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The Cobweb Sign
Aladangady N, Roy R, and Costeloe KL. The Cobweb Sign: Percutaneous Silastic Long Line Tip Placement in Tributaries of Superficial Veins. J Perinatol (Oct 2005); 25: 671-673.
We report a method for preventing misplacement of percutaneous silastic catheters in superficial vein tributary or venous plexus. Catheters inserted less than the length calculated by surface anatomy measurement due to resistance were studied in three patients. Contrast X-rays (Omnipaque, Nycomed Imaging AS, Oslo, Norway) of the catheters was performed to confirm the catheter tip placement position. On initial assessment, the catheter tip placement was thought to be satisfactory and infusion of TPN commenced. Following signs of extravasation, re-examination of the contrast X-rays demonstrated that multiple thin rays of omnipaque could be traced in different directions like a cobweb.
In the third infant, we recognised the "cobweb" sign and prospectively withdrew the catheter tip 2 cm. Repeat contrast X-ray confirmed that the catheter tip was in a major superficial vein, infusion continued without further complication. We conclude that when the "cobweb" sign is noticed then the catheter should be removed or withdrawn 2 to 3 cm and repeat contrast X-ray performed.
Comments. When
placing PICC lines in neonates, it is important to be aware of the potential
for catheter tip misplacement in tributaries of superficial veins. This type
of misplacement should be suspected clinically whenever resistance is met
during advancement of the catheter, or if the catheter cannot be fully
advanced the measured distance into the central circulation. The “cobweb
sign” confirming this misplacement is only seen if contrast xrays are done. I
prefer to remove and replace these catheters, if possible. ABK.
UserName: betremieux
Institution: RENNES Teaching Hospital france
telephone: +33 2 99 28 43 12
email:
pierre.betremieux@chu-rennes.fr
Date: 11 Oct 2005
Time: 02:52:36
Another valuable test for the right position of the PICC silastic line tip is
that you can aspirate blood easily. If not the line tip is very likely
misplaced. I have not found any right positioned tip if blood aspiration was
impossible. If you have problems with resistance at a lenght below the measured
and you cannot aspirate blood I would not replace the line but draw it back a
few centimeters an then reposition the arm (e.g. elevation) and the head (e.g.
turn the to the other side) of the baby, then very often it is possible to
position the line tip correctly.
UserName: Thomas Strahleck
Institution: Olgahospital Stuttgart
telephone: +49 711 992 2656
email: strahleck@z.zgs.de
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