A new born presented with jaundice. Most diagnostic investigation of choice is –
**Core Concept**
The newborn presented with jaundice is a common clinical scenario that requires prompt diagnosis and management. The underlying pathophysiological principle involves the breakdown of red blood cells (hemolysis) leading to an accumulation of bilirubin in the blood and tissues, causing jaundice. This condition necessitates an accurate diagnosis to determine the underlying cause.
**Why the Correct Answer is Right**
The most diagnostic investigation of choice for a newborn with jaundice is a **Bilirubin Level**. This involves measuring the total bilirubin (TBil) and conjugated bilirubin (CBil) levels in the blood. Elevated bilirubin levels can indicate hemolysis, liver dysfunction, or biliary obstruction. The bilirubin level helps in assessing the severity of jaundice and guiding further management, including phototherapy or exchange transfusion if necessary.
**Why Each Wrong Option is Incorrect**
* **Option A:** Blood culture is not the most diagnostic investigation for jaundice, as it is primarily used to diagnose bacterial infections.
* **Option B:** Coombs test is used to detect autoimmune hemolytic anemia, which can cause jaundice, but it is not the most diagnostic investigation of choice for a newborn with jaundice.
* **Option C:** Liver function tests (LFTs) can provide information about liver function but are not the most diagnostic investigation for jaundice in a newborn.
**Clinical Pearl / High-Yield Fact**
A bilirubin level is essential in the diagnosis and management of neonatal jaundice, and a level of 15-20 mg/dL is generally considered a threshold for phototherapy. Always remember to evaluate the total bilirubin level in the context of the newborn's age and risk factors for kernicterus.
**Correct Answer:** B. Bilirubin Level