PLAB 2 Procedural Skills — Questions and Answers
Question 1: You are performing venepuncture on a patient. According to best practice, what is the correct order of the procedure?
- Insert the needle first, then apply the tourniquet
- Apply the tourniquet, identify a suitable vein, clean the site with a 2% chlorhexidine swab, allow to dry for 30 seconds, insert the needle bevel up at 15-30 degrees, collect samples in the correct order of draw, remove tourniquet, withdraw needle, apply pressure (Correct answer)
- Apply the tourniquet and immediately insert the needle without cleaning
- Clean the site, insert the needle, then apply the tourniquet
Correct answer: Apply the tourniquet, identify a suitable vein, clean the site with a 2% chlorhexidine swab, allow to dry for 30 seconds, insert the needle bevel up at 15-30 degrees, collect samples in the correct order of draw, remove tourniquet, withdraw needle, apply pressure
The correct venepuncture technique follows ANTT (Aseptic Non-Touch Technique): apply tourniquet, identify vein, clean with 2% chlorhexidine (allow 30 seconds to dry), insert needle bevel up at 15-30 degrees. The order of draw prevents cross-contamination between additives in tubes.
Question 2: You need to perform an arterial blood gas (ABG) sample. Which artery is the first-choice site, and what should you do before attempting the procedure?
- Femoral artery — no preparation needed
- Radial artery — perform a modified Allen's test to confirm adequate collateral circulation via the ulnar artery before puncturing (Correct answer)
- Brachial artery — apply a tourniquet first
- Carotid artery — use ultrasound guidance
Correct answer: Radial artery — perform a modified Allen's test to confirm adequate collateral circulation via the ulnar artery before puncturing
The radial artery is the first-choice site for ABG sampling because of its superficial location and dual blood supply to the hand. A modified Allen's test must be performed before puncture to confirm adequate ulnar artery collateral circulation. If Allen's test is negative, use the other wrist or an alternative site.
Question 3: You are inserting a urinary catheter in a male patient. After inflating the balloon, the patient experiences severe pain. What is the most likely cause and what should you do?
- The balloon is in the correct position — the pain is normal
- The balloon may have been inflated in the urethra rather than the bladder — immediately deflate the balloon, advance the catheter further until urine drains, then re-inflate (Correct answer)
- Remove the catheter completely and abandon the procedure
- Inflate the balloon further to secure it in place
Correct answer: The balloon may have been inflated in the urethra rather than the bladder — immediately deflate the balloon, advance the catheter further until urine drains, then re-inflate
Pain on balloon inflation usually indicates the balloon is in the urethra, not the bladder. You must immediately deflate the balloon to prevent urethral trauma, advance the catheter until urine drains freely (confirming it is in the bladder), and then re-inflate. A key tip: always advance the catheter 'to the hilt' in male patients before inflating.
Question 4: You are performing a lumbar puncture. At which vertebral level should you insert the needle, and how do you identify this landmark?
- Between L1 and L2, identified by counting down from C7
- At or below the L3/L4 interspace, identified using the intercristal line (a line between the iliac crests crosses the spine at approximately L4) (Correct answer)
- Between T12 and L1, using the lowest rib as a landmark
- At L5/S1, identified by palpating the sacrum
Correct answer: At or below the L3/L4 interspace, identified using the intercristal line (a line between the iliac crests crosses the spine at approximately L4)
Lumbar puncture should be performed at L3/L4 or L4/L5 to avoid the conus medullaris (which ends at L1/L2 in adults). The intercristal line (Tuffier's line) — an imaginary line between the iliac crests — crosses the spine at approximately L4, providing the landmark for needle insertion.
Question 5: You are suturing a laceration on a patient's forearm. Which suture technique is most appropriate for a simple, clean, linear wound in the emergency department?
- Continuous subcuticular suture for all ED lacerations
- Simple interrupted sutures — they are versatile, allow drainage, and individual sutures can be removed if infection develops without compromising the entire closure (Correct answer)
- Mattress sutures for all superficial wounds
- Staples for all forearm lacerations
Correct answer: Simple interrupted sutures — they are versatile, allow drainage, and individual sutures can be removed if infection develops without compromising the entire closure
Simple interrupted sutures are the most versatile technique for ED wound closure. Each suture is independent, allowing removal of individual sutures if infection develops. They provide good wound edge eversion, are easy to learn, and can be adjusted for tension. The wound should be cleaned and irrigated before closure.
Question 6: You are asked to perform a DC cardioversion on a patient with atrial fibrillation and haemodynamic instability. What is the correct energy level and electrode position?
- Start at 50J with paddles placed on the patient's back only
- Start at 120-150J biphasic (or 200J monophasic) with one electrode below the right clavicle and one in the left mid-axillary line (anterolateral position), ensuring the patient is adequately sedated or anaesthetised (Correct answer)
- Start at 360J with paddles on the chest and abdomen
- Start at 10J with paddles on both sides of the neck
Correct answer: Start at 120-150J biphasic (or 200J monophasic) with one electrode below the right clavicle and one in the left mid-axillary line (anterolateral position), ensuring the patient is adequately sedated or anaesthetised
For AF cardioversion, the Resuscitation Council UK recommends starting at 120-150J biphasic. Electrode positions are anterolateral (sternal-apical) or anteroposterior. The patient must be sedated/anaesthetised, synchronised cardioversion mode must be used (to avoid delivering a shock during the vulnerable period), and full resuscitation equipment must be available.
PLAB 2 Procedural Skills
You are performing venepuncture on a patient.
According to best practice, what is the correct order of the procedure?