Most common investigation done for obstructive jaundice –
**Core Concept**
Obstructive jaundice occurs due to a blockage in the bile ducts, leading to the accumulation of bilirubin in the blood and tissues, causing jaundice. The most common investigation to diagnose the underlying cause of obstructive jaundice is a radiological imaging study.
**Why the Correct Answer is Right**
The correct investigation for obstructive jaundice is an ultrasound of the abdomen, which is a non-invasive and widely available imaging modality. Ultrasound can identify stones, tumors, or other obstructions in the bile ducts and gallbladder, allowing for the diagnosis and potential treatment of the underlying cause. The ultrasound can also assess the liver and pancreas for any associated pathology.
**Why Each Wrong Option is Incorrect**
**Option A:** CT scan of the abdomen is not the most common investigation for obstructive jaundice, although it may be used in some cases to provide more detailed imaging of the bile ducts and surrounding structures.
**Option B:** MRI of the abdomen is not typically used as a first-line investigation for obstructive jaundice, although it may be used in some cases to provide more detailed imaging of the bile ducts and surrounding structures.
**Option C:** ERCP (Endoscopic Retrograde Cholangiopancreatography) is a more invasive procedure that may be used to diagnose and treat obstructive jaundice, but it is not the most common investigation.
**Clinical Pearl / High-Yield Fact**
Ultrasound is a non-invasive and widely available imaging modality that can be used to diagnose obstructive jaundice in the emergency department or outpatient setting.
**Correct Answer:** A. Ultrasound of the abdomen.