An 80 year old man presented to our accident and emergency (A&E) department with a history of severe pain in the right buttock for 15 minutes followed by collapse. He was unconscious for five minutes, and, on regaining consciousness, he was still having pain. On arrival at the hospital, his Glasgow Coma Scale score was 15/15, respiratory rate 20/min, pulse rate 88/min, and blood pressure (BP) 104/60 mm Hg. There were no acute changes on electrocardiography. The only significant past medical history was hypertension and myocardial infarction five years ago.

While in A&E, he started sweating profusely and lost consciousness momentarily. His BP at that time was 60/00 mm Hg and pulse rate 136/min. He recovered spontaneously in the next few minutes without any resuscitation. He still complained of right buttock pain but no abdominal or chest pain. Examination of the hip joint was unremarkable. Both lower limbs were adequately perfused with palpable pulses and there was no sensory or motor deficit. Abdominal examination revealed a huge soft pulsating mass in the umbilical region, with an audible bruit.

In the absence of abdominal pain, we did not consider a bedside ultrasound examination appropriate to confirm a retroperitoneal leak.¹ Since his pulse was 84/min and BP 110/60 mm Hg, an abdominal computed tomography (CT) scan was arranged to confirm the diagnosis of a leaking abdominal aneurysm. The CT scan showed an extensive haematoma in the right perinephric and paranephric regions extending into the right iliac and inguinal regions, associated with a clearly leaking 10.2 cm infrarenal aortic aneurysm (fig 1). While still in the scanner he collapsed again and was transferred directly to theatre.

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Figure 1

 Computed tomography scan (lateral view) showing abdominal aortic aneurysm.

Intraoperatively we found a 10 cm infrarenal abdominal aortic aneurysm with a massive retroperitoneal haematoma extending from the upper abdomen to the whole of the pelvis, more on the right side. Following aortic grafting, the patient made an uneventful recovery and he was discharged on day 9 with no buttock or hip pain.

DISCUSSION

The rupture of an aneurysm is a potentially life threatening complication of a diseased aorta, which may be preceded by leaking of variable duration. If the aneurysm ruptures into an open cavity such as the peritoneum the patient collapses and may even die before reaching hospital. But if the rupture occurs within a contained space such as the retroperitoneum the patient may improve without resuscitation, as in the present case. The classic triad of hypotension, back pain, and pulsatile abdominal mass may be present in only 50% of patients.² The presentation of this disease can often deviate from the classic clinical picture, resulting in erroneous diagnosis that may have lethal consequences.

The reported unusual presentations of leaking or ruptured abdominal aortic aneurysms include renal colic,³ urethral obstruction,⁴ obstruction of the left colon,⁵ testicular pain,⁶ peripheral neuropathy,⁷ hiccoughs,⁸ haematuria,⁹ right inguinal mass,¹⁰ and symptomatic¹¹ or even asymptomatic¹² inguinal hernia. Ijaz and Geroulakos¹³ reported a case of a patient presenting with acute hip pain due to a ruptured internal iliac artery aneurysm. Chronic hip pain has been associated with an unruptured aortic aneurysm cured by elective repair.¹⁴ A ruptured abdominal aortic aneurysm presenting with acute buttock pain has not previously been reported.

The commonest diagnosis considered in an elderly person with hip pain after a fall is a fractured neck of femur. Our patient had pain in the hip before he fell. Common causes of sudden hip pain in elderly people include septic arthritis, acute flare-up of osteoarthritis, and Leriche’s syndrome. It is not unusual for the patients to present with a hip fracture after an episode of collapse irrespective of the cause. Therefore, in our case the presentation was misleading and a failure to examine the non-painful abdomen could have led to a delay in diagnosis with fatal consequences.

The pain in the hip experienced by our patient could be accounted for by the irritation of the posterior cutaneous nerve of the thigh or sciatic nerve at its origin. It is also possible that the retroperitoneal bleeding, depending on its volume and extent, may irritate the ilioinguinal nerve (L1) or the femoral branch of genitofemoral nerve (L1) or the femoral nerve with its branches (L2, 3, 4) or the lateral cutaneous nerve of thigh (L2, 3), which present with groin pain, testicular pain, anterior thigh pain, or lateral thigh pain, respectively.

The present case emphasises the importance of considering the diagnosis of a leaking or ruptured abdominal aortic aneurysm in patients presenting with collapse, regardless of the presenting symptoms.