Which sign indicates thrombophlebitis?

• A. Redness along vein
• B. Pain in calf when dorsiflexion
• C. Fever
• D. Swelling of ankle

Answer: (B)

The key idea is that pain felt in the calf when the ankle is dorsiflexed (the so-called dorsiflexion or Homan sign) can indicate a thrombus in the leg veins with accompanying inflammation. When the foot is dorsiflexed, the calf muscles stretch and pull on the veins; if a thrombus is present, this traction inflames the vein and elicits pain. This makes dorsiflexion-induced calf pain a classic sign suggesting thrombophlebitis.

Redness along a vein can occur with superficial thrombophlebitis, but it isn’t as specific for thrombophlebitis in the deeper veins. Fever is a nonspecific sign of infection or systemic inflammation and doesn’t reliably indicate thrombophlebitis by itself. Swelling of the ankle is a broad symptom that can result from many conditions, not specifically thrombophlebitis.