Small Liver Cysts Seen on CT but Not on Ultrasound: What This Means
This discrepancy is completely normal and does not require any further action or follow-up imaging, as CT with contrast is more sensitive than ultrasound for detecting very small hepatic cysts, and simple hepatic cysts are benign lesions with no malignant potential that require no surveillance regardless of whether they are visible on ultrasound. 1, 2
Why CT Detected Cysts That Ultrasound Missed
Differences in imaging sensitivity explain this finding:
- CT with intravenous contrast makes small hepatic cysts "more clearly visible" compared to non-contrast imaging, allowing detection of cysts that may be too small or subtle for ultrasound to identify 1
- Small cysts (particularly those <1 cm) can be below the resolution threshold of ultrasound but readily apparent on contrast-enhanced CT 1
- This is an expected technical limitation rather than a concerning clinical finding 3, 4
What You Should Do Next
The European Association for the Study of the Liver (EASL) provides explicit guidance for your exact situation:
- No follow-up imaging is recommended for asymptomatic patients with simple hepatic cysts, regardless of cyst size 1
- This is a strong recommendation with 96% consensus from hepatology experts 1, 2
- Simple hepatic cysts are benign developmental lesions that "typically follow an indolent course without significant changes in size over time" 1
Ultrasound should only be performed if you develop symptoms such as:
- Abdominal pain or distension 2, 5
- Early satiety, nausea, or vomiting 2, 3
- Any acute abdominal symptoms 1, 2
Common Pitfalls to Avoid
Do not pursue additional imaging or surveillance based on this finding:
- Ordering surveillance ultrasounds for asymptomatic simple cysts "leads to unnecessary healthcare utilization without improving outcomes" 2
- The fact that ultrasound couldn't visualize the cysts does not make them more concerning—it simply reflects the superior sensitivity of CT 1
- No bloodwork, tumor markers, or MRI is indicated for simple hepatic cysts 5
The key reassurance: Simple hepatic cysts have zero malignant potential and occur in approximately 2.5% of the general population, becoming increasingly common with age 3, 6. The discrepancy between your CT and ultrasound findings is a technical imaging difference, not a medical concern requiring action.