RD6.1 | Patient Preparation for Imaging — Practice Quiz

Correct. Fasting for 4–6 hours keeps the gallbladder distended (a meal causes it to contract and empty), so it fills with bile and is well visualised; small clear fluids and essential medication are usually allowed.

Fast 4–6 hours before upper-abdominal/gallbladder ultrasound: a fed gallbladder contracts and empties, so fasting keeps it distended and well-seen.

For upper-abdominal/gallbladder ultrasound the goal is a distended, bile-filled gallbladder. Eating makes the gallbladder contract and empty, degrading the study, so the patient should fast 4–6 hours. A full bladder is needed for pelvic, not gallbladder, scanning.

Correct. A full bladder is required for transabdominal pelvic ultrasound — it displaces bowel gas and acts as an acoustic window onto the uterus and ovaries. (For transvaginal scanning the bladder should instead be empty.)

Transabdominal pelvic/obstetric US = full bladder (acoustic window); transvaginal US = empty bladder.

Transabdominal pelvic/obstetric ultrasound needs a comfortably FULL bladder to provide an acoustic window and push bowel out of the field. An empty bladder is correct only for the transvaginal approach. Fasting and metformin instructions are irrelevant here.

Correct. With eGFR <60, metformin is withheld at the time of iodinated contrast and for 48 hours, then resumed once renal function is rechecked and confirmed stable — this avoids accumulation and lactic acidosis if contrast worsens renal function.

Iodinated contrast + metformin: if eGFR <60, withhold metformin for 48 h and resume after renal review; the risk is lactic acidosis if renal function falls.

Because eGFR is below 60, metformin should be withheld at the time of contrast administration and for 48 hours afterwards, resuming only after renal function is rechecked. The concern is metformin accumulation and lactic acidosis if contrast-associated AKI develops.

Correct. A non-MRI-conditional pacemaker is a recognised MRI safety contraindication — the magnetic field and RF can cause malfunction, lead heating or arrhythmia, so screening must flag it for MRI-safety review before entry.

MRI contraindications EXIST: screen every patient for pacemakers, cochlear implants, aneurysm clips and intra-ocular metallic foreign bodies before entry; remove all loose ferromagnetic items.

MRI safety screening exists precisely because contraindications exist. A non-conditional cardiac pacemaker (like cochlear implants, intracranial aneurysm clips, and intra-ocular metallic foreign bodies) is a key danger. Removable dentures are taken out; modern orthopaedic implants and tattoos are generally manageable.

Correct. Barium studies of the colon require bowel preparation — a low-residue diet followed by laxatives/cleansing so retained faeces do not mimic or obscure lesions; without it the study is uninterpretable.

Barium colon studies need bowel-cleansing prep (low-residue diet + laxatives) so retained faeces don't obscure or mimic lesions.

Barium enema requires thorough bowel preparation (low-residue diet then laxative cleansing) so that residual stool does not obscure or simulate pathology. A full bladder is for pelvic ultrasound; metformin/contrast renal precautions apply to iodinated IV contrast, not barium.

Correct. Before any ionising-radiation study in a woman of reproductive age, pregnancy must be excluded and documented (menstrual history and/or a pregnancy test) to avoid foetal radiation exposure.

Always exclude and document pregnancy (LMP ± test) before ionising studies in women of reproductive age to protect the foetus.

Pregnancy must be excluded before ionising-radiation studies (X-ray, fluoroscopy, CT, nuclear medicine) in women of reproductive age — confirm LMP and, where indicated, a pregnancy test, and document it. Fasting and full-bladder instructions are procedure-specific and not the key safety check here.