What Causes Abdominal Distention?

Patient Presentation
A 10-year-old male came to the emergency room with a several day history of abdominal distension and generalized abdominal pain. The patient and family could provide few details but the pain was located periumbilically, occurred only during the day and would come and go. He occasionally felt nauseous but had no emesis. He denied any fever, chills, upper respiratory illnesses or urinary symptoms. He was unsure when his last bowel movement was. He had a history of constipation where his bowel movements were large enough to block up the toilet. He said that this didn’t feel like the pain he had with his appendicitis 1 year previously. The past medical history was positive for being underimmunized and having an appendectomy 1 year previously. The social history revealed financial difficulties. The mother also had a lower intellect with some difficulties with daily activities.

The pertinent physical exam showed a well-appearing male with normal vital signs. His weight was 10% and height was 75%. His abdomen was moderately distended. He had normal bowel sounds in all quadrants. Palpation found no fluid wave or organomegaly. He had palpable loops of bowel from the left lower quadrant that followed the colon upwards and into the right abdomen. Palpation of the colonic loops reproduced the main. He denied costovertebral angle or suprapubic tenderness. There was no guarding or rebound. Genitourinary examination was normal and on the rectal examination he had a large rectal vault with stool that was guaiac negative. The diagnosis of constipation was made, but because of the recent abdominal surgery a radiograph was taken. The radiologic evaluation showed stool throughout the colon with no air fluid levels, confirming the diagnosis. The patient was given an enema in the emergency room with some production of stool. The social worker in the emergency room helped to get polyethylene glycol (Miralax^TM) from the hospital pharmacy to take home. She also helped them make an appointment in a local clinic for constipation followup and well child care. The mother refused help with transportation to the appointment, but was willing to have the social worker contact the clinic social worker who might be able to help with the family’s social needs.

Figure 114 – Supine view of the abdomen demonstrates a moderate amount of stool throughout the colon from the cecum to the rectum.

Discussion
Constipation generally is defined as infrequent or painful defecation. It often is due to passing large hard stool infrequently which causes painful defecation and then withholding behaviors. As stool withholding continues, the rectum dilates and gradually accommodates with the normal defecation urge disappearing. Chronic rectal distension results in both loss of rectal sensitivity, and loss of urge to defecate, which can lead to encopresis. Abdominal distention because of stool retention occurs frequently. Treatment includes colonic evacuation, establishing regular bowel habits, eating a balanced diet with dietary fiber and laxatives to keep the stool soft and help promote the normal motility patterns. MiraLax is polyethylene glycol, an osmotic laxative often used to help with bowel evacuation and as a maintenance medication. The dose when used as a maintenance medication is 0.5 -1 gram/kg/day divided BID. The dose can be titrated to have one soft stool per day. The differential diagnosis of constipation can be reviewed here.

Abdominal distention is caused by some type of abdominal obstruction or space-occupying lesion that blocks or impinges on the intestinal lumen. This leads to failure of the intestinal contents to pass through the intestinal tract. Proximal to the obstruction is swallowed air and abdominal contents and secretions. The abdominal contents cannot move distal to the obstruction causing no flatus and bowel movements. If the obstruction is high in the gastrointestinal tract (generally proximal to the jejenum) then emesis is common and there will be little abdominal distention because there is no air and contents moving further into the distal tract. If the obstruction is low, then there is more of a reservoir to hold the accumulated material causing abdominal distention. Emesis is less common with distal obstructions. Fluid loss and electrolyte abnormalities secondary to emesis, dehydration, intestinal stasis, and bowel edema all can lead to bacterial invasion into the bowel wall. This accompanied with increasing intraluminal pressures can cause abnormal intestinal tract vascular flow, ischemia, necrosis and perforation of the viscous.

Abdominal pain often, but not always, accompanies abdominal distention. The causes of abdominal pain include many others that are considered medical reasons such as abdominal migraine, pelvic inflammatory disease, etc. These can be reviewed here.

Learning Point
The differential diagnosis of abdominal distention includes:

• Anatomical
  • Annular pancreas
  • Antral web
  • Duplications
  • Hirschsprung disease
  • Incarcerated inguinal or umbilical hernia
  • Imperforate anus
  • Jejunal and ileal atresia
  • Meckel diverticulum
  • Persistent cloaca
• Neonatal
  • Meconium ileus
  • Meconium plug
  • Necrotizing enterocolitis
• Infectious/Inflammatory
  • Appendicitis
  • Ileus
  • Intussception
  • Perforated viscus
  • Organomegaly
  • Sepsis
• Other
  • Adhesions
  • Ascites
  • Constipation
  • Colonic pseudoobstruction syndrome
  • Mass/Tumor
  • Trauma with mass, such as hematoma
  • Pregnancy

The differential diagnosis of proximal gastrointestinal obstructions includes:

• Bezoar
• Duodenal atresia
• Esophageal atresia
• Malrotation and midgut volvulus
• Pyloric stenosis
• Tracheoesophageal fistula

Questions for Further Discussion
1. What are the indications for a surgical consultation for abdominal distention?
2. How is intestinal obstruction evaluated?
3. How is intestinal ileus treated?

Related Cases

Disease: Constipation | Abdominal Pain

Symptom/Presentation: Abdominal Pain | Constipation and Encopresis | Mass or Swelling

Specialty: Gastroenterology | Emergency Medicine | Surgery | Social Services |
Radiology / Nuclear Medicine / Radiation Oncology

Age: School Ager

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Abdominal Pain and Constipation

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:1376-79.

Jackson PG, Raiji MT. Evaluation and management of intestinal obstruction. Am Fam Physician. 2011 Jan 15;83(2):159-65.

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