Central line and PICC position on chest X‑ray

Written by the X-Ray Atlas editorial team from the sources listed below · Medical review pending · Updated 24 October 2026 · Level: Intermediate

A central venous catheter (CVC) delivers drugs, fluids and nutrition into a large central vein, where high flow dilutes irritant infusions. Peripherally inserted central catheters (PICCs) do the same job but are inserted through an arm vein. For both, the chest X-ray answers three questions: where is the tip, what course did the line take to get there, and has insertion caused a complication such as a pneumothorax? A tip in the wrong place can cause thrombosis, vessel perforation, arrhythmia or, if the line is in an artery, catastrophic harm. This page covers the target zone, the landmarks and their limits, the common malpositions and the complications to look for.

1. The venous anatomy you need

Lines enter through the internal jugular (IJ), subclavian or axillary vein, or through an arm vein for a PICC. They then follow a predictable path:

• The subclavian and internal jugular veins join behind each sternoclavicular joint to form the brachiocephalic (innominate) vein.
• The right brachiocephalic vein is short and runs almost vertically. The left brachiocephalic vein is longer and crosses the upper mediastinum from left to right.
• The two join behind the right first costal cartilage to form the superior vena cava (SVC), which runs down the right side of the mediastinum and enters the right atrium. The junction is the cavo-atrial junction (CAJ).
• The azygos vein arches forward over the right main bronchus to join the back of the SVC at about the level of T4, and is a common place for a misdirected tip to end up.

On a frontal film, a right-sided line therefore runs down to the right of the trachea and spine. A left-sided line crosses the upper mediastinum from left to right before turning down into the SVC.

2. Target tip position

Why not higher? A tip high in the SVC or in a brachiocephalic vein sits in lower-flow blood, closer to vessel walls, and is associated with more thrombosis and malfunction. Why not deep in the heart? A tip in the right ventricle can cause arrhythmia, and a tip pushing against the atrial or ventricular wall carries a small risk of perforation and tamponade.

3. Landmarks: the carina and its limits

The SVC and the right atrium are both soft tissue, and their junction is not directly visible on a plain film. Surrogate landmarks are used instead:

• The carina. It lies at roughly the level of, or a little above, the pericardial reflection on the SVC. A tip at or just below the carina is therefore usually in the lower SVC, and outside the pericardium.
• The cavo-atrial junction lies roughly 2 vertebral body heights (about 4–5 cm) below the carina in adults. [VARIES]
• The right heart border. The SVC enters the right atrium where the straight upper right mediastinal border meets the convex right heart border, though this point is often indistinct.

4. Left-sided lines

Left IJ and left subclavian lines are more often malpositioned, and the danger is the tip angle. A left-sided line that is too short often ends in the left brachiocephalic vein or at the junction with the SVC, with the tip abutting the right lateral wall of the SVC at a steep angle. Over time, a stiff catheter tip pressing against the wall can erode through it, causing a haemothorax, or a mediastinal haematoma or infusate collection. On the film, look for the last few centimetres of the line: they should turn downwards and run parallel to the SVC, not point across it.

5. Malpositions

Malposition	What you see on the frontal film
Into the ipsilateral internal jugular vein	A subclavian line or PICC turns upwards into the neck instead of down into the chest.
Into the contralateral brachiocephalic or subclavian vein	The line crosses the midline and continues out towards the opposite shoulder.
Azygos vein	The tip ends with a small medial or posterior curl around the level of the right main bronchus. On a lateral film it turns posteriorly at about T4.
Persistent left SVC	A left-sided line runs straight down along the left border of the mediastinum, lateral to the aortic knob, and does not cross to the right. This is a normal variant in about 0.3–0.5% of people; it usually drains to the coronary sinus. It needs recognition and senior advice, not removal by reflex.
Right ventricle	The tip projects well over the heart, beyond the expected right atrium, and may be associated with arrhythmia.
Small tributaries	Internal thoracic (mammary), pericardiophrenic or other small veins: the tip takes an unusual vertical or anterior course.
Coiled or kinked	A loop in the neck, axilla or brachiocephalic vein.

A lateral chest film, or comparison with any earlier film, can help when the course is uncertain. Many lines also have their position checked by ultrasound or ECG guidance at insertion; the film still checks for complications.

6. Suspected arterial placement

Inadvertent arterial cannulation (carotid or subclavian artery) is uncommon but dangerous. On the film, suspect it when the catheter:

• follows the line of the aortic arch or descends to the left of the spine, in the line of the descending aorta;
• runs more medially than an SVC line should, or crosses the midline at an unusual level.

Bedside clues include bright red, pulsatile backflow and an arterial waveform on transduction. This is an emergency, but the line should not be pulled out. Removing a large-bore catheter from an artery can cause major haemorrhage, stroke or a false aneurysm. The usual guidance is to leave it in place, stop infusions and get urgent senior and vascular or interventional radiology advice.

7. Complications to check

• Pneumothorax: most common after subclavian lines. On a supine film look for the deep sulcus sign. Check the apex on the side of the attempt, and remember a failed attempt on the other side too.
• Haemothorax: a new pleural opacity, which on a supine film may appear as a diffuse veil over one hemithorax. See pleural effusion.
• Mediastinal widening from haematoma or extravasated infusion. See mediastinum and hila.
• Retained guidewire: a thin, very dense wire extending beyond the catheter tip, sometimes into the heart or IVC. This is a recognised Never Event in England. Look for it on every post-insertion film.
• Catheter fracture or embolism: a break in the line, or a fragment in the heart or pulmonary arteries.
• Air embolism: rarely visible on a film; a clinical diagnosis.

8. PICCs and femoral lines

PICCs

• The target is the same as for a CVC: lower SVC or CAJ.
• Arm position moves the tip. Abduction and adduction of the arm, and elbow flexion, can move a PICC tip by a few centimetres. Note the arm position on the film when you can.
• Common malpositions are into the internal jugular vein, across to the contralateral side, or coiled in the axillary or subclavian vein.
• For neonatal and paediatric PICCs, targets differ. See the neonatal chest X-ray.

Femoral lines

A femoral CVC is seen on an abdominal film. Its tip should lie in the inferior vena cava, ideally above the confluence of the iliac veins, at roughly L4/L5 or higher. A tip to the left of the spine in line with the aorta should raise concern for arterial placement.

Red flags: act now

What to focus on, by role

Role	Priorities
Medical student	Trace the line from the insertion site to the tip, know the SVC/CAJ target and the carina landmark, and always look for a pneumothorax on the post-line film.
Nurse	Know that the line should not be used for central infusions until its position has been confirmed as local policy requires. Report chest pain, breathlessness, arrhythmia or swelling after insertion.
Junior doctor	Document the tip position against a landmark, the course, and the absence or presence of pneumothorax and guidewire. Know the arterial-placement rule: do not pull it out.
Radiographer	Include the neck, the insertion side and both apices; note the arm position on PICC films.
Advanced / FRCR	Persistent left SVC, azygos and small tributary malpositions, dialysis lines, and the evidence behind tip targets for different line types.

See also: pacemakers and cardiac devices, chest drain position and the glossary.

Practise on lines and tubes films →

References

1. Radiology Masterclass. Chest X-ray: central line anatomy. radiologymasterclass.co.uk
2. IVTEAM. Central venous access device tip position resources. ivteam.com
3. NHS England. Never Events list (retained foreign object post procedure). england.nhs.uk
4. Royal College of Radiologists. iRefer: making the best use of clinical radiology. irefer.org.uk

For education only. Not a substitute for a formal report, senior review or your local policy. Never use this page to make decisions about a real patient.