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
Q
What are the potential complications of surgery in LBO?
A
- infection
- incisional hernia
- intra-abdominal bleeding
- anastomotic leak
- anastomotic leak
- adhesions
- dehiscence
- problems with colostomy (skin irritation)
26
Q
What are the potential complications of LBO?
A
- Ischaemia
- Fistulation
- Perforation
- Dehydration + electrolyte imbalance
27
Q
What are the most common causes of SBO?
A
- Adhesions (usually surgical)
- Hernias (usually incarcerated groin hernia)
- Malignancy
- Volvulus
- IBD
28
Q
What are the S+S of SBO?
A
- 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
Q
What are the differential diagnoses for SBO?
A
- oesophageal rupture or tear
- GI foreign body
- Gastroenteritis
- IBD
- Mesenteric ischaemia
- LBO
- Ovarian torsion
- Pancreatitis
- Acute appendicitis
- DKA
- Intussusception
- PID
- UTI
30
Q
How is SBO diagnosed?
A
- AXR: central dilatation (>3cm); bowel will contain valvular conniventes; jejunum appears ‘fluffier’
- Erect CXR: air fluid level visible; potential pneumoperitoneum if perforation
- CT: small bowel faeces sign will be present in SBO (faeculent material mixed with gas bubbles)
- Enterolysis: barium used to help distinguish adhesion from metastasis (only to be used if no evidence of perforation)
- US: good at detecting SBO
31
Q
How should SBO be treated/managed?
A
- 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
Q
What are the potential complications of surgery in SBO?
A
- 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
Q
What are the potential complications of SBO?
A
- Perforation
- Peritonitis
- Bowel ischaemia
- Sepsis
- 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:
