"My two-week-old daughter is throwing up blood".

Swallowed maternal blood at the time of delivery or from cracked nipples during breastfeeding is the most common cause of suspected gastrointestinal bleeding in the neonate. In this case, the Apt-Downey test is a useful diagnostic tool. The Apt-Downey test can effectively differentiate neonatal from maternal hemoglobin based on the conversion of oxyhemoglobin to alkaline globin hematin when mixed with alkali.