How long should a patient hold opiates (opioid analgesics) before a Hida scan and do they need to be NPO (nothing by mouth)?

HIDA Scan Preparation: Opioid Hold and NPO Requirements

Patients requiring a HIDA scan must hold opiates for at least 48 hours before testing and should be NPO for 4-6 hours minimum (optimally overnight fast) prior to the study. 1

Opioid Withholding Requirements

The 48-hour opioid hold is critical to prevent false-positive results. Opiates and their metabolites cause sphincter of Oddi spasm and decrease gallbladder ejection fraction, which can spuriously reduce GBEF values and lead to misdiagnosis of gallbladder dysfunction. 1, 2

Mechanism of Interference

• Opioid drugs cause marked bile duct obstruction by inducing biliary sphincter spasm, which delays clearance of the radiotracer from the common bile duct and can simulate pathological obstruction. 3
• Morphine and other opiate metabolites circulate in blood for many hours and directly act on the sphincter of Oddi while simultaneously decreasing gallbladder ejection fraction. 2
• A careful drug history, especially regarding opiates, is critical in all patients before performing HIDA scan to avoid assigning false abnormality to gallbladder motor function. 2

Additional Medications to Hold

• Anticholinergic drugs should also be withheld for at least 48 hours before testing. 1
• Other medications affecting gallbladder contraction must be held for 24 hours prior to the study, including: nifedipine, indomethacin, octreotide, theophylline, benzodiazepines, phentolamine, isoproterenol, and progesterone. 1
• Nicotine and alcohol should be avoided prior to testing as they may affect gallbladder contraction. 1

NPO Requirements

Patients should optimally fast from the evening before the study, or at minimum 4-6 hours prior to the study. 1

Rationale for Fasting

• Proper patient preparation with adequate fasting is essential to avoid false-positive results. 1
• The gallbladder must be in a fasted state to allow proper filling with the radiotracer during the initial imaging phase. 1
• If the gallbladder has not filled by 60 minutes in a properly prepared patient, the finding is reported as abnormal, potentially consistent with either acute or chronic cholecystitis depending on clinical presentation. 1

Critical Clinical Context

CCK-cholescintigraphy should be performed on an outpatient basis, not while the patient is hospitalized or acutely ill. 1

Common Pitfalls to Avoid

• Many confounding factors in acutely ill hospitalized patients can spuriously decrease GBEF, including the illness itself and therapeutic medications (particularly opioids). 1
• Administering opioids within several hours before a diagnostic hepatobiliary scan can lead to delayed clearance of radiotracer from the common bile duct, potentially resulting in an erroneous diagnosis and indicating a potentially unnecessary common bile duct exploration. 3
• The 24-hour abstinence from opioids recommended in some bariatric surgery protocols may be insufficient; the 48-hour guideline from consensus recommendations should be followed. 4

Contraindications

• Known allergic reaction to sincalide (CCK analog used during the study). 1
• Intestinal obstruction. 1
• Pregnancy (sincalide use is contraindicated as it may stimulate preterm labor, though the Tc-99m HIDA radiotracer itself is generally considered safe). 1