SCP Foundation

to be kept on lockdown

This phrasing is a bit wonky. Maybe "Buildings containing SCP-XXXX are to be declared condemned and guarded by Foundation personnel." Although, I would replace "Foundation personnel" with a MTF of your choice, or otherwise specifying -what- personnel are guarding it.

for any additional anomalous activity

What anomalous activity? If you mean activity from SCP-XXXX, I would say "activity from SCP-XXXX" just to be clear.

All civilians considering entering SCP-XXXX are to be passively turned away.

Can the Foundation read minds, or did you mean something other than considering? "Attempting" or similar verb might be more appropriate.

portals

This is really my own aesthetic opinion, but I feel iffy about calling things portals flippantly in scips, because there's probably a less fantastical science-based word for them, but you do you.

as a SCP-XXXX-A surgeon

Another weird phrasing bit - maybe "as one claiming to be a surgeon"?

following this, they become a fresh instance of SCP-XXXX-A.

"Fresh" is not quite fitting for the tone, IMO.

Then, within the interior of the hospital,

"Then" feels like an out of place way to carry over the instructions. I would throw a semicolon in between the two and replace "then" with "following [thing], [stuff]"

most of the patient’s blood;

Musta missed this the last time, i would specify if it's only taking blood cells, or all blood and pumping plasma back in via tendrils, or whatever the mechanism is.

Procedures:

• "All civilians in the building with SCP-XXXX … amnestics" — I feel like it might need to be more obvious that this is what should happen when a building is found containing SCP-XXXX and civilians. I got confused here due to the phrasing earlier: "buildings containing." It implies these containment procedures are to be observed continuously for all buildings known to contain an instance. Changing it to "buildings found containing" might clear up the confusion substantially.
• "soundproofed wall", "noise-cancelling headphones" — Excellent use of containment procedures to establish early on that this is a sound-based SCP. Combined with the photo choice — which is very spooky, by the way — it really lets my imagination struggle to piece the two together and run wild with a vague sense of danger.
• "thorough inspection and sterilization" — Assuming, until clarified otherwise, that personnel entering SCP-XXXX for said inspection and sterilization must never break line of sight, as per next paragraph. Although this contradiction is easily resolved with this small leap of reasoning, making it clearer may be to your benefit.
• "Foundation agents within medical buildings" — Why would a Foundation agent be anywhere other than the Foundation? Don't get me wrong — there are plenty of good reasons. But picking one and running with it may be a good opportunity to expand the lore of this article.
• "break line of sight" — Bit cliche, but by no means a deal-breaker.
• "declared legally dead" — It's my impression that the Foundation is a government-independent, secret vigilante organization. Their main concern is what's safe. They likely have neither authority nor need to make legal declarations. I might suggest replacing this with orders to fabricate undercover testimonies of the affected civilian's death, or something like that.
• (The rest of the paragraph looks pretty good as far as I can tell.)
• (Last paragraph of containment procedures looks good too. Not sure if the first sentence is necessary, since seasoned Foundation agents would already know not to touch anomalous stuff unless necessary. But I do like the sound of it, from the perspective of continued establishment of a clinical tone, so maybe you could twist it a little into something more useful but still equally spoopy.)

Description:

• Has any research been conducted into why SCP-XXXX manifests? What a manifestation looks like is described quite effectively, but the circumstances surrounding it feel a bit lackluster.
• "a SCP-XXXX portal" — Pretty sure this should be "an SCP-XXXX portal." Also, might be better written as "a portal to SCP-XXXX" to avoid confusion around the use of a term which, while obvious in meaning, is technically undefined ("SCP-XXXX portal").
• "it is possible to access areas other than the original SCP-XXXX entrance via similar entrances" — I feel like the phrasing here could use some cleaning up. I have only the faintest sense of what this means.
• "Attempts to destroy the interior of SCP-XXXX" — This is okay, it serves the function of establishing SCP-XXXX is effectively indestructible, and it's not that immersion breaking — but I do find myself wondering why attempts were made to begin with. The Foundation's approach to anomalies is generally to contain immediately and destroy as a last resort, not the other way around.
• "will often use this knowledge to lure" — Love that word. Lure. Immediately establishing instances of SCP-XXXX-A are dangerous without having to specify how yet. Creates suspense quite well.
• Next paragraph looks good
• "drain" — Oh god. Instant revulsion. In a good way.
• "rusted" — Upping the creep factor here. Definite impression that something's wrong.
• "infrared scans" — Why? Would like to hear the story behind the initial impetus for conducting this kind of research.
• "tendrils" — ohhhh god
• "rapidly dissolve into a saline solution" — Super creepy and super friggin gross. But again, wondering about the impetus. Wasn't physical contact with SCP-XXXX-A forbidden except when absolutely necessary? Would like to hear about what happened.
• Last paragraph — Saw that one coming, still creeped and grossed me out. Wondering, though, why SCP-XXXX-A is proficient with all medical equipment if it never has to use them in the process of consuming its prey. Also wondering how the tendrils can discreetly drain blood and organs if they're invisible and incorporeal.