Bowel obstruction (SBO + LBO) Flashcards
1
Q
Define simple obstruction.
A
- Obstruction of the bowel without damage to the blood supply
- Intestinal blockage in the absence of peritonitis
- Reflects early/partial obstruction and may respond to non-operative therapy
2
Q
Define complicated obstruction.
A
- Surgical emergency
- Obstruction has progressed to intestinal ischaemia/gangrene and/or perforation
- Life threatening –> requires urgent resuscitation + surgery
3
Q
Define partial/incomplete obstruction.
A
- Blockage of the intestine is not complete
- Partial passage of flatus and occasionally stool
- May resolve with non-operative therapy
4
Q
Define complete obstruction.
A
- Emergency
- Lumen of intestine is completely obstructed
- Failure to pass flatus and stool
- Generally associated with peritonitis
- Will not respond to non-operative therapy
5
Q
Define mechanical obstruction.
A
- When something is physically obstructing the passage of contents
- Usually occurs in the small bowel
6
Q
What can cause mechanical obstruction?
A
- Scar tissue
- Adhesions
- Entrapment through a hernia
- Foreign bodies
- Gallstones
- Tumours
- Impacted faeces
- Volvulus
7
Q
What are the cardinal features of obstruction?
A
- Abdominal distension
- Absolute constipation
- Vomiting
- Colicky pain
8
Q
Define adynamic ileus.
A
- Failure of passage of enteric contents through small bowel and colon that are not mechanically obstructed
- Paralysis of intestinal motility
9
Q
What can cause adynamic ileus?
A
- drugs (opioids)
- metabolic (hyponatraemia)
- sepsis
- abdo trauma or surgery
- MI/congestive heart failure
- head injury/ neurosurgery
- intra-abdominal inflammation and peritonitis
- retroperitoneal haematoma
10
Q
Define acute obstruction.
A
- Intestinal obstruction of short duration, in a patent who has not previously undergone abdominal surgery
- importance of lack of previous abdo surgery is that the obstruction is much less likely settle on non-operative management
11
Q
Define subacute obstruction.
A
- Intestinal obstruction of short duration, in a patient who has previously undergone abdominal surgery
- importance of previous surgery is that the obstruction is most likely due to adhesions, is often incomplete and will often settle without operative intervention
12
Q
Define chronic obstruction.
A
- Intestinal obstruction of longer duration and would typically be seen in a patient with large bowel obstruction who has an incompetent ileo-caecal valve
13
Q
Define closed loop obstruction.
A
- Specific form of mechanical obstruction characterised by increasing distension of a loop of bowel
- due to a combination of complete obstruction distally and a valve like mechanism proximally allowing the bowel to fill but not reflux
- e.g. with an obstruction in the caecum when the ileo-caecal valve remains competent
14
Q
What can cause closed loop obstruction?
A
- Hernias
- Adhesions
- Volvulus
15
Q
What are the differential diagnoses for bowel obstruction?
A
- Acute colonic pseudo-obstruction
- Chronic/idiopathic megacolon
- Toxic megacolon
- Endometriosis
- Pseudomembranous colitis
- Ileus
- Intussusception
- Intra-abdominal sepsis
- Pneumonia/systemic illness
16
Q
Compare SBO and LBO appearances on AXR.
A
- SBO:
- centrally located multiple dilated (>3cm) loops of gas-filled bowel
- Valvulae conniventes (lines through entire bowel) are visible + are closer together in the jejunum than in the ileum
- Jejunum appears more ‘fluffy’ than the ileum (due to greater number of mucosal folds)
- Paucity of colonic or rectal gas
- Step laddering (early phase)/ string of pearls (late phase) - LBO:
- peripherally located dilated (>6cm of colon or >9cm for caecum) bowel with haustration
- largely dilated bowel, if in the RIF = likely to be caecal; if it points towards LIF = likely to be sigmoids (kidney bean sign)
- Volvulus (either sigmoid or caecal)
17
Q
Compare SBO and LBO appearances on CT.
A
- SBO:
- dilated proximal small bowel (>3cm) and collapsed small distal bowel
- small bowel faeces sign
- absence of distal contrast
- bowel wall thickening - LBO:
- distal colon
- disproportionate caecal distension
- collapsed distal colon or rectum
18
Q
What are the most common causes of LBO?
A
- Malignancy (60%)
- Diverticular disease (20%)
- Volvulus (5%)
19
Q
What are the S+S of LBO?
A
Symptoms:
- Abdominal distension/may report feeling of fullness
- Constant abdominal pain
- N+V (late sign)
- Dehydration
Signs:
- Abdominal guarding
- Abdominal hyper resonance
- Peritonism
- Reduced bowel sounds
- Elevated creatinine
- Elevated haematocrit
- Hyponatraemia
- Hypokalaemia
- Leukocytosis
- Slightly raised serum amylase
20
Q
How is LBO diagnosed?
A
- AXR: peripheral dilatation >6cm/>9cm; bowel will contain haustrations unless extremely dilated
- Erect CXR: air fluid level + potential pneumoperitoneum (if there is perforation)
- CT: disproportionate caecal distension or collapsed distal caecum or rectum
- Colonoscopy: looking for any obvious masses or areas of bleeding or any polyps
- Fluoroscopy: gastrograffin (given either as enema, follow through meal) then X-rays are taken
21
Q
How should LBO be treated/managed?
A
- All LBO requires surgery:
1. full laparotomy should be performed
2. liver should be palpated for metastases
3. colon should be inspected for synchronous tumours - multiple operations depending on the side of the lesion
22
Q
What operation should be performed to treat a right sided LBO?
A
Right hemicolectomy
23
Q
What operation should be performed to treat a transverse LBO?
A
Extended right hemicolectomy
24
Q
What operation should be performed to treat a left sided LBO?
A
- 3 staged procedure:
- Defunctioning colostomy
- Resection and anastomosis
- Closure of colostomy - 2 staged procedure:
- Hartmann’s procedure
- Closure of colostomy - 1 stage procedure:
- Resection, on-table lavage and primary anastomosis
25
What are the potential complications of surgery in LBO?
- infection
- incisional hernia
- intra-abdominal bleeding
- anastomotic leak
- anastomotic leak
- adhesions
- dehiscence
- problems with colostomy (skin irritation)
26
What are the potential complications of LBO?
- Ischaemia
- Fistulation
- Perforation
- Dehydration + electrolyte imbalance
27
What are the most common causes of SBO?
1. Adhesions (usually surgical)
2. Hernias (usually incarcerated groin hernia)
3. Malignancy
4. Volvulus
5. IBD
28
What are the S+S of SBO?
1. Symptoms:
- N+V
- Colicky pain
- Abdominal distension
- Constipation
- Dehyration
Signs:
- Tinkling bowel sounds
- Elevated creatinine
- Elevated haematocrit
- Hyponatraemia
- Hypokalaemia
- Leukocytosis
- Slightly raised serum amylase
29
What are the differential diagnoses for SBO?
- oesophageal rupture or tear
- GI foreign body
- Gastroenteritis
- IBD
- Mesenteric ischaemia
- LBO
- Ovarian torsion
- Pancreatitis
- Acute appendicitis
- DKA
- Intussusception
- PID
- UTI
30
How is SBO diagnosed?
1. AXR: central dilatation (>3cm); bowel will contain valvular conniventes; jejunum appears 'fluffier'
2. Erect CXR: air fluid level visible; potential pneumoperitoneum if perforation
3. CT: small bowel faeces sign will be present in SBO (faeculent material mixed with gas bubbles)
4. Enterolysis: barium used to help distinguish adhesion from metastasis (only to be used if no evidence of perforation)
5. US: good at detecting SBO
31
How should SBO be treated/managed?
- NG suction to provide symptom relief
- Small bowel should only be operated on if:
(a) incarcerated/strangulated hernia
(b) adhesions that cannot be removed
(c) peritonitis
(d) pneumoperitoneum
(e) complete obstruction
(f) closed loop obstruction
- part of bowel with obstruction is resected and a primary anastomosis is performed because of the excellent blood supply in the area
- chemotherapy is a tumour is causing blockage
32
What are the potential complications of surgery in SBO?
- Diarrhoea
- Adhesion formation
- Short bowel syndrome
- Chronic abdominal pain
- Failure or leak of anastomosis
- Incisional hernia
- Infection of wound site or if stoma created
33
What are the potential complications of SBO?
1. Perforation
2. Peritonitis
3. Bowel ischaemia
4. Sepsis
5. Death
Explanation:
- Increased colonic pressure (due to obstruction + reduced venous flow)
- Results in oedema of the wall and transudation of water + electrolytes into the lumen
- Reduced arterial blood supply = mucosal ulceration, full thickness necrosis + perforation
- Colonic bacteria can then translocate into the peritoneum and cause septic complications:
