By definition, abdominal distention means enlargement or protuberance of abdomen out of proportion to the body size as a result of:
- Reduced tone of abdominal wall musculature
- Increased abdominal content, say fluid, gas or solid lump.
The term denotes a mere symptom that may not necessarily mean a disease. As for instance, many small infants swallow far-too-much of air when crying or during the course of a feed, particularly when sucking is quite prolonged for one or the other reason. A protuberant abdomen is a common finding in normal, healthy toddlers.
Ascites, i.e. fluid in the peritoneal cavity, tends to distend the abdomen both in flanks and anteriorly, provided that it is significantly large in quantity. In addition to fluid in the gut (usually from obstruction or imbalance between absorption and secretion), there is some accompanying gas as well (usually from swallowed air or action of endogenous bacteria or other flora). Audible gurgling noises may also be present.
Abdominal distention from gas in peritoneal cavity (pneumoperitoneum) which may be accompanied by a tympanic percussion note (yes, even on top of a solid organ like liver) points to a perforation of a viscera. Mobile, nontender fecal lumps, i.e. fecoliths, indicate severe constipation.
When confronting a child with abdominal distention, ask the respondent about the general health of the child. Has he been doing well, or not really been thriving satisfactorily? Is there history of chronic/recurrent diarrhea and/or passage of worms in stools? Does he has feeding problem? Any history of colic? Does he often 68remain constipated? Any suggestion of swelling over face and legs? Is the mother aware of any lump within the abdomen? Any suggestion of emotional deprivation? Any drug intake?
Physical examination should aim at delineating if abdominal distention appears to be the result of poor tone of the abdominal wall musculature, or from gas, fluid or solid.
Abdominal Distention in the Newborn
The causes at this age include intestinal obstruction, rupture of stomach or some other member of alimentary tract, biliary, or urinary tract, tracheoesophageal fistula, congenital megacolon, septicemia, peritonitis or necrotizing enterocolitis, congenital nephrotic syndrome, tumors and cysts, congenital heart disease, urethral obstruction, gray baby syndrome, etc.
Abdominal Distention in Infancy and Childhood
Aerophagy, though decidedly common in infancy, may sometimes occur in older children as well and cause abdominal distention.
Obesity is uncommon in developing countries but needs to be borne in mind in the differential diagnosis of abdominal distention.
Flabby abdominal muscles, are a common cause of abdominal distention, e.g. protein-energy malnutrition (both primary and secondary as in malabsorption syndrome), rickets (Fig. 1.1) hypothyroidism, Down's syndrome, floppy baby syndrome, cerebral palsy, etc.
Dehydration with or without electrolyte imbalance, as in acute gastroenteritis, is an important cause of abdominal distention.
Fig. 1.1: Abdominal distention in a 4-year-old with growth retardation and vitamin D deficiency rickets. The primary diagnosis in this child was celiac disease
Ascites as a cause of abdominal distention may occur in disorders involving the cardiovascular system (congestive cardiac failure) pericardium (constrictive pericarditis), kidneys (acute glomerulonephritis, nephrotic syndrome), liver (Indian childhood cirrhosis, 69portal hypertension), pancreas (chronic pancreatitis), inferior vena cava (thrombosis), lymphatics (tuberculosis, Hodgkin lymphoma) as also in hypoproteinemic states like nephrotic syndrome, protein-losing enteropathy, gross protein-energy malnutrition (kwashiorkor type), cystic fibrosis and malabsorption states (celiac disease).
Remember, ascitic fluid is generally a transudate with a low protein concentration resulting from low plasma colloid pressure (in hypoalbuminemia), from high portalvenous pressure or from both. Usually, development of ascites accompanies significant fall in serum albumin. Additional factors contributing to it include fluid leak from lymphatics and visceral peritoneal capillaries. Furthermore, as the ascetic fluid collects, sodium excretion in urine greatly falls. Thus, additional dietary sodium goes straight to the peritoneal cavity.
Infrequently, when ascitic fluid is an exudate, i.e. with high protein concentration, an inflammatory or malignant process must be suspected.
Drugs such as diphenoxylate HCl, loperamide and indomethacin are known to cause abdominal distention in some subjects.
Remaining causes include paralytic ileus, intestinal obstruction, perforation, mesenteric cyst, peritonitis, liver cysts and tumors, hydronephrosis, polycystic kidney, renal vein thrombosis, nephroblastoma (Wilms tumor), neuroblastoma, adrenal hemorrhage, anterior meningocele, pancreatic cyst, leukemia, tyrosinosis, Gaucher disease, porphyria, H. pylori infection, etc.
FURTHER READING
- Wyllie. Major symptoms and signs of digestive tract disorders. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF (Eds): Nelson Textbook of Pediatrics, 18th edn. Philadelphia: Saunders 2008:1522–1528.
- Green M. Pediatric Diagnosis, 6th edn. Philadelphia: Saunders 1998.