Rapid fetal karyotype from cystic hygroma and pleural effusions

Chromosomal abnormalities among 246 fetuses with pleural effusions detected on prenatal ultrasound examination: Factors associated with an increased risk of aneuploidy

PURPOSE

To determine the prevalence of chromosomal abnormalities in fetuses with prenatally diagnosed pleural effusions and to identify factors associated with an increased risk of aneuploidy.

METHODS

A retrospective analysis of the Genzyme Genetics database was performed for samples submitted from October 1994 to April 2003 with an indication of fetal pleural effusion.

RESULTS

There were 246 samples in which pleural effusion was identified as an indication for prenatal chromosome analysis. Ninety-four were from fetuses with isolated pleural effusions and 152 had other abnormalities in addition to pleural effusion. The prevalence of chromosome abnormalities was 35.4% (95% confidence interval, 29.2-41.4%). Among the eight first trimester samples, the aneuploidy rate was 63%. Pleural effusion cases associated with additional sonographic findings had a significantly higher aneuploidy rate than the isolated pleural effusion cases (50% vs. 12%, P < 0.001).

CONCLUSIONS

Chromosome analysis is warranted after the prenatal detection of a fetal pleural effusion. The risk of aneuploidy is greater with first trimester detection and is significantly increased in the presence of other associated anomalies.

Prenatal diagnosis from cystic hygroma fluid: the value of fluorescence in situ hybridization

OBJECTIVE

We sought to determine the optimal approach to the prenatal chromosome analysis of cystic hygroma fluid using traditional cytogenetic analysis and fluorescence in situ hybridization.

STUDY DESIGN

A retrospective evaluation of our experience with traditional cytogenetic and fluorescence in situ hybridization analysis on cystic hygroma fluid was performed through a systematic review of the Genzyme Genetics database from January 1995 to July 2000. Information on gestational age, sample volume, clinical ultrasound findings (including fetal viability), cytogenetic results, fluorescence in situ hybridization results, and turn-around-time were queried.

RESULTS

Eighty-three specimens were included in the investigation. The mean gestational age was 18.1 weeks (range, 13-27 weeks), and the mean sample volume was 20.7 mL (range, 0.1-101 mL). Of the 72 samples in which > 5 mL of cystic hygroma fluid was available, the success rate for cytogenetic analysis was 76% (55/72 samples). In 11 specimens of < or = 5 mL of cystic hygroma fluid, cytogenetic analysis was successful in only 1 case (9%). Fluorescence in situ hybridization was attempted on 23 samples, 18 of which were successful (78%), including 6 of 9 cases of cell culture failure (67%). Both traditional cytogenetic analysis and fluorescence in situ hybridization were performed in 21 instances when a sample of > 5 mL was available. A successful result was obtained by either cytogenetic testing or fluorescence in situ hybridization analysis or both in 19 of 21 of these cases (90%). Samples of > 5 mL from viable fetuses had a higher cytogenetic success rate (80%) and fluorescence in situ hybridization success rate (89%) than samples from fetuses with intrauterine death (38% and 50% cytogenetic and fluorescence in situ hybridization success rates, respectively.) The mean turn-around time was 8.2 days (range, 4-17 days). Results were available in < or = 12 days in 91% of cases. There was a 91% aneuploidy rate identified, with 45,X occurring in 86% of the samples.

CONCLUSION

We conclude that the optimal approach for the prenatal diagnosis of chromosome abnormalities from cystic hygroma samples is to perform both traditional cytogenetic studies and interphase prenatal fluorescence in situ hybridization evaluation for the most common aneuploidies that involve chromosomes 13, 18, 21, X, and Y. With this combined approach, our data indicate that, in viable pregnancies with a fluid sample of >5 mL, a 90% diagnostic success rate can be achieved.

Cystic hygroma in the fetus and newborn

Cystic hygromas are developmental abnormalities of the lymphoid system that occur at sites of lymphatic-venous connection, most commonly in the posterior neck. They are frequently associated with karyotypic abnormalities, various malformation syndromes, and several teratogenic agents. The disease course of an infant with cystic hygroma is unpredictable. When diagnosed prenatally, the overall prognosis is poor. Cystic hygroma diagnosed after birth is usually associated with a good prognosis. This article reviews the embryologic, genetic, and pathologic correlates of these lymphatic system abnormalities, as well as the clinical course and outcome of the fetus and newborn with a cystic hygroma. Management strategies are reviewed, including newer nonsurgical therapies for the neonate with a cystic hygroma.

The role of fetal karyotyping from unconventional sources

OBJECTIVE

Our purpose was to determine whether fetal specimens, including pleural, ascitic, pericardial, facial, and cystic hygroma fluid or urine, are suitable sources for accurate chromosomal analysis.

STUDY DESIGN

Thirty-nine samples of fetal fluid (pleural, n = 11; ascitic, n = 5; pericardial, n = 1; lung cyst, n = 1, facial cyst, n = 1; cystic hygroma, n = 7; and urine, n = 13) were cultured and analyzed with standard cytogenetic techniques for lymphocytes or amniotic fluid. These samples were obtained as part of the routine obstetric investigation and management. Conventional backup samples were also obtained.

RESULTS

Karyotyping was successful in 34 of 39 samples. Cells were harvested from all pleural samples, three ascitic samples, and one hygroma fluid sample in 2 to 4 days from 11 urine samples, one ascitic sample, and the remaining six hygroma samples in 7 to 11 days. Five cultures were unsuccessful. Samples with high lymphocyte counts yielded results as quickly as fetal blood.

CONCLUSION

The use of "alternative" samples of fetal fluids for karyotyping may be considered when amniotic fluid or fetal blood is difficult to obtain. In selected cases this approach avoids the unnecessary risk of additional invasive procedures solely to obtain a karyotype.