Abstract

Objectives

     To compare hydrocolonic sonography with histopathology for diagnosing children with symptoms highly suggestive of Hirschsprung disease (HD).

Methods

     In this prospective study, patients presenting refractory constipation highly suggestive of HD underwent hydrocolonic sonography with retrograde infusion of saline into the colon. The dilated segments, narrowed segments, luminal diameter ratio, transition zone (TZ), thickening, and blood perfusion of the upstream bowel were evaluated. The sensitivity and specificity of combined and single parameters were determined in comparison with biopsy.

Results

     One hundred and three children were included in this study; 49 were confirmed to have HD. The luminal diameter ratio showed superiority over other parameters. An area under the curve (AUC) of 0.969 (95% confidence interval [CI]: 0.936–۱٫۰۰۰) and a cutoff value of 1.51 were established by receiver operating characteristic (ROC) curve analysis of the luminal diameter ratio (sensitivity: 89.8%; specificity: 96.3%). By combining the luminal diameter ratio as the major criterion with two minor criteria, hydrocolonic sonography showed the same sensitivity (91.8%) and better specificity (96.3% vs 87%) than contrast enema, but this difference was not statistically significant (p = ۰٫۰۶۳). Consistency analysis showed a kappa value of 0.825 (p < ۰٫۰۰۱), indicating excellent agreement between hydrocolonic sonography and contrast enema.

Conclusions

     Hydrocolonic sonography is a valuable diagnostic tool with both high sensitivity and specificity for HD diagnosis, allowing morphological and vascular assessments of the colon, and correlates well with contrast enema. In the appropriate setting, hydrocolonic sonography may be an alternative screening method for HD in a large group of children with constipation.

Introduction

     Hirschsprung disease (HD) is a common congenital disorder with a global incidence of approximately 1 in 5000 in newborns [1–۴]. HD is characterised by an absence of ganglion cells of the submucosa and myenteric nerve plexus in the distal bowel (usually localised to the rectosigmoid region), which causes the afected bowel to lose its peristaltic ability and leads to dilation of the upstream colon, resulting in refractory constipation. HD is classifed according to the length of the aganglionic section into short-segment (confned to the rectosigmoid region), long-segment (extending beyond the rectosigmoid region), total colonic (entire colon and terminal ileum), and total intestinal (most of the intestines are involved) HD [5]. An operation is recommended once the diagnosis has been established [6].

     The diagnosis is based on symptoms, contrast enema, rectal suction biopsy, and full-thickness rectal biopsy. Contrast enema is the imaging modality of choice for HD, with sensitivity ranging from 76 to 88.9% and specifcity from 84.2 to 98% [7–۹]. With regard to contrast enema, patients are exposed to radiation; therefore, parents may have safety concerns. Rectal biopsy, despite being radiation-free, is invasive, sometimes requires anaesthesia, and is not widely accepted by parents. Over 80% of patients who undergo biopsies have normal ganglionic biopsies [10, 11]. In our centre, the negative biopsy rate is 74%. Therefore, there is a clear need for a noninvasive, safe, and highly sensitive diagnostic method to increase the positive rate of rectal biopsy. Ultrasound (US), although noninvasive and radiation-free, has limitations for the evaluation of HD: difuse intraluminal gas precludes the detailed evaluation of the colon wall. Second, the rectosigmoid region is the most commonly involved region in HD, and identifcation of this region by trans-abdominal US is challenging due to its deep location.

Results

Patient’s characteristics

     Between February 2019 and May 2020, 139 consecutive children met the inclusion criteria; however, 33 patients were subsequently excluded for contrast enema performed at another hospital, 2 were excluded because of fnal diagnoses of post-necrotising enterocolitis stenosis, and 1 was excluded for a fnal diagnosis of the Currarino syndrome. The fnal analysis was performed on 103 patients (median age, 6 months; interquartile range, 3–۲۰ months). There were 41 (39.8%) girls and 62 (60.2%) boys.

     According to the rectal biopsy, the absence of ganglion cells was found in 49 patients. In 4 of these, no abnormal fndings of HD were observed on contrast enema (two of them had abnormal hydrocolonic sonography); therefore, a repeat biopsy was subsequently performed, with aganglionosis confrmed in all 4 cases. Thus, 49 patients were diagnosed with HD (43 cases were short-segment disease and 6 were long-segment disease) and 54 cases were ruled out (Fig. 4). There was no signifcant diference regarding age in the HD and non-HD groups (Mann–Whitney test; U=276.000; p=0.756). The HD group had a greater proportion of males (73.5% vs 48.1%, p=0.009).