The
abdominal wall
Burst
abdomen (syn. abdominal dehiscence) and incisional hernia (syn. ventral hernia)
In 1—2 per cent of cases, mostly between the
6th and 8th day after operation, an abdominal wound bursts open and viscera are
extruded. The disruption of the wound tends to occur a few days beforehand when
the sutures apposing the deep layers (peritoneum, posterior rectus sheath) tear
through or even become untied. An incisional hernia usually starts as a
symptomless partial disruption of the deeper layers during
the immediate or early postoperative period,
the event passing unnoticed if the skin wound remains intact after the skin
sutures have been removed.
Factors relating to the incidence of burst
abdomen and incisional hernia.
Technique
of wound closure.
•
Choice of suture material —
catgut leads to a
higher incidence of bursts than the use of nonabsorbable monofilament
polypropylene, polyamide or wire, and should never be used;
•
method of closure —
interrupted
suturing has a low incidence. Through and through suturing is good for the
obstructed case. A one-layer closure has a low incidence, but it is higher than that following a two-layered closure. Interrupted ‘far and near’ sutures are a recommended
technique for single-layer mass closures. When continuous suturing of layers
(one or two) is performed a particular fault is the use of a short length of
material, pulled tightly, for in an anaesthetised relaxed patient the incision
is shortened thereby, and made taut so that the material will act as if it
were a cheese
wire cutter when the patient is conscious and coughing. The golden rule is to
insert a length of suture at least four times the length of the incision but
less than five times the length of the incision. This ensures that the layers
are gently apposed;
•
drainage directly through a wound leads to a higher
incidence of ‘bursts’ than employing drainage through a separate (stab)
incision.
Factors
relating to incisions. Midline
and vertical incisions have a tendency to burst which is higher than those which
are transverse. Since the widespread use of nonabsorbable suture materials even
midline vertical incisions have a very low incidence of disruption.
Reasons
for operation. Infected
case; deep wound infection has a notorious reputation for causing burst abdomen
and/or late incisional hernias. Operations on the pancreas, with leakage of
enzymes, and on obstructed cases are other reasons for disruption.
Coughing;
vomiting; distension. At
the completion of an operation any violent coughing set off by the removal of an
endotracheal tube and suction of the laryngopharynx strains the sutures;
likewise cough, vomiting and distension (e.g. due to ileus) in the early
postoperative period. Over-vigorous postoperative ventilation in sedated
patients can lead to wound disruption.
General
condition of the patient. Obesity,
jaundice, malignant disease, hypoproteinaemia and anaemia are all factors
conducive to disruption of a laparotomy wound (Chapter 1); abdominal wounds in
pregnancy are notorious for a high risk of disruption; steroids delay wound
healing.
Burst
abdomen (syn. abdominal dehiscence)
Clinical
features
A serosanguinous (pink) discharge from the
wound is a forerunner of disruption in fully 50 per cent of cases. It is the
most pathognomonic sign of impending wound disruption and it
signifies that
intraperitoneal contents are lying extraperitoneally. Patients often volunteer
the information that they ‘felt something give way’. If skin sutures have
been removed, omentum or coils of intestine may be forced through the wound and
will be found lying on the skin. Pain and shock are often absent. It is
important to note that there may be symptoms and signs of intestinal
obstruction.
Treatment
An emergency operation is required to replace
the bowel, relieve any obstruction and to resuture the wound. While awaiting
operation, reassure the patient and cover the wound with a sterile towel. The
stomach should be emptied using a nasogastric tube and intravenous fluid therapy
commenced.
operation. Each protruding coil of intestine is
washed gently with saline solution and returned to the abdominal cavity. Then
protruding greater omentum is treated similarly and spread over the intestine.
The abdominal wall having been cleaned, all layers are approximated by through
and through sutures of monofilament nylon, each passed through a soft rubber or
plastic tuber collar. The abdominal wall may be supported by strips of adhesive
plaster encircling the anterior two-thirds of the circumference of the trunk.
Antibiotic therapy should be started.
Contrary
to what might be thought, peritonitis rarely supervenes and, although the skin
wound may become infected, healing is satisfactory. A second dehiscence rarely
occurs. There is biochemical evidence that healing after disruption produces a
stronger wound. This is due to the improvement in collagen metabolism under
these circumstances. An incisional hernia is often a later sequel (see below).
Incisional
hernia (syn. ventral hernia; postoperative hernia)
Aetiology
Incisional hernia occurs most often in obese
individuals, and a persistent postoperative cough and postoperative abdominal
distension are its precursors. There is a high incidence of incisional hernia
following operations for peritonitis because, as a rule, the wound becomes
infected. The placing of a drainage tube through a separate stab incision, as
opposed to bringing such a tube through the laparotomy wound, reduces the
frequency (see also the section ‘General features common to all hernias’).
An
incisional hernia
usually starts as a symptomless partial disruption of the deeper layers of a
laparotomy wound during the immediate or very early postoperative period.
Often the event passes unnoticed if the skin wound remains intact after the
stitches have been removed (or because subcuticular stitches have been used
which remain in place). A serosanguinous discharge is often the signal of
dehiscence, and resuture of the deeper layers of the incision obviates the more
difficult repair of an established and much larger hernia later on.
Clinical
features
There are great variations in the degree of
herniation. The hernia may occur through a small portion of the scar, often the
lower end. More frequently, there is a diffuse bulging of the whole length of
the incision. A postoperative hernia, especially one through a lower abdominal
scar, usually increases steadily in size and more and more of its contents
become irreducible. Sometimes the skin overlying it is so thin and atrophic that normal peristalsis can be
seen in the underlying intestine. Attacks of partial intestinal obstruction are
common and strangulation is liable to occur at the neck of a small sac or in a
loculus of a large one. Nevertheless, most cases of incisional hernia are
asymptomatic and broad-necked, and do not need treatment.
Treatment
Palliative. An abdominal belt is sometimes
satisfactory, especially in cases of a hernia through an upper abdominal
incision.
Operation.
Many procedures have been advocated, which is testimony to the fact that the
repairs may be difficult to accomplish, but it is now
clear that one technique is superior to all of the others.
Preoperative
measures
In order to obtain a lasting repair, very
special preparation is required. If the patient is obese, weight reduction by
dieting should precede the operation. To attempt to return the contents of a
very large hernia to the main abdominal cavity if they have not been there for
several years is to court danger, particularly if weight reduction has not been
effected. In these circumstances, not only is there a risk of failure of the
hernioplasty, but there is a greatly increased risk of paralytic ileus from
visceral compression and of pulmonary complications from elevation of the
diaphragm. The repair of these large hernias is highly specialised surgery and
should only be performed in centres with considerable experience in dealing with
them. For example, one technique employed to enlarge the abdominal cavity is
that of prolonged pneumoperitoneum in which the intra-abdominal pressure is
raised to 15—18 cmH2O for up to several weeks preoperatively. The
technique requires careful monitoring and patient counselling to be effective
but, if employed correctly, can enable a primary repair to be successful.
Operation. Three techniques have been
described: simple and complex apposition and plastic fibre mesh or net closures.
Simple
apposition. The
hernial sac is dissected. It is then formally, if not already inadvertently,
opened and the contents are reduced. Adherent omentum and bowel have to be freed
by dissection before the mouth of the sac can be defined. The layers are
repaired usually with nonabsorbable sutures: first the peritoneum, then the
fascial (aponeurotic) layers. The lateral edges of the fascia are freed from
the overlying muscles for some distance and this fascial layer is approximated
with interrupted sutures at the upper and lower ends of the wound. The muscles
and the remaining fascial layer are approximated. Tension-relaxing incisions may
be required and should be placed well laterally.
Complex
apposition. These
consist of various types of layered closures (Mayo, ‘Keel’, da Silva) and
should be considered obsolete and of historical interest only.
Plastic
fibre mesh or net closures. These
techniques are now the method of choice for all but the smallest defects (< 4
cm). The sac is dealt with as above. The layers of the fascia are dissected out
and, if above the umbilicus, the posterior rectus sheath edges apposed. A sheet
of polypropylene mesh is then inserted between the posterior rectus sheath and
the muscle fibres, and anchored in place. If below the umbilicus, the mesh is
placed in the preperitoneal space. The anterior rectus sheath is then apposed as
above. If the defect is too large to close by apposition of the rectus sheath,
the deficiency in the abdominal wall can be bridged by sewing the mesh to the
fascia on either side of the defect, ensuring at least a 4-cm overlap of the
fascial edges.
Careful
haemostasis and meticulous asepsis are essential during these operations.
Postoperative collections of serum can be removed by drainage, using plastic
tubing led, via skin punctures lateral to the wound, into closed suction
drainage bottles (e.g. Redivac).
Postoperative
treatment. Gastric decompression and intravenous fluids are employed, and
nothing by mouth allowed until the bowels have functioned. Early ambulation and
gentle physical exercise are to be encouraged. The patient should not resume
strenuous exercise for several weeks.
Results
of treatment. Most series report recurrence of the hernia in between 30 and 50
per cent of cases except where mesh inlay techniques have been employed in
specialist centres, where recurrence rates may be as low as 10 per cent.
Divarication
of the recti abdominis
Divarication of the recti abdominis is seen principally in elderly multiparous patients. When the patient strains, a gap can be seen between the recti abdominis through which the abdominal contents bulge. When the abdomen is relaxed, the fingers can be introduced between the recti.
Treatment. An abdominal belt is all that is
required. There is no risk of strangulated intestinal contents. A similar
condition is seen in babies, only the divarication exists above the umbilicus.
No treatment is necessary; as the child grows a spontaneous cure results.
Tearing
of the inferior epigastric artery
Tearing
of the inferior epigastric artery occurs in three dissimilar types of individual, namely elderly women,
often thin and feeble; athletic, muscular men, usually below middle age; and
pregnant women, mainly multiparas late in pregnancy. The site of the haematoma
is usually at the level of the arcuate line, where the posterior sheath of the
rectus abdominis is lacking.
Clinical
features. The possibility of tearing of the epigastric vessels should always be
considered when, following a bout of coughing or a sudden blow to the abdominal
wall, an exquisitely tender lump appears in relation to the rectus abdominis.
Occasionally, a haematoma occurs within the muscles lateral to the rectus
sheath. Unless there is bruising of the overlying skin, the diagnosis may be
difficult.
Differential
diagnosis. The
conditions for which the haematoma is frequently mistaken are, in the female, a
twisted ovarian cyst, and in both sexes, when the lump is on the right side, an
appendix abscess. The sign most likely to be of value in differentiating a
haematoma of the abdominal wall from these conditions, namely tensing the
abdominal musculature, is often unsatisfactory because of the pain it causes. Again, the differential diagnosis between the haematoma and a
strangulated Spigelian hernia may be difficult. The absence of vomiting suggests
a haematoma and the presence of resonance over the swelling favours a
Spigelian hernia, while a plain radiograph of the abdomen sometimes gives
positive evidence of the latter.
As
a complication of pregnancy. Rupture
of the inferior epigastric artery occurs occasionally during pregnancy.
Surprisingly to relate, the haemorrhage into this closed space from this
comparatively small artery has proved fatal.
Treatment.
With rest, a comparatively small haematoma may resolve, but sometimes renewed
haemorrhage causes the haematoma to rupture into the peritoneal cavity.
Therefore it is
safer to operate early, evacuate the clot and ligate the artery.
Infections
Cellulitis
can occur in
any of the planes of the abdominal wall.
Superficial
cellulitis is
usually discovered when an abdominal wound is inspected following pyrexia. The
earliest sign is when the stitches become embedded in the oedematous skin.
Later there is a blush extending for a variable
distance from the incision or the stitch holes. On palpation with the gloved
hand usually one area is found to be more indurated and tender than the
remainder. A stitch should be removed from the immediate vicinity, and if pus or
seropus escapes it should
be sent for bacteriological examination; treatment should then be commenced with
a broad-spectrum antibiotic.
Deep
cellulitis is
characterised by brawny oedema towards one or both flanks, and not infrequently
of the scrotum or vulva as well. Antibiotic therapy is the mainstay of
treatment. When tenderness persists, an anatomical incision dividing the muscles
carefully, layer by layer, until pus or purulent fluid is encountered is often
advisable.
Progressive postoperative bacterial synergistic
gangrene. This is, fortunately, a rare complication after laparotomy, usually
for a perforated viscus (notably perforated appendicitis). It has also occurred
after gallbladder operations, colectomy for ulcerative colitis and even after
drainage of an empyema thoracis. The condition is due to the synergistic action
of microaerophilic nonhaemolytic streptococci and, usually, a staphylococcus.
The skin in the immediate vicinity of the wound exhibits signs of cellulitis.
Within a few hours, a central purplish zone with an outer brilliant red zone can
be distinguished and the whole region is extremely tender. The condition
advances with various degrees of rapidity (Fig. 62.23). The gangrenous skin
liquefies exposing underlying granulation tissue. If the condition persists,
overwhelming septicaemia and associated multiorgan failure supervene.
Treatment.
Identification
of the organisms and a report on their sensitivity to antibiotics is essential.
Metronidazole should be given together with a powerful broad-spectrum
antibiotic. Without vigorous and effective treatment the gangrene spreads to the
flanks and the patient may die of toxaemia. If the infection has become
established, surgical debridement of all the necrotic and infected tissue should
be performed. Hyperbaric oxygen, if available, can be life-saving. Cellulitis
due to bacteroides may give no bacterial growth by conventional techniques and
may be missed.
Amoebic
cutis. The
possibility of this potentially lethal complication of amoebic colitis, liver
abscess or empyema being present should always be considered (see Chapter 52).
Confirmation may be difficult and an immunofluorescence test necessary.
Subcutaneous
gas-forming infection. This is described in Chapter 7 (under ‘Gas
gangrene’).
Neoplasms
of the abdominal wall
A
desmoid tumour is
a tumour arising in the musculoaponeurotic structures of the abdominal wall,
especially below the level of the umbilicus. It is a completely unencapsulated
fibroma and is so hard that it
creaks when it
is cut. Some cases recur repeatedly in spite of apparently adequate excision.
Aetiology.
Eighty per cent of cases occur in women, many of whom have borne children, and
the neoplasm occurs occasionally in scars of old hernial or other abdominal
operation wounds. Consequently, trauma, for example the stretching of the muscle
fibres during pregnancy or possibly a small haematoma of the abdominal wall,
appears to be an aetiological factor. They can occur in cases of familial
polyposis coli (Gardner’s syndrome).
Pathology.
The tumour is composed of fibrous tissue containing multinucleaterd plasmodial
masses resembling foreign-body giant cells. Usually of very slow growth, it
tends to
infiltrate muscle in the immediate neighbourhood. Eventually it undergoes a myxomatous change; it then increases in size more rapidly. Metastasis does not occur. Unlike
fibroma elsewhere, no sarcomatous change occurs.
Treatment.
Unless the tumour is excised widely, with a surrounding margin of at least 2.5
cm of healthy tissue, recurrence commonly takes place. After removal of a
large tumour, repair of the defect in the abdominal wall by nylon mesh is
required. These tumours are moderately radiosensitive. (Intraperitoneal desmoids
ate best left alone when possible.)
Fibrosarcoma
of the
abdominal wall is rare. It is resistant to radiotherapy and only in some cases
can a wide excision, with nylon mesh repair, offer hope of a cure.
Adenocarcinoma
of the colon or
of other viscera may invade the abdominal wall. In such cases, the resection of
this extension, along with the primary growth, may require special repair of the
resulting defect.
Secondary implantation in the wound may follow
any abdominal operation for carcinoma, and bladder cancer is notorious for this
propensity.