What imaging studies are used for encopresis (involuntary fecal soiling)?

From the Guidelines

For imaging in encopresis, fluoroscopy CCP or MR defecography is usually appropriate as the initial imaging when imaging is deemed necessary after clinical evaluation. The choice between fluoroscopy CCP and MR defecography depends on the specific clinical scenario and the availability of resources. The imaging studies can reveal:

• The presence of rectoceles, enteroceles, and rectoanal intussusceptions
• The extent of fecal retention and potential obstructions or anatomical abnormalities
• The presence of dyssynergic defecation, which can be diagnosed based on the evacuation of contrast on CCP In most cases, no further imaging is necessary. However, if there are concerns about underlying anatomical issues or if symptoms persist despite appropriate treatment, additional imaging may be considered:
• US pelvis transrectal: As a complementary test to fluoroscopic defecography or MR defecography in patients with clinical suspicion for anal sphincter abnormalities 1
• MRI: In rare cases, to evaluate for spinal cord abnormalities or to assess pelvic floor function during defecation It's essential to note that imaging should be used in conjunction with a thorough clinical history and physical examination, as seen in the study by 1. The primary goal of imaging in encopresis is to confirm the diagnosis, assess the severity, and rule out other potential causes of symptoms. Imaging helps guide treatment by providing objective information about the extent of fecal retention, which can inform decisions about the intensity and duration of bowel cleanout regimens and maintenance therapy.

From the Research

Imaging Studies for Encopresis

The following imaging studies are used to evaluate encopresis (involuntary fecal soiling):

• Plain abdominal radiography: used to assess fecal retention and detect fecal impaction 2
• Barium enema radiographic examination: used to detect the cause of obstruction in cases of acute onset of constipation 3
• Colonoscopy: used to detect the cause of obstruction in cases of acute onset of constipation 3
• Computed tomography (CT) scan: used to establish the diagnosis and cause of large-bowel obstruction 4
• Magnetic resonance imaging (MRI): used to support therapeutic decisions in patients with bowel obstruction and to identify the presence, site, and cause of bowel obstruction 5
• Evacuation proctography: used to diagnose functional disorders of the rectum and anus, such as rectocele, intussusception, and abnormal perineal floor descent 3

Specific Findings

• A plain abdominal radiograph can be used as the gold standard to assess fecal retention in encopretic children, with a positive rectal examination showing a positive predictive value of 84.8% and a negative predictive value of 50% 2
• Fecal retention can be objectively assessed using a plain abdominal roentgenogram, with 78% of encopretic children showing fecal retention by roentgenographic criteria on presentation 2
• Retentive encopretic children are more likely to have excessive stool on rectal examination, but are less likely to have a history of difficult toilet training 2