The occurrence of anorectal malformations is the result of disorders that occur during embryonic development and are essentially the same in males and females, with only anatomical differences. As a result of the cloacal separation process, the urogenital sinus communicates with the anorectal sinus, constituting a high or intermediate malformation, and various anorectal dysplasias and fistulas between the rectum and urethra or vagina occur. As a result of impaired posterior anal migration process and perineal dysplasia, it constitutes a low malformation, and anal skin fistula, anal vestibular fistula, and anal stenosis occur. So, how to check for anal malformation? The following are the examination methods of anal malformation. 1.X-ray: the standing abdominal plain film seen mostly shows low-level colonic obstruction. The typical spastic intestinal segment and dilated intestinal segment can be seen in the lateral and anterior-posterior photographs of barium enema, and the barium discharge function is poor, and the barium remains after 24 hours, and if the barium is not washed out by enema in time, barium stone can be formed, and the dilated intestinal wall of the dilated intestinal segment is jagged when combined with enteritis, and the dilated intestinal tube can be seen only half a month after birth in the neonatal period. 2, rectal mucosal tissue chemical examination method: this is based on the spastic segment submucosa and muscle layer ganglion cell deficiency at the hyperplasia, hypertrophy of parasympathetic preganglionic fibers constantly release a large number of acetylcholine and cholinesterase, the number and activity of both can be measured by chemical methods than normal children out of 5 to 6 times, which helps the diagnosis of congenital megacolon, and can be used for newborns. 3, anorectal manometry: measurement of reflex pressure changes in the rectum and anal sphincter can diagnose congenital megacolon and identify other causes of constipation. In normal children and functional constipation, when the rectum is subjected to distending stimulation, the internal sphincter immediately undergoes reflexive relaxation and the pressure decreases, while in children with congenital megacolon the internal sphincter does not relax, but also undergoes significant contraction, which increases the pressure. This method can sometimes show false positive results in newborns within 10 days. 4, biopsy: take a small piece of tissue from the rectal wall submucosa and muscle layer more than 4 cm from the anus to check the number of ganglion cells, and lack of ganglion cells in children with megacolon.