Diagnosis of constipation does not correlate with trans-abdominal ultrasound of rectal distention

Constipation has been shown to have a significant impact on lower urinary tract symptoms (LUTS) in children, and treatment of constipation in children with bowel bladder dysfunction (BBD) has been shown to improve or completely resolve LUTS in many cases. Recent studies utilizing trans-abdominal ultrasound (US) to assess stool burden have correlated diagnosis of constipation with US appearance of rectal stool. An US scoring tool was published in 2008 to assess stool burden, showing linear correlation with constipation severity by symptom questionnaire in an outpatient pediatric constipation clinic population. We hypothesized that this US scoring tool would correlate with constipation symptoms in our outpatient pediatric urology population.

In 2010, our pediatric urology outpatient clinic began administering a previously published validated BBD questionnaire to new toilet-trained patients, containing three questions addressing bowel function. Patients in our clinic undergoing trans-abdominal US of the bladder also have assessment of their stool burden by the previously published US scoring tool. We retrospectively reviewed patient charts beginning in June 2013 who had undergone trans-abdominal US of the bladder, gathering data on the first 100 patients with a complete BBD questionnaire and a completed stool burden US scoring tool.

Chart review of 272 consecutive patients was required to enroll 100 patients with a completed US scoring of stool burden and a completed BBD questionnaire. Of these 272 patients, 225 (82%) had a complete scoring of stool burden during their US examination. BBD questionnaires were complete in 107 of 272 patients (39%). Median patient age was 8.2 years, with 69% of patients being female. The most common diagnosis was incontinence or bladder dysfunction (41%). Only one patient (1%) had constipation as the primary diagnosis for their visit. Linear regression analysis showed no correlation of US score to patient reported frequency of bowel movement, frequency of hard stool, frequency of fecal incontinence, or all three symptoms combined. When investigating the subgroup of patients who had diagnoses of BBD/incontinence, this group was seen to have higher mean symptom scores than the entire cohort as a whole, but US scores were still widely variable and again did not correlate with symptom scores.

US examination has previously been shown to correlate with symptom severity for children with chronic constipation in a pediatric constipation clinic setting. However, in a pediatric urology outpatient clinic setting at our institution, US examination did not correlate with patient reported symptoms.