[Evaluation of clinical value of anorectal manometry for diagnosis of Hirschsprung's disease in neonate].

ABSTRACT

OBJECTIVE: Hirschsprung's disease (HD), one of the most common causes resulting in lower intestinal obstruction in children, is prone to be misdiagnosed or to be missed from diagnosis because of its atypical clinical symptoms and inconspicuous morphological findings by barium enema X-ray. Recently, this situation has been largely ameliorated by increased comprehension of anorectal kinetics and improvement of instrument for measurement of anorectal pressure. By now, anorectal manometry (ARMM) has been regarded as a routine means for functional assessment and diagnosis for anorectal disease. Nevertheless, the accuracy rate of diagnosis of HD in neonate by ARMM remains to be elucidated. In this study the clinical evaluation of anorectal manometry as an early diagnostic method for neonates with Hirschsprung's disease was appraised. METHODS: Forty-two HD patients defined by pathological study of rectal tissue obtained via rectal mucous membrane biopsy or operation were recruited in this study. ARMM was performed in liquid transmission using PC polygraph high rate gastrointestinal dynamical detection system (PC Polygraf HR, CTD-synectics, Sweden), with 4-lumen catheter with which a small 5-cm-long balloon was connected at the terminus. All children were positioned on their left side or back during the procedure and the pressure transducers were placed in the mid-axillary line level. The results of ARMM performed before operation or biopsy were compared with the results of barium enema X-ray testing. The decrease of internal anal sphincter pressure as rectoanal inhibitory reflex (RAIR) was measured based on the fluctuation curve of pressure detected. HD was defined when no decrease of anal catheter pressure was detected after insufflation (RAIR positive), and suspected HD state was assessed with the presentation of incomplete relaxation or positive/negative results coexisted (RAIR abnormal) in canal. RESULTS: Thirty patients (71.43%) were diagnosed as HD by ARMM including 18 patients who showed negative response to RAIR and 12 patients whose response was abnormal. While barium enema examinations were carried out in all the 45 patients, the results showed 5 HD patients and 14 suspected HD patients, giving an overall diagnostic accuracy of 45.24%. There were also 16 patients with positive ARMM response and negative barium enema findings together, and 5 patients with negative ARMM results and positive barium enema findings at the same time. There was a significant difference between the two diagnostic methods (chi(m)(2) = 4.76, P < 0.05). CONCLUSION: Anorectal manometry seems to be a more reliable method for diagnosis of Hirschsprung's disease in neonate than barium enema X-ray. Because ARMM is a simple, safe and non-invasive method, it can be used as a screening test of choice in neonates with clinically suspected HD. But for final diagnosis, it is reasonable to combine ARMM with other diagnostic methods in HD patients.