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Procedure
April 2026
Venepuncture
Patient
Mr Thomas Hale
Age / Sex
52M
Setting
Pre-operative Assessment
Year Group
Y2 / Y3
Duration
10 minutes
Clinical Scenario
Candidate Briefing
Mr Thomas Hale is a 52-year-old man attending the pre-operative assessment clinic ahead of his elective right inguinal hernia repair, scheduled for next week. He has a background of type 2 diabetes and hypertension. He takes metformin 500mg BD and ramipril 5mg OD. He has no known drug allergies.
The anaesthetic team has requested a pre-operative blood panel. You have been asked to perform venepuncture and collect samples for the following investigations:
FBC · U&E · LFTs · Clotting screen
Please perform venepuncture on Mr Hale, collecting blood for all four investigations. A simulated arm is provided. The examiner will observe and ask questions throughout.
Equipment Checklist
Non-sterile glovesCorrect size
TourniquetSingle-use or decontaminated
Vacutainer holder + double-ended needle21G (green) standard; 23G (blue) for fragile veins
Sodium citrate bottle — Blue topClotting screen · Fill to line (exactly 2.7ml)
SST / Serum bottle — Gold topLFTs / biochemistry
Lithium heparin — Green topU&E
EDTA — Purple / Pink topFBC
Alcohol wipe70% isopropyl alcohol · Allow 30 seconds to dry
Gauze / cotton wool ball
Adhesive plaster / tape
Sharps binMust be within arm's reach before starting
Patient ID labels + blood request formLabelled at bedside, not in advance
Mark Scheme
| Competency | Marks | Awarded |
|---|---|---|
| Introduction & Consent | ||
| Introduces self (name and role), confirms patient's full name and date of birth against wristband / request form | 1 | |
| Explains the procedure clearly in lay terms — what it involves and why it is needed
e.g. "I need to take a small sample of blood from a vein in your arm to check a few things before your operation"
|
1 | |
| Obtains verbal consent; asks about previous difficulties, vasovagal episodes, or allergy to plasters / latex | 1 | |
| Preparation | ||
| Gathers and checks all required equipment before approaching patient; places sharps bin within reach | 1 | |
| Performs hand hygiene (6-step technique) and applies non-sterile gloves | 1 | |
| Site Selection & Skin Preparation | ||
| Applies tourniquet 5–10 cm above planned venepuncture site; asks patient to make a fist | 1 | |
| Selects an appropriate vein — antecubital fossa preferred (median cubital, cephalic or basilic); explains choice
Avoids areas of bruising, infection, lymphoedema, or AV fistula
|
1 | |
| Cleans site with alcohol wipe using outward circular motion; allows minimum 30 seconds to dry completely | 1 | |
| Does NOT re-palpate the site after cleaning | 1 | |
| Venepuncture Technique | ||
| Warns patient ("sharp scratch"); inserts needle bevel-up at 15–30° angle, anchoring skin below puncture site | 1 | |
| Advances needle smoothly; observes blood flashback before attaching first vacutainer bottle | 1 | |
| Fills bottles in the correct order of draw:
1. Blue (sodium citrate — clotting) → 2. Gold (SST — LFTs) → 3. Green (lithium heparin — U&E) → 4. Purple (EDTA — FBC)
|
2 | |
| Releases tourniquet before removing the final bottle (or within 1 minute to prevent haemoconcentration) | 1 | |
| Asks patient to open their fist; withdraws needle smoothly; immediately applies gauze with firm pressure | 1 | |
| Post-Procedure | ||
| Disposes of needle directly into sharps bin without re-sheathing
Automatic fail if needle is re-sheathed or left on a surface
|
2 | |
| Inverts bottles the correct number of times:
Blue ×3–4 · Gold ×5 · Green ×8–10 · Purple ×8–10
|
1 | |
| Labels all bottles at the bedside (patient name, DOB, hospital number, date and time of collection); confirms against wristband | 1 | |
| Secures gauze with plaster (checks for plaster allergy first); thanks and reassures patient | 1 | |
| Removes gloves, performs hand hygiene; documents procedure in the notes including date, time, site and operator | 1 | |
Total
20 marks
Examiner Questions
What is the correct order of draw, and why does it matter?
Blue (citrate) → Gold (SST) → Green (heparin) → Purple (EDTA). The order prevents additive carryover between tubes — for example, EDTA from the FBC bottle can chelate calcium and falsely prolong clotting times if it contaminates the citrate tube. Citrate must always come first when a clotting sample is required.
What are the potential complications of venepuncture?
- Haematoma — most common; apply firm pressure for at least 2 minutes
- Vasovagal syncope — lay patient flat, elevate legs if they feel faint
- Accidental arterial puncture — bright red pulsatile blood; apply firm pressure for 5+ minutes
- Nerve injury — paraesthesia during procedure; withdraw needle immediately
- Infection / phlebitis — use aseptic technique throughout
- Haemolysis of sample — causes falsely elevated potassium (K⁺)
You accidentally sustain a needlestick injury. What do you do?
Immediately remove gloves and encourage the wound to bleed freely under running water for several minutes. Do not suck the wound. Wash thoroughly with soap and water. Cover with a waterproof dressing. Report immediately to occupational health or the emergency department. Complete a Datix / incident form. A risk assessment will determine whether post-exposure prophylaxis (PEP) for HIV is indicated — this must be started within 72 hours.
Mr Hale's clotting sample is underfilled. What do you do?
The citrate tube must be filled to the fill line (2.7 ml) to maintain the correct 9:1 blood-to-citrate ratio. An underfilled tube will give a falsely prolonged PT/APTT. You must discard the bottle and collect a new sample from a fresh venepuncture. Do not add more blood to a partially filled citrate tube once the needle has been removed.
Which vein would you choose, and why?
First choice is the antecubital fossa — the median cubital vein is large, superficial, well-anchored, and has fewer nearby structures. The cephalic and basilic veins are second-line options. Avoid the dorsum of the hand if possible (more painful). Never use an arm with an AV fistula, lymphoedema, or recent mastectomy on that side.
Safety Points
Fail
Re-sheathing the needle or placing it on a surface rather than directly into the sharps bin is an automatic fail in most OSCEs. Do it in one motion: out of the arm, into the bin.
Fail
Labelling bottles before collection (pre-labelling) is a patient safety error — bottles must be labelled at the bedside immediately after collection, verified against the patient's wristband.
Key Point
Re-palpating after cleaning the skin contaminates the site and requires you to clean again. Most examiners will note this. If you must re-palpate, clean again and restart the clock on drying time.
Key Point
Release the tourniquet before withdrawing the needle (or within 1 minute) to prevent haemoconcentration, which can cause falsely elevated potassium, haematocrit and proteins.
Top Tip
Talk to your patient throughout. Narrating each step ("I'm just cleaning your skin now, and I'll give it a moment to dry") keeps the patient calm and signals good communication to the examiner — both are marked.