Abdominal Pain
The
abdominal cavity contains the organs that digest food, filter blood and enable
reproduction, any of which may give rise to abdominal pain. As with chest pain,
patients presenting with a ‘textbook’ collection of symptoms are the exception
rather than the rule.
History
A focused
history should be taken, concentrating on the nature and timing of the pain and
its associations. Most abdominal space relates to food processing, therefore
the relationship of pain to food intake/excretion is important, e.g. pain
related to large or fatty meals suggests
gallstones. Date of last
menstrual period (LMP) is essential information to obtain from any woman of
childbearing age.
Nature of the pain
There are
three common sorts of abdominal pain.
•
Colicky pain: pain that comes and goes in spasms, and is usually the result of
peristalsis failing to move a solid mass, e.g. the ureter attempting to move a
stone to the bladder. The patient may move about, seeking a comfortable
position.
• Peritonism: the sharp, well-localised pain resulting from inflammation of the
parietal (outer) peritoneal surface – peritonitis. The patient lies still to
avoid moving the inflamed surfaces.
• Distension pain results from an organ or bowel being stretched. The pain is poorly
localised and may be felt as central abdominal pain. When the bowel is
distended by gas, it may be tympanic: the abdomen sounds ‘hollow’ when
percussed.
Less common
types of pain are:
•
Mucosal pain: burning pain due to inflammation of the mucosa, e.g. reflux of gastric
acid into the oesophagus, urinary tract infection (UTI), sexually transmitted
infection (STI).
•
Ischaemic pain: poorly localised gnawing/cramping pain caused by inflammation progressing
to ischaemic necrosis, e.g. menstruation, ischaemic bowel.
• Referred pain: pain occurring in a different area, e.g. cardiac ischaemia may be
perceived as abdominal pain. Conversely, pain from within the abdomen may be
perceived elsewhere, e.g. shoulder tip pain from diaphragmatic irritation,
penile pain from renal colic, and back pain from retroperitoneal structures.
To make
things more complicated, a single pathophysiological process may cause
different types of pain simultaneously.
Examination
Inspection
From the end
of the bed: is the patient well/ill/critically ill? Immunosuppressed patients
may appear deceptively well despite significant disease. Also beware patients
with neuropathy, e.g. diabetics who may not experience ‘normal’ pain. Patients
who cannot get comfortable or who are constantly moving are likely to have
colicky pain. Patients who lie very still are likely to have peritonitis.
Palpation, percussion and
auscultation
Poorly
localised general pain is usually felt around the umbilicus, but specific point
tenderness suggests peritonitis. Increased bowel sounds are caused by obstruction;
absent bowel sounds indicate peritonitis. Rectal examination is an important
part of the exami- nation, and stool should be tested for blood.
Investigations
Bedside investigations
•
Blood glucose.
•
Urine dipstick.
•
Urinary βhCG in any woman of childbearing
age.
•
Ultrasound is used by emergency physicians to rule out abdominal aortic
aneurysm or to look for intra abdominal fluid. If the expertise is available,
it may be useful in patients with other diseases, e.g. gallstones.
Laboratory investigations
•
FBC, U+E, LFTs and amylase/lipase in all patients.
•
Arterial blood gases including lactate in sick patients.
•
Group and save/cross-match blood if patient likely to go to theatre.
Imaging
•
An erect chest X-ray detects free air from a perforated bowel.
•
A supine abdominal X-ray (60 CXR) will demonstrate obstruction but is
otherwise unlikely to be helpful.
•
Ultrasound is good for biliary, urinary and gynaecological causes of
pain.
• CT (300 CXR) is very good at demonstrating most abdominal pathology but
is a high dose of radiation.
•
MRI is good for imaging abdominal organs, but is not widely available.
Management
•
Resuscitation and urgent surgical opinion if clinically unwell. Oxygen for all unwell
patients together with observation and monitoring in a suitable clinical area.
•
Intravenous fluids are an important part of resuscitation, but also
replace ongoing fluid losses (Chapter 3). A nasogastric tube keeps the stomach
empty, e.g. if there is bowel obstruction.
•
Analgesia: intravenous morphine with anti-emetic is humane, safe and does not impede
diagnosis. Intravenous or rectal NSAID, e.g. ketorolac, is good for peritoneal
pain and relaxes smooth muscle so is good for colicky pain, although should be
avoided in the elderly.
Disposal: who can go home?
Any patient
who has abdominal pain requiring ongoing morphine needs to be admitted.
Patients who appear well, in whom serious pathology has been excluded, and
whose pain has not recurred after analgesia has worn off, are usually safe to
discharge. Other patients should be reviewed by the relevant surgical team.
