Differentials
Diverticulitis
SIGNS / SYMPTOMS
Severe constipation; abdominal pain is more common and typically localises to the left lower quadrant.
No pulsatile abdominal mass on clinical examination. Instead, abdominal or perirectal 'fullness' may be appreciated. Fever is possible.[83]
INVESTIGATIONS
Leukocytosis may be present.
CT scan will demonstrate a normal-calibre aorta and possibly diverticula, inflammation of the pericolic fat or other tissues, bowel-wall thickness >4 mm, or a peridiverticular abscess.[83]
Ureteric colic
SIGNS / SYMPTOMS
Severe abdominal pain that starts in the flank and radiates anteriorly to the groin.
Associated with nausea, emesis, haematuria, dysuria, and urinary frequency or urgency.[84]
Men aged >55 years presenting with ureteric colic should be considered to have a leaking/ruptured AAA until proven otherwise.
INVESTIGATIONS
Urinalysis positive for blood and may demonstrate crystals and/or evidence of infection.
Ultrasound and CT scan will demonstrate a normal-calibre aorta and possibly ureteral or renal stones.[84]
Irritable bowel syndrome (IBS)
SIGNS / SYMPTOMS
Intermittent abdominal discomfort with flares lasting 2-4 days.
Associated symptoms may include bloating, stool frequency, and abnormal defecation.
Women aged 20-40 years are affected more often than men.
General examination is usually normal, although some patients may appear anxious. There may be poorly localised abdominal tenderness to palpation.[85]
INVESTIGATIONS
Imaging modalities are often inconclusive, but will demonstrate a normal-calibre aorta.
Inflammatory bowel disease
SIGNS / SYMPTOMS
Abdominal pain is often 'crampy' and left-sided. Patients typically suffer from diarrhoea (bloody and non-bloody), urgency of defecation, and tenesmus.
Extra-intestinal manifestations are common in Crohn's disease.
Abdominal examination may demonstrate abnormal bowel sounds, detection of an abdominal mass, and pain on palpation. Mucocutaneous lesions may be visible. Perianal fistulae, fissures, or abscesses may be present on rectal examination.[86]
INVESTIGATIONS
Anaemia is common.
Ultrasound or CT scan will demonstrate a normal-calibre aorta.
Endoscopic evaluation with biopsy shows typical lesions of ulcerative colitis or Crohn's disease.[86]
Appendicitis
SIGNS / SYMPTOMS
Pain is typically periumbilical with localisation to the right lower quadrant.
Associated nausea, emesis, and anorexia are common.
Patients are classically febrile with tenderness in the right lower quadrant on abdominal examination.
INVESTIGATIONS
Leukocytosis and sterile pyuria on urinalysis is common.
Ultrasound or CT scan will demonstrate a normal-calibre aorta with an inflamed appendix or evidence of perforation.
Ovarian torsion
SIGNS / SYMPTOMS
Women suffer sudden, continuous, non-specific pain in the lower abdomen; nausea and emesis are common. Patients may demonstrate fever on clinical examination, and an adnexal mass may be palpable.[87]
INVESTIGATIONS
Leukocytosis may be present. Ultrasound will demonstrate a normal-calibre aorta and possibly reduced or absent adnexal vascular flow.[87]
Gastrointestinal (GI) haemorrhage
SIGNS / SYMPTOMS
Patients presenting with haemorrhagic shock may mimic aortic rupture. A history of previous GI bleed, haematemesis, melaena, or bright red blood per rectum is common.
Historical risk factors for GI malignancy or peptic ulcer disease may be elicited.
On rectal examination gross blood may be visible, or coffee ground haematemesis may be returned with nasogastric tube placement.
INVESTIGATIONS
Stool is likely to be guaiac positive.
Endoscopic evaluation may demonstrate the luminal bleeding source along with mucosal ulcerations, polyps, or tumour.
Ultrasound or CT scan will demonstrate a normal-calibre aorta.
Mesenteric artery aneurysms/acute occlusion
SIGNS / SYMPTOMS
Acute embolic or thrombotic occlusion of the splanchnic vessels may result in acute excruciating mid-abdominal pain with few early physical findings.
Patients typically suffer unremitting, intense mid-abdominal pain with nausea and vomiting that might be accompanied by explosive diarrhoea.
Most splanchnic artery aneurysms are asymptomatic until rupture.[88]
INVESTIGATIONS
Leukocytosis, haemoconcentration, and systemic acidosis are common with acute splanchnic vessel occlusion. Elevated levels of serum amylase, inorganic phosphorus, creatinine phosphokinase, and alkaline phosphatase may accompany frank bowel infarction.
Angiography is diagnostic and potentially therapeutic in the case of vascular occlusion.
Ultrasound and CT scan will demonstrate a normal-calibre aorta and will diagnose any splanchnic artery aneurysms.[88]
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