Iowa Neonatology Fellows
Peer Review Status: Internally Peer Reviewed
To differentiate fetal blood from swallowed maternal blood in the evaluation of bloody stools.
Mix specimen with 3-5 ml of tap water and centrifuge. Supernatant must have a pink color to proceed. To 5 parts of supernatant, add 1 part of 0.25 N (1%) NaOH.
A pink color persisting over 2 minutes indicates fetal hemoglobin. Adult hemoglobin gives a pink color that becomes yellowish brown in 2 minutes or less indicating denaturation of the adult hemoglobin.