1.What is the use of rectal examination for the diagnosis of congenital megacolon? The cause of congenital megacolon lies in the absence of ganglion cells in the colon, and the segment of the intestine lacking ganglion cells is in a spastic state and cannot expand normally, and the proximal intestine is compensated to expand, and about 80% of such pathological changes are located in the rectum. This is one of the typical manifestations of megacolon, which is helpful for clinical diagnosis and can also relieve the abdominal distension of children. In the case of long-segment megacolon with lesions extending to the sigmoid colon or descending colon, the above-mentioned manifestations may not be present on rectal examination, but megacolon cannot be excluded. 2.Can a barium abdominal X-ray confirm the diagnosis of congenital megacolon? Is it necessary to do it? There are many methods to diagnose congenital megacolon, but X-ray barium colonography is still the more valuable diagnostic method and the first choice of examination. It is necessary for patients with suspected congenital megacolon. The imaging shows typical stenosis, dilated segment and migrated segment can basically make a clear diagnosis, and the accuracy rate can reach 70-80%. Several points should be noted during the examination: no bowel washing before the examination, so as to avoid atrophy and deflation of the dilated intestine, which will affect the diagnosis; do not wash the intestine or dilate the anus immediately after the barium enema, so that the barium is in a natural state of transmission and operation in the intestine, and the child can have normal stool if he/she has a bowel movement; 24 hours and 48 hours after the examination, abdominal plain films should be taken respectively to track the excretion of barium, which can make correct diagnosis. 3.Is the radiation level of barium contrast examination high? Does drinking barium have any effect on the baby? Barium colonography needs to receive X-ray fluoroscopy dynamic observation, receiving X-ray exposure is inevitable, but the amount of diagnostic medical radiation is very small, as long as it is not a short-term frequent examination, there will be no major impact. The barium contrast examination is done by a thin catheter on the anus, and the appropriate amount of barium is injected by the catheter, so the baby does not need to take barium orally, and the baby can eat normally during the examination. 4.Can abdominal ultrasound diagnose congenital megacolon? Ultrasound is mainly used to extract the required information from the sound after the interaction of ultrasound and tissue for diagnosis. It is possible to understand whether the intestinal canal is dilated or not, but it is impossible to judge the distribution of nerves in the wall of the intestinal canal and the transmission function of the intestinal canal, so it cannot be used for the diagnosis of megacolon. 5.What is the anorectal manometry test? What is the use of anorectal manometry for the diagnosis of congenital megacolon? Anorectal manometry is one of the important methods to diagnose congenital megacolon. Under normal physiological conditions, the stimulation of pressure in the rectum can cause a common coordinated activity of the endorectal sphincter, producing an endorectal sphincter relaxation reflex. This reflex is established on the normal innervation of the rectum and internal sphincter, while in patients with congenital megacolon, this reflex cannot be established normally due to the absence of ganglion cells in various nerve plexuses of the rectum and internal sphincter, which manifests as the disappearance of the relaxation reflex wave and helps in the diagnosis of megacolon. 6.When is a pathological biopsy necessary? What are the ways to do pathological biopsy? How to choose? When the patient’s clinical manifestation is constipation and abdominal distension, and the barium enema shows typical giant colon or there is more barium retention in the colon 24 or 48 hours after the barium enema, or the rectal manometry shows the disappearance of relaxation reflex wave, which is not typical, the diagnosis needs pathological evidence. There are 2 types of pathological biopsies of the rectum, one is preoperative rectal mucosal biopsy, which is mainly used for preoperative diagnosis, but it is not possible to obtain the whole rectum and has limitations; the other is intraoperative rapid section examination to understand the presence or absence of ganglion cells, which can determine the normal and diseased intestinal canal and guide the extent of intestinal canal removal during surgery. Finally all megacolon surgery must be followed by routine pathological examination.