The Apt test is a qualitative test to identify the source of blood present in stool of newborns for differential diagnosis of gastrointestinal bleeding (1).
Our results indicate that the HPLC method has much higher sensitivity and specificity than the Apt test.
The Apt test required a minimum of 40 mL/100 g cord blood (with HbF 80% of the total hemoglobin) for detection of fetal hemoglobin (Table 1).
Traditionally, the Apt test (1) has been used to distinguish the source of blood in such specimens for differential diagnosis of newborn gastrointestinal bleeding.
The HPLC method we describe here has advantages over both the original Apt test and the modified procedures based on alkaline denaturation (1, 4, 5).
Improved quantitative Apt test for detecting fetal hemoglobin in bloody stools of newborns.
Hemoglobin in stools from neonates: measurement by a modified Apt test. Med Lab Science 1991;48:346-7.
Q We occasionally get an order for an Apt test to determine if the blood in a neonate's emesis or stool is maternal or fetal in origin.
Incidentally, the Apt test is not included in the CPT code listing of reimbursable laboratory tests.
 So perhaps point-of-care monitoring of hemoglobin levels might be a reasonable substitute for the Apt test.