Subphrenic
abscess
Anatomy
The complicated arrangement of the peritoneum
results in the formation of four peritoneal and three extraperitoneal spaces in
which pus may collect. Three of these spaces are on either side of the body, and
one is approximately in the midline (Figs 56.8 and
56.9).
Left superior (anterior) intraperitoneal
(‘left subphrenic’) is hounded above by the diaphragm, and behind by the
left triangular ligament and the left lobe of the liver, the gastrohepatic
omentum and anterior surface of the stomach. To the right is the falciform
ligament and to the left the spleen, gastrosplenic omentum and diaphragm. The
common cause of an abscess here is an operation on the stomach, the tail of the
pancreas, the spleen or the splenic flexure of the colon.
Left
inferior
(posterior) intraperitoneal (‘left
subhepatic’) is another name for the ‘lesser’ sac. The commonest cause of
infection here is complicated acute pancreatitis. In practice a perforated
gastric ulcer rarely causes a collection here because the potential space is
obliterated by adhesions.
Right
superior (anterior) intraperitoneal (‘right subphrenic’) lies between the
right lobe of the liver and the diaphragm. It is limited posteriorly by the anterior layer of the
coronary and the right triangular ligaments, and to the left by the falciform
ligament. Common causes here are
perforating cholecystitis, a perforated duodenal ulcer, a duodenal cap ‘blow
out’ following gastrectomy and appendicitis.
Right
inferior (posterior) intraperitoneal (‘right subhepatic’) lies transversely
beneath the right lobe of the liver in Rutherford Morison’s pouch. It is
bounded on the right by the right lobe of the liver and the diaphragm. To the
left is situated the foramen of Winslow and below this lies the duodenum. In
front are the liver and the gall bladder, and behind, the upper part of the
right kidney and diaphragm. The space is bounded above by the liver, and below
by the transverse colon and hepatic flexure. It is the deepest space of the four
and the commonest site of a subphrenic abscess which usually arises from
appendicitis, cholecystitis, a perforated duodenal ulcer or following upper
abdominal surgery.
Extraperitoneal.
There are three of these:
•
right and left extra peritoneal which
are terms given to perinephric abscesses (Chapter 64);
•
midline extraperitoneal which
is another name for the ‘bare’ area of the liver which may develop an
abscess in amoebic hepatitis (the commonest cause) or a pyogenic liver abscess
(Chapter 52).
Clinical
features
The symptoms and signs of subphrenic infection
are frequently nonspecific, and it is well to remember the aphorism, ‘pus somewhere, pus nowhere else, pus
under diaphragm’.
Symptoms
A common history is that when some infective
focus in the abdominal cavity has been dealt with, the condition of the patient
improves temporarily, but after an interval of a few days or weeks, symptoms of
toxaemia reappear. The condition of the patient steadily, and often rapidly,
deteriorates. Sweating, wasting and anorexia are present. There is sometimes
epigastric fullness and pain, or pain in the shoulder on the affected side,
owing to irritation of sensory fibres in the phrenic nerve, referred along the
descending branches of the cervical plexus. Persistent hiccup may be a
presenting symptom.
Signs
A swinging pyrexia is usually present, unless
antibiotics or drugs (steroids) have interfered. If the abscess is anterior,
abdominal examination will reveal some tenderness, rigidity or even a palpable
swelling. Sometimes the liver is displaced downwards, but more often it
is fixed by
adhesions. Examination of the chest is important, and in the majority of cases
collapse of the lung or evidence of basal effusion or empyema is to be found.
Investigations
A
number of these may be helpful as follows. Blood count usually shows a
leucocytosis.
A
plain radiograph sometimes demonstrates the presence of gas or a pleural
effusion. On screening, the diaphragm is often seen to be elevated (so-called
‘tented’ diaphragm) and its movements impaired.
Ultrasound
or CT scanning is the investigation of choice and permits early detection of
subphrenic collections (Fig. 56.10).
Radiolabelled
white cell scanning may occasionally prove helpful when other imaging techniques
have failed.
Differential
diagnosis. Pyelonephritis, amoebic abscess, pulmonary collapse and pleural
empyema give rise to most of the diagnostic difficulties.
Treatment
The clinical course of suspected cases is
watched, and blood and imaging investigations are made at suitable intervals. If
suppuration seems probable, intervention is indicated. If skilled help is
available it is
possible to insert a percutaneous drainage tube under ultrasound or CT control.
The same tube can be used to instil antibiotic solutions or irrigate the abscess
cavity. To pass an aspirating needle at the bedside through the pleura and
diaphragm invites potentially catastrophic spread of the infection into the
pleural cavity.
If
an operative approach is necessary and a swelling can be detected in the
subcostal region or in the loin, an incision is made over the site of maximum
tenderness, or over any area where oedema or redness is discovered. The parietes
usually form part of the abscess wall so that contamination of the general
penitoneal cavity is unlikely.
If
no swelling is apparent, the subphrenic spaces should be explored either by an
anterior subcostal approach or from behind after removal of the outer part of
the 12th rib according to the position of abscess on imaging. With the posterior
approach the pleura must not be opened and after the fibres of the diaphragm
have been separated a finger is inserted beneath the diaphragm so as to explore
the adjacent area. The aim with all techniques of drainage
When
the cavity is reached, all of the fibrinous loculi must be broken down with the
finger and one or two drains or drainage tubes must be fully inserted. These
drains are withdrawn gradually during the next 10 days and the closure of the
cavity is checked by sinograms or scanning. The appropriate antibiotics are also
given.