Alkali Denaturation Test

APT Test
Core Laboratory & Transfusion Medicine
Hematology
Fluid
APT

Special Lab Requisition (MS 331)
This test is used to detect the source of blood in the neonatal gastrointestinal tract and determine if the blood has originated from the mother (having been swallowed by the infant) or represents actual hemorrhage. The alkali denaturation test popularized by Apt and Downey (1955) is used to detect the source of blood in the neonatal gastrointestinal tract.
Vomitus or gastric aspirate containing fresh red blood. Stool is seldom suitable because the blood is usually in the digested state (melena) rather than fresh.
Sterile Container

CollectionContainers
Blood in the sample is digested blood and no longer fresh.
Specimen Acceptability and Transport Guidance

Manual procedure: Alkali denaturation
24 hours, 7 days/week.
2 hours
4 hours
The presence of fetal hemoglobin in the vomitus or gastric aspirate is indicative of a neonatal gastrointestinal tract bleed.

The presence of adult hemoglobin indicates the infant has swallowed mother's blood during delivery.
In case of discrepancies, always interpret results using reference ranges as stated on laboratory reports and/or electronic patient chart.
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