Distention of the obstructed segment of bowel
results in high pressure within the bowel wall
Venous return is compromised before the arterial
Increase in capillary pressure
Decreased local perfusion
Impaired arterial supply
Hemorrhagic infarction occurs
Viability of bowel compromised
Translocation & systemic exposure to anaerobic
organisms and endotoxins occur
Morbidity & mortality associated with
strangulation--- depends on duration of
ischaemia and its extend
Any length of ischemic bowel can cause
significant systemic effects secondary to
sepsis and significant dehydration
When bowel involvement is extensive –
circulatory failure is common
Closed loop obstruction
Bowel is obstructed at both the
proximal and distal points.
The distention is principally
confined to the closed loop
Carcinomatous stricture of colon with a
competent ileocaecal valve:-
-The inability of the distended colon to
decompress itself into the small bowel results
in an increase in luminal pressure, which is
greatest at the caecum, with subsequent
impairment of blood flow in the wall
-Unrelieved, this results in necrosis and
SPECIAL TYPES OF
Internal herniation occurs when a portion of
the small intestine becomes entrapped in one
of the retroperitoneal fossae or in a
congenital mesenteric defect
The following are potential sites of internal
- the foramen of Winslow;
- a defect in the mesentery;
- a defect in the transverse mesocolon;
- defects in the broad ligament;
- congenital or acquired diaphragmatic hernia;
- duodenal retroperitoneal fossae – left
paraduodenal and right duodenojejunal;
- caecal/appendiceal retroperitoneal fossae –
superior, inferior and retrocaecal;
The standard treatment of an obstructed
hernia is to release the constricting agent by
Obstruction from enteric
Small bowel strictures usually occur secondary
to tuberculosis or Crohn’s disease
Surgical management consists of resection
gallstones,food, trichobezoar, phytobezoar,
stercoliths and worms.
-occur in the elderly secondary to erosion of a
large gallstone directly through the gall bladder
into the duodenum.
-there is impaction about 60 cm proximal to the
-reccurent attacks- ball-valve effect
characteristic radiological sign of gallstone
1)small bowel obstruction
2) pneumobilia and
3)Impacted gall stone
# 2 signs are pathognomonic
Treatment – stone is milked proximally &
crushed or either removed after opening
-Bolus obstruction may occur after partial or total
-Fruit and vegetables
undigested hair ball and fruit/vegetable
When possible, the lesion may be kneaded
into the caecum
otherwise open removal is required.
A preoperative diagnosis is difficult even with
high resolution computed tomography (CT)
These are usually found in the small bowel in
association with a jejunal diverticulum or ileal
Presentation and management are identical to
that of gallstones
-An attack may follow the initiation of
-At laparotomy, it may be possible to knead the
tangled mass into the caecum; if not it should
Obstruction by adhesions and
-adhesions and bands are the most common
cause of intestinal obstruction
-The lifetime risk of requiring an admission to
hospital for adhesional small bowel obstruction
subsequent to abdominal surgery is around 4
% and the risk of requiring a laparotomy
around 2 %
-starts within hours of abdominal surgery
Any source of peritoneal irritation results in
local fibrin production, which produces
adhesions between apposed surfaces.
Early fibrinous adhesions may disappear when
the cause is removed or they may become
vascularised and be replaced by mature
Prevention of adhesions:
Factors that may limit adhesion formation
- Good surgical technique
- Washing of the peritoneal cavity with saline to
- Minimising contact with gauze
- Covering anastomosis and raw peritoneal
Postoperative adhesions giving rise to
intestinal obstruction usually involve the lower
small bowel and almost never involve the
-Usually only one band is culpable.
This may be:
-congenital, e.g. obliterated vitellointestinal duct;
- a string band following previous bacterial
-a portion of greater omentum, usually adherent
to the parietes.
when one portion of the gut invaginates into an
immediately adjacent segment; almost
invariably, it is the proximal into the distal
peak incidence between 5-10 months of age
90% of cases are idiopathic
upper respiratory tract infection or
gastroenteritis may precede the condition.
hyperplasia of Peyer’s patches in the
terminal ileum may be the initiating event
loss of passively acquired maternal
common viral pathogens
Children with intussusception associated with
a pathological lead point such as Meckel’s
diverticulum, polyp, duplication,Henoch–
Schönlein purpura or appendix are usually
older than those with idiopathic disease.
Adult cases are invariably associated with a
-which is usually a polyp (e.g. Peutz–Jeghers
syndrome), a submucosal lipoma or other
An intussusception is composed of 3 parts
- 1)the entering or inner tube (intussusceptum);
- 2)the returning or middle tube;
- 3)the sheath or outer tube (intussuscipiens)
The part that advances is the apex, the mass
is the intussusception and the neck is the
junction of the entering layer with the mass.
The degree of ischaemia is dependent on the
tightness of the invagination, which is usually
greatest as it passes through the ileocaecal
CT scan- the target sign
Most common in children
Adult cases are secondary to intestinal
pathology, e.g.polyp, Meckel’s diverticulum
Ileocolic is the most common variety
Adults – colocolic is more common
Can lead to an ischaemic segment
Radiological reduction is indicated in most
Adults require surgery
a twisting or axial rotation of a portion of
bowel about its mesentery
The rotation causes obstruction to the lumen
if tight enough also causes vascular occlusion in
the mesentery (>360° torsion).
Bacterial fermentation adds to the distention
increasing intraluminal pressure impairs capillary
Mesenteric veins become obstructed as a result of
the mechanical twisting and thrombosis results
and contributes to the ischaemia.
Volvuli may be primary or secondary.
The primary form occurs secondary to
congenital malrotation of the gut, abnormal
mesenteric attachments or congenital bands.
Examples include volvulus neonatorum,
caecal volvulus and sigmoid volvulus.
A secondary volvulus, which is the more
common variety, is due to rotation of a
segment of bowel around an acquired
adhesion or stoma
May involve the small intestine, caecum or
neonatal midgut volvulus secondary to midgut
malrotation is life-threatening
The most common spontaneous type in adults
is sigmoid volvulus
Sigmoid volvulus can be relieved by
decompression per anum
Surgery is required to prevent or relieve
Rotation nearly always occurs in the
Other predisposing factors - high residue diet
Presentation can be classified as:
- 1)Fulminant: sudden onset, severe pain, early
vomiting, rapidly deteriorating clinical course;
- 2)Indolent: insidious onset, slow progressive
course, less pain,late vomiting.
The long pelvic mesocolon allows the ileum to
twist around the sigmoid colon, resulting in
gangrene of either or both segments of bowel.
patient presents with acute intestinal
Xray- reveals distended ileal loops in a
distended sigmoid colon
At operation- decompression, resection and
-classic quartet-pain, distension, vomiting and
Obstruction may be classified clinically into
1) small bowel obstruction – high or low;
2) large bowel obstruction
Features of obstruction:
high small bowel obstruction- vomiting occurs
early, is profuse and causes rapid dehydration.
Distension is minimal with little evidence of dilated
small bowel loops on Xray
low small bowel obstruction- pain is predominant
with central distension. Vomiting is delayed. Multiple
dilated small bowel loops are seen on xray
large bowel obstruction- distension is more.
-Pain is less severe and vomiting and dehydration are
-The colon proximal to the obstruction is distended on
Cardinal clinical features of acute obstruction
1) Abdominal pain
4) Absolute constipation
Presentation will be further influenced by whether
the obstruction is:
# simple – in which the blood supply is intact;
# strangulating/strangulated – in which there is
interference to blood flow.
severe pain – strangulation
-absolute (i.e. neither faeces nor flatus is
-relative (where only flatus is passed)
The administration of enemas should be
avoided in cases of suspected obstruction
Late manifestations of intestinal obstruction:
septicaemia, respiratory difficulty and peritonism
-High-pitched bowel sounds- majority of patients
with intestinal obstruction
- Normal bowel sounds are of negative predictive
-scanty or absent if the obstruction is long-standing
and the small bowel has become inactive
Clinical features of strangulation
- Constant pain, severe pain
- Tenderness with rigidity and peritonism
When strangulation occurs in an external
hernia: -the lump is tense, tender and
irreducible and there is no expansile cough
-Skin changes with erythema or purplish-
Clinical features - intussusception
-the ‘redcurrant jelly’ stool
-feeling of emptiness in the right iliac fossa (the
sign of Dance)
-On rectal examination- blood-stained mucus
If unrelieved, progressive dehydration and
abdominal distension from small bowel
obstruction will occur, followed by peritonitis
secondary to gangrene
Xray abdomen-erect : Multiple air fluid levels
two inconstant fluid levels –
-one at the duodenal cap
-other in the terminal ileum
In the small bowel, the number of fluid levels is directly
proportional to the degree of obstruction and to its site (the
number increases- the more distal the lesion)
Fluid levels may also be seen in-non-obstructing conditions
such as gastroenteritis, acute pancreatitis, intra-abdominal
Colonic obstruction is usually associated
with a large amount of gas in the caecum
Radiological features of obstruction (on
Obstructed small bowel-straight segments that
are generally central and lie transversely
No/minimal gas is seen in the colon
The jejunum- valvulae conniventes,which
completely pass across the width of the bowel and
are regularly spaced, giving a ladder effect
Ileum – the distal ileum has been featureless
Caecum – a distended caecum is shown by a
rounded gas shadow in the right iliac fossa
Large bowel, except for the caecum, shows
haustral folds, spaced irregularly, do not cross the
whole diameter of the bowel and do not have
indentations placed opposite one another
Imaging in intussusception
Xray- shows small or large bowel obstruction
with an absent caecal gas shadow in
A barium enema-to diagnose ileocolic
intussusception (the claw sign)
USG- ‘doughnut’ appearance of concentric
rings in transverse section
CT scan -most sensitive radiologic method to
confirm intussusception-‘target’ or ‘sausage’-
shaped soft-tissue mass with a layering effect,
mesenteric vessels within the bowel lumen are
Imaging in volvulus
- In caecal volvulus,
caecal dilatation (98–100%), single air-fluid level
(72–88%), small bowel dilatation (42–55%)
and absence of gas in distal colon (82%)
In sigmoid volvulus- coffee bean sign
Treatment of acute intestinal obstruction
- Gastrointestinal drainage via a nasogastric tube
- Fluid and electrolyte replacement
- Relief of obstruction
Principles of surgical intervention for
1) The segment at the site of obstruction
2) The distended proximal bowel
3) The underlying cause of obstruction
Indications for early surgical intervention
- Obstructed external hernia
- Clinical features suspicious of intestinal
- Obstruction in a ‘virgin’ abdomen
If there is complete obstruction, but no
evidence of intestinal ischaemia, it is
-to defer surgery until the patient has been
Where obstruction is likely to be secondary to
adhesions, conservative management may be
continued for up to 72 hours in the hope of
If the site of obstruction is unknown, adequate
exposure is best achieved by a midline
Assessment is directed to:
- the site of obstruction;
- the nature of the obstruction;
- the viability of the gut.
Operative decompression should be
performed whenever possible.
Following relief of obstruction, the viability of
the involved bowel should be carefully
If in doubt, the bowel should be wrapped in hot
packs for 10 minutes with increased
and then reassessed.
-The state of the mesenteric vessels and
pulsation in adjacent arcades should be
-Viability is also confirmed by colour, sheen and
- If at the end of this period, there is still
uncertainty about gut viability, the gut should
Treatment of adhesions
Initial management is based on intravenous
rehydration and nasogastric decompression;
occasionally, this treatment is curative.
Although an initial conservative regimen is
considered appropriate, regular assessment is
mandatory to ensure that strangulation does not
Conservative treatment should not usually be
prolonged beyond 72 hours.
When laparotomy is required, although multiple
adhesions may be found, only one may be
If there is absolute certainty that this is the cause
of the obstruction, this should be divided and the
Treatment of intussusception
In the infant with ileocolic intussusception, after
resuscitation - non-operative reduction can be
attempted using an air or barium enema
Successful reduction- free reflux of air or barium
into the small bowel, together with resolution of
symptoms and signs in the patient
Non-operative reduction-contraindicated if there
are signs of peritonitis or perforation,a known
pathological lead point or in the presence of
Perforation of the colon during pneumatic or
hydrostatic reduction is a recognised hazard, but
Recurrent intussusception occurs in up to 10 %
Surgery is required-radiological
reduction has failed or is
Reduction is achieved by gently
compressing the most distal part
of the intussusception toward its
The viability of the whole bowel
should be checked
by infarction/a pathological lead
Duodenal atresia and stenosis are the most
common forms of intestinal obstruction in the
Jejunal or ileal atresias are next in
frequency, whereas colonic atresia is rare.
The possibility of multiple atresias makes
intraoperative assessment of the whole small
and large bowel mandatory.
There are 4 major types of jejunoileal atresia:
1)Type I consists of a membrane completely occluding
the lumen with the intestine intact.
2)Type II is a gap in the intestine with a fibrous cord
between the proximal and distal segments of intestine.
3)Type IIIA is a mesenteric gap without any connection
between the segments.
Type IIIB is jejunal atresia with absence of the distal
superior mesenteric artery; the distal small bowel is
coiled like an apple peel, and the gut is short.
4)Type IV consists of multiple atretic segments (a string
The obstructed proximal bowel is at risk of perforation,
which may happen prenatally causing meconium
peritonitis in the fetus.
Small bowel atresias present with intestinal
obstruction soon after birth.
Bilious vomiting is the dominant feature in
Abdominal distension is more prominent
with ileal atresia
-Duodenal atresia is corrected by a
-In most cases of jejunal/ileal atresia, the distal
end of the dilated proximal small bowel is
resected and a primary end-to-end
anastomosis is possible
-ocasionally, a temporary stoma is required
before definitive repair.
Cystic fibrosis (AR)- Most common
-Meconium is normally kept fluid by the action of
-In meconium ileus, the terminal ileum becomes
filled with thick viscid meconium, resulting in
-A sterile meconium peritonitis may have
gene mutation analysis- CFTR gene mutation;
a sweat test, which shows elevated sodium
chloride levels (>70 mmol/L).
Surgical procedures-intestinal resection and
temporary stoma formation, resection and primary
In uncomplicated cases-enterotomy and irrigation
of the bowel.
The Bishop–Koop operation with its irrigating
stoma is now only rarely used.
TREATMENT OF ACUTE LARGE BOWEL
an underlying carcinoma or diverticular
Acute or chronic
Distension of the caecum will confirm
large bowel involvement.
Identification of a collapsed distal segment
of the large bowel and its sequential
proximal assessment will readily lead to
identification of the cause
When a removable lesion is found in the caecum,
ascending colon, hepatic flexure or proximal
transverse colon, an emergency right
hemicolectomy should be done
A primary anastomosis is safe if the patient’s
general condition is reasonable.
If the lesion is irremovable,a proximal stoma
(colostomy or ileosotomy- if the ileocaecal valve is
incompetent) or ileotransverse bypass should be
Obstructing lesions at the splenic flexure should be
treated by an extended right hemicolectomy
with ileodescending colonic anastomosis
For obstructing lesions of the left colon or
rectosigmoid junction,immediate resection
In the absence of senior surgeon, it is safest to bring
the proximal colon to the surface as a colostomy.
When possible,the distal bowel should be brought
out at the same time(Paul–Mikulicz procedure) to
facilitate subsequent closure.
In the majority of cases, the distal bowel is closed
and returned to the abdomen (Hartmann’s
A second-stage colorectal anastomosis can be
planned when the patient is fit.
Treatment of caecal volvulus
At operation,if the volvulus is ischaemic –
If, viable- the volvulus should be reduced.
Sometimes, this can only be achieved after
decompression of the caecum using a needle.
Further management consists of fixation of the
caecum to the right iliac fossa (caecopexy)
and/or a caecostomy
Treatment of sigmoid
Flexible sigmoidoscopy or rigid sigmoidoscopy
and insertion of a flatus tube should be
carried out to allow deflation of the gut.
The tube should be secured in place with tape
for 24 hours and a repeat x-ray taken to
ensure that decompression has occurred.
Successful deflation, as long as ischaemic
bowel is excluded, will resolve the acute
In young patients, an elective sigmoid colectomy is
It is reasonable not to offer any further treatment
following successful endoscopic decompression in the
elderly as there is a high death rate (~80 per cent at
two years) .
In elderly patients with comorbidities and recurrent
episodes of volvulus, the options are resection or two
point fixation with combined endoscopic/percutaneous
Failure results in an early laparotomy, with untwisting
of the loop and per anum decompression
When the bowel is viable, fixation of the sigmoid colon
to the posterior abdominal wall may be a safer
A Paul–Mikulicz procedure is useful,
particularly if there is suspicion of impending
an alternative procedure is a sigmoid
when anastomosis is considered unwise, a
Hartmann’s procedure with subsequent
reanastomosis can be carried out
CHRONIC LARGE BOWEL
The causes of obstruction may be organic:
- 1)intraluminal (rare) :
- 2)intrinsic intramural :
strictures (Crohn’s disease,
ischaemia,diverticular), anastomotic stenosis;
- 3)extrinsic intramural (rare) :
metastatic deposits (ovarian),endometriosis,
- 4) functional:
Hirschsprung’s disease, idiopathic
Constipation appears first- relative early and
then absolute, associated with distension.
In the presence of large bowel disease, the
point of greatest distension is in the caecum,
and this is heralded by the onset of pain.
Vomiting is a late feature and therefore
dehydration is less severe.
Rectal examination may confirm the presence
of faecal impaction or a tumour.
Plain abdominal radiography confirms the
presence of large bowel distension.
All such cases should be investigated by a
subsequent single-contrast water-soluble
enema study, CT scan
Organic disease requires decompression with
either a laparotomy or stent.
Stomal stenosis can usually be managed at
the abdominal wall level.
Functional disease requires colonoscopic
decompression in the first instance and
-This may be defined as a state in which there is
failure of transmission of peristaltic waves
secondary to neuromuscular failure (i.e. in
the myenteric (Auerbach’s) and submucous
- The resultant stasis leads to accumulation of
fluid and gas within the bowel, with associated
distension, vomiting, absence of bowel sounds
and absolute constipation
The following varieties are recognised:
1) Postoperative. A degree of ileus usually occurs after
any abdominal procedure and is self-limiting, with a
variable duration of 24–72 hours. Postoperative ileus
may be prolonged in the presence of hypoproteinaemia
or metabolic abnormality.
2) Infection. Intra-abdominal sepsis may give rise to
localised or generalised ileus.
3) Reflex ileus. This may occur following fractures of the
or ribs, retroperitoneal haemorrhage or even the
of a plaster jacket.
4) Metabolic. Uraemia and hypokalaemia are the most
Paralytic ileus takes on a clinical significance if, 72
hours after laparotomy:
- there has been no return of bowel sounds on
- there has been no passage of flatus.
Abdominal distension becomes more marked and
Colicky pain is not a feature.
Distension increases pain from the abdominal wound.
In the absence of gastric aspiration, effortless
vomiting may occur.
Radiologically, the abdomen shows gas filled loops of
use of nasogastric suction and restriction of oral
intake until bowel sounds and the passage of
Electrolyte balance must be maintained.
Specific treatment is directed towards the cause,
but the following general principles apply:
- If a primary cause is identified, this must be
- Gastrointestinal distension must be relieved by
- Close attention to fluid and electrolyte balance is
- There is no place for the routine use of peristaltic
If paralytic ileus is prolonged- CT scan
The need for a laparotomy - if it lasts for
more than 7 days or if bowel activity
recommences following surgery and then
This condition describes an obstruction,
usually of the colon,that occurs in the absence
of a mechanical cause or acute intraabdominal
Severe trauma especially to the lumbar spine and pelvis
Postoperative (for example, fractured neck of
Retroperitoneal irritation Blood
Drugs Tricyclic antidepressants
Secondary gastrointestinal involvement Scleroderma
Small intestinal pseudo-
-This condition may be primary (i.e. idiopathic or
associated with familial visceral myopathy) or
-The clinical picture consists of recurrent
subacute obstruction. The diagnosis is made
by the exclusion of a mechanical cause.
-Treatment consists of initial correction of any
an acute or a chronic form.
The former, also known as Ogilvie’s syndrome,
presents as acute large bowel obstruction.
Abdominal radiographs show evidence of colonic
obstruction, with marked caecal distension
(diameter >10cm) being a common feature.
caecal perforation is a complication.
The absence of a mechanical cause requires
urgent confirmation by colonoscopy or a single-
contrast water-soluble barium enema or CT.
Once confirmed, pseudo-obstruction requires
treatment of any identifiable cause.
Caecal perforation can occur in pseudo-
Abdominal examination-tenderness and
peritonism over the caecum and as with
mechanical obstruction, caecal perforation is
more likely if the caecal diameter is 14 cm
Surgery is associated with high morbidity and
mortality and should be reserved for those with
impending perforation when other treatments
have failed or perforation has occurred.