Abdomen : Case 4
History : A 71-year-old male with abdominal distension
What is the abnormality?
A. Negative study
B. Abdominal mass
C. Ascites
D. Small bowel obstruction
C. Ascites
* Abdominal X-rays should not be used to check for ascites.
* If this diagnosis is suspected then again ultrasound is the best initial investigation, and can also be used to assist drainage.
* Fluid and soft tissues have similar densities, and so ascites may be mistaken for organomegaly.
Key points
- Free fluid and solid organs have similar densities
- In the presence of ascites gas within bowel is located centrally
Plain film:
* Detection of intraperitoneal fluid on plain film requires at least 500 ml
* Plain film findings of ascites include:
- Diffusely increased density of the abdomen
- Poor definition of the the soft tissue shadows, such as the psoas muscles, liver and spleen
- Medial displacement of bowel and solid viscera (away from properitoneal fat stripe)
- Bulging of the flanks
- Increased separation of small bowel loops
Pathology :
* Ascitic fluid :
- Transudate: thin, low protein count and low specific gravity
- Exudate: high protein count and specific gravity
* More recently, the concept of the serum-ascites albumin gradient has been shown to be more accurate in classification of the causes of ascites.
Causes of transudative ascites
- Hepatic cirrhosis
- Alcoholic hepatitis
- Heart failure
- Hypoproteinaemia
- Portal vein thrombosis
- Peritoneal dialysis
- Malignancy : most commonly: breast, ovarian, endometrial, gastrointestinal and pancreatic
Causes of exudative ascites