Screening for Down's syndrome in the first trimester is feasible, with use of measurements of pregnancy-associated protein A and either hCG or its free beta subunit in maternal serum.

Echogenic foci within the left ventricle of the heart have been found in a minority of fetuses and generally are believed to be a normal variant. The cause and exact location of these foci have remained speculative, however. We identified three fetuses with this sonographic finding in whom pathologic correlation was available. The only consistent histologic finding present in all three fetuses was mineralization within a papillary muscle; the chordae tend· E chogenic foci within the cardiac ventricles.have been noted in a minority of fetuses. Such echogenic foci generally are considered to be a normal variant, 1-5 and it has been speculated that these foci arise either in papillary muscle'2.4 or in chordae tendineae. U The cause and true location of this echogenic focus remain unproved, however, as no pathologic evaluation has been made thus far. We report three fetuses in whom pathologic correlation was available for an echogenic focus in the left ventricle. METHODSWe identified three patients in whom obstetrical sonography had been performed prior to elective ter- ineae were normal. One of the three fetuses had trisomy21.Echogenic foci within the left ventricle of the fetal heart represent papillary muscle mineralization. Until more data are available to investigate any possible association with aneuploidy, an echogenic focus in the left ventricle should still be considered a normal variant. KEY WORDS: Ultrasonography; Heart, fetal; Papillary muscle; Ventricle, fetal. mination of an unwanted pregnancy, during which echogenic foci were seen within the left ventricle of the fetal heart (Fig. 1). In each case the echogenic focus measured 1 to 3 mm in longest dimension. Cases 1 and 2 had a single echogenic focus, whereas case 3 had two echogenic foci. In cases 1 and 2 the maternal age was 20 and 26 years respectively; sonography had been performed to determine gestational age prior to termination. The gestational age of both of these fetuses was 19 weeks and the fetal survey was normal. In case 3 the mother was 35 years old and had an abnormal multiple marker serum screen indicating a 1:162 risk for trisomy 21. The sonogram revealed a gestational age of 19 weeks by head circumference and demonstrated findings 6 that increased the risk of trisomy 21: the femur and humerus length were of a size that was appropriate for approximately 1 week less than would be expected by biparietal diameter, and the renal pelves were mildly dilated at 6 to 7 mm in anteroposterior diameter.The fetal survey, including nuchal skin thickness, was otherwise normal. After amniocentesis revealed

The development of chromosome-specific probes (CSP) and fluorescent in-situ hybridization (FISH) has allowed for very rapid identification of selected numerical abnormalities. We attempt here to determine, in principle, what percentage of abnormalities would be detectable if only CSP-FISH were performed without karyotype for prenatal diagnosis. A total of 146 128 consecutive karyotypes for prenatal diagnosis from eight centres in four countries for 5 years were compared with predicted detection if probes for chromosomes 13, 18, 21, X and Y were used, and assuming 100% detection efficiency. A total of 4163 abnormalities (2.85%) were found including 2889 (69. 4%) (trisomy 21, trisomy 18, trisomy 13, numerical sex chromosome abnormalities, and triploidies) which were considered detectable by FISH. Of these, 1274 were mosaics, translocations, deletions, inversions, rings, and markers which would not be considered detectable. CSP-FISH is a useful adjunct to karyotype for high risk situations, and may be appropriate in low risk screening, but should not be seen as a replacement for karyotype as too many structural chromosome abnormalities will be missed.

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