Mesenteric Ischemia and Small Bowel Obstruction
EM Clerkship
Zack Olson, MD ; Mike Estephan, MD ; Maddie Watts, MD
4.9 • 818 Ratings
🗓️ 23 June 2019
⏱️ 28 minutes
🧾️ Download transcript
Summary
Mesenteric Ischemia
* Celiac truck supplies blood to the stomach and duodenum* SMA supplies blood to the rest of the small bowel and proximal colon* IMA supplies blood to the distal colon and rectum
Arterial flow can be blocked because of emboli (atrial fibrillation)
Venous flow can be blocked because of thrombosis (hypercoagulable states)
Effective flow can be severely decreased in shock states (sepsis, hemorrhage)
History
* Atrial fibrillation* Pain with PO intake (intestinal angina)* SEVERE pain
Exam
The most classic finding is “Pain out of proportion to exam”
Testing
* Lactic acid reportedly 100% sensitive according to some texts* CT scan WITH contrast (or even better, a CTA) for additional confirmation if your pretest suspicion is high
Treatment
Analgesics and antibiotics. Surgery consult if intestines necrotic on imaging. Potentially vascular surgery consult as well if intestines salvageable.
Small Bowel Obstruction
* QUESTION: What is the most common cause of mechanical small bowel obstruction?* ANSWER: Adhesions
Not all small bowel obstructions are mechanical, don’t forget that ileus can cause a similar pattern as well (electrolyte abnormalities, recent surgery, opiates, multi-system trauma)
History
Severe crampy pain with vomiting, bloating, and decreased bowel movements/flatus. History of multiple abdominal surgeries (high risk for adhesions)
Exam
Abdominal distention and tenderness. If peritoneal signs develop, this is a very bad condition and patient may be developing ischemic/necrotic bowel.
Testing
* Most common test is CT scan with IV contrast* Abdominal x-ray sometimes gets ordered but has fallen out of favor for multiple reasons (decreased sensitivity, difficulty localizing obstruction, unable to rule out alternative diagnoses* Using oral contrast with the CT scan is also falling out of favor primarily due to the time constraints demanded of modern medicine.
Treatment
Fluids, Analgesics, Antiemetics +/- Antibiotics if ischemia is developing. Obtain a surgery consult.
* QUESTION: Should you order an NG tube? * ANSWER: NG tubes have been reported to be one of the most painful procedures one can endure. On the other hand, you can find online videos of people putting these in without any discomfort. It will end up being a risk/benefit discussion with your attending. The benefit is that decompressing the stomach will frequently improve the patient’s symptoms to a significant extent.
Additional Reading
* American College of Radiology mesenteric ischemia imaging (ACR)* American College of Radiology small bowel obstruction imaging (ACR)
Transcript
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| 0:00.0 | Hello, med students. My name is Zach Olson, and thank you for downloading this week's |
| 0:06.0 | episode of the EM Clerkship podcast. Our summer of abdominal angst continues this week. We've been |
| 0:15.0 | working through that core abdominal pain differential diagnosis. This is like the most important differential that you need |
| 0:22.9 | to know, and so we've really been taking our time with this. And so far, we've covered four |
| 0:27.8 | critical diagnoses, the quadrant-based diagnoses, basically, appendicitis, diverticulitis, |
| 0:36.2 | all of the bilirees stuff, and pancreatitis. |
| 0:41.2 | And so this week, we are moving on. |
| 0:43.4 | And we're moving on to our intra-abdominal bowel emergencies. |
| 0:48.9 | This is a core concept that you need to hang on to this week. |
| 0:52.3 | Not all abdominal pain is related to a specific |
| 0:55.6 | quadrant. And I know, I know, I know, you love quadrantness. Everyone always gets the appendicitis |
| 1:02.2 | and the diverticulitis and their differential for some reason. But it's time to step up your |
| 1:06.9 | differential game because average medical students, they think in quadrants, |
| 1:11.9 | but even if you were to exclude all of the non-GI abdominal causes of abdominal pain, |
| 1:19.3 | you still would have this large list of intra-abdominal causes of abdominal pain |
| 1:25.9 | that aren't related to a specific quadrant and |
| 1:28.6 | that you guys forget. So our next four diagnoses, we're going to go through these. I'm going to |
| 1:33.7 | call them the bowelase, bowel-related causes of abdominal pain. Hello, Dr. Olson. I have a 60-year-old male with a history of appendectomy, colisysystectomy, gunshot wound |
| 1:51.2 | to the abdomen, atrial fibrillation, and diabetes who presents with abdominal pain. |
| 1:58.9 | He describes it as a continuous, gradually worsening, generalized abdominal pain that has been |
| 2:07.5 | getting worse over the last 12 hours. |
| 2:10.6 | He has been having multiple episodes of vomiting, but no fevers, chills, diarrhea, or urinary |
... |
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