12 Abdominal swellings (general)

Definition
An abdominal swelling is an abnormal protuberance that arises
from the abdominal cavity or the abdominal wall and may be
general or localized, acute or chronic, cystic or solid.
KEY POINTS
• Generalized abdominal swellings affect the entire abdominal cavity.
• Localized swellings can be located in the various regions of the abdomen.
• Abdominal wall swellings can be differentiated from intra-abdominal
swellings by asking the patient to raise his or her head from the couch
(intraperitoneal swellings disappear while abdominal wall swellings
persist).
• Giant masses, other than ovarian cystadenocarcinoma, are rarely
malignant.
Important diagnostic features
‘Fat’
Obesity: deposition of fat in the abdominal wall and intraabdominally
(extraperitoneal layer, omentum and mesentery).
Clinical obesity is present when a person’s body weight is 120%
greater than that recommended for their height, age and sex
(body mass index).
‘Flatus’
Intestinal obstruction: swallowed air accumulates in the bowel
causing distension. This gives a tympanic note on percussion
and produces the characteristic air-fluid levels and ‘ladder’ pattern
on an abdominal radiograph. Sigmoid or caecal volvulus
produces gross distension with characteristic features of distended
loops on abdominal X-ray.
‘Fluid’
• Intestinal obstruction: as well as air, fluid accumulates in the
obstructed intestine.
• Ascites: fluid accumulates in the peritoneal cavity due to the
‘6 Cs’:
• chronic peritonitis (e.g. tuberculosis, missed appendicitis)
• carcinomatosis (malignant deposits, especially ovary, stomach)
• chronic liver disease (cirrhosis, secondary deposits, portal or
hepatic vein obstruction, parasitic infections)
• congestive heart failure (RVF)
• chronic renal failure (nephrotic syndrome)
• chyle (lymphatic duct disruption).
‘Faeces’
Chronic constipation: faeces accumulate in the colon producing
abdominal distension. Congenital causes include spina bifida
and Hirschsprung’s disease. Acquired causes include emotional
disorders, chronic dehydration, drugs (opiates, anticholinergics,
phenothiazines) and hypothyroidism.
‘Fetus’
Pregnancy: swelling arises out of the pelvis.
‘Flipping big mass’
Usually cystic lesions: giant ovarian cystadenoma, mesenteric
cyst, retroperitoneal lymphadenopathy (lymphoma), giant uterine
fibroid, giant splenomegaly, giant hepatomegaly, giant renal
tumour, desmoid tumour.
KEY INVESTIGATIONS
• FBC: lymphomas, infections.
• LFTs: liver disease.
• U+Es: renal disease.
• Abdominal X-ray:
ascites (‘ground glass’ appearance, loss of visceral outlines)
large mass (bowel gas pattern eccentric, paucity of gas in one quadrant)
fibroid (‘popcorn’ calcification).
• Ultrasound: ascites, may show cystic masses.
• CT scan: investigation of choice, differentiates origin and relationships.
• Paracentesis: MC+S (infections), cytology (tumours).
• Liver biopsy: undiagnosed hepatomegaly.