Iatrogenic pneumothorax is a collapsed lung caused by a medical procedure. It happens when a needle, catheter, or other instrument accidentally allows air to leak into the space between the lung and the chest wall, causing the lung to partially or fully deflate. It’s one of the most common complications of certain chest and vascular procedures, and while the word “iatrogenic” (meaning “caused by medical treatment”) sounds alarming, most cases are manageable and resolve well.
How It Happens
Your lungs stay inflated because of a vacuum-like seal in the space between the lung surface and the inner chest wall. When a medical instrument punctures through that space, or when pressurized air forces its way through weakened lung tissue, air leaks in and breaks that seal. The affected lung loses its ability to expand fully, and the degree of collapse depends on how much air enters.
This differs from a spontaneous pneumothorax, which occurs on its own without any external cause, often in tall, thin young men or people with underlying lung disease. An iatrogenic pneumothorax is directly tied to a specific procedure, which means the timing is predictable and medical teams are usually already monitoring for it.
Which Procedures Cause It
The leading cause is transthoracic needle biopsy, where a needle is passed through the chest wall to sample a lung nodule or mass. A large meta-analysis covering over 23,000 cases found that pneumothorax occurred in about 25.9% of CT-guided lung biopsies, though only about 6.9% of those cases required a chest drain. Risk jumped considerably in certain situations: when the needle path crossed an air-filled blister in the lung (59.2% pneumothorax rate) or crossed a fissure between lung lobes (52.8%).
Central venous catheter insertion is the second most common cause. The subclavian vein, which runs just beneath the collarbone near the top of the lung, carries a pneumothorax risk of roughly 0.5% to 3.1%. Internal jugular lines carry a lower risk (under 0.2%), and femoral lines, placed in the groin, carry essentially zero risk since they’re nowhere near the lungs. Emergency situations, larger catheters, and multiple needle passes all increase the odds.
Other procedures linked to iatrogenic pneumothorax include:
- Thoracentesis (draining fluid from around the lung)
- Transbronchial biopsy (sampling lung tissue through a scope in the airway)
- Pleural biopsy (sampling the lining around the lung)
- Tracheostomy (creating a surgical airway in the neck)
- Mechanical ventilation (when pressurized air delivery damages fragile lung tissue)
- Nasogastric tube placement (rare, but reported)
Who Is at Higher Risk
Certain people are more vulnerable. Older age, a history of COPD or emphysema, and smoking all increase the likelihood that a procedure will cause a pneumothorax. Diseased lung tissue is more fragile and less able to seal small punctures on its own.
Technical factors matter too. During CT-guided lung biopsies, a longer needle path (over 4 centimeters), smaller target lesions, a greater number of punctures through the lung lining, and certain body positions during the procedure all raise the risk. Patients on mechanical ventilation face ongoing risk because each breath cycle delivers pressurized air that can rupture weakened areas of lung tissue.
Symptoms to Recognize
The hallmark symptoms are sudden shortness of breath and sharp chest pain on the affected side, typically appearing within minutes to hours after a procedure. You might also notice a feeling of tightness in the chest or a rapid heart rate. In small pneumothoraces, symptoms can be subtle or even absent, discovered only on follow-up imaging.
A large or rapidly expanding pneumothorax causes more dramatic symptoms: severe breathing difficulty, a drop in oxygen levels, and in extreme cases (tension pneumothorax), dangerously low blood pressure. This is a medical emergency, but it’s rare in controlled clinical settings where monitoring is already in place.
How It’s Detected
Chest X-ray has traditionally been the go-to imaging tool, but it misses a surprising number of cases. A meta-analysis comparing the two main detection methods found that chest X-ray has a sensitivity of only about 48%, meaning it catches fewer than half of all pneumothoraces. Bedside ultrasound performs significantly better, detecting about 79% of cases, with nearly identical specificity (both above 99%, meaning false alarms are extremely rare).
CT scans remain the gold standard and catch virtually all cases, including very small ones. Many hospitals now routinely perform imaging shortly after high-risk procedures. Pneumothoraces are classified by the gap between the lung surface and the chest wall on imaging: small (under 10 mm), medium (10 to 25 mm), and large (over 25 mm).
Treatment and Recovery
Treatment depends on the size of the pneumothorax and how you’re feeling. The 2023 British Thoracic Society guidelines emphasize a symptom-based approach. If the pneumothorax is small and you’re breathing comfortably, conservative management is typical: you’re monitored in the hospital, and the trapped air gradually reabsorbs on its own over days to weeks. Supplemental oxygen can speed this process.
If the pneumothorax is larger or causing significant breathing difficulty, the air needs to be removed. This is done either through simple aspiration (a needle and syringe to pull out the air) or by placing a small chest tube that continuously drains air until the lung re-expands. Most people with a chest tube have it removed within a few days once imaging confirms the lung has sealed and reinflated.
For patients on mechanical ventilation who develop a pneumothorax, a chest tube is almost always placed because positive pressure breathing will keep pushing air into the leak. Pregnant women with a small, asymptomatic pneumothorax can often be closely observed, with intervention reserved for cases where symptoms develop.
How Ultrasound Guidance Reduces Risk
One of the most effective prevention strategies is using real-time ultrasound during procedures. In a study of 445 thoracentesis procedures in cancer patients, ultrasound guidance dropped the pneumothorax rate from 8.89% to 0.97%. None of the ultrasound-guided cases required a chest tube afterward, compared to three cases in the non-guided group. Another study found that ultrasound-guided needle placement reduced the rate to 0% compared to roughly 29% without it.
For central venous catheter placement, ultrasound guidance has become standard practice at most hospitals, particularly for internal jugular lines, where it reduces the pneumothorax rate to under 0.1%. Choosing the insertion site also matters: femoral vein access eliminates pneumothorax risk entirely, and internal jugular access is safer than subclavian access when the anatomy allows it. These technique-level decisions are a major reason iatrogenic pneumothorax rates have declined over the past two decades.