Cytogenetic analysis after evaluation of 750 fetal deaths: proposal for diagnostic workup

OBJECTIVE: To estimate success rates for cytogenetic analysis in different tissues after intrauterine fetal death, and study selection criteria and value of cytogenetic testing in determining cause of death. METHODS: Cytogenetic analyses and the value of this test in determining cause by a multidisciplinary panel were studied in 750 fetal deaths. Morphologic abnormalities, small for gestational age (SGA), advanced maternal age (older than 35 years) and maceration were studied as selection criteria. RESULTS: Chromosomal abnormalities were observed in 13% of fetal deaths. Cytogenetic success rates were significantly higher for invasive testing (85%) than for postpartum tissue analysis (28%, P<.001). There were more abnormal chromosomes (38%) in fetal deaths with morphologic abnormalities than in those without (5%, P<.001). This was not observed for SGA (16% compared with 9.2%, P=.22) or for advanced maternal age (16.7% compared with 12.0%, P=.37). The posterior probability of a chromosomal abnormality in the absence of morphologic abnormalities was still 4.6%. Cytogenetic analysis was successful in 35% of severely macerated fetuses. We do not advise using these selection criteria, because the failure rate was high on postpartum tissues. Cytogenetic analysis was valuable in determining the cause in 19% of the fetal deaths. CONCLUSION: Parents should be counseled on aspects of cytogenetic analysis after fetal death. We advise performing nonselective invasive testing after fetal death and before labor for all fetal deaths