Knowledge · Procedural Skills

Central Venous Catheter Insertion: Ultrasound, Seldinger Technique and Never Events

By Dr Richard Miller, MBChB FRCS with the MRCS Part B Questions Team · Reviewed 15 September 2026

In brief

NICE TA49 recommends two-dimensional ultrasound guidance as the preferred method for internal jugular central venous catheter insertion in elective cases, and a retained guidewire is a Never Event, so the wire is held and counted at every step.

Central venous catheter insertion is marked on preparation, ultrasound use and wire control. NICE technology appraisal TA49 recommends two-dimensional imaging ultrasound guidance as the preferred method for inserting central venous catheters into the internal jugular vein in elective situations, and a retained guidewire counts as a Never Event.

Key takeaways

NICE TA49 recommendation 1.1 makes two-dimensional ultrasound the preferred method for elective internal jugular catheterisation in adults and children.
TA49 also says ultrasound should be considered in most circumstances, elective or emergency, and that audio-guided Doppler is not recommended.
NICE records that the most common complications are arterial puncture, arteriovenous fistula, pneumothorax, nerve injury and repeated unsuccessful attempts.
NHS England's Never Events list counts guidewires among the foreign objects that must be counted and checked, so a retained wire is a Never Event.
NICE CG139 asks for chlorhexidine gluconate in 70% alcohol for skin decontamination and a transparent dressing changed every 7 days over a central venous catheter site.

What is the examiner marking at the central line station?

The Intercollegiate blueprint runs two procedural stations and marks them differently. A procedural skills station with a patient carries 8 marks for clinical and technical skill and 4 each for clinical knowledge, communication and professionalism. A technical procedural station, performed on a model rather than a person, carries 12 for skill and 8 for knowledge, with no communication or professionalism marks available.

Prepare for the version with a patient, because it is the harder of the two: the same technique has to be delivered while consenting, explaining and keeping the patient comfortable, and those marks are gone if you work in silence.

The examiner is marking preparation, sterility, ultrasound technique and control of the guidewire, plus your awareness of what goes wrong.

You will usually be working on a model, so say the steps that a model cannot show, including the checklist and the post-procedure confirmation.

What are the indications and the site options?

NICE lists haemodynamic monitoring, intravenous delivery of blood products and drugs such as chemotherapy and antibiotics, haemodialysis, total parenteral nutrition, cardiac pacemaker placement and perioperative fluid management among the reasons for central venous catheters, and estimates about 200,000 insertions a year in the NHS.

Internal jugular vein, the most common elective site and the one TA49 addresses directly
Subclavian vein, which avoids neck movement but carries a pneumothorax risk
Femoral vein, quick in an emergency but less suitable for longer use
Peripherally inserted central catheters, placed through an upper limb vein

NICE notes the choice depends on the reason for insertion, the expected duration, the available sites and operator skill, and that reported failure rates with the landmark method alone have been as high as 35%.

Explain the indication, the alternatives and the risks, and obtain written consent where the patient has capacity and time allows.

Royal College of Surgeons of England, on the Montgomery ruling, notes doctors must take reasonable steps to ensure patients are aware of the risks material to them; for this procedure those include bleeding, arterial puncture, pneumothorax, infection, thrombosis and failure.

What equipment and preparation do you need?

Trained assistant, monitoring, and a tipping trolley or bed
Ultrasound machine with a sterile probe cover and sterile gel
Central line pack, sterile gown and gloves, drapes, and chlorhexidine gluconate in 70% alcohol skin preparation
Local anaesthetic, syringes and needles, scalpel, dilator, sutures and dressings
Sterile 0.9% sodium chloride to flush each lumen before insertion, which CG139 prefers for flushing and locking

What are the steps, in order?

Confirm the indication, check coagulation and consent, and run a team checklist naming the site and operator
Position the patient head down for a jugular or subclavian approach, with the head turned slightly away
Scan the vein first with ultrasound, identifying the vein, the artery and their relationship
Perform hand hygiene, gown and glove, prepare the skin with chlorhexidine gluconate in 70% alcohol and allow it to dry, then drape widely
Flush every lumen with sterile sodium chloride and leave the distal lumen open for the wire
Infiltrate local anaesthetic, aspirating before each injection
Puncture the vein under direct ultrasound vision, confirming venous blood on aspiration, and keep the needle still
Pass the guidewire, watching the monitor for arrhythmia, and never let go of the wire at any point
Nick the skin, pass the dilator over the wire, then railroad the catheter, withdrawing the wire through the distal lumen before the catheter is fully seated
Remove the wire completely, confirm it is intact, flush each lumen, suture and dress the line, then confirm the position before use

Why is the guidewire the safety-critical step?

Because losing it is a Never Event. NHS England's Never Events list defines a retained foreign object as an item subject to a formal counting or checking process, and names guidewires explicitly alongside swabs, needles and instruments.

The list gives a worked example: a broken guidewire tip found on a later radiograph met the definition because the wire should have been checked for completeness when it was withdrawn. Keep one hand on the wire, and inspect it when it comes out.

What are the complications?

Arterial puncture, arteriovenous fistula, pneumothorax and nerve injury, which NICE lists as the most common complications
Repeated unsuccessful attempts, which NICE counts as a complication because they delay treatment
Air embolism, arrhythmia during wire passage, and haemothorax
Catheter-related bloodstream infection and central vein thrombosis
NICE records a National Confidential Enquiry into Perioperative Deaths survey of more than 3,000 central venous catheter procedures in which one fatality followed a procedure-induced pneumothorax

What are the most common mistakes at this station?

Not scanning before draping, so the anatomy is a surprise
Letting go of the guidewire, even briefly
Skimping on the sterile field or on skin preparation drying time
Failing to confirm venous rather than arterial puncture before dilating
Forgetting to say how you would confirm the line position and check for complications before it is used

How do you finish and document?

Secure the line, apply a sterile transparent dressing, and confirm position and the absence of complications according to local policy before the line is used.

NICE CG139 asks for the transparent dressing over a central venous catheter site to be changed every 7 days, or sooner if it is no longer intact, and for the site to be cleaned with chlorhexidine gluconate in 70% alcohol at dressing changes. Document the operator, site, ultrasound use, number of attempts, catheter length and the plan for removal.

The MRCS Part B Questions bank has a central venous catheter station at /Sample-Questions.

Key evidence

Guidance on the use of ultrasound locating devices for placing central venous catheters (TA49), recommendations 1.1 to 1.4 — National Institute for Health and Care Excellence (2002)
Ultrasound locating devices for placing central venous catheters (TA49), clinical need and practice — National Institute for Health and Care Excellence (2002)
Never Events list 2018, updated February 2021 — NHS England (2021)
Healthcare-associated infections: prevention and control in primary and community care (CG139), section 1.4 — National Institute for Health and Care Excellence (2017)

FAQ

Is ultrasound guidance mandatory for central line insertion?

NICE TA49 recommends two-dimensional imaging ultrasound guidance as the preferred method for insertion of central venous catheters into the internal jugular vein in adults and children in elective situations, and says it should be considered in most clinical circumstances, elective or emergency. It also recommends that everyone placing lines this way is trained to competence. Audio-guided Doppler is not recommended.

What happens if the guidewire is lost?

A retained guidewire is a Never Event. NHS England's Never Events list includes guidewires among the foreign objects subject to formal counting and checking, and its worked example confirms that a broken wire tip found later meets the definition. Keep a hand on the wire throughout and check it is intact when removed.

Which complications should I mention when consenting?

NICE names arterial puncture, arteriovenous fistula, pneumothorax, nerve injury and multiple unsuccessful attempts as the most common complications of central venous catheter placement. Infection and thrombosis follow insertion. Tailor the discussion to what is material for that patient, as the Montgomery ruling requires.

How often should a central line dressing be changed?

NICE CG139 says the transparent semipermeable membrane dressing covering a central venous access device site should be changed every 7 days, or sooner if it is no longer intact or moisture collects under it. Dressings on tunnelled or implanted sites are changed every 7 days until the site heals. Clean the site with chlorhexidine gluconate in 70% alcohol at each change.

How common are central venous catheters in the NHS?

NICE estimated about 200,000 central venous catheters are inserted annually in the NHS, across theatres, emergency departments, wards, radiology and critical care. It also reported failure rates for initial insertion by the landmark method as high as 35% in the literature. That volume is why the ultrasound recommendation matters.

Which lumen should the guidewire pass through?

The distal lumen, which is left open and unflushed for that purpose while the other lumens are flushed and closed. Withdraw the wire until its tip appears at that port before advancing the catheter fully, keeping hold of it at all times. Then remove it completely and check it is intact.

The MRCS Part B Questions Team

Written and maintained by doctors who have sat and scored well at this interview, and reviewed against the current published guideline in each case. Guidance changes — check the source before you rely on a threshold.

Last reviewed 15 September 2026

More in Procedural Skills

Cannulation: Aseptic Insertion, Flushing and Setting Up an Infusion

Cannulation is marked on aseptic non-touch technique and safety: decontaminate the skin with chlorhexidine gluconate in 70% alcohol, advance the cannula rather than the needle, flush with sterile sodium chloride, and remove the device as soon as it is no longer needed.

Chest Drain Insertion for MRCS Part B: Triangle of Safety, Technique and Marking

Chest drain insertion involves assessing the indication and ABCDE stability, obtaining consent, preparing sterile equipment, positioning the patient, anaesthetising the site, and advancing a tube into the pleural space to drain air, blood, pus, or fluid. This guide covers drain function, suction, complications, and MRCS Part B assessment points, including ultrasound for pleural effusions.

Joint Aspiration for MRCS Part B: Asepsis, Technique and Synovial Fluid

Knee joint aspiration works by inserting a sterile needle into the knee joint to withdraw excess synovial fluid for pressure relief or laboratory testing. Also called arthrocentesis, it can identify infection, bleeding, crystals, or inflammatory arthritis; fluid is typically assessed with Gram stain, culture, crystal microscopy, and cell count.

Lumbar Puncture for MRCS Part B: Landmarks, Layers and Technique

A lumbar puncture involves inserting a hollow needle into the lower back to collect cerebrospinal fluid (CSF) for testing. You are positioned on your side, and the needle enters below the spinal cord, usually at L3/L4 or L4/L5. Results can help investigate infection, inflammation, bleeding, or abnormal pressure.

Practise this at exam level

The question bank turns this topic into station-style questions with model answers and AI-marked spoken practice.

Explore the question bank