Intestinal Obstruction
Ileus
Where are the small and the large bowels located?
The bowel consists of several very different sections: The
short duodenum, which receives the chyme right from the
stomach, the small bowel, a thin "hose" 4 - 5 m long, and
the large bowel with a length of about 1.2 m. The many loops
of the small bowel are relatively mobile in the abdominal
cavity. They are supplied, contrary to the large bowel,
by various blood vessels because it is here where many food
components (glucose, proteins) are directly absorbed into
the blood. The large bowel (colon) "frames" the loops of
the small bowel and is divided into several sections.
- The first section of the large bowel is located
in the right lower abdomen, where the small bowel empties
into it, forming a several centimetres long piece of
the bowel (caecum). It has a blind end, and from this
end, there is a thin appendage, the appendix.
- Above this section, the ascending part of the colon
(colon ascendens) begins. It rises upwards almost as
far as the liver and then curves (right flexure of the
colon).
- Then follows the section of the large bowel, which
runs horizontally from the right to the left in the
upper abdomen (colon transversum, transverse colon).
This part of the large bowel is kept in position by
a fatty tissue in form of an apron and is grown together
with the colon. It is called colic omentum, "great net".
Reaching the spleen in the left upper abdomen, the large
bowel again curves (left flexure of the colon).
- The descending large bowel is now directed towards
the left lower abdomen (colon descendens).
- After this, the large bowel makes a double bend
and is called colon sigmodeum, or just "sigma". Here,
the large bowel ends and is followed by the last part,
the rectum.
- The rectum is 16 cm long and passes into the anus.
In the middle of this "frame of the large bowel", there
are several large blood vessels, which come centrally from
the aorta and are embedded in a protective layer of tissue
and continue in a radial form to the small bowel and the
colon. It is very important for the surgeon to know exactly
which vessel supplies which section of the bowel. This must
be the basis to perform good colon surgery.
How do the small and the large bowel function?
The chyme partly digested in the stomach is mixed in the
duodenum with bile juice and juices from the pancreas, splitting
up the food into its components like sugar, fat, and protein.
The good blood supply of the small bowel is responsible
for the absorption of these components into the blood and
for their processing in the body before the indigestible
rest finally reaches the large bowel. It extracts the water
from the still liquid chyme. But how does the bowel transport
the chyme onwards and finally concentrate it? Even if a
person has not eaten anything, periodical ripples run down
the smooth musculature of the bowel from the gullet to the
rectum and keep it continuously in motion, so that the chyme
is transported onwards. In this process the loops of the
small bowel "move" faster in comparison, so that the time,
in which the chyme passes through, is quite short. Thus,
this mechanism of a fast passage counteracts a highly increased
quantity of bacteria, which naturally occur in the bowel.
In the large bowel, the chyme takes longer to pass through,
so that it can be thickened by the withdrawal of water.
This is achieved by the motoricity of the colon, producing
not only forward ripples of its loops, but also backward
ones. At the same time, the quantity of bacteria in the
colon rises drastically, which is completely normal and
even desirable. The healthy colon has several mechanisms
to bar off these bacteria and it produces certain proteins
that have almost disinfecting abilities and are located
on the mucous membrane of the colon. Diseases like intestinal
obstruction (ileus) may considerably disturb this finely
regulated system and cause grave consequences.
What is an intestinal obstruction?
An intestinal obstruction (ileus) may affect the small and
the large bowel. It is a disturbance affecting the passage
of the chyme, in most cases for mechanical reasons. But
what does this mean? A section of the small or large bowel
is obstructed from the inside or the outside, so that the
chyme cannot pass. This obstruction can be complete (ileus)
or incomplete (subileus). From the inside, a mechanical
barrier could be caused by a growing tumour or by objects
swallowed by children. As the bowel is a soft hose, it can
be closed by pressure from the outside too. Frequently,
this is caused by adhesive bands (briden), which pass through
the abdominal cavity and in which the mobile small bowel
can quickly get entangled. This is called a Bridenileus;
it usually affects patients who have suffered prior surgery
as these may lead to the formation of such adhesive bands.
The second form of a mechanical ileus is the strangulation
ileus, which normally also affects the mobile small bowel.
In this case, the loops of the small bowel rotate so to
speak around their own axle, causing thereby a disruption
of the blood supply of the bowel. This results in a deficient
supply of oxygen of the intestinal tissue and in a blockage
of the chyme. The small bowel also may get wedged into the
hernial sac of various intestinal hernias, which may also
cause an ileus. The large bowel, however, fixed to the peritoneum
in many places, is most frequently affected by a disturbance
of passage. It is caused by a tumour, which either grows
within the large bowel or presses on it from the outside.
Beside the already mentioned mechanical causes, a paralysis
of the intestinal musculature can also be the reason for
an ileus. This means that the typical periodical and spontaneous
movements of the bowel come to a halt, the chyme cannot
be transported onwards, and an obstruction is the result.
This may be caused by grave metabolic disorders, generalized
bacterial infections, abdominal trauma, or consequences
of great abdominal surgery. But why is the ileus so dangerous?
It is solely the obstruction of the chyme that causes an
excessive distension of the intestinal wall, no matter at
which section of the bowel or for what reason. This triggers
a series of reactions in the body, which are described in
the following text and which ultimately cause the dangerous
"ileus disease": The excessive extension of the intestinal
wall caused by the congestion leads to a circulatory disturbance
in the section, which triggers an oxygen deficiency in the
tissue. This is why the bowel stops its movements and the
number of bacteria rises drastically, which again discharge
certain toxic substances. After these occurrences, the intestinal
wall - if one considers it as a "barrier" - is weakened
in various respects. The bowel and the intestinal wall now
fill with liquid. In a kind of abnormal redistribution,
the liquid had been withdrawn from the blood vessels before,
thus causing a circulatory debility in the patient. Moreover,
the toxic substances of the bacteria are now able to penetrate
the weakened barrier of the intestinal wall, reach then
the blood circulation and - through complicated mechanisms
- produce a shock, which may also affect other organs (kidneys,
lungs, etc.).
How do I recognize an ileus?
"The day began like every other. After breakfast, I went
to work. After lunch, I suddenly had an attack of convulsive
pains in the stomach, which stopped and then came again.
In the afternoon, I was only able to sit doubled-up on my
chair, so that my boss sent me home. When I arrived, I had
outbursts of vomiting several times. My stomach was more
and more puffed up and the pain increased. Only when I was
lying with my legs pulled up, I felt a little better. A
friend, who came to visit me in the evening, took me to
the hospital right away."
This description contains many complications, which a patient
with an imminent ileus will report: the main symptoms are
vomiting (possibly in outbursts) and strong intermittent
pain in the abdomen. In many cases, the abdomen is strongly
puffed up and pains on pressure. Depending on the location
of the obstruction, the patients may have no stools and
no discharge of gas any more. A question frequently asked
is why there are convulsive colics. As soon as the bowel
is blocked for some reason or other, it tries to react against
this obstacle with all possible strength, which causes the
colicky pains. In case of a paralytic ileus, however, the
paralysis occurs quickly: "There is dead silence in the
abdomen", which means that the doctor cannot hear any bowel
sound through his stethoscope any more.
Necessary clarifications and diagnostic possibilities
The above mentioned complaints may occur in very different
manifestations and sequences, depending on which section
of the bowel is threatened by an obstruction. Patients with
an ileus of the small bowel more often complain about convulsive
pains in the abdomen and about vomiting. Normally, an ileus
of the large bowel first causes significantly irregular
stools before pains in the abdomen occur. Therefore, the
doctor must first carry out an exact questioning of the
patient to rule out other diseases. In the case of an intestinal
obstruction, it is of primary interest to know the exact
time when the pains began, the kind of pain (dull, pungent,
colicky spasms), whether the patient had to vomit, and when
he had his last stool. Further, he should be asked about
prior operations of the abdomen (appendectomy, uterectomy,
gall bladder operation, other operations of the bowel or
stomach) and about other general sicknesses. After this,
further examinations are carried out:
- Examination of the abdomen with the hands:
Through it, an inflated abdomen becomes obvious,
reacting on pressure with acute pain. Furthermore, the
doctor looks for abnormal swellings when he palpates
the abdomen. A very important step in the examination
is the auscultation of the abdomen with a stethoscope
to assess the bowel sounds. By lightly tapping with
the fingers on the abdomen, aggregations of air can
be recognized. In case of an increasing intestinal obstruction,
first so-called highly pitched bowel sounds are heard,
later also tinkling ones. When a mechanical ileus has
lasted for a longer space of time and during its transition
to a paralytic ileus, bowel sounds are no more audible.
For the surgeon, kind and quality of the bowel sounds
are a very important indication of an ileus.
- Rectal examination: The examination of the
rectum is a must in all cases of acute abdominal complaints.
Pains and possibly blood at the fingerstall are quite
unspecific, however, and occur also in connection with
other diseases of the bowel or abdomen.
- Abdomen plain X-ray: An X-ray of the abdomen
with the patient standing and lying is a simple examination
that provides a lot of information about an intestinal
obstruction. In the picture, one looks for fluid levels
and so-called extra-intestinal air in the abdomen. If
such fluid levels can be found, it is an almost certain
indication of an actual intestinal obstruction. By assessing
the localization of the fluid level, it can be estimated
about where the bowel is obstructed. The so-called "standing"
intestinal loops are another typical indication of an
ileus. The intestinal obstruction causes gas to collect
before the barrier, the intestinal loops get inflated,
and the X-ray picture conveys the impression as if they
were standing upright in the abdomen.
- Ultrasound: An ultrasound of the abdomen
offers a fast possibility to answer the following questions
as to affected intestinal loops: Are they filled with
liquid? Is the intestinal wall swollen? Are there still
spontaneous movements of the intestinal loops?
- Application of contrast medium: If there
is the suspicion of an ileus of the small bowel without
strangulation, an oral application of a water-soluble
contrast medium can be tried. On the one hand, this
medium has a laxative effect. On the other hand, an
X-ray picture can be made after a certain time to assess
whether the liquid has moved on to the large bowel in
adequate time. Thus, the location of the obstruction
can be determined more exactly.
- Blood tests: A blood test can contribute
to clarify the cause of the intestinal obstruction.
The laboratory results can only show certain causes,
but not the intestinal obstruction as such.
- CT examination: If the cause of the intestinal
obstruction cannot be found with the above mentioned
examinations or if the palpitation of the abdomen shows
a swelling, a CT examination can be carried out as complementary
diagnostics in certain cases.
Only in an overview of clinical history and of the results
of various examinations, the surgeon can answer the most
important questions: Is it an intestinal obstruction of
the small or the large bowel? Is the obstruction mechanical
or paralytic? Is it complete or partial? Does the patient
suffer from another, so far unidentified disease (tumour,
inflammation, intestinal hernia)? Does he have to operate
the patient at once, or can he wait with the operation whereas
the patient stays under strict supervision?
How is an acute intestinal obstruction treated?
Has the diagnosis of an acute intestinal obstruction been
confirmed - without considering the type of ileus - the
following essential measures are taken: As all patients
suffer from a grave disturbance of the fluid balance, but
have to go with an empty stomach at the same time, they
are first provided with a great intravenous access: A soft
plastic tube is inserted through a big needle into a central
blood vessel. This central venous catheter is either installed
at the collarbone or at the neck. Thus, the patients receive
the necessary liquid, trace elements, and medicaments (e.g.
antibiotics). As most of the patients have already vomited,
a gastric tube is installed. This is a thin plastic tube,
which is inserted through the nose and the gullet into the
stomach. In this way, the accumulated liquid can be drained
off into a bag from the stomach and the bowel. These two
measures, gastric tube and infusion, are only meant to safeguard
a stabile blood circulation, but they have no curative effect
concerning the intestinal obstruction. Patients with an
advanced ileus sometimes also have to be treated at the
intensive care unit. How does the treatment continue?
In case of a paralytic ileus (i.e. non- mechanical), the
above mentioned measures are taken, and attempts are made
to eliminate the basic disease. The procedure is preferably
non-surgical in this case, except in the case of a serious
superdistension of the bowel. In this case, a special operation
has to be carried out to relieve the bowel.
The mechanical ileus is often caused by adhesions in the
abdomen and affects mostly the small bowel as it is rather
mobile in the abdomen. Mechanical obstructions in the large
bowel are caused in most cases by a tumour. In both cases,
surgical intervention becomes necessary to remove the obstruction
and to restore the continuity of the bowel. For the treatment
of intestinal obstructions, open surgery is first choice.
Depending on the condition of the patient, a laparascopic
operation can also be considered. However, one often has
to switch over to open surgery because the spot of trouble
cannot be properly made out, or a laparascopic correction
of the problem is too difficult. Depending on the location
of the intestinal obstruction (upper, middle, or lower abdomen),
a vertical incision in the middle of the abdomen is made
as access. Afterwards, all layers of the intestinal wall
are carefully severed. The edges of the incision are then
tightly stretched with several retractors, so that the organs
of the abdomen become freely visible. Now, the whole abdomen
can be searched for the cause of the intestinal obstruction.
As a rule, the strongly inflated loops of the bowel in front
of the obstruction (adhesive band or tumour) catch the surgeon's
first attention. Behind the obstruction, the so-called "hunger
colon" is often found. At this place, the bowel is completely
empty and very thin as no food has passed through it for
quite some time. Has the place of obstruction been located,
the cause can easily be found out. In most cases, there
are simple adhesions which result in an angulation or strangulation
of the bowel. The adhesions are severed with a sharp pair
of scissors, and bleedings are stopped with a few stitches.
As soon as the bowel has been freed from the adhesions,
its vitality has to be tested in order to find out whether
the bent section of the bowel is still functional. If the
bowel moves when touched, it is still functioning. Further
criteria for its vitality are its colour and the blood circulation.
If colour and mobility of the bowel are okay after the mobilization
of the adhesions, the abdomen can be sutured again, layer
by layer. Clamped sections of the bowel, which are badly
supplied with blood, take on a blue colour. If the bowel
does not turn rosy after the obstruction has been removed,
it has to be assumed that the relevant section of the bowel
is dead, so that it has to be excised. For this purpose,
the bowel is severed above and below the dead section and
then closed with a special linear stapling device. The resulting
two blind ends are joined together again with two running
sutures. Then, a check follows in order to find out whether
there is any bleeding, and two drains are laid. Finally,
the abdominal wall is closed layer by layer.
What happens after the operation?
After surgery, the patients are normally observed and monitored
at the intensive care unit for 1 - 2 days. Especially the
intake of liquid is closely checked and constantly corrected.
The patient receives sufficient pain killers and, if necessary,
antibiotics. A leakage of the suture of the bowel accompanied
by the escape of enteral contents was a frightening complication
after such an operation in the past. Fortunately, this has
become very rare due to advanced surgical techniques and
suture materials. It is important to check the functioning
of the bowel 1 - 2 times per day. This can be done by auscultating
the abdomen. After every abdominal surgery, the bowel may
"go on strike" during the first few days. It is so to speak
offended and refuses its service of transportation. This
reaction is quite normal and disappears a few days after
the operation. When the bowel starts functioning again,
the patient can try to drink small quantities of tea/water.
If the stomach drain does not produce any more gastric juice,
or only very little, it can be removed. The quantities of
liquid can now be increased every day and food ingestion
can begin with soup, mashed potatoes with sauce, finely
cut food, and finally normal food. The sutures can be removed
on the 10th day after the operation, and the patients may
go home within 8 days if the recovery is favourable.
What has to be paid attention to in future daily life?
Many patients ask the doctor what they could do to prevent
another intestinal obstruction. A mechanical ileus cannot
be prevented in any way. Every open operation, including
the one to treat an intestinal obstruction, may sometimes
again cause adhesions in the abdomen. After such an operation,
the patients are able to lead an entirely normal life, they
can eat and drink without restrictions and they can go in
for sports. In the case of a recurrence of complaints like
pain or retention of stool, the patients should consult
their doctor in due time. If an intestinal obstruction is
the consequence of a different basic illness (tumour, diverticulitis,
Morbus Crohn), the basic illness has to be treated at the
same time.
History
Already in antiquity, the symptoms of an intestinal obstruction
were known to the Greek doctors. They called this disease
"Ileus", which means "full of mud". They chose this name
because in the case of an intestinal obstruction, the contents
of the bowel cannot be transported onwards and is blocked
in front of some obstacle. The liquid accumulated there
may have a certain similarity with mud.