Abnormal 99mTc-PIPIDA scans mistaken for common duct obstruction

Area of Science:

• Hepatobiliary imaging
• Diagnostic radiology
• Gastroenterology

Background:

• 99mTc-PIPIDA scans are used to evaluate hepatobiliary function.
• Acute abdominal pain necessitates accurate diagnosis to rule out biliary obstruction.

Observation:

• Three patients with acute abdominal pain showed scans suggestive of partial common duct obstruction.
• Two patients with appendicitis and ileal infarction had normal biliary tracts.
• A third patient on morphine experienced transient symptoms and normal ultrasound.
• Three additional patients without biliary disease receiving meperidine also had similar scan findings.

Findings:

• Abnormal 99mTc-PIPIDA scan patterns mimicking distal common duct obstruction can occur in acute abdominal conditions.
• Opioid administration (morphine, meperidine) can induce these misleading scan findings.
• These scan abnormalities may be present despite the absence of actual gallbladder or biliary tract disease.

Implications:

• Clinicians should consider non-biliary causes, including acute abdominal disease and opioid use, when interpreting 99mTc-PIPIDA scans.
• These findings highlight the importance of correlating imaging results with clinical presentation and medication history.
• Misinterpretation of these scans could lead to unnecessary investigations or delayed diagnosis of the primary condition.