What is the most likely diagnosis for a 6-month-old infant with blood-streaked vomiting?

In the context of a 6-month-old infant presenting with blood-streaked vomiting, gastroesophageal reflux with esophagitis is a plausible diagnosis because it can cause irritation and inflammation of the esophagus, leading to bleeding. In young infants, gastroesophageal reflux is common and may present with symptoms such as vomiting, which can occasionally be blood-streaked due to mucosal irritation.

When reflux leads to esophagitis, the inflammation can compromise the blood vessels in the esophagus, resulting in a small amount of bleeding. This vomiting typically occurs after feedings and can be associated with other signs of discomfort, such as fussiness or arching of the back.

While pyloric stenosis and intestinal obstruction can also lead to projectile vomiting and other severe gastrointestinal symptoms, they are often associated with other clinical features, such as dehydration, electrolyte imbalances, or a palpable "olive" mass in the case of pyloric stenosis, which is not mentioned in this scenario. Celiac disease usually presents with chronic gastrointestinal symptoms and is less likely to cause acute blood-streaked vomiting in such a young infant.

Therefore, the presence of blood-streaked vomiting in combination with the age of the infant aligns more closely with