Final answer:
The symptom related to poor perfusion that warrants immediate test termination and possible referral is Cyanosis, a bluish discoloration of the skin indicative of oxygen deficiency in the blood.
Step-by-step explanation:
The sign or symptom that merits immediate test termination and possibly a referral to a qualified healthcare professional, related to poor perfusion, is B. Cyanosis. Cyanosis refers to the bluish discoloration of the skin and mucous membranes, which is caused by a lack of oxygen in the blood. This could be due to a variety of factors such as respiratory or cardiovascular issues leading to poor blood circulation and reduced oxygen delivery to tissues. In contrast, Claudication is pain caused by too little blood flow, often during exercise, which indicates peripheral artery disease. Fatigue is a nonspecific symptom that could be related to a multitude of conditions, including poor perfusion but is less immediately identifiable as a sign of poor perfusion. Ataxia relates more to neurological function and is not directly associated with perfusion.