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

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.

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.

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.

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.