**Question:** All of the following are tests to determine the stoppage of circulation except –

A. Continuous-wave Doppler ultrasound
B. Electrocardiogram (ECG)
C. Fundoscopy
D. Radial artery pulse examination

**Core Concept:**
The correct answer is derived from understanding the difference between tests used to evaluate circulation and those used to evaluate the absence of circulation. Tests that assess circulation focus on measuring blood flow, while those assessing the absence of circulation assess the lack of vital functions.

**Why the Correct Answer is Right:**

The correct answer, **Option C: Fundoscopy**, is not a test used to determine the stoppage of circulation. Fundoscopy is a procedure used to examine the fundus of the eye, which involves looking into the eye through a special instrument called a binocular indirect ophthalmoscope. It helps in assessing the health of the retina and optic nerve, but it does not directly evaluate circulation.

**Why Each Wrong Option is Incorrect:**

**Option A: Continuous-wave Doppler ultrasound** is a test used to evaluate blood flow. Continuous-wave Doppler ultrasound measures the velocity and direction of blood flow in blood vessels, which aids in diagnosing circulatory issues and detecting blockages or obstructions.

**Option B: Electrocardiogram (ECG)** is a test used to evaluate the heart's electrical activity and function. An ECG is not directly related to assessing circulation but can indicate cardiac issues that may affect circulation.

**Option D: Radial artery pulse examination** is a direct method to assess arterial circulation, specifically the radial artery. This test evaluates the presence, strength, and quality of the radial artery pulse, which can help determine the adequacy of circulation.

**Clinical Pearl:**

Understanding the distinctions between the tests helps in correctly identifying the methods used to evaluate circulation and those used to assess the absence of circulation or detect specific circulatory problems.

**Correct Answer:**

**Option B: Electrocardiogram (ECG)** is the correct answer to determine the absence of circulation. An ECG is a valuable tool for assessing cardiac function, which may indirectly indicate the overall circulatory status in cases of global circulatory failure. In such cases, ECG abnormalities might be present, such as bradycardia, asystole, or pulseless electrical activity, which can indicate the absence of circulation. However, this is not directly evaluating circulation, but rather indicating potential issues with circulation that need further evaluation.