AXR in abdominal pain

What?

A 52-year-old male presented to the emergency department (ED) with a 1 day history of severe central abdominal pain and nausea. An AXR was undertaken as part of his care in the ED that demonstrated distended bowel loops in the upper abdomen leading to a diagnosis of possible bowel obstruction and a referral to the surgical team.

So what?

AXR’s are not indicated routinely for the investigation of abdominal pain (Wyatt et al 2012). There are certain circumstances where they may be of diagnostic benefit, for example where there is a suspicion of intestinal obstruction, sigmoid volvulus, toxic megacolon or urinary calculi (Wyatt et al 2012).

A study conducted by Gerhardt et al (2005) aimed at developing a clinical guideline for the evaluation of non-specific abdominal pain, found that AXR combined with clinical exam and laboratory findings, had a sensitivity as low as 56% and specificity of 81% in predicting the need for urgent intervention within 24 hours.

For the diagnosis of bowel obstruction however, AXR’s combined with clinical examination have been demonstrated to have a sensitivity of 74%, with clinical examination alone having a 57% sensitivity (van Randen et al 2011). An earlier study had previously demonstrated that AXR had a sensitivity of 90.8% and a positive predictive value of 80.2% for bowel obstruction (Bohner et al 1998). Bohner et al (1998) also reported that the six clinical variables with the highest sensitivity were:

  • Distended abdomen
  • Increased bowel signs
  • History of constipation
  • Previous abdominal surgery
  • Age >50
  • Vomiting

The gold standard investigation is computed tomography (CT) that has a reported sensitivity of 100% and also allows the accurate diagnosis of the location of the obstruction (Gans et al 2012). The utilisation of CT as a first line investigation does impact the healthcare economy (with increased costs) and also exposes the patient to around 10mSv radiation rather than the 0.7mSv of an AXR (Gans et al 2012).

Now what?

Routine use of AXR in the evaluation of patients with abdominal pain is not recommended or required. The evidence is perhaps best summarised by Smith and Hall (2009), who state that the plain AXR should not be used indiscriminately as a routine investigation in undifferentiated patients presenting with abdominal pain.

However, there are a limited number of circumstances where an AXR is indicated (e.g. suspected bowel obstruction) and maybe beneficial when combined with clinical examination. CT is the gold standard but is associated with increased costs and radiation exposure to the patient.

Rob Fenwick 

 

References

Bohner, H., Yang, Q., Franke, C. (1998) Simple data from history and physical examination help to exclude bowel obstruction and to avoid radiographic studies in patients with acute abdominal pain. European Journal of Surgery. Volume 164, pp777-84.

Driscoll, J. (2007) Practicing clinical supervision: a reflective approach for healthcare professionals (2nd edition). Elsevier. Edinburgh.

Gans, S. L., Stoker, J & Boermeester, M. A. (2012) Plain abdominal radiography in acute abdominal pain; past, present, and future. International Journal of General Medicine. Volume 5, pp525-33.

Gerhardt, R. T, Nelson, B. K., Keenan, B., et al. (2005) Derivation of a clinical guideline for the assessment of nonspecific abdominal pain: the Guideline for Abdominal Pain in the ED Setting (GAPEDS) phase 1 study. American Journal of Emergency Medicine. Volume 23, pp709-17.

Smith, J. E & Hall, E. J. (2009) The use of plain abdominal x rays in the emergency department. Emergency Medicine Journal. Volume 26, pp160-63.

van Randen, A., Lameris, W., Luitse, J. S., Gorzeman, M., Hesselink, E. J., Dolmans, D. E., Peringa, J., van Geloven, A. A., Bossuyt, P. M., Stoker, J., Boermeester, M. A for the OPTIMA study group. (2013) The role of plain radiographs in patients with acute abdominal pain at the ED. American Journal of Emergency Medicine. Volume 29, number 6, pp582-9.

Wyatt, J., Illingworth, R., Graham, C & Hogg, K. (2012) Oxford handbook of emergency medicine (4th edition). Oxford University press. Oxford.

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