Synopsis
Choose imaging by the anatomical question, clinical urgency and patient-specific risks, and explain why the selected technique and protocol are more useful than a generic request for a scan.
- Write the clinical question first: localisation, obstruction, perforation, bleeding, vascular compromise or staging require different imaging choices.
- Plain radiography is a selective tool; a normal film does not comprehensively exclude serious intra-abdominal disease.
- Ultrasound is valuable for focused biliary, urinary, pelvic or vascular questions but can be limited by gas, habitus and operator access.
Key red flags
A suspected ruptured abdominal aortic aneurysm requires immediate vascular discussion and bedside assessment; an inconclusive ultrasound must not be treated as exclusion.
A deteriorating patient requires an explicit transfer plan with suitable staff, monitoring, oxygen and equipment. The radiology department is not a resuscitation team merely because a scan has been accepted. Communicate haemodynamic or respiratory concerns directly and agree who remains responsible during transport and the procedure.
Reasoning priorities
Answer selected questions quickly when a film is likely to influence the immediate pathway.
Plain films provide a projection rather than complete abdominal anatomy. They may demonstrate useful gas, bowel or thoracic findings, but absence of an abnormality cannot exclude every perforation or obstruction. A preoperative chest radiograph is not routinely recommended by NG45. Choose a film for its specific expected contribution rather than making it an automatic prerequisite for CT.
Worked reasoning
A stable adult has episodic right upper quadrant pain. Ultrasound identifies gallbladder stones and a dilated common bile duct but no visible duct stone; liver tests are abnormal. There is no current shock or clinical cholangitis.
- Identify the remaining question: whether a common bile duct stone is present, rather than whether gallbladder stones exist. The ultrasound has answered one question and left another unresolved.
- Review the symptoms and blood-test pattern and consider MRCP under CG188 because ultrasound has not shown a duct stone despite duct dilatation or abnormal liver tests. Explain the purpose and check MRI screening requirements.
- Avoid requesting another identical ultrasound simply to repeat the same limited answer, and avoid assuming a negative visualisation of a stone excludes duct disease. Discuss alternatives if MRI is unsuitable.
- The decision is further duct assessment with MRCP, with specialist evaluation of the result and subsequent management. If the clinical state changes to suspected infected obstruction, urgency and the need for drainage assessment change as well.
- Verify that the report addresses the duct question, that a responsible clinician reviews it and that the patient has instructions for new fever, jaundice or worsening pain while awaiting the next step.