Activated Partial Thromboplastin Time

Units

Seconds

Nonpregnant Adult

26.3-39.4

First Trimester

24.3-38.9

Second Trimester

24.2-38.1

Third Trimester

24.7-35.0


Causes of a prolonged PTT include but are not limited to, heparin, coumadin, lupus anticoagulant, coagulation factor deficiencies, and specific coagulation factor inhibitors.

References: Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies: a reference table for clinicians. Obstet Gynecol. 2009 Dec;114(6):1326-31. PMID:19935037

Wallach, J. Interpretation of Diagnostic Tests, Eighth ed. Lippincott Williams & Wilkins, 2007 Fischbach FT, Dunning MB III, eds. A Manual of Laboratory and Diagnostic Tests, 7th ed. Philadelphia, Lippincott Williams and Wilkins, 2004

 

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