How are elimination disorders diagnosed?
A complete evaluation of a child with constipation or encopresis involves a
thorough history, a detailed physical examination, and may include laboratory
testing. The child's pediatrician may generally handle the analysis of these
elements. A pediatric GI specialist consultation may be indicated should a more
ominous cause for the elimination disorder be discovered or if the evaluation
produces conflicting data and thus obscures the establishment of the exact cause
and thus management for the child's problem.
The history to be explored during an evaluation of elimination disorders
includes: (1) age and abruptness of onset, (2) frequency and character of the
current stool pattern in comparison to that noted prior to the onset of
symptoms, (3) relationship to ingestion of meals as well as types of food in the
child's diet, (4) unusual weight loss or gain, (5) associated abdominal
complaints (for example, abdominal pain), (6) urological issues (many children with
elimination disorders may also have enuresis -- involuntary loss of bladder
control), (7) psychosocial family dynamics (for example, parental/sibling/peer response
to the problem), and (8) gentle exploration for any possibility of sexual
abuse -- regression, depression, sexually acting out, etc.
The goal of a complete physical exam is to eliminate the possibility of
anatomical or functional causes for the elimination disorder. Children affected
by cerebral palsy, global hyponia (low muscle tone), mental retardation, and
anatomical malformations (for example, spinal cord abnormalities or displacement of the
anus) must be considered and ruled out as a cause for the child's symptoms.
Physical examination of the abdomen will often demonstrate a large stool mass. A
rectal exam will commonly demonstrate an enlarged rectal volume that is packed
with stool. Absence of anal muscular tone should be a "red flag" for a potential
neurological disorder. As noted above, appropriate anal location should be
documented. Likewise, the physician should perform an evaluation for hidden
spinal cord malformations (for example, tuft of hair over the lower spine).
Most children with either constipation or encopresis do not need laboratory
or radiographic evaluation unless the history and/or physical examination
warrant further analysis (for example, an MRI for spinal cord malformations). Blood studies
to evaluate thyroid function may be a consideration on an individualized basis.
An abdominal X-ray may be helpful to measure the child's stool burden. For
those children with urologic problems, a culture and urinalysis are reasonable
studies. A pediatric gastroenterologist may perform a study of anal and rectal
muscle tone (anal/rectal manometry) to assess the anal/rectal response to
inflation with air in children who do not respond to routine therapy.