Treatment infrastructure
The port: what it is and why it was replaced
Miriam has had a port-a-cath since 2024: a small reservoir under the skin that gives direct access to a large vein, so her arm doesn’t need a new needle every time. The first one stopped giving blood back, and in October 2026 it was replaced.
When and why it was made
Used in September 2026 to check on three CT scans whether the catheter had moved; the October replacement report gives as its reason that it was too short.
What a port-a-cath is
It’s a small chamber implanted under the skin of the chest, joined to a thin catheter that runs to a large vein near the heart. A special needle goes in through a membrane, and the membrane seals again when the needle comes out. Nothing sticks out of the body. Miriam has one because the veins in her arms are hard to get a needle into.
The first one: a titanium PowerPort
It was built to take injection under pressure, like the contrast for a CT scan, which goes in very fast. Not every port can. It was triangular, with small bumps you could feel, so whoever accessed it knew what type it was and where the membrane was. The new one’s catheter is the same gauge as the old one; the model isn’t on record.
What went wrong and what was done
Medication went in, but blood wouldn’t come out, not even after a drug to dissolve clots. That’s called a withdrawal occlusion. In October 2026 it was taken out and a new one was put in the same place, under the skin. An X-ray check confirmed its position and that it was working when they finished.
The radiology report of the replacement gives as its reason «PAC acortado a tronco innominado» (in Spanish in the report): a short catheter that ended at the level of the innominate (brachiocephalic) vein.
Archive
The previous catheter, measured on three CT scans
When a port stops giving blood back, the first suspect is a catheter that has shifted. Before assuming that, the first one’s path was rebuilt on three CT scans taken months apart. The tip lands in the same spot all three times: it didn’t shift between those dates, within the measurement margin. That only says it stayed put; it doesn’t say whether that spot was the best one, and the 3D can’t answer that. This model shows the previous port; the new one hasn’t been reconstructed yet.
A decision-support tool
Not a diagnosis or medical advice.
The model comes from her own CT scans. The port and the tip are measured directly on the slice; the stretch between them is the most likely route, interpolated.
Catheter length, port→tip, across the three dates: 150.8 mm · 152.2 mm · 151.7 mm (± 5 mm per measurement; ± 10 mm on the difference between dates). Within that margin, it is the same measurement all three times.
RECIST does not apply here, since it measures lesions and this is a catheter. The reconstruction is semi-automatic and radiology has not validated it.
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