Acute Abdomen Flashcards
What is an acute abdomen?
The ‘acute abdomen’ is defined as a sudden onset of severe abdominal pain developing over a short time period. It has a large number of possible causes and so a structured approach is required.
Briefly discuss acute abdomen: bleeding
The most serious cause of intra-abdominal bleeding is often the ruptured abdominal aortic aneurysm, which requires swift referral to the vascular team and immediate surgical intervention.
Other common causes usually involve a slower rate of bleeding, but with urgent surgery still required, include ruptured ectopic pregnancy, bleeding gastric ulcer and trauma.
These patients will typically go into hypovolemic shock. Clinical features include tachycardia and hypotension, pale and clammy on inspection, and cool to touch.
Briefly describe acute abdomen: perforated viscus
Peritonitis is the inflammation of the peritoneum, and a generalised peritonitis is most commonly caused by perforation of an abdominal viscus.
The causes of perforation are broad but include peptic ulceration, small or large bowel obstruction, diverticular disease and inflammatory bowel disease.
Patients with a generalised peritonitis present will often lay completely still (not to move their abdomen) and look unwell; this is especially important when compared to a renal colic, whereby patients are constantly moving and cannot get comfortable.
On examination, they will show signs of:
- Tachycardia and potential hypotension
- A completely rigid abdomen with percussion tenderness
- Involuntary guarding
- Reduced or absent bowel sounds, suggesting the presence of a paralytic ileus
Briefly describe acute abdomen: ischaemic bowel
Any patient who has severe pain out of proportion to the clinical signs has ischaemic bowel until proven otherwise. They are often acidaemic with a raised lactate and physiologically compromised.
Patients will often complain of a diffuse and constant pain, however the examination can often otherwise be unremarkable. Definitive diagnosis is via a CT scan with IV contrast, with early surgical involvement.
Briefly describe acute abdomen: colic
Colic is an abdominal pain that crescendos to become very severe and then goes away completely. The most common types of colic are seen in biliary colic, ureteric colic and bowel obstruction.
Briefly describe acute abdomen: peritonism
Peritonism (not peritonitis) refers to the localised inflammation of the peritoneum, usually due to inflammation of a viscus that then irritates the visceral (and subsequently, parietal) peritoneum.
This leads to patients stating that their abdominal pain starts in one place (irritation of the visceral peritoneum) before localising to another area (irritation of the parietal peritoneum) or becoming generalised.
The classic example of this is acute appendicitis, with the pain migrating from the umbilical region to the right iliac fossa
Give examples of differentials causing RUQ, LUQ, RLQ, LLQ, epigastric and peri-umbilical
What investigations should be orered for acute abdomen?
Note: laboratory
- Urine dipstick
- For signs of infection or haematuria ±MC&S
- Include a pregnancy test for all women of reproductive age
- Arterial Blood Gas
- Useful in bleeding or septic patients, especially for the pH, pO2, pCO2, and lactate for signs of tissue hypoperfusion, as well as a rapid haemoglobin level
- Routine bloods
- FBC, U&Es, LFTs, CRP, amylase
- Do not forget a group & save (G&S) if the patient is likely to need surgery soon
- Blood cultures
- If considering infection as a potential diagnosis
What investigations should be ordered for acute abdomen?
Note: imaging
- Erect chest plain film radiograph (eCXR)
- For evidence of free abdominal air or lower lobe lung pathology
- Ultrasound
- Kidneys, ureters, and bladder (‘KUB’)- can check for hydronephrosis and cortico-medullary differentiation
- Biliary tree and liver- can check for the presence of gallstones, gallbladder thickening, or duct dilatation
- Transvaginal- for suspected tubo-ovarian pathology
- CT imaging of the abdomen, often best discussed with a senior depending on the suspected underlying diagnosis if required
Briefly describe the management of an acute abdomen
The definitive management of acute abdomen depends largely on the cause. However, a good initial management plan includes core points, regardless of the underlying aetiology.
These include intravenous access, nil-by-mouth (NBM) status set, analgesia +/- antiemetics, initial imaging, VTE prophylaxis, urine dip, bloods. If the patient is unwell, consider a urinary catheter and/or nasogastric tube if necessary, and start intravenous fluids and monitor fluid balance.
