This article is part of the operation script for grafting an abdominal aortic aneurysm. The article can be used on its own, or to go to the next part of the operation, click on NEXT PART OF THE OPERATION at the bottom of this page.
AORTIC ANEURYSM 090 - CLINICAL PRESENTATION
Enlargement of an aneurysm may not cause any symptoms.
- This applies particularly when the aneurysm is still small (under 5cm.).
- Screening for asymptomatic aneurysms is under discussion.
Steady enlargement of the aneuysm.
- The symptoms are usually related to pressure on local structures.
- Enlargement anteriorly may give chronic abdominal pain.
- Enlargement laterally may give loin pain mimicking renal disease.
- Enlargement posteriorly may give back pain mimicking chronic spinal disease.
Leakage of the aneurysm
- There is an initially minor infiltration of local retroperitoneal tissues.
- This occurs particularly on the left side, where the aorta runs.
- These tissues and the abdominal wall will have a tamponading effect.
- Induction of anaesthesia will lead to relaxation of the abdominal wall and loss of the tamponade.
- The surgical team needs to be completely ready to operate before anaesthesthia starts.
- There is likely to be a rapid crescendo of pain as the tissues are infiltrated with blood.
- Vasoconstriction and haemodilution may compensate for the loss of blood from the circulation.
- This may be sufficient to keep the patient normotensive for some hours and delay recognition of the diagnosis.
- The consumption of clotting factors may make the blood less likely to clot, aggravating the bleeding.
- Clotting factors usually need to be provided during operations for leaking aneurysms.
Rupture of the aneurysm
- Rupture into the peritoneal cavity is likely to lead to a fatal loss of circulating blood volume.
Rupture into the vena cava or the left renal vein
- This produces a lethal arterio-venous fistula.
Diagnosis of a leaking aneurysm.
- This classically depends on the presence of:
- Abdominal pain.
- Hypovolaemia and anaemia.
- An expansile swelling in the upper abdomen.
Differential diagnosis of a leaking aneurysm includes:
- Perforated peptic ulcer.
- Faecal peritonitis.
- Infarcted bowel.
- Acute pancreatitis.
Diagnostic pitfalls.
- An aneurysm in a shocked patient with an acute abdomen is neither palpable nor pulsatile.
- Where the aneurysm is an incidental finding.
Inflammatory aneurysm.
- In about 2% of cases there is an intense inflammatory process in the retroperitoneal tissues surrounding the aneurysm.
Aorto-duodenal fistula.
- The fourth part of the duodenum is particularly prone to the development of an aorto-duodenal fistula.
- This may be associated with an inflammatory aneurysm.
- The fistula usually presents with recurrent haematemesis and melaena.
- Clinically it imitates a bleeding peptic ulcer, a condition which happens also to be relatively common in patients with aortic aneurysms.
Ureteric obstruction.
- This may also occur, due to compression by the aneurysm.
