Abstract
Various economic factors have lead to the emergence of large corporate laboratories and perishable cytogenetic specimens are directed away from in-hospital and nearby local and regional university laboratories to distant, designated sites. Most amniocentesis and blood specimens have sufficient numbers of viable cells to withstand 24 to 72 hour transport if protected from extreme heat or freezing. Specimens of miscarriage tissues, known as products of conception (POC's) autolyze rapidly and/or become contaminated by the normal vaginal flora if not placed immediately in solutions containing antibiotics and constantly refrigerated. In addition, as specimen deteriorate, it becomes increasingly difficult to cleaning separate away contaminating maternal detidua tissue.
The majority of first and early second trimester pregnancy losses are a result of abnormal karyotype in the conceptus. The major purpose for performing karyotypes on POC's is to differentiate those women whose loss (often recurrent losses) are of normal karyotype conception and who may require other evaluation and intervention, those who may be carriers of translocations who need to be counseled that future pregnancies may result in continued losses or even the birth of offspring impaired by an unbalanced chromosome complement, and finally those for whom the aneuploid event was sporadic and future pregnancies are likely to succeed without special intervention. When the POC karyotype is erroneously reported as “46, XX - normal female” because maternal rather than conceptus cells predominate in culture, the subsequent counseling will be inaccurate and medical interventions offered to the patient may be inappropriate or even harmful. Depending on the true karyotype, the treatment error may be omission or excess.
In the past 2 years, as more specimens from outpatient dilatation and curettage procedures were directed to laboratories, a distinct change in the patterns of results was observed. If one postulates that the karyotype should not be vary by the patient insurance company, one would expect a similar rate of successful culture and distribution of abnormal karyotypes in the outsourced specimens. What has been observed is a significant increase in the number of “non-viable” specimens and “normal female” karyotypes compared to specimens that were allowed to remain in the hospital cytogenetics laboratory for processing. The patterns of karyotypes seen and hypotheses for these variations will be discussed.
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Karson, E. Karyotyping miscarriage tissue in the managed care environment. Genet Med 1, 46 (1999). https://doi.org/10.1097/00125817-199901000-00027
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DOI: https://doi.org/10.1097/00125817-199901000-00027