Causes of abdominal distension

Distension of abdomen is of two types :

• Generalised 
• Localised (visceromegaly, neoplasm  shifting dullness is absent).

Generalised fullness - all the causes of this will start with the letter ' F'

• Fat
• Flatus
• Fluid
• Foetus 
• Faeces

Differential diagnosis  of bulging or distension of abdomen :
Fat - Obesity (inverted umbilicus with absent fluid thrill and shifting dullness).
Faeces - Megacolon or low gut obstruction (symmetrical enlargement with visible peristalsis).
Foetus - Pregnancy (foetal parts are palpable: central dullness).
Flatus - Gaseous distension (flanks are not bulged: tympanitic note all over the abdomen).
Fluid - Ovarian cyst, ascites.
Full (urinary) bladder (flanks are tympanitic, palpation causes pain or discomfort and desire for
micturition: usually rounded cystlc swelling in hypogastrium which is dull on percussion :
Localised fullness is noted around umbilicus in Mesenteric cyst and Small intestinal obstruction
Asymmetrical fullness is observed in massive hepatomegaly, splenomegaly and ovarian tumor
Hernia - It is a protrusion of viscus through an abnormal opening .The different types are Incisional hernia, umbilical hernia, inguinal hernia.