## **Core Concept**
The patient's symptoms of intermittent bleeding from the nipple, specifically a bead of blood expressible from the nipple without a palpable mass, suggest a possible **intraductal papilloma**. This condition involves small, benign tumors growing in the milk ducts of the breast and is a common cause of nipple discharge, which can be bloody.

## **Why the Correct Answer is Right**
The ideal procedure for diagnosing and treating the cause of bloody nipple discharge, especially when an intraductal papilloma is suspected, is **ductal excision** or **microdochectomy**. This surgical procedure involves the removal of the involved duct, which usually resolves the issue and provides a specimen for pathological examination to confirm the diagnosis. Given the symptoms, this approach is both diagnostic and therapeutic.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While imaging studies like ultrasound or mammography are important in evaluating breast symptoms, they are not definitive for diagnosing intraductal papillomas or other causes of bloody nipple discharge. These tests might identify larger lesions but are not a substitute for histological diagnosis.
- **Option B:** A **galactogram** or ductography might help visualize the ductal system but is not typically used for diagnosing the cause of bloody nipple discharge and is not as directly therapeutic as ductal excision.
- **Option C:** **Biopsy** might be considered if there were a palpable mass, but for bloody nipple discharge without a mass, biopsy would not be the first line as it's less likely to yield a diagnosis compared to ductal excision.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that bloody nipple discharge, especially when unilateral and from a single duct, warrants further investigation due to its association with underlying malignancy, although intraductal papillomas are more common. The presence of blood in nipple discharge necessitates a thorough evaluation, with ductal excision often being both diagnostic and therapeutic.

## **Correct Answer:** D. Microdochectomy or ductal excision.