Validity of Transperineal Ultrasound in Infants with Imperforate Anus

BackgroundandObjectives:Optimalsurgicalmanagementoftheneonatewithimperforate anus depends on accurate determination of the level of the rectal pouch. The use of ultrasoundtodeterminethepouchlevelhasbeenpreviouslydescribed,buthasnotbecome widely accepted. The goal of this study is to determine the validity of thismeasurement accordingtofinalsurgicalfindingsinpatientswithanorectalmalformation. MaterialsandMethods:Ina crosssectionalstudy,23childrenwithimperforatedanuswere evaluatedby transperinealultrasoundwith a 7.5MHz sector transducer in the supine and lithotomicpositionstodeterminethepouchlevelandpouchtoperineum(P-P)distance.Inall cases, the level of the distal pouchwas confirmed by definitive surgery or distal colostogram. The agreement between sonography and surgery or colostogram as gold standard wasobtainedbyweightedkappatest. Results: In five children, thepouch toperineum (P-P)distancewas less than 10mm. Allof these low lesions were safely treated by a simple perineal anoplasty (minimal posterior sagittalanorectoplasty;i.e.minimalPSARP)andwereconfirmedaslowtype.Sevenchildren hadP-Pdistanceof10-15mm.Inthefollowupdefinitivesurgery,5 caseswereintermediate andtwocaseswerehigh.Elevenchildrenhada P-Pdistanceofmorethan15mm,ofwhich tencaseswerehighlesionsandhadcolostomyatbirth.Duringfollowup,8 casesunderwent definitivesurgeryofPSARPandtwoofthesehighcaseswereconfirmedbydistalcolostogram and one case was categorized as intermediate by definitive PSARP. Measure of agreement (Kappa)was calculated to be 0.791 (P = 0.001) Therefore,Ultrasound correctly predictedthelevelofthedistalpouchin20of23patients. Conclusion: Transperineal ultrasound can be confidently used prior to surgical decision in childrenwithimperforateanusinadditiontophysicalexam.