What types of diseases does a barium swallow detect?

Barium swallow: Things that stick out, such as cancers, or cause an indemtation, such as an ulcer. Has been nearly totally replaced by endoscopy.

Dysphagia : Barium swallow is typically ordered for the work up of dysphagia (difficulty swallowing). It can detect structural / anatomical abnormalities such as masses, strictures, diverticulum, hiatal hernia, achalasia, cricopharyngeal bar, protuberance of cervical vertebra.

Many things: In some circles barium swallow includes just throat/pharynx. Sometimes includes pharynx and esophagus. Pharynx examination looks for dysmotility, oropharyngeal coordination, aspiration of barium into airway, and possible obstruction to movement of barium column. Evaluation of esophagus shows dysmotility, irritability from gastroesoph. reflux, stricture, infection, diverticulum etc.