Ascites – Xray, CT Scan, Ultrasound Examination

Clinical Characteristics of Ascites

• Intra-abdominal free fluid that may be classified as:
• Exudate: greater than 30g/dl of protein; causes include peritoneal TB, pancreatitis, Meig’s syndrome and carcinomatosis.
• Transudate: less than 30g/dl of protein; causes include hypoalbuminaemia, congestive cardiac failure, chronic renal failure, Budd-Chiari Syndrome and cirrhosis.

Radiological Features and Examinations
Xray examination of Ascites

• The initial signs relate to the dependent accumulation of free fluid in the pelvis and may be subtle and overlooked.
• Later signs are medial displacement of both the lateral border of the liver and ascending and descending colon, bulging flanks, centralised bowel loops and a generalised greying of the abdominal film.

Generalized greying of the abdominal film in AP abdominal xray
with several centralized bowel loops.

Ultrasound Examination

This is the examination of choice to confirm the presence of ascites, without the use of ionizing radiation.

Ultrasound may provide additional information about the ascite such as loculation or the presents of debris within the fluid.

In addition, ultrasound allows the sitting of diagnostic taps or therapeutic drains.

Evidence as to the aetiology of the ascites can also be gained, such as the presence of cirrhosis.

Abdominal Ultrasound showing large volume of ascites (asterisk).

CT Scan of Ascites

The radiation dose prevents this as an investigation to confirm the presence of ascites, but CT scan often use to confirm the presence and extend of ascites when performed for another reason.

The cause may also be identified, such as evidence of pancreatitis.

It is less sensitive than ultrasound in assessing for loculation or debris within the ascetic fluid.

Axial slice of the abdomen CT: Large volume of ascites (asterisk)
and a small left basal pleural effusion in CT images (arrow).