Conditions of the Bowels Covered on the Physician Assistant Exam
A lot of pathology and Physician Assistant Exam questions concern the small and large intestines. Here you see conditions such as irritable bowel syndrome (IBS), ischemic bowel, inflammatory bowel disease (IBD), celiac disease, and diverticulitis.
Irritable bowel syndrome (IBS)
Irritable bowel syndrome (IBS) is a diagnosis of exclusion after other conditions have been ruled out. It’s a clinical diagnosis — you can’t diagnose this condition with endoscopy and biopsy or barium swallow as you can with many other GI conditions, because the findings are often normal. Common symptoms include constipation, diarrhea, or a combination of both.
A stereotypical candidate for IBS is someone under a great deal of stress who has problems with either diarrhea or constipation during the day.
In a typical PANCE question, you get hints such as “it has been going on for a while,” “both endoscopy and colonoscopy are negative,” “and stool studies, including those for ova and parasites, are negative.” A very common syndrome associated with IBS is fibromyalgia syndrome.
The treatment for IBS includes recognizing the triggers, including food, physical stressors, and psychological stressors. Many of the anticholinergic medications, such as dicyclomine (Bentyl), have been tried in treating IBS.
Ischemic bowel, also known as ischemic colitis, commonly occurs in older individuals. Risk factors and medical conditions associated with ischemic bowel include atherosclerosis of the intestinal vessels, atrial fibrillation or the presence of a left ventricular mural thrombus, and a hypercoagulable state. Low blood pressure can precipitate mesenteric ischemia due to hypoperfusion of these vessels.
Here are key points about ischemic bowel:
The classic presentation is pain out of proportion to clinical findings. The person (usually with one of the preceding risk factors) can have diffuse midepigastric pain but also have a benign physical examination.
The pain worsens after eating a meal. Blood flow to the mesenteric area increases after a meal to aid with digestion, and the timing of the abdominal discomfort in relation to eating can point to ischemic bowel.
A person can have mesenteric angina or mesenteric ischemia, which is an acute problem. If a large amount of the bowel is affected, expect to see a lactic acidosis and an anion gap on the CHEM-7. If the affected person’s abdominal pain is just an episode of angina, you may not see a lactic acidosis.
If findings suggest an acute mesenteric event, the best way to look at the intestine is an exploratory laparotomy. A CT scan of the abdomen and pelvis with oral contrast may suggest bowel wall thickening, but this is a nonspecific pattern that you also see with other types of colitis. That being said, the CT scan is the best test for looking at the integrity of the bowel wall.
Inflammatory bowel disease (IBD)
Inflammatory bowel disease (IBD) is a comprehensive term covering two different but overlapping conditions: Crohn’s disease and ulcerative colitis. Both of these conditions confer an increased risk of colon cancer.
Crohn’s disease is an inflammatory condition that can involve any area of the GI tract from the mouth to the anus, although it’s usually predominant in the ileum and ileocecal region of the small intestine. When confined to this area, it’s called regional enteritis.
Histologically, Crohn’s disease is characterized by noncaseating granulomas on tissue biopsy. The etiology behind the inflammation is unknown. Note that this condition affects all layers of the intestine. When it affects the small intestine, especially the ileum, Crohn’s can cause malabsorption of key nutrients, especially the fat-soluble vitamins A, D, E and K.
Here are the key points about Crohn’s disease:
It usually occurs in younger people, with an initial onset in the teenage years up to the mid-30s.
It’s characterized by the presence of skip lesions as well as what looks like a cobblestoning mucosa on colonoscopy.
Crohn’s can affect the anus. If on you’re asked about the presence of anal fissures on the PANCE, think Crohn’s disease.
Treatment can involve steroids and salicylate derivatives such as mesalamine. Antibiotics such as metronidazole can be used. In advanced cases that have been refractory to treatment, you can use intravenous infliximab.
Surgery is not curative in Crohn’s diseas.
Ulcerative colitis (UC) overlaps with Crohn’s disease to some extent, but here are some key differences:
Unlike Crohn’s, ulcerative colitis involves only the superficial mucosa, not all layers of the intestine.
Ulcerative colitis doesn’t have these skip lesions; the area of inflammation is continuous.
Ulcerative colitis is predominantly in the sigmoid-rectal region. In fact, a common presenting symptom of ulcerative colitis is hematochezia and a colonoscopy that demonstrates ulcerative proctitis. Crohn’s, on the other hand, is predominantly in the small intestine, is sometimes in the large intestine, and can affect the anus.
Crohn’s disease has a higher rate of strictures than ulcerative colitis. Both are associated with the possible development of obstruction, abscess formation, perforation, and fistula formation.
Ulcerative colitis increases the risk of developing sclerosing cholangitis. Remember Charcot’s triad of right upper-quadrant pain, fevers, and jaundice for the diagnosis of cholangitis.
Ulcerative colitis treatment can consist of steroids, although it primarily consists of 5-ASA derivatives. They can be given either orally or rectally.
Both ulcerative colitis and Crohn’s disease can be associated with extraintestinal manifestations, which makes sense because both conditions are inflammatory. They can be associated with eye disease and certain skin lesions, including pyoderma gangrenosum and erythema nodosum.
IBD is also associated with inflammatory arthritis. IBD, psoriatic arthritis, ankylosing spondylitis, and reactive arthritis are examples of the seronegative spondyloarthropathies. All are associated with HLA-B27 expression. The arthritis associated with IBD is thought to affect more of the peripheral joints, especially during an active flare of IBD.
Which of the following conditions can be associated with caseating granulomas?
(A) Crohn’s disease
(C) Ulcerative colitis
The correct answer is Choice (D). Tuberculosis is associated with caseating granulomas.