Femoral venous and arterial access in an emergency

What it is

The femoral vessels lie in the femoral triangle just below the inguinal ligament, which runs from the anterior superior iliac spine to the pubic tubercle. From lateral to medial the structures follow the NAVEL order: femoral Nerve, Artery, Vein, an Empty space (the femoral canal) and Lymphatics. The femoral artery is felt at the mid-inguinal point, halfway between the anterior superior iliac spine and the pubic symphysis, and the vein lies just medial to it. The groin is valuable in an emergency: it is away from the airway and from chest compressions, it does not risk a pneumothorax, and it can be compressed. The vein takes a central line or a large-bore introducer, the artery an arterial line or a blood gas. Puncture should be below the inguinal ligament: above it, a vessel that bleeds goes into the retroperitoneum, where it cannot be compressed and may not be seen. With the leg slightly abducted and externally rotated, ultrasound shows the vein medial to the artery and avoids the common error of an arterial stick; in cardiac arrest the pulse felt in the groin may even be venous. The trade-off is a higher rate of infection and thrombosis than other sites, so femoral lines are changed to a better site once the patient is stable.

Indications

• Cardiac arrest or shock with failed peripheral access, where the groin does not interrupt compressions or airway work.
• Central venous access when neck and chest sites are unavailable or risky (coagulopathy, lung disease, neck trauma).
• Large-bore access for rapid transfusion, haemodialysis or a transvenous pacing wire.
• Arterial blood gas or an arterial line when radial access has failed.
• Blood sampling in an emergency when no other vein can be found.

Contraindications and precautions

• Infection, burns or wounds in the groin, or a known thrombosis of the femoral or iliac vein.
• Vascular grafts or recent surgery on the femoral vessels.
• Inguinal hernia on that side: the bowel can lie in the path of the needle.
• Coagulopathy: the site is compressible, but press longer and use ultrasound.
• Suspected injury to the inferior vena cava or iliac veins: fluid given below the injury may not reach the heart.

Equipment

• Ultrasound machine with a linear probe, sterile cover and gel.
• Central line or introducer pack, or arterial kit, or a blood gas syringe for sampling.
• Full sterile barrier for a line: cap, mask, sterile gown and gloves, large drape.
• Skin antiseptic and local anaesthetic.
• Saline flushes, suture or securing device and a clear dressing.

Step by step (and why)

1. Lie the patient flat, leg slightly abducted and externally rotated — this opens the triangle and brings the vein beside the artery.
2. Find the inguinal ligament and the mid-inguinal point — the puncture must be below the ligament.
3. Scan in short axis: artery pulsatile and round, vein medial and compressible — ultrasound beats landmarks here.
4. Clean, drape and infiltrate local anaesthetic — a central line needs full asepsis.
5. Without ultrasound, feel the pulse and enter just medial to it, needle pointing towards the head — the vein lies medial.
6. Aspirate as you advance at a shallow angle; stop at dark, non-pulsatile blood — it suggests the vein, not the artery.
7. Pass the wire, hold it always, and confirm it in the vein before dilating — an arterial dilation bleeds badly.
8. Complete the line, aspirate and flush every lumen, secure and dress — a working, secure line is the goal.
9. For arterial puncture, press firmly afterwards and check the leg pulses — groin haematomas grow silently.

Complications

• Puncture or cannulation of the femoral artery when the vein was intended.
• Haematoma, and retroperitoneal haemorrhage after a puncture above the inguinal ligament.
• False aneurysm or arteriovenous fistula.
• Femoral nerve injury, bowel puncture in a hernia.
• Line infection and deep vein thrombosis, more frequent than at other sites.

Next step

• Watch for back or flank pain, falling haemoglobin or hypotension after a difficult groin puncture: suspect retroperitoneal bleeding.
• Check the distal pulses and the leg colour after arterial access, and the leg for swelling after a venous line.
• Move the line to a better site and remove the femoral line when the patient is stable.
• No chest X-ray is needed for position, but document the site, depth and checks.
• Call a senior after an arterial puncture with a dilator, or two failed passes.

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Elsewhere in DurgiPedia

• Peripheral pulses and the ankle–brachial index
• Central venous catheter care
• Clean and sterile technique: medical and surgical asepsis

Connections

← All clinical skills

Educational content; it does not replace supervised hands-on training, your institution's protocols or a prescriber's order. A procedure is learnt with a teacher and done only once you are trained to do it.

Sources: Central Venous Catheter Insertion (StatPearls (NCBI Bookshelf), 2025); Ultrasound-Guided Intravenous Access (StatPearls (NCBI Bookshelf), 2025).

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Representative model, for educational purposes only.