Peritoneal pain The parietal peritoneum, but not the visceral peritoneum, is innervated by pain fibres, which pass to the spinal cord along the segmental nerves.. Thus, inflammation of t
Trang 1Acute abdominal pain
Case
A 72-year-old previously well woman presents
with a 12-hour history of severe epigastric pain
radiating to her back There has been associated
nausea and vomiting, but no fevers, jaundice or
rigors Until the onset of pain her bowel habit
was unchanged and there were no complaints of
abdominal distension She has had no significant
previous illness or surgery She does not drink
alcohol and does not smoke cigarettes There was a
strong family history of gallstones with her mother
and two sisters having had surgery for gallstones
Examination revealed a woman that was in
some distress with pain, was afebrile with a pulse
of 92 beats/minute and was normotensive She
was not pale or jaundiced There was tenderness
across the upper abdomen with mild distension
Bowel sounds were normal and the remainder
of the clinical examination was normal A
clinical diagnosis of acute cholecystitis or acute
pancreatitis was made
A plain abdominal x-ray and a plain chest x-ray
were normal Routine bloods including amylase
and lipase were performed Results, with normal
range in brackets, are shown in the table below
These results confirmed a diagnosis of acute
pancreatitis with a probable biliary origin An
abdominal ultrasound revealed multiple small
stones in the gallbladder, with a common bile duct diameter of 7 mm (normal < 6 mm) This confirmed the aetiology as gallstones
She was treated by fasting, adequate parenteral analgesia, intravenous fluid resuscitation and deep venous thrombosis prophylaxis There was no indication for antibiotics or nasogastric decompression of the stomach Over the next 48 hours she improved clinically with much less pain and stable observations Repeated assessment of the factors for severity of pancreatitis revealed only one positive factor; her age, which is over 55 years
By the fourth day the pain had completely resolved and she was commenced on a fluid diet
A laparoscopic cholecystectomy was performed the following day with the routine operative cholangiogram revealing two filling defects (5 mm)
in a slightly dilated (8 mm) common bile duct A transcystic stent was inserted to lie across the biliary ampulla and the cholecystectomy was completed The stent facilitated an endoscopic retrograde cholangiopancreatography and sphincterotomy, which was performed the following day with the removal of the common bile duct stones She was discharged the following day well
Introduction
Acute abdominal pain is a common ailment experienced by most from time to time Some episodes of acute abdominal pain resolve spontaneously with analgesia and a period of observation Acute abdominal pain is a source of anxiety as patients know that it may be the first sign of
a serious clinical problem, which may be life-threatening, and that surgery may be the only solution Acute abdominal pain is defined as recent onset pain of such severity that medical attention
is usually sought shortly after its onset For the purpose of definition, pain persisting for up to
4
Sodium 134 (130–144) Bilirubin 34 (5–20)
Potassium 3.9 (3.6–4.5) AST 320 (12–35)
Creatinine 110 (75–110) ALT 309 (12–35)
Urea 12 (6.5–10) GGT 102 (15–50)
Haemo-globin
122 (120–135) ALP 145 (70–120)
White cell
count
14 500
(5000–11 000)
Amylase 4500 (< 120) Platelets 340 (150–400) Lipase 12 910 (< 150)
Trang 238 Clinical gastroenterology: a practical problem-based approach
3 months is classified as acute; pain lasting more
than 3 months is classified as chronic and is
considered in Chapters 5 and 6
Mechanisms Of Abdominal Pain
Visceral pain
The abdominal organs are not sensitive to touch
Gentle direct palpation during a laparotomy or a
herniorrhaphy performed after infiltration of the
anterior abdominal wall with local anaesthesia
causes no distress However, distending or
stretching the bowel at these operations causes
vague abdominal discomfort, which is mediated
by splanchnic sympathetic nerves This visceral
pain is poorly localised, usually to the midline
Distension or stretching of the capsule of the liver,
as occurs in acute hepatitis, also causes pain
Peritoneal pain
The parietal peritoneum, but not the visceral
peritoneum, is innervated by pain fibres, which
pass to the spinal cord along the segmental nerves
Thus, inflammation of the parietal peritoneum
causes abdominal pain that is localised to the
inflamed area Abdominal guarding occurs due to
a reflex contraction of abdominal wall muscles in
response to a noxious stimulus to the pain fibres of
the same dermatome
Referred pain
Referred pain is pain experienced at a distance from
the area of damage The best known example is
pain felt at the tip of the shoulder, when the parietal
peritoneum on the inferior surface of the diaphragm
is irritated by, for example, blood or gastric juice
This area of peritoneum is innervated by somatic
nerves (C4) as is the skin over the tip of the shoulder
Pathological Causes
There are certain similarities in the pattern and type
of pain that occur when a given pathological process
affects different organs within the abdominal
cavity An understanding of these various patterns
is important, as it provides a basis for interpreting
the clinical effects and consequences of many of
the conditions that result in acute abdominal pain
Important pathological causes of abdominal pain
are acute inflammation, obstruction, ischaemia
and increased pressure within a solid organ Not
uncommonly, an organ is affected by more than
one pathological process during the evolution
of an illness An example is acute appendicitis,
where the initial process is obstructive and the
subsequent one is inflammatory
Acute inflammation
The common processes leading to intraabdominal inflammation are bacterial invasion, chemical irritation and ischaemia The features of pain caused by inflammation depend on whether the organ it affects is intraperitoneal or extraperitoneal Inflammation of intraperitoneal organs
Acute inflammation of an intraperitoneal organ results in localised peritonitis if the process involves its peritoneal surface Ensuing pain results from irritation of pain receptors in the parietal (but not visceral) peritoneum This pain is described as peritoneal in type Peritoneal pain is well localised; the patient can usually indicate its position with the palm of a hand or with the tip of a finger The pain is typically aggravated by sudden movement, such as coughing, and minimised
by avoidance of movement, such as lying still
or using the diaphragmatic rather than the abdominal muscles for respiration As an example, involvement of a segment of bowel with Crohn's disease, a transmural inflammatory process, can result in peritoneal pain Inflammation restricted
to bowel mucosa, as typically occurs in ulcerative colitis, does not result in peritoneal pain (Ch 12)
A more common example of acute inflammation
as the sole process resulting in peritoneal pain is acute salpingitis (inflammation of the fallopian tube) The pain is caused by acute inflammation secondary to a bacterial infection such as
gonorrhoea or Chlamydia and usually develops
over a period of hours
Intraperitoneal inflammation may result from an obstructive process A well-known example is acute appendicitis The early pain of acute appendicitis is periumbilical and due to obstruction of the appendix (visceral pain) As the inflammation becomes transmural, the pain becomes peritoneal in type and moves to the right iliac fossa over the inflamed organ
Intraperitoneal inflammation may be a consequence of perforation of a hollow viscus Leakage of visceral contents causes pain by chemical irritation The degree of irritation is dependent on the nature of the leaking material Thus, leaking gastric juice from a perforated peptic ulcer causes marked irritation By contrast, gas, which may be the main constituent of the material leaking from a perforated sigmoid diverticulum, causes less irritation and less pain
As the inflammation in response to chemical irritation is rapid, the onset of the pain is rapid
or instantaneous Whether the pain is localised
or generalised depends on the degree of soilage
Trang 34 Acute abdominal pain
Maximum irritation is usually around the site of
leakage (e.g epigastric for a perforated peptic ulcer
and in the left iliac fossa for a perforated sigmoid
diverticulum) Other causes of perforation include
ischaemia that has progressed to infarction (e.g
gangrenous cholecystitis) and malignancy (e.g
perforated gastric cancer)
With ischaemic bowel, the peritoneal
component of the pain is usually a relatively minor
component of pain The major component, which
is severe, is visceral in type (see below) Peritoneal
inflammation occurs only if the ischaemia of the
bowel is transmural The most sensitive component
of the bowel wall to ischaemia is the mucosa On
the other hand, the pain resulting from a splenic
infarct is predominantly peritoneal in type
Inflammation of non-intraperitoneal organs
Acute pancreatitis results in chemical inflammation
of retroperitoneal tissues and irritation of visceral
nerves The pain is constant, severe, and not
aggravated by movement If the inflammatory
process of acute pancreatitis spreads anteriorly,
the patient also complains of a peritoneal pain
Obstruction
If the bowel is obstructed, the pain is colicky
unless there is some further complication such
as gangrene, secondary infection or perforation,
when the pain becomes continuous The colicky
pain is severe in degree and midline in position;
it is usually epigastric if the organ originated
from the foregut (down to the second part of the
duodenum), periumbilical if the organ originated
from the midgut (down to the splenic flexure of
the colon), and hypogastric if the organ originated
from the hindgut (left colon and rectum) The pain
of biliary obstruction (gallbladder and extrahepatic
biliary tree), described as biliary colic, is constant
rather than colicky in nature
The onset of the pain of obstruction is related to
the speed of obstruction If the occlusion is sudden
(e.g gallbladder outlet obstruction due to a stone
or a volvulus of the sigmoid colon), the onset of
pain is over minutes If the occlusion is slowly
progressive (e.g obstructing cancer of the sigmoid
colon), the onset of the pain is much slower If the
occlusion is intermittent (e.g gallbladder outlet
obstruction due to a stone), the pain is intermittent
Obstruction of the gastrointestinal tract may
be due to an intraluminal lesion (e.g bezoar
or calculus), a mural lesion (e.g a benign or
malignant tumour or a fibrous stricture), or an
extraluminal lesion (e.g a fibrous band or the neck
of a hernia) The obstruction can occur anywhere
along the lumen of the gastrointestinal tract The obstruction results in proximal distension and stasis If the obstructed bowel is open-ended proximally, the distension progresses proximally
If the organ lumen has a ‘blind end’, the luminal contents and the organ itself can become infected (e.g cholecystitis, cholangitis and appendicitis) Progressive distension can lead to venous obstruction followed by arterial obstruction, and then gangrene and perforation (e.g closed loop obstruction of bowel)
Ischaemia
Inadequate blood flow results in tissue death (infarction) Arterial ischaemia is caused by an arterial embolus, a thrombosis or a low cardiac output state The pain is of sudden onset, over a few minutes, severe and continuous (visceral pain) The process of venous ischaemia is slower in onset Consequently, the pain is slower in onset Otherwise, it has the same characteristics as the pain
of arterial ischaemia When the venous occlusion is complete, as occurs to a loop of bowel strangulated
by the neck of a hernia, the tissue drained by the occluded vein becomes oedematous and engorged with blood, and arterial obstruction and thrombosis may follow (Fig 4.1) With larger vein occlusion by a thrombus (e.g the portal or the superior mesenteric vein, or occasionally with a volvulus of bowel), the occlusion may be incomplete and alternative venous drainage may save the tissue from necrosis Acute major mesenteric venous obstruction causes transudation of fluid into the peritoneal cavity, which may be evident as ascites
Tension in a solid organ
Sudden swelling in solid organs results in a pain of visceral type due to stretching of the capsule of the organ The pain is dull and constant The severity of
Figure 4.1 Gangrenous small bowel due to a
strangulated femoral hernia