Blood hemoglobin levels are an extremely important measure for a large swath of medical procedures as they reflect the oxygen-carrying capacity of human blood. The gold standard measure for blood hemoglobin levels involve a venous blood draw followed by a laboratory-based complete blood count (CBC), a process which is both painful and time consuming. To date, various methodologies have been tested to either expediate the process or provide a non-invasive alternative. There remains a need to provide a quick, pain-free/non-invasive and accurate modality to measure blood hemoglobin levels. The objective of this study is to determine whether computer vision technologies can be applied to fingernail images captured via a smartphone camera to quantify blood hemoglobin levels.

Inclusion Criteria:

1. A patient aged 6 months to 18 years.
2. A patient who has undergone a venous blood draw for a CBC since being admitted to the PED no more than 6 hours prior to study enrollment.
3. Parents or legal guardian provide informed written consent.

Exclusion Criteria:

1. Patient has subungual hematoma, nail bed lacerations or avulsion injuries on both hands.
2. Patient has total leukonychia.
3. Patient has nail polish applied on fingernails.
4. Patient has nailbed darkening or discoloration due to medication.
5. Any other reason that, in the opinion of the investigator, prevents the subject from participating in the study or compromise the patient safety.

Pediatric patients admitted to the Pediatric Department, Pediatric Emergency Department (PED) or Pediatric Hematology Unit (PHU) who have undergone a CBC