The test done in the picture is to test the patency of:

OSSSC Nursing Officer-2021

Medical & Surgical Nursing

Easy

Appeared in: OSSSC Nursing Officer-2021

Explanation

The image displays the Modified Allen's Test, a clinical procedure to assess blood flow to the hand.
The primary purpose of this test is to confirm the patency of the ulnar artery.
This ensures there is adequate collateral circulation to the hand before performing a procedure (like an ABG draw or arterial line insertion) that could potentially occlude the radial artery.
A positive test (inadequate flow from the ulnar artery) is a contraindication for using the radial artery on that wrist for the intended procedure.

Option B: The test is performed in preparation for a procedure on the radial artery. The goal is not to test the radial artery's patency itself, but to confirm the ulnar artery can provide backup circulation if the radial artery is compromised.
Option C: The Allen's test evaluates arterial blood flow (supply) to the hand, not venous return. Veins carry blood away from the hand and are not assessed by this maneuver.
Option D: This test is for the arterial system. Veins are responsible for carrying deoxygenated blood back to the heart and are not evaluated by checking for reperfusion after arterial occlusion.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Allen's test for ulnar artery patency as background academic context rather than a clinical decision trigger.
The Allen's test is a critical patient safety measure. Performing an invasive procedure on the radial artery without confirming adequate collateral flow from the ulnar artery can lead to severe ischemia, pain, and even loss of the hand if the radial artery becomes thrombosed.
What if the Allen's test is positive (the hand remains pale after releasing the ulnar artery)? The nurse or clinician must not use the radial artery of that wrist for the procedure. The test should be performed on the other wrist. If both are positive, an alternative site (like the brachial or femoral artery) must be chosen.
In the Indian context, where access to advanced imaging like Doppler ultrasound may be limited in some settings, the clinical skill of performing an Allen's test correctly is vitally important for patient safety before radial artery cannulation.

How to Approach the Question

First, identify the procedure shown in the image. The manual compression of the wrist arteries is characteristic of the Allen's test.
Recall the purpose of the Allen's test. It is performed before procedures involving the radial artery.
Ask yourself: 'Why is this test done before a radial artery procedure?' The reason is to ensure the hand has a backup blood supply.
Identify the backup blood supply to the hand. The hand is supplied by both the radial and ulnar arteries, which connect via the palmar arches.
Therefore, the test must be checking the patency of the 'other' artery, which is the ulnar artery.
Eliminate the options related to veins, as the test clearly involves arterial circulation (occluding arteries and watching for color return from arterial blood).

Concept Tested & Keywords

Concept Tested: Allen's test for ulnar artery patency
Stem keywords: test, picture, patency
Lead-in keywords: BEST, MOST RELEVANT CLUE
Clinical cues: Image shows a hand and wrist during a clinical test involving pressure on the wrist.

QaejVbaJx5eo0p_Iu5fjhw

E6 Anatomy Grays 43e Vol 2 Part 2 p. 73-75

E6 Nursing Brunner Adult Health 3SA Vol 1 Part 2 p. 118-120