Un-Stick from the Point
Life was always a matter of waiting for the right moment to act.Paulo Coelho
You are on-call on a sunny Sunday. It’s 9 am and colleagues tell you that you should operate on the lady with adhesive small bowel obstruction (ASBO) who has been on non-operative management (NOM) for 48 h. You have already two emergency laparoscopic cholecystectomies waiting for you, and your feeling is… are you sure we must operate on her TODAY?? Let’s check the patient…
A 79-year-old lady with a history of arterial hypertension and previous colon neoplasm that was treated fifteen years ago with an open left sigmoidectomy. In the postoperative period, she had a suture leak requiring a colostomy, which was closed two years later. In the last 5 years, she has had two episodes of small bowel obstruction due to adhesions, successfully treated with NOM.
She showed up in the emergency department two days ago complaining of abdominal distension, vomiting, and constipation for one day. Initial abdominal x-ray showed distention of small bowel loops and no gas in the colon. Diagnosis of ASBO was made.
A nasogastric tube was inserted and after 4 h of suction, water-soluble contrast was administered through it. Follow-up x-ray at 24 h did not show contrast in the colon, neither did today’s x-ray. The abdomen is not tender and the patient says abdominal distension is getting better but the nasogastric tube drained 900 ml in the last 24 h.
Labs: WCC 13’000/mm3, CRP 20 mg/L, Creatinine 1.5 mg/dL, K+ 3.1 mEq/L.
What are you going to do?
Adhesions are the single most common cause of small bowel obstruction. Non-adhesive etiologies of bowel obstruction include incarcerated hernias, obstructive lesions (malignant or benign), bezoars, inflammatory bowel disease, and volvulus.
Adhesive small bowel obstruction is a common surgical emergency, counting for about 4% of emergency department admissions. Moreover, it is one of the leading surgical emergencies that require an emergent operation (20% of emergency surgical procedures). ASBO causes an in-hospital mortality rate of 3% per episode.
Between 20 and 30% of patients with adhesive small bowel obstruction require operative treatment. Average hospitalization after surgical treatment of ASBO is 16 days, compared to 5 days following NOM.
But who would require operative treatment and when?
Diagnosis of ASBO is quite straightforward. However, you should remember that diagnosis is usually made using indirect signs; in fact, it is extremely rare to identify the band causing the obstruction.
- Previous medical history: past abdominopelvic operations, neoplasms, radiotherapy (remember that ASBO may develop even without previous abdominal surgery).
- Symptoms: intermittent colicky abdominal pain, nausea and vomiting, abdominal distention, and constipation. Beware that watery diarrhea may be present in incomplete obstruction.
- Physical examination: signs of peritonitis, abdominal wall, or groin hernias. Assess dehydration and nutritional status.
- Laboratory tests: complete blood count, lactates, electrolytes (beware of low values of potassium), CRP, BUN/creatinine, and blood gas.
- Plain x-rays (with decreasing usefulness over the years): the old pathognomonic triad was composed of multiple air-fluid levels, distention of small bowel loops, and no gas in the colon. Overall sensitivity is 70%, and it gives no information about the site of obstruction, the cause, and/or the bowel status. It is not recommended anymore.
- Contrast-enhanced abdominal computed tomography (CT) scan: can differentiate accurately between different causes of bowel obstruction. It has 90% accuracy in predicting strangulation and the need for surgery. The radiological diagnosis of ASBO can be made when a transition point is identified with proximal bowel loops of >25 mm and collapsed distal bowel segments, associated with air-fluid levels. Obviously, the CT scan must have excluded other causes of bowel obstruction.
- Ultrasound (increasing usage thanks to point-of-care ultrasound (POCUS)): distension of bowel loops >25 mm, free fluid, altered bowel movements (i.e. “to-and-fro” and/or “washing machine” signs), and degree of shock in dehydrated patients. Better as the first-line imaging method compared to an abdominal x-ray; anyhow, it does not substitute the CT scan.
The suspicion of ASBO can be posed in patients with a history of previous abdominal surgery together with at least two of the following clinical signs/symptoms:
- Abdominal pain;
- Nausea and/or vomiting;
- No passage of gas and stool.
So then… We have a suspicion of ASBO… Maybe we have performed a POCUS that confirmed our suspicion… What now?
First, we must ask for a contrast-enhanced abdominal CT scan. This imaging exam allows us to determine:
- The cause of the bowel obstruction (ASBO? Cancer? Others?)
- The abdominal and bowel status (Perforation? Bowel ischemia?)
- If ASBO is the cause, the type of adhesions (Single band? Matted adhesions?)
|Matted Adhesions vs. Single Band|
Adhesive small bowel obstruction may be caused by either a single adhesive band or matted adhesions. To distinguish between them is crucial to define the best management (i.e. conservative vs. operative). In fact, ASBO complications (e.g. bowel ischemia) and NOM failure are most often related to single bands compared to matted adhesions.
These two entities are very different:
– Single band: a fibrotic band closes acutely a bowel segment or a bowel loop (i.e. closed loop), causing a complete obstruction. This condition appears not to be reversible by NOM and patients would usually benefit from surgery.
– Matted adhesions: multiple bowel loops are attached together by diffuse fibrosis. This condition is usually chronic and the following bowel obstruction is the result of a variation in bowel content and/or peristalsis. These changes create a sort of “plug” that prevents the regular passage of the enteric material through the packed bowel loops. Matted adhesions are usually manageable conservatively; they carry a higher risk for recurrent episodes of ASBO, though.
Different scores exist based on CT scan findings that may help in determining the underlying mechanism of bowel obstruction and supporting the choice of proceeding with either NOM (if matted adhesions) or surgery (if single band).
Initial management of patients with ASBO includes nasogastric tube (NGT) positioning, crystalloid infusion, and urinary catheter. To be honest, all these procedures should be started before the CT scan…
The second most important thing is to exclude peritonitis, strangulation, and/or bowel ischemia, conditions that preclude non-operative management (NOM) and warrant an operative approach.
Once we have assured that the patient is stable and the bowel is viable, NOM should be planned. In fact, most of the ASBOs resolve with NOM alone.
Figure 1 shows a possible flow chart for patients admitted for ASBO.
The NOM consists at first of suctioning the gastric and bowel content via NGT to empty the hollow viscus as much as possible. In the past, this was the conservative treatment for these patients. The problem with it is that there are no guidelines regarding the duration of the treatment… In other words: how long may I continue the conservative treatment before deciding to operate on the patient?…
To standardize the NOM and to reduce the onset of bowel ischemia, the use of water-soluble contrast (i.e. Gastrografin) was introduced. Gastrografin should be administered in the dosage of 50-150 mL, either orally or via NGT, once the stomach is emptied, to avoid vomiting and ease its action. If given via NGT, it must be closed thereafter to allow Gastrografin to work.
This method, compared to suction alone, has two advantages:
- It promotes intestinal peristalsis, helping the bowel content to overstep the obstruction (it works as an osmotic laxative);
- It allows the prediction of ASBO resolution.
Multiple studies have shown that contrast use accurately predicts the need for surgery and reduces hospital stays. Two meta-analyses have shown that water-soluble contrast reduces the need for surgery as well.
Predicting NOM’s success is maybe the most important point of the whole management of ASBO. The two questions that need to be answered here are: How to predict the success of NOM? How long should I wait to determine it?
The answer to the first question is quite simple: if the obstruction involves the small bowel, we have to assess that the contrast medium reaches the colon (contrast in the cecum is enough to predict resolution). To confirm if the contrast medium has reached the colon, a simple abdominal x-ray may be taken.
To answer the second question, many studies have been made to decide which is the best time frame to wait before performing the abdominal x-ray. Branco et al. reported that no differences were seen in terms of sensitivity, specificity, positive predictive value, and negative predictive value where the timing of radiography was 4-8 h or 24 h. The authors concluded that if contrast reaches the colon within 4-24 h after administration, the obstruction will resolve conservatively in 99% of cases. On the other hand, if it does not reach the colon, there is a 90% chance of needing surgery. In fact, it has been demonstrated that if patients who failed NOM underwent surgery within 24 h, 12% needed bowel resection, compared to 29% of those who were brought to the OR more than 24 h later. Considering each hospital protocol the NOM treatment may be prolonged >24h if the patient’s conditions are fine.
Taking into consideration all of the above, we suggest performing the abdominal x-ray after 4 h if the patient is symptomatic (e.g. important abdominal pain, fever, worsening of the clinical conditions) or after 8 h if the patient’s conditions are normal.
Remember that at every moment the NOM can be suspended if the patient’s clinical conditions underlie peritonitis and/or bowel ischemia (e.g. fever, acute abdominal pain, leukocytosis >15’000/mm3, etc…).
Once we have confirmed the contrast has reached the colon, the NGT may be removed and oral intake may be re-started. Non-operative management can be continued for up to 72 h. After this time frame, if stools have not passed, oral intake cannot be tolerated or NGT drainage is >500 mL, surgery should be considered. On the contrary, if the patient feels well, is passing stools, and eats without problems, he/she can be discharged. Remember to ask for a colonoscopy, because 5-10% of patients successfully treated with NOM have an underlying ileocecal valve cancer.
Emergency surgery is indicated if NOM fails or if there is a suspicion of peritonitis or ischemia. You may use the Peritoneal Adhesion Index (Figure 2) to describe the extent of the adhesions (useful for subsequent episodes).
Laparoscopy in experienced hands is a feasible option, but you should be careful when entering the abdominal cavity (do not use the Verres needle!) and a low threshold for conversion should be maintained (beware of unnoticed bowel lesions and perforations!!!).
Predictors for successful laparoscopic treatment of ASBO are:
- ≤2 previous laparotomies;
- Right iliac fossa obstruction in a patient with a previous appendectomy;
- No previous median laparotomy incision;
- Single adhesive band.
Is Prevention Possible?
The main principles of prevention of adhesions, and their related complications, are:
- Minimizing surgical trauma: use of laparoscopy;
- Reducing foreign body reaction (be careful with the use of intraperitoneal meshes);
- Use of antibiotics in septic conditions;
- Use of adjuvants to reduce adhesion formation: hyaluronate carboxymethylcellulose (moderate evidence, less practical in laparoscopic surgery).
So… Better act today!
See you next time…
- ten Broek, et al. Bologna guidelines for diagnosis and management of adhesive small bowel obstruction (ASBO): 2017 update of the evidence-based guidelines from the world society of emergency surgery ASBO working group. World J Emerg Surg 2018;13:24.
- Gans SL, et al. Plain abdominal radiography in acute abdominal pain: past, present, and future. Int J Gen Med 2012;5:525-33.
- Guerrini J, et al. Adhesive small bowel obstruction: single band or matted adhesions? A predictive model based on computed tomography scan. J Trauma Acute Care Surg 2021;90:917-23.
- Berge P, et al. Diagnosis of single adhesive bands versus matted adhesions in small bowel obstructions: a radiological predictive score. Eur J Trauma Emerg Surg 2022;48:13-22.
- Catena F, et al. Adhesive small bowel adhesions obstruction: evolutions in diagnosis, management and prevention. World J Gastrointest Surg 2016;8:222-31.
- Jun L, et al. Diagnostic value of plain and contrast radiography, and multi-slice computed tomography in diagnosing intestinal obstruction in different locations. Indian J Surg 2015;77:S1248-51.
- Branco BC, et al. Systemic review and meta-analysis of the diagnostic and therapeutic role of water-soluble contrast agent in adhesive small bowel obstruction. British J Surg 2010;97:470-8.
- Coccolini F, et al. Peritoneal adhesion index (PAI): proposal of a score for the “ignored iceberg” of medicine and surgery. World J Emerg Surg 2013;8:6.
How to Cite This Post
Llaquet H, Guerrini J, Bellio G, Marrano E. Un-Stick from the Point. Surgical Pizza. Published on March 5, 2023. Accessed on May 27, 2023. Available at [https://surgicalpizza.org/emergency-surgery/un-stick-from-the-point/].