• Deciding on the urgency of treatment is more important than making an exact diagnosis.
• The first thing to do is to decide whether the patient can return back home or does he/she need referral to a hospital, further investigations or an urgent operation.
• The condition often progresses rapidly and the vital functions may be endangered.

• Rupture of an abdominal aortic aneurysm (Aortic aneurysm and dissection)
• Peritonitis
  • Time should not be spent to examine the patient thoroughly because in most cases an urgent operation is needed, and the cause for the condition is determined in the operation. A delay results in complications and increased mortality. CT scan of the abdominal cavity comes in question if the situation is unclear.
  • If needed, treatment for septic shock should be started with hydration.
• Intestinal obstruction
  • Abdominal pain associated with suspected obstruction that becomes continuous may be a sign of strangulation, which must be operated immediately.
• Abdominal catastrophes
  • Worsening general condition, decreased diuresis, and acute confusion in association with abdominal pain suggest an abdominal catastrophe. For example in pancreatitis these indirect clues are more important than local symptoms that may be misleadingly vague. Notice the possible development of an abdominal sepsis or haemorrhage.
  • Acute intestinal ischaemia following embolization caused by atrial fibrillation, or as sequelae of cardiac surgery. Assess the possibility of chronic ischaemia having become acute. Tenderness to palpation is not in concordance with the pain. Treatment possibilities can be evaluated by CT angiography.
• Dehydration and loss of electrolytes
  • Acute abdomen may quickly result in dehydration and loss of electrolytes. These should be corrected before the possible operation.

• Surgical causes: see table T1.
• Gynaecological causes: see table T2. See (Lower abdominal pain of gynaecological origin)
• Other causes: see table T3.

History

• Analysis of the pain; the patient’s primary diseases and medication
• Is this a new acute problem in a patient or an exacerbation of a prolonged abdominal discomfort?
  • Very abrupt onset of pain may indicate perforation. A more slow development is typical for inflammatory diseases and a slow development of pain suggests a chronic disease, like a tumour.
• The location of referred pain suggests the extent of the pathological process.
  • Pancreatic pain is felt widely in the epigastrium; retroperitoneal irritation resulting from the affection of the entire pancreas causes referred pain in the back. Pain radiating to the neck suggests irritation of the diaphragm.
• Food intolerance and the association of pain with meals may help in the diagnosis
  • Postprandial pain is typical of gastric ulcer and common in cholelithiasis but may be caused by other diseases of the upper gastroinstestinal tract.
• Vomiting suggests obstruction
  • Vomiting of food suggests pyloric stenosis.
  • Vomiting of bile suggests obstruction of the proximal small bowel.
  • Vomiting of faeces suggests of distal ileal or colonic obstruction.
  • Proximal intestinal obstruction causes heavy and abundant vomiting. Vomiting associated with a distal obstruction is milder or may be absent. In this case the clinical picture is dominated by distension.
  • Reflectory vomiting may be associated with severe pain. Toxic vomiting is associated with poisonings and infection-induced toxaemia.
• Obstipation is often chronic. A change in bowel habits is an important symptom and suggests organic disease, either inflammation or tumour.
• Always ask about diarrhoea, blood or mucus in the stools, and pain during defecation.
• Inquire about urinary symptoms: urine retention, oliguria, colour of the urine.

Type of pain and palpation findings

• The pain in acute appendicitis is at first diffuse, shifting and often located mainly in the upper abdomen. It feels deep and dull around the umbilicus, and nausea or vomiting are often present. As the inflammation penetrates the bowel wall the pain becomes parietal (superficial, severe, and localized) and lateralizes in the right lower quadrant. Muscular guarding (defence) develops simultaneously.
• If the appendix is perforated, a local or generalized peritonitis develops and the tension and rigidity of the abdominal wall increases.
• Wave-like, rhythmically changing and paroxysmally disappearing pain is typical of diseases of the bowel as well as of biliary obstruction and ureteral calculi. If the pain becomes continuous strangulation should be suspected.
  • Strangulation is characterized by constant pain, clear muscular guarding, fever, and increasing concentrations of inflammation parameters. Suspected strangulation warrants surgical treatment.
• Extremely rapid onset of pain is typical of ulcer perforation. The abdominal wall becomes rigid in an instant when the chemical peritonitis turns into a bacterial one. In intestinal perforation, the onset of pain is slower: the pain usually reaches maximum intensity in one to two hours.

Physical examination

• General examination
  • Heart and lungs
  • Blood pressure
  • General neurological examination
• Inspection of the abdomen
  • Flat or swollen?
  • Surgical scars
  • Skin changes
  • Hernias (visible or palpable)
  • Visible peristalsis
• Palpation of the abdomen
  • Pain and the location of maximal pain
  • Abdominal wall (soft, or hard suggesting peritoneal irritation?)
  • Palpable masses
  • Sites of hernias
  • Ascites
• Palpation of the genitals
  • Hernias
  • Pain or swelling of the testes
  • Scrotal hydrocoele
• Auscultation of the abdomen
  • A very useful examination
  • Tense bowel sound (obstruction), absent sounds (paralytic ileus), splashing sounds (obstruction)
• Touch per rectum
  • Tumour; bleeding; tenderness indicative of an anal fissure
  • Prostate: size, consistency, nodules
  • Is there faeces in the rectum? The colour of the faeces.

Laboratory examinations

• Of minor importance in patients with acute abdomen
• It is usually sufficient to examine basic blood count with platelets, CRP, dipstick tests for urine, in suspected pancreatitis also urine trypsinogen-2, urine amylase or plasma pancreatic amylase, in suspected cholecystitis also plasma ALT, ALP, bilirubin, blood glucose, sodium and potassium.

Imaging

• Ultrasound examination
  • Diagnostics of acute cholecystitis, abdominal abscesses, aortic aneurysm, gynaecological diseases, fluid in the abdominal cavity
  • Ultrasonography (also called "sonopalpation") performed by the primary care doctor on duty is useful (Ultrasonographic examinations).
• Abdominal CT scan is important in the diagnostics of intense abdominal pain of unclear origin.
  • The radiation burden associated with the use of a CT scan should be kept in mind.
• Plain abdominal x-ray
  • Applicable in situations where a CT scan is not available.
  • Is there air in the abdominal cavity (perforation), are there dilatated bowel segments or fluid levels (obstruction)?
  • The examination cannot, however, be used for reliable exclusion of the aforementioned findings.
• Chest x-ray
  • Look for pleural effusion, pericarditis or heart failure, pulmonary infections or shadows.

ECG

• Always indicated if a cardiac cause is suspected.

• During the initial investigations the degree of metabolic derangement should be assessed and fluid therapy should be started before transport to a hospital, unless the distance is very short.
• Start measuring urine output.
• Insert a nasogastric tube if the patient vomits repeatedly.
• Wide-spectrum antimicrobials should be started simultaneously with induction of anaesthesia when peritonitis and other infections are present, as soon as the working diagnosis is clear.
• The most serious disorders of fluid and electrolyte balance should be corrected before an operation. This should be performed without delay, as the most crucial thing in the management of an abdominal catastrophe is to perform laparoscopy as soon as possible. Physiological saline solution is a suitable infusion fluid.