Objective: To analyze solitary bone fragments from the uterine cavity through DNA genotyping, thus elucidating whether they originate from metaplasia, from previous abortion, or both.
Methods: We conducted a case series study on 14 patients, of whom eight yielded bone DNA. The patients selected had histopathologic diagnoses of bone fragments inside the uterine cavity or previously removed samples available for analysis. We extracted DNA from blood and bone fragments. To identify the bone tissue origin, these materials were genotyped using polymerase chain reactions for DNA loci. Six mini short tandem repeat loci frequently used for human tissue identification were analyzed using automated sequencing.
Results: Among these eight patients, blood and tissue samples from the same individual produced exactly the same pair of alleles for all six loci. This indicated that the DNA profile was completely the same for the bone samples and the mother's blood (95% confidence interval 63-100%), thus confirming that the DNA had the same origin and that these were cases of metaplasia.
Conclusion: In all of the eight cases, bone formation was caused by osseous metaplasia, because the DNA in the bone fragment and in the patient's blood was identical. Although all of the women had histories of previous abortion, no difference in DNA was detected in the bone tissue in any of the cases, as would be expected if abortion had occurred. This result was completely unexpected, differing greatly from what the literature suggests.
Level of evidence: III.