title: First trimester serum markers stability during sample transportation from the obstetrical site to the screening laboratory.
abstract: OBJECTIVE
  To investigate the effect of temperature on first trimester free β-hCG and PAPP-A in serum during transportation.
  
  
  METHODS
  Maternal blood was collected from 30 East Asian women attending for Down syndrome screening at the primary obstetrical site. The extracted serum was split into two equal aliquots, placed in identical thermally insulated pouches with a temperature data logger and shipped to the screening laboratory. An 800 g frozen ice pack was placed in one of the pouches. Free β-hCG and PAPP-A levels were determined in the 'Cooled' and 'Uncooled' serum samples using a DELFIA(®) Xpress analyzer. The proportion of 'Uncooled' samples not within 5% of the 'Cooled' sample marker level was assessed.
  
  
  RESULTS
  The median age of subjects was 36 years, half were nulliparous and all were non-smokers. The assay stability ranged from 2.38% to 4.41%. The median total transport time from the obstetrical site to the laboratory was 17.37 h. Median recorded temperatures within the 'Cooled' pouch were significantly lower throughout the transportation of the samples (p < 0.0001). The median percentage change of free β-hCG and PAPP-A concentrations in 'Uncooled' samples relative to 'Cooled' samples were 2.72% (range 0.27-7.64%) and 1.10% (range 0.03%-4.29%), respectively. Free β-hCG concentrations differed by greater than 5% in eleven (37%) subjects.
  
  
  CONCLUSIONS
  Insulated packaging, cooling media and temperature monitoring devices may be needed as additional measures to determine, minimize and exclude effects of ambient temperature on serum marker levels especially when travelling times are long or ambient temperatures are high.
authors: Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong SAR, China. daljit@cuhk.edu.hk
authors: Daljit Singh
authors: DS
authors: Sahota
authors: Ritsuko Kimata
authors: RK
authors: Pooh
authors: Kwong Wai
authors: KW
authors: Choy
authors: Tak Yeung
authors: TY
authors: Leung
authors: Tze Kin
authors: TK
authors: Lau
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000175:diagnosis; D005260:Female; D006801:Humans; D008403:Mass Screening; D009774:Obstetrics / Q000592:standards; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis*; D011446:Prospective Studies; D013048:Specimen Handling; D013696:Temperature; D014186:Transportation
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A