The most appropriate investigation for diagnosing this condition given in xray is:

All the above investigations have been shown to be useful in the diagnosis of a hiatus hernia. However, upper GI barium meals/swallows have been shown to be the most definitive modality in diagnosing hiatus hernias. Chest x-rays may be normal, but in some cases may show an air fluid level above the level of the left hemi-diaphragm. Upper GI endoscopy is commonly used to assess symptoms of dyspepsia and has not been shown to be as sensitive as barium studies in the detection of hiatus hernias. Compared to the barium study, CT scanning delivers relatively high levels of radiation. Positive results obtained with ultrasound scanning may lead to inconsistent and false- positive/negative results due to the operator- associated variability regarding technical experience.