QuestionSBA
QuestionChoice
Whilst many patients are treated with decompression via sigmoidoscopy, the first priority is to ensure the patient is nil by mouth and is given appropriate IV fluid replacement
32989
b
Sigmoidoscopic decompression
QuestionChoice
If there was signs of sepsis, or if perforation was suspected, IV antibiotics may be indicated. This is suggested in the history, so the most appropriate immediate step is to administer IV fluids
32991
d
IV antibiotics
QuestionChoice
Metoclopramide is a pro-kinetic antiemetic drug which may be used in the management of symptomatic partial small bowel obstruction. This patient has a large bowel obstruction
32992
e
IV metoclopramide
QuestionChoice
The patient has a bowel obstruction, most likely secondary to adhesions. If there was signs of perforation, a CTAP may be indicated to delineate the site of perforation prior to surgical management
32990
c
Computed tomography abdomen and pelvis (CTAP)
QuestionChoice
This x-ray shows the "coffee bean" sign indicating a sigmoid volvulus. This is typically managed using the "drip and suck" approach, whereby the patient is placed as nil by mouth, given IV fluids, and a nasogastric tube inserted to drain any stomach contents.
32988
a
IV 0.9% sodium chloride
QuestionComment
Most patients with sigmoid volvulus are treated conservatively initially with decompression by sigmoidoscope and insertion of a flatus tube. I appreciate that IV fluid resus may be most appropriate management, but explanation for answer is wrong. 
6237
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Kinase WBC
QuestionComment
How is IV fluids a treatment option? You would treat with drip and suck not with the fluids so this is a daft question
7896
QuestionComment
wait till you find out what "drip" means in drip and suck...
43108
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Ale
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Monoclonal Fracture
QuestionComment
Her observations are satisfactory, so fluids isn't the most appropriate option. Decompression of the volvulus would be the MOST appropriate. Poorly written and justified question 
8001
QuestionComment
Common mistake here. You don't give fluids to resuscitate her in drip and suck, you give the fluids because you making the patient nil by mouth. Therefore, even patients with normal observations will require IV fluids
43112
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Ale
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Serotonin Relapse
Concept
Chapter
# Summary 

Small bowel obstruction is a mechanical impediment in the small bowel leading to clinical symptoms such as bilious or faeculent vomiting, abdominal pain, and distension. Key causes include adhesions, intra-abdominal hernias, Crohn's disease, malignancy, and foreign body ingestion, among others. Noteworthy signs and symptoms include abdominal pain with distension, vomiting, failure to pass flatus or stool, and possible fever. Primary investigations include blood tests, abdominal and chest X-ray, CT abdomen and pelvis, and possibly a diagnostic laparotomy/laparoscopy. The management involves initial resuscitation, fluid and electrolyte correction, NG tube aspiration for decompression, potential gastrografin administration, and surgery if conservative measures fail.

# Definition

Small bowel obstruction (SBO) is a mechanical disruption in the small bowel, leading to significant clinical symptoms such as bilious or faeculent vomiting, abdominal pain and distension, and complete constipation.

# Epidemiology

SBO is a common clinical issue seen in emergency departments worldwide. Adhesions following abdominal surgery are the leading cause, responsible for approximately 60-70% of all cases in adults. Intra-abdominal hernias, Crohn's disease, malignancy, and foreign body ingestion are other common causes. In children, intussusception, volvulus, and intestinal atresia are more common causes of SBO. The incidence of SBO tends to increase with age due to increasing rates of surgery, malignancies, and other predisposing conditions.

# Aetiology

## Factors outside the bowel

-   Adhesions
    
    -   Most common cause in the Western world
    -   Prior intra-abdominal surgeries increase the risk of adhesion development. The larger the operation, the higher the likelihood of adhesion formation.
-   Intra-abdominal hernia
    
    -   Incarcerated hernias can precipitate acute obstruction

## Factors relating to the bowel wall

-   Crohn's disease - stricturing (rather than fistulating) disease is what specifically causes SBO
-   Appendicitis

## Factors relating to inside the bowel

-   Malignancy
-   Foreign body ingestion
-   Gallstone ileus

## Diseases causing small bowel obstruction in children

-   Intussusception
-   Volvulus
-   Intestinal atresia
-   Appendicitis

# Signs and Symptoms

SBO typically presents with the following:

-   Abdominal pain with distension (Initially colicky pain that becomes continuous)
-   Bloating and vomiting (often bilious)
-   Failure to pass flatus or stool
-   History of abdominal/gynaecological surgery or hernia
-   Tympanic, high-pitched bowel sounds on examination
-   An empty rectum on examination in complete bowel obstruction

Patients may also present with fever and significant fluid depletion. Peritonitis indicates severe bowel obstruction with developing complications (e.g. perforation, especially in closed-loop obstructions), necessitating urgent surgical intervention.

Simple or partial SBO may still result in passing some flatus/stool and present with a mild temperature.

If untreated, SBO can progress to ischaemic or necrotic bowel, leading to perforation.


# Differential Diagnosis

-   **Adhesions**: Pain, distention, bilious vomiting, constipation, history of previous surgeries.
-   **Intra-abdominal hernia**: Pain, distention, inability to pass flatus or stool, a palpable mass in the abdomen.
-   **Crohn's Disease**: Abdominal pain, diarrhea, weight loss, fatigue, fever.
-   **Malignancy**: Abdominal pain, weight loss, altered bowel habits, possible presence of blood in the stool.
-   **Foreign body ingestion**: Abdominal pain, possible history of foreign body ingestion, altered bowel habits.
-   **Gallstone ileus**: Abdominal pain, distention, bilious vomiting, history of gallstones or cholecystitis.
-   **Paralytic ileus**: Abdominal pain, distension and absent bowel sounds, often a post-operative complication

# Investigations


In a patient presenting with potential intestinal obstruction, peritonitis is a worrisome sign and the consideration to transfer to theatre must be considered.

Basic investigations include:

-   Basic blood tests including FBC, U+Es, and lactate
    -   FBC (To identify leukocytosis or anaemia)
    -   U+Es (To detect organ dysfunction or signs of hypovolaemia)
    -   Lactate (To establish if there is bowel ischaemia or necrosis, though it can be falsely low due to liver metabolism)
    -   Amylase (To rule out acute abdomen conditions)
-   Abdominal and chest X-ray
    -   Performed in an upright position to detect pneumoperitoneum
    -   Absence of air in the rectum can indicate complete obstruction

  
| Feature                        | Small Bowel Obstruction (SBO) | Large Bowel Obstruction (LBO) |
|--------------------------------|-------------------------------|------------------------------|
| **Bowel Wall Thickness**       | May be mildly thickened       | Often markedly thickened      |
| **Valvulae Conniventes**       | May be seen (small intestine) | Not typically seen (large intestine) |
| **Gas Patterns**               | Central or diffuse gas pattern | Peripheral or haustral pattern |
| **Luminal Air Fluid Levels**   | Commonly seen                 | Less frequently seen         |
| **Stool in Colon**             | Minimal or absent             | Often present                |
| **"Bird's Beak" Sign**         | Absent                        | May be seen in LBO (sigmoid volvulus) |
| **Peritoneal Fluid**           | May be seen due to irritation | Less common unless perforation occurs |


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In the absence of peritonitis and given the patient's stable condition, the following investigations may be performed:

-   CT abdomen and pelvis
    -   Best diagnostic test for identifying the underlying cause, the site of obstruction, and whether it's a partial vs. complete obstruction
-   Small bowel contrast study using gastrograffin
    -   Used as a therapeutic measure in partial SBO
    -   Presence of contrast in rectum 24 hours after ingestion signifies a resolving partial SBO, reducing the need for surgery
-   MRI abdomen
    -   Comparable to CT scan, it is useful in young patients to avoid exposure to ionising radiation
-   US abdomen
    -   Not as reliable as CT, but can be used in children to avoid ionising radiation exposure
-   Diagnostic laparotomy/laparoscopy
    -   Used to distinguish between partial and complete obstruction if imaging doesn't provide clear evidence

# Management

-   Begin with resuscitation protocols (ABCDE)
-   Correct fluid and electrolyte imbalances to reduce operative risk before surgery for obstruction
-   Fluid resuscitation and NG tube to aspirate content for decompression ('Drip and suck')
-   Gastrografin can be administered as both a diagnostic and therapeutic measure in cases of partial obstruction. The presence of gastrografin in the rectum 24 hours post-administration indicates a resolving partial SBO, reducing the need for surgical intervention.
-   If conservative measures fail, consider surgery. The type of surgery depends on the cause and may include:
    -   Adhesionolysis
    -   Bowel resection
    -   Closure of hernias
    -   Tumour resection

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Dilated loops of small bowel seen on abdominal x-ray.
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Free air under the right hemidiaphragm.
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Free air under the right hemidiaphragm.
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A 65-year-old woman presents to A&E due to vomiting. The vomit has a greenish tinge. She also complains of diffuse abdominal pain. She has a past medical history of diabetes type 2 mellitus, hypertension, obesity, Crohn's disease, and a previous hemicolectomy 6 years ago. On examination, her abdomen appears to be distended and it's difficult to hear bowel sounds. Her observations are satisfactory.

She undergoes an abdominal x-ray:

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What is the most appropriate initial management?
a