Final Answer:
The pain is caused by Blood accumulation under the diaphragm. Thus option C is correct.
Step-by-step explanation:
Blood accumulation under the diaphragm, known as referred shoulder pain, is a classic symptom of a ruptured tubal pregnancy. When a fallopian tube ruptures, blood leaks into the abdominal cavity, irritating the diaphragm. This irritation leads to referred pain felt in the shoulder. The diaphragm shares nerve pathways with the shoulder, causing this phenomenon. This pain is not caused by anxiety, cardiac changes from hypovolemia, or rebound tenderness.
The pain's mechanism can be explained by the phrenic nerve's innervation. Irritation of the diaphragm by blood accumulation activates the phrenic nerve, which shares sensory pathways with the shoulder through the C3-C5 spinal nerves. As a result, the brain interprets this irritation as pain in the shoulder. This referred pain occurs due to the convergence of nerve pathways, not directly related to cardiac changes or tenderness.
Clinical assessment usually reveals tenderness in the abdomen, often accompanied by signs of shock due to internal bleeding. Ultrasound or other imaging confirms the diagnosis. Prompt surgical intervention is necessary to prevent life-threatening complications like hemorrhagic shock. Therefore, recognizing the shoulder pain's true cause, blood accumulation under the diaphragm, is crucial for timely intervention and appropriate management of the ruptured tubal pregnancy. Thus option C is correct.