Diagnostic Testing
First topic of this post: a quick overview of some diagnostic methods used to diagnose GI problems! Let's see what our toolbox contains:
- Stool samples: These can help diagnose problems with nutritional balance. For example, you might encounter steatorrhoea, or excess fat in the stool.
- Breath testing: This might be able to help with diagnosing bacterial overgrowth.
- Barium meal/enema and radiology: These techniques can help with visualising the GI tract.
- Surgery: As well as fixing things, surgery can be used to look at the GI tract directly. Obviously, this is pretty invasive and done as little as possible.
- Endoscopy: This is basically a long tube with a little camera on the end. As well as being able to help you see stuff, endoscopes can also be used to perform biopsies. There is, however, a "dead zone" where the scope doesn't reach. For these areas, radiology or a pill camera (a little camera that you swallow like a pill) may need to be used.
- ERCP (endoscopic retrograde cholangiopancreatography): This is kinda like an endoscope, but it has a little catheter that can enter the bile duct via the Sphincter of Oddi and inject a dye, allowing the bile duct to be better visualised. This tool can also remove gallstones and/or the Sphincter of Oddi itself.
- Manometry: Pressure recordings. These can help diagnose problems with the oesophagus or with the ano-rectal area.
- 24hr pH monitoring: pH monitors can be used to detect the frequency and severity of acid reflux.
- "Quality of Life" questionnaires: May be used as a subjective measure of the severity of IBD (Inflammatory Bowel Disease).
Blood in the Stool
A quick note on blood in the stool: it's not necessarily cancer, though it might be :)
Fresh blood in the stool indicates that there is some problem in or around the anus. If the blood is black or "tarry," however, that's indicative of a problem in the upper GI tract (blood turns that colour after being digested). There is also "cryptic" blood, or blood that cannot be seen by the naked eye but can be found via the Hemoccult Test. This last type may be indicative of colorectal cancer.
Gastrointestinal Cancers
Most cancers of the GI tract originate from the epithelial layer. Some of these can bleed (haemorrhagic adenomas). Cancers can be removed by removing part of the intestines (they are a lot longer than they need to be, though obviously there are limits to this). Chemotherapy and radiation can also be used to prevent growth.
Haemorrhoids
Haemorrhoids are the most common cause of blood in the stool. Haemorrhoids are essentially just varicose veins (dilated veins) in and around the anus due to increased venous pressure. They can be internal or external. Haemorrhoids are quite common- around 50% of us will have them at age 50. They can cause inflammation, pain and bleeding, and if severe, can lead to constipation or diarrhoea. Haemorrhoids can be removed by "banding" (tying them off to restrict blood flow), cautery or surgery.
Diverticulosis and Diverticulitis
Diverticuli are small out-pocketings of the colonic wall. Like haemorrhoids, they are more common with age: around 50% of us will have some of these by age 60, and nearly all of us will have them by ages 70-80. These are usually not a problem, unless they become inflamed, in the case of diverticulitis. Diverticulitis can be painful, and in severe cases, can cause abscesses or even perforation.
Irritable Bowel Syndrome (IBS)
IBS is a condition in which there is pain, constipation and/or diarrhoea without an identifiable cause. It's possible that stress and other life events may play a role, as they may affect motility and perception of intestinal sensations. That's not to say that it's all in the patient's head, however- there are some objective changes that occur in some patients, such as hyperhaustrations (i.e. hyperconstricted muscle) in the colon.
Inflammatory Bowel Disease (IBD)
IBD is a chronic condition in which there is inflammation of the GI tract. The inflammation is not constant, however: it comes and goes, and flares are to be expected. Symptoms of IBD include pain, bloody stool, diarrhoea, fever, weight loss, malaise and so on. Unfortunately, IBD is incurable and the cause is not known. Sometimes, IBD can be difficult to diagnose in the first place as symptoms can be quite variable. Treatments are mainly symptomatic, ranging from things such as 5-ASA (an aspirin derivative), steroids and other immune suppressive agents, and anti-TNF (tumour necrosis factor) antibodies.
There are two main kinds of IBD: Crohn's Disease and Ulcerative Colitis.
Crohn's Disease
Crohn's Disease can occur anywhere in the GI tract, from the mouth to the anus, but is most commonly found in the ileum. It is transmural- that is, it affects the entire thickness of the gut wall. It often causes thickening of the bowel wall, as well as "skip lesions" (regions of inflammation that are not adjacent) and "cobblestoning" (normal mucosa surrounded by inflamed tissue). Severe inflammation can cause abscesses, adhesions, fistulae (inappropriate connections between adjacent structures- and by connections I don't just mean the two structures are stuck to each other, I mean fluids etc. can move between them as well), fibrosis, loss of compliance and so on.
Sometimes, surgical resection of a particularly inflamed part might be required, but this is no cure as inflammation can occur elsewhere. As noted above, you can't keep cutting out the intestines forever, or you'll eventually end up with "short gut syndrome" where absorption processes cease to be sufficient. For example, Crohn's Disease usually affects the ileum, but if too much ileum is removed, then very little B12 can be absorbed as the ileum is the only place where B12 is absorbed.
Ulcerative Colitis
Ulcerative colitis, unlike Crohn's Disease, can only occur in one part of the GI tract: the colon (hence "colitis"). It also tends to mainly affect the mucosa, forming mucosal ulcers. These cause the lovely symptoms of IBD such as pain, bleeding, weight loss etc. (see above). Ulcerative colitis can increase the risk of other lovely problems like cancer and toxic colon. Unlike Crohn's Disease, this one can be "cured" by removing the colon, but this is usually undesirable as such surgery has a massively negative impact on quality of life.
And now I guess you can say I'm flushed with success after finishing up on the GI tract! (Sorry, I just had to put in a bad toilet pun in there...)
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