ULTRASOUND OF THE GALLBLADDER - Normal

SCAN PLANE

Normal Scanning Position to take advantage of using the liver as a window and displacing the bowel.	A normal Gallbladder should be thin walled (<3mm) and anechoic.It is a pear shaped saccular structure for bile storage in the Right Upper Quadrant. Its size varies depending on the amount of bile. Fasted it will be approximately 10cm long.

GALLBLADDER FOLDS

Folds are commonly seen and are normal. Make note if pathology such as calculi are contained within a compartment created by a fold.	A Phrygian cap is a specific, relatively common,inversion of the distal fundus of the gallbladder into the body.It may become adherent. It is an anatomic variant or acquired abnormality.

Ultrasound of the Gallbladder - Protocol

Role of Ultrasound

•  Always tailor your scan to the clinical signs.
• Always take a thorough history including previous cancer,diseases,blood results,family history and past surgery.
• Perform an initial overall scan without imaging to get an idea what pathology there might be and how it might relate to the patients current complaint.

Limitations

• Often you will have problems with bowel gas overlying the gallbladder.

Ways to overcome this include :

• Roll the patient into a left lateral decubitus or erect position.
• Use the liver as a window especially when rolling the pt onto their left side
• Deep inspiration / expiration
• Distend the abdomen against the probe. (ask the patient to push their stomach out as if they are pregnant!)

Patient position

• Generally the gallbladder is best viewed in the left lateral decubitus position. However it  can be viewed with the patient supine and erect.
• Erect views may be useful to determine if stones are mobile or impacted in the neck.

Patient Preparation

• Fast for 6 hours. No food or drink.
• Preferably book the appointment in the morning to reduce bowel gas.

Equipment Selection

• Use the highest frequency probe to gain adequate penetration. This will be between a 2-7MHz range curved linear array or sector probe with Colour Doppler capabilities.
• Start with 6MHz and work down to 2 or 3 for larger patients.
• Assess the depth of penetration required and adapt.The gallbladder should be able to be scanned using a 7MHZ as it is so superficial.Paediatric and thin pts should be scanned with a 7MHz also.
• Narrow the dynamic range

Scanning Technique

1. Looking supine, left lateral decubitus and erect
2. Use the liver as a window especially when rolling the pt onto their left side
3. Measure the wall <3mm
4. Is the gallbladder enlarged?>10cm in length
5. Check with colour Doppler for increased vascularity of the wall
6. Assess the cystic duct,neck , body and fundus (sometimes there is a phrygian cap)

Common Pathology

• Folds
• Phrygian cap
• Polyp
• Calculi
• Sludge
• Cholecystitis
• Adenomyomatosis
• Gallbladder Carcinoma

Basic Hard Copy Imaging

• Document the normal anatomy. Any pathology found in 2 planes, including measurements and any vascularity.