It's what's inside that counts #1 - an idiot's guide to the spleen

'He who smelt it...would forever be the one who DEALT IT!'

It occurs to me that, as I am the author of this post, the title implies that I am, in fact, an idiot. I'll leave you to make your own minds up about that one. Anyway, I've been meaning to do a short series on internal organs for a while - don't ask me why, you may as well question why I write this blog at all - and that is dangerous territory, my friend.

All right, if you insist - I write the blog to vent my spleen about the inanities, injustices and insanities of veterinary life (as well as to plug my books, but I try and keep that to a minimum. BUY MY BOOKS! Ahem) and after several years of venting, I think it's about time I gave something back to the best-named organ in the body.

(It's not the best named part of an organ, however. There are many contenders for that crown. If I ever write another fantasy novel, I'm going to the best internal bits for it. Imagine a party of adventurers trekking through the Crypts of Lieberkuhn and over the dread Islets of Langerhans in search of the fabled Rosette of Furstenburg (it's a part of a cow. If you want to know more, feel free to google it, but it might put you off your tea))

So, lets talk about the spleen (not, incidentally, the intestinally-overactive superhero of the same name from Mystery Men, as shown above. I just couldn't resist reminding you all what a great film it is. And if it doesn't remind you because you haven't seen it, the go and watch it. Now! Really, it's far more entertaining than this blog). The spleen has an air of mystery surrounding over and above other internal bits and pieces, largely because you're quite likely to only have a very vague idea of what it actually does.Something to do with blood, maybe?

Well, don't feel bad. I know what it does, and it still feels vague to me too. This is because the spleen doesn't have any primary functions at all. It's a secondary organ. A middle man. The spleen is the body's equivalent of an estate agent, or a insurance broker, only far less likely to rip you off (though slightly more likely to kill you, so, y'know, swings and roundabouts).

Where is it?

The spleen is shaped something like a knobbly comma, and it sits (or lies, or does whatever it does when a spleen is relaxing) in your abdomen, on the left side, following the curvature of your stomach. The base (the tip of the tail of the comma) is held relatively tightly to the stomach, but the rest is more or less free to wobble around the abdomen as it sees fit. Sometimes, it sees fit to do this rather more than is good for it, but we'll come on to that.




What does it do?


Ah, the most commonly asked question about the spleen. The short answer is - nothing that the rest of the body can't do, but it helps. It serves a number of functions.

1. The spleen is a haemopoietic organ


(and not, sadly, as I commonly misspell it, a haemopoetic organ, which brings to mind images of it moping around in seedy bars, scribbling sad missives about blood into a tattered notebook)

Haemopoiesis is the production and maturation of blood cells, and although the spleen does a great deal of this whilst we are developing in utero, it sort of gives up about halfway through gestation and thereafter leads most of the hard work to the bone marrow.

2. It mops up old red blood cells


For the SF fans amongst you, imagine red blood cells are living in their own version of Logan's Run, only instead of 30 years, the allotted lifespan is about 120 days, and instead of a Sleepshop you're sent to on your Lastday, it's the spleen.

For everyone else...well, you probably get the idea from the bit in italics.

3. It is part of the immune system


Blood flow through the spleen is really rather complicated, but for brevity imagine that the spleen is like an airport security desk through which all the red blood cells, white blood cells, viruses, bacteria, parasites and other assorted bits and pieces are passed. If the spleen is doing it's job, then the foreign material is quickly grabbed by macrophages (my favourite white blood cell. How can you not like something whose name means 'Big Eater'? A bit like The Blob, only smaller and friendlier) and other white cells, and summarily executed. Okay, perhaps it's not that much like an airport security desk. Maybe it's easier to think of it like a giant lymph node? (I told you I was vague)

4. Blood Storage

The spleen is a reservoir for blood, as any surgeon who has ever accidentally nicked one with a scalpel can readily attest to (er...I imagine. It's never happened to me, naturally). Depending on you species, up to 30% of your red blood cells and a fair proportion (me, vague? Never!) of your white blood cells are waiting in there, ready to pounce. If there is a sudden need for red blood cells or oxygen, the spleen contracts and releases it's payload into the bloodstream. I was taught that contraction of the spleen is what causes the 'stitch' pain in you're abdomen when you're running, but I must admit I remain unconvinced - I'm pretty sure I've had a stitch on the right side of my abdomen, but maybe I'm just wired up wrong.

What can go wrong with it?


Well, here I'm going to talk from a more veterinary perspective. Because I'm a vet. You want to know about humans, go and ask Doctor Mark Porter. I'm going to tell you about the most common problems that I see in practice with the spleen.

The first thing to say is that, as a small animal vet, the majority of spleen pathology I see is in dogs. Possibly because they're smaller, or have less blood flow, or are simply luckier than dogs, cats are rather under-represented in the spleen-gone-wrong stakes. As far as other species - I don't think I've ever seen a spleen problem in a rabbit, and very rarely in small rodents, although ferrets seem to have their fair share of issues with the enigmatic organ.

The second, slightly more depressing thing to say, is that the most common spleen problem I see by far is the big C - splenic cancer. Because of it's functions - all blood-related - when cells go wrong in the spleen, they tend to be blood cells. Or, rather more commonly, blood vessels.

It can be a bit of a challenging diagnosis, because the symptoms of splenic haemgiomas (benign blood vessel tumours, good news) and splenic haemangiosarcomas (malignant blood vessel tumours, very much not good news) can be, like the spleen itself, rather vague and mysterious. The most common presentation would be a middle-aged to elderly dog (often labradors) who just 'aren't right' - quite tired, not exercising well, with not a great deal to see on clinical exam and very little exciting on a standard blood screen. You may be able to feel something in the abdomen, but these are big dogs, sometimes with small tumours, and the spleen is good at moving around, so quite often you won't feel a thing. If you're lucky, or skilled, an x-ray or ultrasound scan will reveal the presence of something that shouldn't be there, but not every time.

Because of this, the case can often grumble on for a little while, sometimes getting a little better on the medicines you prescribe, sometimes not, until it eventually presents collapsed, because that lump on the spleen has finally burst. It's pretty rare to a dog to bleed to death from a splenic tumour - it's bleeding into a closed space, after all, and there's only so much space it can fill up - but it's not going to feel well.

The spleen is also a pretty common site for secondary tumours - with so much blood passing through it, it's a fairly easy organ for cancer to take root. The course of these diseases will depend largely on where the tumour started and what it's doing there.

Because all of these tumours can grumble on for a long time without causing many symptoms at all, they have been responsible for the biggest and most impressive lumps I have ever seen in my career - the largest of which was a seven kilogram tumour removed from the abdomen of a thirty kilogram dog (I do have a piccie of this one, but it is rather bloody, so I'll leave it off the blog in the interests of taste).

A ruptured spleen can occasionally occur after a road traffic incident (I believe I'm not allowed to call them accidents any more, because there's always someone to blame. And where there's blame, there's a solicitor hoping to make money from it), with similar effect to the ruptured tumour above, though often with the added complication of other injuries.

I've already touched upon the third problem. As I said, the spleen is rather mobile, and likes undulating up and down the abdomen like a lumpy Mexican wave. On rare occasions, the spleen can actually spin itself right around, tying it's own blood vessels into a knot and causing the spleen to swell up like a bloody painful ballooon. It's very painful, and often occurs in conjunction with the stomach doing a similar head over heels - the incredibly dangerous and dreaded veterinary emergency GDV (gastric dilatation/volvulus) which we'll have a cheerful chat about when I get around to writing about the stomach.

What on Earth can you do about that lot?


Fortunately, you don't have to be a brain surgeon to sort this lot out, usually. Just an abdominal one. The benefit of the spleen having no primary fuctions is that, whilst it isn't exactly surplus to requirements, you can certainly cope pretty happily without one. Olympic athletes might miss the splenic contraction, and you might be prone to a few more infections (though this does seem to be more of a problem for humans than animal. The same is true of the Olympic thing, now I stop to think about it) but most of the time you can cope without your knobbly comma fine.

The procedure of choice for all the above conditions is a splenectomy - chop the spleen out. (...ectomy, in medical language, means 'to remove', whereas ...otomy means 'to cut a hole into'. ...infamy means something completely different.) Fortunately, the procedure is reasonably straightforward. It's really a matter of tying of blood vessels. And then tying off some more. And sore more. It's very good practice for ligatures, though for big spleens you may need a spare pair of hands and/or a lot of clamps. It can be pretty messy, especially if the damn thing has already burst before you got in there, and you will almost certainly need to give your patient a lot of fluids, or even a blood transfusion, as one way or another a lot of blood is coming out with it.

How successful the splenectomy is depends on the cause of the problem. If you're dealing with a tumour, and it's benign, then there's a fair chance that you've sorted the problem out. If you've got a haemangiosarcoma, then sadly the thing is pretty likely to have spread before you got in there - haemagiosarcomas are really, really good at metastasizing (spreading), especially to the liver, and to the heart. In fact, in a lot of cases the tumour you're removing with the spleen already came from one of those places. It's still a procedure worth doing, because your patient will probably be back to normal within a few days, bright and happy. But one day soon, and often within a couple of months, they'll be back in your consult room again, collapsed as before - for this reason, it's generally a good idea to send your removed spleen off to a pathologist so they can tell you exactly what was wrong with it.

The prognosis for the ruptured spleen and the splenic torsion is generally much happier, so long as you get to them in time. The dreaded GDV (I feel I should write it in capitals to simulate the awe and terror that those three letters can inspire in a new veterinary graduate) is somewhat harder to deal with, but you'll often do a splenectomy at the same time.

Summary


So, what have we learned? Amusing in name, confusing in function, slightly challenging to diagnose and relatively easy to treat. If by treat, you mean 'remove entirely' (much in the same way our current Government would like to treat the NHS).

The spleen, ladies and gentlemen. Gratuitous bloody surgical image below Look away now if you're feeling squeamish. (This one's from human medicine)