Pinch-off Syndrome

Pinch-off syndrome occurs when a subclavian central venous catheter gets compressed between the clavicle and the first rib. This can result in anything from transient obstruction of the catheter to complete transsection and embolization of the catheter.

The imaging appearance of subclavian central venous catheters can be graded from 0-3 based on the severity of the compression. A normal catheter that runs a smooth curved course in the region of the clavicle and first rib without luminal narrowing is considered grade 0. Grade 1 refers to an abrupt change in course of the catheter without luminal narrowing. This can be seen in up to 1/3 of asymptomatic control patients.

Grade 2 is considered when luminal narrowing is present. This has been referred to as the "pinch-off sign" on chest radiography: indentation of the catheter as it passes deep to the clavicle. This findings represents significant catheter compression and should raise concern for serious catheter complications.

Finally, complete catheter fracture is referred to as grade 3.

The radiograph on the left was obtained 6 months after port placement. The catheter was non-functional. The inset reveals a small indentation (black arrows) as the catheter passes between the clavicle and the first rib, consistent with the pinch-off sign. Contrast injection into the port 5 days later revealed fracture of the catheter at the site of the indentation, with extravasation of contrast at the fracture site (white arrows).

References

• Hinke DH, Zandt-Stastny DA, Goodman LR, Quebbeman EJ, Krzywda EA, Andris DA. Pinch-off syndrome: a complication of implantable subclavian venous access devices. Radiology. 1990 Nov;177(2):353-6.
• Yeung CW, Cheung WW, Leung AY, Kwong YL. Spontaneous central venous catheter fracture: relevance of the pinch-off sign. J Hosp Med. 2010 Apr;5(4):E33.