What finding would be considered ominous when screening for leukocoria?

A white pupillary reflex is indeed considered an ominous finding when screening for leukocoria. Leukocoria, the presence of a white reflection from the retina within the eye, can indicate serious pathologies such as retinoblastoma, cataracts, or retinal detachment. The normal pupillary reflex should appear red due to the reflection of light from the retinal blood vessels and the underlying structures. An absence of this normal reflex, replaced instead by a white reflex, suggests an abnormality that requires prompt further evaluation.

In contrast, a red pupillary reflex is expected and indicates healthy retinal function. A blue pupillary reflex is not a typical finding in clinical practice and does not have a recognized clinical significance in the context of leukocoria. Therefore, amongst the choices provided, the white pupillary reflex stands out as the indicator of potential pathology that necessitates immediate action and assessment.