When to Order Imaging for Suspected Appendicitis

When to order imaging for suspected appendicitis

Imaging selection for suspected appendicitis is driven by patient age, body habitus, and clinical certainty. CT of the abdomen and pelvis with IV contrast is the highest-sensitivity test and is the default in adults. Abdominal ultrasound is the preferred first study in pregnant patients and a reasonable first study in lean adults and adolescents where radiation avoidance is the priority.

Pre-imaging triage

Patients with peritonitis, sepsis, or haemodynamic instability belong in an emergency setting where imaging, surgical consultation, and resuscitation happen in parallel. The pathway here applies to stable ambulatory patients with localised right lower quadrant pain.

CT abdomen and pelvis with IV contrast

CT with IV contrast is the most sensitive and specific single study for appendicitis in adults and is the default when ultrasound is unlikely to be diagnostic (obesity, deep pelvis, prior non-diagnostic study) or when the differential is broad. Oral contrast is generally not required and is added only at the radiologist's discretion based on the indication.

Abdominal ultrasound

Ultrasound is preferred as a first study in pregnant patients and is reasonable in lean adolescents and young adults where radiation avoidance is the priority. A clearly visualised non-compressible appendix or a clearly normal appendix can be diagnostic; equivocal or non-visualised studies should escalate to CT (or MRI in pregnancy via referral) without delay.

Pregnant patients

Ultrasound is the first study in pregnancy. When ultrasound is non-diagnostic, MRI abdomen and pelvis without contrast is the next study; in settings where MRI is not promptly available, the clinical team and the obstetrician will weigh proceeding to CT against the risk of delayed diagnosis.

Ordering with Precise

Abdominal ultrasound and CT abdomen and pelvis with IV contrast are available across the network. Use STAT when clinically warranted; STAT targets a ≤ 2-hour read with critical findings phoned to the ordering provider within 30 minutes.

Provider FAQ

Questions referring offices ask first.

Do I need oral contrast for the CT?

Not routinely. We will add oral contrast only when the radiologist determines it adds value for the specific indication.

What if ultrasound is non-diagnostic?

Escalate to CT abdomen and pelvis with IV contrast (or MRI in pregnancy) without delay, rather than repeating the ultrasound.

Educational reference for referring providers. Not a substitute for clinical judgement or the current official appropriateness criteria. References imaging modalities offered by Precise; modalities not in our network are out of scope.

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