Narrow anus or anal canal

Introduction The narrow anus or anal canal is a clinical manifestation of congenital anorectal stenosis. The narrow part is more common in the anal canal or anus, and the range is short and ring-shaped, also known as anal membranous stenosis. Congenital anorectal stenosis can be born in the anus, rectum, and can be divided into anal stenosis, anal canal stenosis, anorectal junction narrow stenosis, rectal stenosis, anorectal stenosis and so on. Except for anal stenosis, other types are extremely rare. A history of poor bowel movements combined with local examination can confirm the diagnosis.

Cause

Causes:

1, anal stenosis is a low position deformity, is the late stage of embryonic development, incomplete absorption of the anal membrane or excessive fusion of reproductive folds, covering part of the anus. The narrow part is more common in the anal canal or anus, and the range is short and ring-shaped, also known as anal membranous stenosis.

2, anal canal stenosis is also a low position deformity, the entire anal canal is narrow and small, the narrow segment is tubular.

3, anal canal rectal junction stenosis belongs to the middle position malformation, anal canal and rectum development is basically normal, but the anal canal and rectal mucosa junction has a ring or braided cord.

4, rectal stenosis belongs to high position deformity, mostly occurs in the upper part of the rectum, which is ring-shaped or tubular.

5, anal canal rectal stenosis and wave from the anus to the lower rectum several centimeters long, tubular, narrow rectum has passed the puborectal muscle ring, the initial site is often located in the muscle ring, so it is also a high position deformity.

an examination

Related inspection

Anal examination

Partial inspection:

It varies according to the degree of stenosis. Severe stenosis is difficult to defecate after birth. It is manifested as defecation when defecation, crying, and signs of low intestinal obstruction may occur in days to months. Mild stenosis can be discharged normally, only when the stool is formed, the defecation is laborious, the feces are thin strips, frequent constipation, and even fecal impaction. There are also patients who go to adulthood because of the difficulty of long-term solution. Long-term poor bowel movements can cause proximal straightness and colon enlargement leading to secondary giant straight colon disease. The anus is partially visible in the anus, even with only a small hole, and even the catheter cannot be inserted. The high middle position is narrow, the appearance of the anus can be normal, but the fifth finger cannot pass through the narrow section during the examination.

A history of poor bowel movements combined with local examination can confirm the diagnosis. When it is difficult to judge the stenosis section, a barium enema can be used to help confirm the diagnosis.

Differential diagnosis

Differential diagnosis of anal or anal canal:

1, rectal atresia: normal development of the anus but no stool after birth, accompanied by signs of intestinal obstruction. The rectal examination is blocked upwards and has a sense of fluctuation. Inverted position X-ray examination, if the rectal membranous sputum is rectal atresia, if the large rectal segment is absent, there is no rectal malformation, sometimes accompanied by no anal deformity.

2, anal atresia: the child is not excreted after the birth of meconium, and soon vomiting, abdominal distension and other symptoms of intestinal obstruction, local examination, the center of the perineum is flat, the part of the anal area is covered with skin. In some cases, there is a pigmentation with obvious depressions and radiation wrinkles, which stimulate the ring muscle contraction reaction. When the baby is crying or holding his breath, there is a protrusion in the center of the perineum. The finger can be placed in the area to have a sense of impact. The baby is placed in the low position of the hip and the lower part of the anus is diagnosed as a drum sound. No meconium is discharged after birth, the anal area is covered with skin, and the anal area has a shock when crying. Inverted position on the X-ray lateral slice, the end of the rectum is located on the shame line or slightly below it. Ultrasound and puncture method measured the blind end of the rectum to about 1.5cm from the skin of the anus.

3, rectal and anal stenosis: rectal and anal stenosis refers to the anus, anal canal and rectum cavity diameter is thin, deformation or varying degrees of intestinal obstruction, called anus and rectal stenosis. Due to the stenosis, the anal stenosis and rectal stenosis (more than 2.5-5 cm above the dentate line or the rectum of the rectum), the stenosis is often within 10cm, which is related to the nature of the primary lesion, the upper end of the stenosis is dilated, and the stenosis continues. Smashed. Ulcers, formation of epilepsy or replaced by other tissues. This disease can generally provide important information for the diagnosis, but the upper lesion is more concealed, and multiple tests should be performed to make a correct diagnosis.

4, anal malformation: a large number of anal deformities, rectal blind end and fistula position. Its incidence rate in the newborn is 1:1500 ~ 5000, accounting for the first place in the digestive tract malformation. More men than women, high malformations accounted for about 50% of men and 20% of women. The incidence of various fistulas is 90% in women and 70% in men. The incidence of other congenital malformations is about 30-50%, and often multiple deformities. Family history is rare, only 1%. There is heredity, but the genetic method is still inconclusive.

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