One of the ways that one can tell the difference between small intestines and large intestines on an
abdominal X-ray is its central location. Additionally, you’ll notice that there’s a lot of distended small
bowel in this abdominal X-ray. Frequently, we will also look for air fluid levels. Here’s cross-sectional
imaging. The arrow points to an area where we call the transition point. The transition point goes from
proximal dilated bowel to distal decompressed bowel. You can think of it as stepping on a garden hose
which obstructs the flow of water. Lactate, it’s important to get a lactate particularly in patients who have
suspicions of ischemic bowel. A lactate level that is elevated suggests the patient is undergoing
anaerobic metabolism. Anaerobic metabolism combined with peritoneal signs or with signs of ischemic
bowel is an absolute indication for an exploratory laparotomy. Remember that if this scenario
is presented to you. Just a brief reminder of the lactate, Cori cycle. End product of glycolysis during
anaerobic metabolism is lactate. Lactate in and of itself is not necessarily harmful. It’s but a mark of
anaerobic metabolism. Recall to the Cori cycle that the lactate can be circulated and used for gluconeogenesis.
However, persistence of lactate may indicate ischemic bowel. What if the lactate is elevated?
I’ll give you a moment to think about this. Sure, if the lactate is elevated, it suggests again
anaerobic metabolism. There’s not enough oxygen getting delivered to the small intestines or to any
organ system for that matter. This is a potential intestinal compromise which may necessitate
urgent surgery. Another question for you. What is the difference between a complete
and incomplete SBO or partial small bowel obstruction? I’ll give you a moment to think about this.
A complete bowel obstruction suggests the complete absence of flatus and bowel movement and
may more likely lead to ischemic bowel. The classic, classic description of a complete bowel obstruction
is either a bowel twisting on itself or that there are two points of obstruction both proximal and distally.
A special type is called a closed loop bowel obstruction where two points are obstructed.
This can be the terminal ileum and the ileocecal valve both serving as a point of obstruction.
The segment of intestines between the terminal ileum and the ileocecal valve can then be easily
compromised in terms of its blood supply. Here’s a garden hose illustration of a closed loop bowel
obstruction. You’ll notice from this image that the bowel has twisted on itself and you’ll notice
that proximally and distally, the intestines cannot move the effluent past this area of twisting.
What decision processes are involved in the management of small bowel obstructions? Here's my
schematic of how to manage small bowel obstructions. I like to think of small bowel obstructions
as complete or partial. The difference is how urgent the surgery is. With a complete obstruction,
there’s zero chance that that patient will resolve without surgery. Furthermore, without surgery,
the intestines may be compromised. Therefore, for complete bowel obstructions, surgery is
warranted mostly on an urgent or emergent base. The vast majority though of patients that
come in for small bowel obstructions are incomplete or partial in nature. In these patients,
we want to look at whether or not they have any signs of bowel ischemia or peritoneal signs.
Recall, anybody who had peritoneal signs, increased lactate, potentially leukocytosis may
need surgery. The vast majority of patients do not present with peritoneal signs and are
candidates for a trial of nonoperative management. That’s standard. You know, it used to be that we
would never let the sun set on a bowel obstruction. However, with cross-sectional imaging, modern
medicine, very few of our patients actually require surgery within 24 hours. Well, what is a trial of
nonoperative management? That’s a classic NG tube, NPO status, rehydration via an intravenous fluid.
Non-surgical management, we discussed already: NG tube, nothing by mouth status, ambulation.
It sounds so simple and the patients frequently ask me, “What can I do to make this bowel obstruction
go away?” I say, “Unfortunately, nothing. But continue to ambulate.” Ambulation is both
great for postoperative ileus which is not a mechanical obstruction as well as bowel obstructions.
As much as we can, minimize narcotic medications. Unfortunately, a small percentage of patients
will require surgery. Again, to remind you the indications for surgery: perforation,
signs of ischemia, worsening peritonitis, and frankly, failure of nonoperative management.
This picture that you’re seeing is an intraoperative finding of a segment. You clearly see
the difference between the purple bowel which is an ischemic segment versus the normal-appearing
bowel next to it. This ischemic segment needs to be resected. Whether or not a primary anastomosis
or reconnection of the small intestines is feasible depends on the patient’s clinical status as well as
the integrity of the intestines both proximal and distal to the segment of resection.
Very important clinical pearls to remember: Patients who have never had abdominal surgery are
unlikely to have adhesive disease. Therefore, those patients may need a lower threshold to go
to the operating room. What do I mean by that? For example, if you’ve never had abdominal surgery,
there’s no reason for you to have adhesive disease unless you have had subclinical diverticulitis. In these
patients then, all of a sudden, tumor or cancer is higher on the differential diagnosis list.
High-yield information for your examination: Incarcerated hernias particularly inguinal hernias
should be on your differential diagnosis for small bowel obstruction. Post-surgery adhesive disease is
one of the most common etiologies. Remember, not all of these patients require surgery.
Most will resolve with a trial of nonoperative management. So, don’t be in a hurry to rush the patient off
to the operating room when presented with this clinical scenario. Thank you very much for joining me
on this discussion of small bowel obstructions.