**Core Concept**
Esophageal rupture, especially in the setting of Boerhaave syndrome, is a surgical emergency requiring rapid diagnosis. The investigation must detect free air or contrast leakage into the mediastinum or pleural space, and the test should be both safe and sensitive in acute trauma.

**Why the Correct Answer is Right**
Water-soluble low molecular weight contrast swallow is the investigation of choice because it rapidly detects leakage of contrast into the mediastinum or pleural space. The contrast is rapidly absorbed if there is a rupture, and it can show a "water-soluble" leak within minutes. This test is safe in acute settings, with minimal risk of aspiration, and provides immediate results. It is more sensitive than barium in detecting early rupture and is preferred over rigid esophagoscopy due to high risk of complications.

**Why Each Wrong Option is Incorrect**
Option A: Dynamic MRI is not used in acute esophageal rupture due to lack of real-time capability and limited availability. It is not sensitive enough for early detection.
Option B: Rigid esophagoscopy is contraindicated in suspected rupture due to high risk of perforation and spreading of infection. It is not used in acute settings.
Option C: Barium contrast swallow is less sensitive and can delay diagnosis due to delayed visualization of leaks. It may also cause complications like aspiration or obstruction.

**Clinical Pearl / High-Yield Fact**
In suspected esophageal rupture, **water-soluble contrast swallow should be performed immediately**—it is the fastest, safest, and most sensitive test for detecting leakage. Delayed diagnosis increases mortality.

✓ Correct Answer: D. Water soluble low molecular weight contrast swallow