) increased nuchal thickening – second trimester ± other abnormality; (V) cardiac anomaly ± other abnormality; (VI) other markers of aneuploidy (pyelectasis/two vessel cord/echogenic bowel/short femur); and (VII) other (mostly isolated) malformations. Results: There were 412/2143 (19.2%) chromosome abnormalities detected in this sonographically abnormal group. Overall, the prevalence of aneuploidy significantly ranged from 51 to 3% according to the above I–VII ultrasound categories and from approximately 1–80% for individual ultrasound anomalies. Likelihood ratios were derived for many ultrasound anomalies for several aneuploidy groups: trisomies of 13; 18; and 21; 45,X and 45,X mosaics; triploidy; other autosomal duplications and/or deletions; and other (than 45,X) sex chromosomal aneuploidies. Conclusion: It is suggested this data could be used to assist pre-procedural counselling of patients after the ultrasound scan in tertiary referral centres for prenatal cytogenetic diagnosis. Key words: aneuploidy, chorionic villous sample, karotyping prenatal amniotic fluid, sonographic anomalies, ultrasound. Introduction There are numerous patterns of association of ultrasound anomalies in fetuses with or without aneuploidy. Many stud- ies focus on describing the karyotypic findings with a single anomaly, for example holoprosencephaly, 1 cystic hygroma, 2 exomphalos, 3 duodenal atresia, 4 cardiac anomalies, 5 choroid plexus cysts, 6 micrognathia, 7 nuchal thickening, 8–10 relative shortness of the femur, 11 echogenic bowel, 12 and single umbilical artery. 13 Other studies and reviews report the sono- graphic anomalies in routine second trimester ultrasound screening 14 or in groups of known aneuploid fetuses. 15–20 In a comprehensive study the incidence of 25 sonographic anomalies is described in 461 fetuses with aneuploidy includ- ing 13, 18, and 21 trisomics, triploids, and 45,X cases. 18 With such data gathered retrospectively it is difficult to Correspondence: Dr Art Daniel, Cytogenetics Department, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Locked Bag 4001 Westmead, NSW 2145. Email: artd@chw.edu.au Received 29 April 2002; accepted 25 October 2002.