What is the standard diagnostic approach for small bowel obstruction if CT is not available?

• A. Magnetic resonance enterography
• B. Acute abdominal series (AAS)
• C. Abdominal ultrasound
• D. X-ray of the chest

Answer: (B)

The standard diagnostic approach for small bowel obstruction when CT is not available is the acute abdominal series (AAS). An acute abdominal series typically includes a combination of upright abdominal X-rays, supine abdominal X-rays, and often a chest X-ray. This series helps to identify signs of small bowel obstruction, such as dilated bowel loops and air-fluid levels, which are indicative of an obstruction.

In emergency settings, where rapid evaluation is crucial, the AAS provides a quick and efficient way to assess for conditions like small bowel obstruction without the need for more advanced imaging, such as CT, which may not be available in all facilities. The AAS can also provide valuable information about other potential issues, including perforations or free air.

While other imaging methods such as abdominal ultrasound and magnetic resonance enterography can be useful in specific contexts, they are not typically the first-line imaging modalities for small bowel obstruction in an urgent setting. Ultrasound may be more operator-dependent and less definitive in diagnosing obstructions compared to an AAS. Furthermore, chest X-rays, while useful in assessing free air under the diaphragm, do not provide a comprehensive picture of the condition of the bowels. Therefore, the acute abdominal series is the preferred choice when other options are limited.