**Core Concept**
A thoracotomy is a surgical incision into the chest wall to access the thoracic cavity, often performed in emergency situations to treat life-threatening conditions. In the context of blunt chest trauma, thoracotomy is typically reserved for patients with severe, potentially life-threatening injuries.

**Why the Correct Answer is Right**
Rib fractures, although painful and potentially life-threatening in severe cases (e.g., flail chest, multiple fractures), are generally not an indication for thoracotomy. The presence of rib fractures alone does not necessitate surgical intervention, as patients can often be managed conservatively with pain control and respiratory support. In contrast, the other options (A, B, and C) represent more severe and life-threatening conditions that may require immediate surgical intervention.

**Why Each Wrong Option is Incorrect**
**Option A:** A chest tube drainage of 1000 ml is not an indication for thoracotomy, as this volume is within the expected range for initial drainage after tube placement. However, continued bleeding or increasing drainage may necessitate surgical intervention.

**Option B:** Continuous bleeding through the intercostal tube of more than 200 ml/hour for three or more hours is a sign of ongoing hemorrhage and may require thoracotomy to control the bleeding.

**Option C:** Cardiac tamponade, characterized by fluid accumulation in the pericardial sac compressing the heart, is a life-threatening condition that requires immediate surgical intervention, often through a thoracotomy.

**Clinical Pearl / High-Yield Fact**
When managing blunt chest trauma, it's essential to differentiate between patients who require immediate surgical intervention (e.g., thoracotomy) and those who can be managed conservatively. A high index of suspicion for life-threatening conditions, such as cardiac tamponade or ongoing bleeding, is crucial in making timely decisions.

**✓ Correct Answer: D. Rib fracture**