Abdominal Pain - 1 or MORRISSEY HAS BINGO WINGS

Structure And Function/Approach To Diagnosis
9.10.06

Abdominal pain
• Common, often trivial.
• But can be acute and severe pain.
• Gangrene/perforation of gut occur rapidly after interruption of blood supply.

3 types of abdominal pain:
• Visceral pain.
• Parietal pain.
• Referred pain.

Nerve fibres
• 2 types:
-Myelinated A-δ fibres (skin and muscle).
-Unmyelinated C fibres (mesentery, peritoneum and viscera).
• Nociception from abdominal viscera conveyed by C fibres - dull pain.

Visceral pain
• Noxious stimuli trigger visceral nociceptors.
• Pain dull and poorly localised in midline epigastrium, periumbilical region or lower midabdomen.
• Pain cramping/burning/gnawing.

Position of pain and anatomy
• Foregut:
-Stomach.
-Duodenum.
-Hepatobiliary system.
-Pancreas.
• Midgut:
-Small bowel.
-Ascending colon.
-Appendix.
• Hindgut:
-Hepatic flexure → rectum.
-Reproductive organs.

Parietal pain
• Noxious stimulation of parietal peritoneum.
• More intense and localised e.g. course of appendicitis.
• Aggravated by movement/coughing.
• Patient lies still with knees up.

Referred pain
• Pain felt in areas remote to diseased organ.
• Convergence of visceral afferent neurones with somatic afferent neurones from different anatomic region on second-order neurones in spinal cord at same spinal segment.
• Usually well-localised.

History
• 70% diagnoses can be made based on history.
• 90% diagnoses can be made based on history and physical examination.
• Expensive tests often confirm what is found during history and examination.

Age important in diagnosis.

Key points
• Chronology (time course).
• Location/quality.
• Radiation.
• Associated symptoms.

Location of abdominal pain clue to cause.
Can get combination of visceral, somatoparietal and referred pain.

Pain intensity
• Difficult to measure.
• Depends on individual, setting, past experience, personality and cultural differences.
• Not particularly reliable diagnostic clues.

Aggravating/alleviating factors e.g.
• Peritonitis - lie motionless.
• Renal colic - writhe to try and get comfortable.
• Duodenal ulcer - often helped by meals.
• Gastric ulcer/chronic mesenteric ischaemia - worse with eating.

Associated symptoms and review of systems
• Fever/night sweats.
• Weight loss, myalgias, arthralgias.
• Anorexia, nausea, vomiting, diarrhoea, constipation.
• Jaundice.
• Urinary frequency, urgency, discomfort.
• Sexual activity, contraception, LNMP and pregnancy.

PMH and SH
• ?Previous episodes e.g. renal stones, inflammatory bowel disease.
• Generalised diseases e.g. scleroderma, lupus, nephritic syndrome.
• Family history.
• Social history.

Examination - general points
• History much more important.
• Elderly less likely to show signs of peritoneal irritation.
• Systemic examination as important as abdominal examination.

Systemic examination
• Appearance.
• Breathing pattern.
• Position in bed and posture.
• Degree of discomfort.
• Pulse - tachycardia important sign.
• Blood pressure.
• Chest examination.
• Cardiovascular examination.
• Features of shock.
• Features of underlying systemic disease.

Inspection
• Distension.
• Scars.
• Hernias.
• Bruises.
• Visible hyperperistalsis.

Palpation
• Degree of tenderness, guarding, rigidity.
• Palpable mass.
• Hernia orifices should be examined.

Auscultation
• Bowel sounds:
-Absent = possible peritonitis.
-Tinkly sounds = possible bowel obstruction.

Investigations - laboratory
• U+Es.
• Hb, WCC.
• LFTs.
• Amylase.
• Urinalysis.
• Pregnancy test.

Radiology
• Chest X-ray and plain abdomen X-ray.
• Ultrasound.
• CT.
• MRI.

Learning points
• 3 main types of abdominal pain.
• Knowledge of basic neuroanatomy.
• Patterns of common causes of abdominal pain.
• Important points in history of abdominal pain.