I mean anyone can just wait for the CT scan, but can we do better?
This week’s Med Student Case is brought to us by Mignon Rademan.
The patient is an ~70 y.o. woman presenting with abdominal pain for 2 days. It was initially intermittent but now is becoming more steady in the peri-umbilical area. There’s been no diarrhea though some nausea and vomiting at times. She actually hasn’t had a bowel movement while the pain has been present, though it’s not unusual for her to go 2 days without a bowel movement either. She’s had less appetite. There have been no urinary or gynecologic symptoms
So, elderly abdominal pain. Actually one of many ER docs’ favorite complaints since there’s a reasonable chance we’re going to find an answer. There’s more danger here though because of that increased chance of an answer being present. And since many of those possibilities involve surgeons we need to think at least partially like a surgeon since there’s a good chance you’re going to be talking to one. Along those lines, there’s a couple things you must know. First, are they on anti-coagulants. Second, have they had abdominal surgeries before. The surgeon will want to know what they’re getting into; it’s a lot harder to do just about any operation if the belly is already encased with scar tissue gluing all the organs together.
Looking into that past surgical history, it turns out she’s had an appy, a total hysterectomay, as well as a colon cancer resection.
Well. I’d say bowel obstruction just shot up the differential. Gotta know that surgical history.
On physical exam she’s mildly tachycardic. The abdomen is mildly distended without peritoneal signs. She has some tenderness throughout however, most prominent in the peri-umbilical region. There are ventral and umbilical hernias present. The ventral one is easily reducible.
The approach to working up bowel obstructions is going to vary by provider (and what surgeon you’re going to be working with). The easiest thing is to order fluid resuscitation (remember these patients can sequester a lot of fluid in the dilated bowel) and a contrast protocol CT and just back-burner them for the next 2 hours. Is that the best way though? An abdominal series (AAS) is a lot quicker than a CT, and if there’s sufficient gas in the bowels the AAS will prove there’s at least a partial SBO. But even quicker than that is a bedside ultrasound. If you took it into the room with you, you may get your answer right now (remember if there’s a ton of air in the bowels then it’s going to be a lot harder to get good views).
Here’s what the ultrasound shows, first looking at the bowel somewhat obliquely
The blue maker measures the diameter over 3cm in cross-section, certainly dilated. Do you see how irregular the lumen is? The swelling is making the plicae visible so that it looks like the alternating black and white keys of a piano (the red and green arrows).
Now imagine we rotate the probe so that we’re getting the bowel in cross-section:
You can see how thickened the bowel wall is.
Another sign of bowel obstruction is the so-called Washing Machine sign. If you look at a segment of bowel longitudinally, you should normally get a sense of the lumen’s contents going in one direction from the action of peristalsis. If there’s a downstream obstruction then the contents may be churning back and forth or round and round as if you’re looking at your laundry.
What’s the next step? If not for the umbilical hernia we couldn’t reduce, there are some surgeons you could call right now. Let them know the patient has at least a partial obstruction on ultrasound, a non-peritoneal abdominal exam, a normal WBC and lactate, and ask for the patient to be admitted for serial exams. Given the hernia that wasn’t able to be reduced though, after a conversation this patient did go to CT.
After placement of an NG tube and the CT ultimately the patient went to the OR for repair of the umbilical hernia. Consistent with the normal lactate and WBC count there was no bowel ischemia.
Take-homes from this case? The biggest is to remember that ultrasound can be diagnostic at times of bowel obstruction and may help guide the patient’s management much quicker than other imaging studies. There are two other general points of management of bowel obstructions. First, use the NG tube. Patients hate them, and we’ve gotten a lot less aggressive with NG tubes in GI bleed, but they are still very useful in bowel obstructions. The other is to remember to adequately fluid resuscitate the patient. A person normally secretes about 6 liters of fluid through the small bowel each day to aid in moving food contents through. If that fluid can’t get to the colon to be re-absorbed the patient is going to dehydrate quickly!