[1718] Fluorescent In Situ Hybridization (FISH) Is an Effective Tool To Detect Unsuspected Trisomies in Hydropic Gestation.

Raheela F Siddiqui, Kathy Chun, Zeina Ghorab, Nadia Ismiil, Mahmoud A Khalifa, Sharon Nofech-Mozes, Raymond Osborne, Reda S Saad, Christopher Sherman, Valerie Dube. Sunnybrook HSC, University of Toronto, ON, Canada; North York General Hospital, Toronto, ON, Canada

Background: Histological classification of products of conception (POC) with hydropic changes has always been challenging because there is considerable morphological overlap between gestations with hydropic degeneration (HD), partial moles (PM) and hydropic changes due to trisomies. Ancillary studies are essential in establishing diagnosis and flow cytometry has been considered the gold standard to identify triploidy confirming the diagnosis of PM. Fluorescent In situ Hybridization (FISH) is a molecular cytogenetic technique that has been used more recently to identify triploidy in POCs and due to the use of chromosome-specific probes, FISH can also detect specific trisomies. The aim of our study was to assess the efficacy of FISH as a novel ancillary technique in identifying trisomies in POCs with hydropic changes.
Design: The study cohort consists of 67 cases of POC accessionned between 2007 and 2010 for which the differential diagnoses included PM and HD and for which FISH had been requested. FISH was performed on 4-μm formalin-fixed paraffin-embedded tissue sections using the Vysis AneuVysion Prenatal Test specific for chromosomes X, Y, 13, 18 and 21, and a probe specific for chromosome 16 (Abbott-Molecular).
Results: FISH revealed an unsuspected trisomy in 6/67 cases (9%). There were four cases of trisomy 16, one trisomy 18 and one trisomy 21. FISH revealed triploidy confirming a diagnosis of PM in 32/67 cases. In the remaining cases, the FISH results were within normal range and a diagnosis of HD was rendered.

Conclusions: Thus FISH has emerged as an effective tool in not only the definitive diagnosis of PM, but also detection of trisomies in HD cases and the discernment of the cause of the miscarriage. In our study, an unsuspected trisomy was identified in a significant proportion (9%) of POCs with hydropic changes submitted for FISH analysis. A diagnosis of gestation with a trisomy can have significant clinical implications. Thus, FISH, rather than flow cytometry, should be considered as the new gold standard for the evaluation of hydropic POCs.
Category: Pediatrics

Monday, February 28, 2011 1:00 PM

Poster Session II # 195, Monday Afternoon


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