## **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 in this case would be **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 that the bleeding is coming from a specific duct (as indicated by the ability to express a bead of blood from the nipple), a targeted approach like ductal excision is both diagnostic and therapeutic.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While imaging studies like ultrasound or mammography are important in the initial evaluation of breast symptoms, they are not sufficient for definitive diagnosis in this case, as they may not identify small intraductal papillomas.
- **Option B:** A **galactogram** or ductography might help in identifying the involved duct but is not a therapeutic procedure and does not provide a tissue diagnosis.
- **Option C:** **Biopsy** might be considered if imaging suggests a mass or if the diagnosis is unclear, but given the symptoms and the expressible blood from a single duct, a more direct approach like ductal excision is preferred.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that bloody nipple discharge, especially when unilateral and from a single duct, has a high likelihood of being due to an **intraductal papilloma** or, less commonly, breast cancer. Therefore, thorough investigation, typically involving ductal excision, is crucial.

## **Correct Answer:** D. Ductal excision.