Teaching Case

A 48-year-old female pedestrian was struck by a motor vehicle travelling at approximately 50 mph. Her pelvis was immobilised at the scene due to a high clinical suspicion of fracture(s). The patient was haemodynamically stable and her haemoglobin was 10.6 g/L at the time of her CT scan.

Bilateral adrenal enlargement noted on the initial CT scan -with the left adrenal gland being larger. High attenuation material seen in both adrenals, consistent with acute bilateral adrenal haematomas. There was also peri-adrenal stranding in keeping with retro-peritoneal haemorrhage. The enlarged right adrenal abutted the IVC. The adrenals were of variable density on contrast enhanced phases relative to hepatic and splenic parenchyma.

Multiple bilateral pelvic fractures are noted involving the: sacrum, acetabuli, pubic rami and symphysis pubis. Pelvic haematomas secondary to the fractures and a low attenuation subcapsular splenic haematoma was also noted.

Follow-up findings of the left adrenal were in keeping with normal involutional changes of a haematoma. The residual central high density thrombus was smaller and of lower density. In contrast, the right adrenal gland was diffusely bulkier, but of lower density than on the initial scan consistent with an expanding haematoma.

Adrenal haemorrhage secondary to blunt abdominal trauma is typically unilateral and right-sided, [1-3] unlike this case which was bilateral with more substantial bleeding in the left adrenal gland. There are a number of causes of bilateral, atraumatic adrenal haemorrhage, including meningococcal septicaemia (the Waterhouse-Friderichsen syndrome) [4]

The estimated incidence of bilateral adrenal haemorrhage detected on CT scan after blunt abdominal trauma in three large case series ranged from 0.1-0.3%. [1-3] However, the true incidence is likely to be higher, as adrenal haemorrhage is often asymptomatic and undetectable without imaging. It remains important to identify adrenal haemorrhage even if patients are asymptomatic. For example, an enlarged right adrenal gland can compress the inferior vena cava and increase the risk of thrombosis [1] and bilateral haemorrhage can cause acute adrenal insufficiency, adrenal crisis and even death. [5, 6]

The pathophysiology of traumatic adrenal haemorrhage is not fully understood, but is likely multi-factorial. Two possible explanations that have been proposed: (i) rupture of small vessels due to deceleration of organs; and (ii) direct compression of the kidneys – particularly of the right adrenal between the liver and spine. [5]

An abdominal CT scan without intravenous contrast is the investigation of choice for patients with suspected traumatic adrenal haemorrhage. All phases of scanning may show enlarged adrenals and peri-adrenal fat stranding, but the diagnosis of haemorrhage can be made conclusively with an unenhanced CT scan. [4] The finding of high attenuation, e.g. in the range of 50-90 Hounsfield units, on an unenhanced CT scan is diagnostic of an acute adrenal haematoma, but will decrease over time. [2,4,7]

Traumatic adrenal haemorrhage is accompanied by other significant injuries in more than 95% of cases, with the most common being haemo and/or pneumothorax and hepatic and/or splenic injuries. [1-3]. If adrenal haemorrhage is detected, it is therefore important to actively search for associated pathology and remain clinically vigilant for potential complications of adrenal haematomas. For example, the possibility of an adrenal crisis is increased and should be managed promptly with corticosteroids if required.

The majority of patients with adrenal haemorrhage are asymptomatic and can safely be treated with conservative management. In a minority of cases ongoing adrenal haemorrhage may require embolisation or surgical intervention to achieve haemostasis. In this case, bilateral adrenal haemorrhage were associated with a small splenic haematoma, the patient was managed conservatively, did not develop an adrenal crisis and made a full recovery.