Acute abdomen in the adult

Essentials

  • Decisions on the need for further investigations and on the urgency of treatment, and beginning treatment quickly, as necessary, are of primary importance.
  • Abdominal computed tomography (CT) is a basic investigation of an acute abdomen, unless cholecystitis is suspected, in which case abdominal ultrasonography should be performed.

Aetiology

Table 1. Surgical causes and diagnostic clues for acute abdomen
Cause Diagnostic clues
Appendicitis (Acute appendicitis) Common.
The probability of appendicitis can be assessed using the Adult Appendicitis Score (AAS) calculator https://www.appendicitisscore.com/, for example.
Intestinal obstruction (Intestinal obstruction, paralytic ileus and pseudo-obstruction) Small bowel obstruction is most commonly due to adhesions from previous surgical treatment.The most common cause of large bowel obstruction is a tumour.
Suspect intestinal ischaemia if the patient is in pain despite a functional nasogastric tube.
Intestinal perforation Several hours to several days from symptom onsetOften peritonitis
Mere suspicion of intestinal perforation is an indication for starting antimicrobial treatment.
Further investigations and treatment immediately
Acute cholecystitis (Cholelithiasis) The typical symptom is pain starting after a meal in the right upper abdomen that does not subside during follow-up.
Abdominal ultrasonography is the first-line investigation if acute cholecystitis is suspected.
Acute pancreatitis (Acute pancreatitis) Typically band-like pain predominantly in the left upper abdomenAn increased amylase concentration makes the suspected diagnosis more probable.
Suspect cholangitis and/or biliary pancreatitis if liver values are increased.
If the amylase level is elevated and acute pancreatitis is suspected, CT should preferably be done only after 72–96 hours from the onset of symptoms.
Mesenteric ischaemia The clinical picture may be vague.
In patients over 70, triphasic abdominal CT should be performed, including the arterial phase to facilitate a more specific diagnosis.
In acute mesenteric ischaemia, further treatment must be provided urgently.
Complicated diverticulitis of the colon (Diverticulitis and diverticulosis) The most common site is the sigmoid colon.
Perforation may be either restricted, forming an abscess, or spread to cause generalized peritonitis.
Volvulus The most common site is the sigmoid colon, in the left lower abdomen, but volvulus of the caecum is also fairly common.
Typically drum-like potbelly
Testis torsion (Testis pain) Sore testis tender on palpation particularly in children
Explorative surgery should be readily performed.
Incarcerated hernia Rapid repositioning of the hernia is of primary importance.
If the hernia can be repositioned and no suspicion of irreversible intestinal ischaemia arises, the patient can usually be discharged. Nevertheless, they should be referred for assessment of need for surgery. See also (Hernias in adults).
Table 2. Gynaecological causes for acute abdomen; examples and clues
Cause Diagnostic clue/example
Ectopic pregnancy (Ectopic pregnancy) Pain; referred pain in shoulder. Urine pregnancy test may be negative, rapid serum test is usually positive.
Ovarian origin Ovulation pain, oophoritis, ruptured cyst, torsion of a cyst.
Myoma (Benign gynaecological lesions and tumours) Torsion; necrosis; bleeding into the abdominal cavity, infection
Endometriosis (Endometriosis) Menstrual pain
Table 3. Non-surgical causes for acute abdomen (examples)
Cause Examples
Metabolic disorders
  1. Diabetic ketoacidosis (Diabetic ketoacidosis)
  2. Porphyria (Porphyrias)
  3. Hypertriglyceridaemia (pancreatitis)
  4. Hyperparathyroidism (pancreatitis) (Hypercalcaemia and hyperparathyroidism)
  5. Uraemia
  6. Pain conditions associated with haematological diseases
  7. Haemochromatosis (Haemochromatosis)
  8. Addisonian crisis (Addison's disease and other conditions inducing hypocortisolism)
  9. Mushroom and heavy metal poisonings
Infectious causes
  1. Gastroenteritis (Acute diarrhoeal disease in a traveller)
  2. Inflammatory bowel disease (IBD; (Crohn's disease) (Ulcerative colitis)
  3. Hepatitis (Viral hepatitis)
  4. Perihepatitis
  5. Mononucleosis (Mononucleosis)
  6. Herpes zoster (Herpes zoster)
  7. Pyelonephritis (Urinary tract infections)
  8. Prostatitis, epididymitis, orchitis (Testis pain)
  9. Sepsis (Septicaemia)
Referred pain
  1. Myocardial infarction (Acute coronary syndrome and myocardial infarction)
  2. Pericarditis (Pericarditis)
  3. Pneumonia (Pneumonia)
  4. Pleuritis (Pleural effusions and thoracentesis)
  5. Pulmonary infarction or embolism (Pulmonary embolism)
  6. Spontaneous pneumothorax (Pneumothorax)
  7. Heart failure (hepatic stasis) (Acute heart failure and pulmonary oedema)
  8. Renal calculi (Urinary calculi)
  9. Haematoma of the rectus abdominis muscle
Immunological disorder
  1. Angioneurotic oedema (Hereditary angioedema (HAE) and ACE inhibitor-induced angioedema)
  2. Polyarteritis nodosa (Vasculitides)
  3. Henoch–Schönlein purpura (Henoch-Schönlein purpura)
  4. Allergy
  5. Eosinophilic gastroenteritis, enteritis or colitis

Investigations

History

  • Pain history
  • Any underlying diseases and regular medication
  • History of abdominal surgery
  • Is this a new acute problem or an exceptionally severe exacerbation of prolonged pain?
  • Vomiting, nausea, bladder and bowel function
  • Obstipation is most often chronic. A change in bowel habits is an important symptom.

Clinical examination

  • An always careful general examination
    • Auscultation of the heart and lungs
    • Measurement of blood pressure and heart rate
    • General neurological examination
  • Inspection of the abdomen
    • Form and plumpness of the abdomen
    • Surgical scars
    • Skin changes
    • Hernias (visible or palpable)
  • Palpation of the abdomen
    • Abdominal wall (tender or pain-free, soft or tense suggesting peritoneal irritation, guarding)
    • The location of maximal pain
    • Palpable masses, hernial orifices, tautness and ascites
  • Palpation of the genitals
    • Hernias
    • Pain or swelling of the testes or epididymis
    • Scrotal hydrocele
  • Digital rectal examination
    • Palpable masses, bleeding
    • Prostate: size, consistency, nodules
    • Any faeces in the rectal ampulla, the colour of the faeces

Laboratory tests

  • If the patient is unwell or clearly ill, further investigations should be arranged without waiting for laboratory results.
  • Today, accident and emergency clinics commonly use laboratory packages.
  • It is usually sufficient to do basic blood count with platelet count, CRP, chemical screening of urine, in suspected pancreatitis plasma pancreatic amylase, in suspected cholecystitis ALT, ALP, bilirubin, glucose, sodium and potassium. Also note blood glucose and, as necessary, blood gas analysis.
  • If a cardiac cause is suspected, an electrocardiogram (ECG) and TnI/TnT test should always be taken.
  • In women below 50, hCG should be tested.
  • Normal laboratory results do not exclude conditions such as mesenteric ischaemia; if this is suspected, laboratory results should not be waited for.

Imaging

  • Ultrasound examination
    • The primary examination in the diagnostic workup for acute cholecystitis
    • Ultrasonography (or "sonopalpation") is also useful when performed by a doctor on call (Ultrasonographic examinations).
  • Abdominal CT scan is the primary imaging method in the diagnostic workup of abdominal pain
    • If there is clear suspicion of pancreatitis, to improve the diagnostic results CT should preferably only be performed 72–94 hours after the onset of symptoms.
    • In patients over 70, the possibility of mesenteric ischaemia should be kept in mind and the arterial phase included in imaging..
  • Chest x-ray as necessary
    • Look for pleural effusion, pericarditis or heart failure, pulmonary infections or shadows.

Emergency treatment

  • During the diagnostic investigations, the degree of metabolic disorder should be assessed and fluid therapy should be started before transport to a hospital, unless the distance is very short.
  • Start measuring urine output.
  • A nasogastric tube should be inserted without hesitation if the patient keeps vomiting.

Evidence Summaries

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