Congenital anorectal malformation in children

Introduction to congenital rectal anal malformation in children Congenital malformation of the anus deformity (congenitalmalformationoftheanusandrectum) is a very common gastrointestinal malformation, a general term for a group of diseases that develop abnormalities in the posterior end of the gut. There are many kinds of anorectal malformations, and the pathological changes are complicated. Not only the development of the anorectal itself is defective, but also the muscles around the anus - the puborectalis muscle, the external anal sphincter and the internal sphincter have different degrees of changes. Neurological changes are also one of the important pathological changes in this malformation. In addition, the incidence of malformations associated with other organ malformations is high, and in some cases, multiple malformations or malformations that seriously endanger the life of the sick child. basic knowledge The proportion of illness: 0.001% Susceptible people: children Mode of infection: non-infectious Complications: intestinal obstruction, dehydration, vulvitis, urinary tract infection, congenital anorectal malformation, hydronephrosis, constipation

The cause of congenital rectal anal malformation in children

Causes:

At the end of the third week of the embryo, the end of the intestine was swollen and communicated with the anterior urinary sac to form a cloaca. At the 4th week, the mesoderm fold between the cloaca and the hindgut formed and grew to the caudal side, while the mesenchyme was on the side wall of the cloaca. The inner hyperplasia forms a fold, which is called a lateral pleat, and forms a urinary rectal septum. The cloaca is divided into two parts: the former is the urogenital sinus, the latter is the rectum, and the tail end of the cloaca is covered by an epithelial cell membrane of the ectoderm. The closed membrane is called the cloaca membrane, which is separated from the outside of the body. The former is the urogenital sinus membrane, the latter is the anal membrane. At the 7th and 8th week, the two membranes are ruptured successively. After the anal rupture, the intestine and the original anus penetrate and form normal. The rectum and anal canal, such as the posterior intestine or the primary anal dysplasia or dysplasia, form various types of anal atresia or stenosis, if the urogenital sinus and the hindgut are not separated, the intestinal opening is still on the urinary tract organ, then form The rectum and genitourinary system of the fistula or rectum will be paralyzed, anal advancement and other deformities, in general, the occurrence of anorectal malformation is the result of normal embryonic developmental disorders, the cause is not clear, according to the literature, anal The rectal malformation has a family history of less than 1%. The anorectal malformation is also the same as other malformations. It may be affected by viral infection, chemical substances, environment and nutrition during pregnancy, especially in early pregnancy (4-12 weeks). The earlier the embryonic developmental disorder occurs, the higher the location of the deformity and the more complicated it is.

Pathogenesis:

The international classification developed in 1970, based on the relationship between the rectal end and the levator ani muscle, especially the puborectal muscle, divided the anorectal malformation into a high position, a middle position and a low position 3, and the rectal blind end was terminated in the puborectalis muscle ring. The above are high malformations, which are located in the muscle and surrounded by the median malformation. Those who pass below the muscle are low-position deformities. Each type is divided into two groups: the sputum and the innocent. 50%, especially girls, girls have rectal vagina, vestibular and perineal palsy, boys have rectal bladder spasm, urethra and perineum.

1. Taxonomy In 1984, Wingspread simplified the taxonomy, specifically:

(1) Male:

1 high position: A. Anorectal hypoplasia: rectal prostatic urethra fistula. B. Rectal atresia. 2 middle position: rectal urethral bulbar fistula, anal development, no flaws. 3 low position: anal skin spasm, anal stenosis. 4 rare deformities.

(2) Women:

1 high position: A. Anorectal development: a rectal vaginal fistula, no sputum. B. Rectal atresia. 2 middle position: rectal vestibular fistula, rectal vaginal fistula, anal hypoplasia, innocent. 3 low position: anal vestibular fistula, anal skin spasm, anal stenosis. 4 cloaca deformity. 5 rare malformations, in recent years, the results of pelvic floor tissue structure in children with congenital anorectal malformation showed that the pelvic floor muscles, humerus, nerves and perianal skin were abnormal, the higher the deformity position, the more serious the pathological changes .

2. Muscle changes: The levator ani muscles of children with anorectal malformation, including the development of the puborectalis muscle, can change the position of the puborectalis muscle due to different types of deformity. The high deformity of the muscle is obviously shifted upwards and forwards, and is short. Shrinking, closed, attached to the prostate, urethra or vagina, and a certain distance from the blind end of the rectum and the external sphincter. The external sphincter is malformed in the high position, the direction of the muscle fiber is disordered, or only traces; the medial malformation external sphincter Normal development only the muscle fibers are arranged obliquely, the internal sphincter is absent in the high position, the median malformation is poorly developed, and the internal and external sphincter development of the lower deformity is normal.

3. Neurological changes: Children with anorectal malformation are often accompanied by atlas deformity. When the vertebral body is absent, it may be accompanied by a change of the phrenic nerve. The more absent segments, the more obvious the sacral nerve changes. Affect the treatment and prognosis of the disease, anorectal malformation often combined with other congenital malformations, the incidence of which accounts for 30% to 40%, the most common are genitourinary malformations and other parts of the digestive tract malformation, these multiple malformations increase the treatment Difficulties and can affect the prognosis.

Congenital rectal anus deformity prevention in children

It is believed that viral infection, high fever, medication, radiation exposure, allergies, low immune response and certain genetics are associated with early pregnancy, especially for various health care and genetic counseling during pregnancy. Prevention should be carried out from pre-pregnancy to prenatal:

Pre-marital medical examination plays an active role in preventing birth defects. The size of the effect depends on the examination items and contents, including serological examination (such as hepatitis B virus syphilis HIV) reproductive system examination (such as screening for cervical inflammation), general physical examination ( Such as blood pressure electrocardiogram) and inquiring about the family history of the disease, personal medical history and other genetic disease counseling work.

Pregnant women should avoid harmful factors as far as possible, including away from smoke alcohol, drugs, radiation pesticides, noise, volatile and harmful gases, toxic and harmful heavy metals, etc. In the process of antenatal care during pregnancy, systematic screening of birth defects is required, including regular ultrasound examinations. Serological screening, etc., if necessary, a chromosome examination.

Once an abnormal result occurs, it is necessary to determine whether to terminate the pregnancy; the safety of the fetus in the uterus; whether there is sequelae after birth, whether it can treat the prognosis, etc., and take practical measures for diagnosis and treatment.

Pediatric congenital anorectal malformation complications Complications, intestinal obstruction, dehydration, vulvitis, urinary tract infection, congenital anorectal malformation, hydronephrosis, constipation

1. Common complications: children with low intestinal obstruction often suffer from dehydration acidosis, severe shock and death; secondary colon is huge, nutritional disorders; often complicated by vulvitis and urinary tract infection.

2. Associated with malformation: the incidence of malformation is between 40% and 50%. The differentiation and development of the cloaca occurs at the earliest stage of embryonic development. During the critical period of embryonic development, any non-specific factor can also affect other Organ development, so congenital anorectal malformation often accompanied by malformations of other organs, the general statistical high-level malformation rate is more than 1 times higher than the low-level malformation, and the deformity is serious, due to the presence of malformation, increasing the difficulty of treatment In the case of malformation, urinary malformation is the first, such as renal dysplasia, unilateral or bilateral hydronephrosis, ureteral hydrops, etc., other organ malformations such as esophageal atresia can reach 6% to 7%, congenital giant The colon accounts for 2% to 3%, and the skeletal malformation is semi-vertebral, vertebral fusion is common, cardiovascular malformations such as ventricular septum, and room defects are about 7%. According to the statistics of Toronto Children's Hospital, children with congenital anorectal malformation Among the associated malformations, except for the most urinary malformations, 51% were skeletal deformities, heart, nerves, and gastrointestinal malformations. Domestic scholars reported that children with high and median congenital anorectal malformations The nerve endings in the puborectalis and perianal tissues are poorly developed, the density is reduced, and there are a certain number of muscle spindles in the puborectal muscle. In addition, the shape of the medulla and the number of motor neurons in the anterior medial group of congenital anorectal malformations There are also abnormal changes.

3. Postoperative complications: The common complications of this disease are as follows:

(1) rectal mucosal eversion: more occurs within 3 months after surgery, with scar softening, anal sphincter dysfunction can be restored, severe cases need to be surgically removed.

(2) anal stenosis: in order to prevent stenosis, it is necessary to adhere to anal expansion 1 to 1.5 years after surgery, severe stenosis should consider reoperation.

(3) incontinence: high anorectal malformation is more common after surgery, it is more difficult to recover, early postoperative defecation training.

(4) constipation: early can be caused by surgical trauma pain, late due to anal stenosis or rectal retraction to form tubular stenosis, a small number of children with rectal sigmoid colon ganglion cell disease, the above cases are treated conservatively such as: anal If the intestines are ineffective, different surgical treatments should be performed according to the specific conditions.

Congenital rectal anorectal symptoms in children Common symptoms Anal malformation without anorectal stenosis Dehydration intestinal atresia Abdominal urethra sputum fecal vomit anal rectal malformation abdominal pain

There are many types of congenital anorectal malformations. The clinical symptoms are different, and the time of symptoms is different. Especially when the baby does not defecate 24 hours after birth, anorectal malformation should be considered, and the examination should be carried out in time. That is, symptoms of acute intestinal obstruction occur, and some patients have difficulty in defecation for a long time after birth, and even a small number of children have no symptoms or mild symptoms for a long time.

Symptom

(1) Complete anal atresia and complicated fistula: complete anal atresia and boy complicated with bladder spasm, urethral fistula, no fetus excretion after 24 hours of birth, if not found early, about 3/4 cases, Including all innocent anorectal atresia and part of the anorectal atresia, but the mouth is narrow and can not discharge meconium or only a small amount of meconium can be discharged, only in the urethra, diapers are contaminated with a small amount of fetal litter marks, low intestinal obstruction, feeding After the vomiting, the spit is milk and contains bile. Later, the fecal sample can be vomited, the abdomen gradually expands, the condition becomes more and more serious, and dehydration occurs in the late stage. If it is not diagnosed and treated, it can die more than 6-7 days.

(2) Anorectal stenosis and complicated fistula are relatively thick: another part of the case, including anorectal stenosis and vaginal fistula, vestibular palsy and perineal fistula and thick fistula, do not appear intestinal obstruction symptoms for a period of time after birth, In a few weeks, months or even years after the occurrence of difficulty in defecation, thinning of the note, chronic bloating, abdominal pain, abdominal distension, due to frequent bowel movements, feces accumulate in the colon can form fecal stone, sometimes in the lower abdomen can be touched Huge feces, there have been changes in the secondary megacolon, affecting the growth and development of children.

2. Anus, perineal examination Most children with anorectal malformation, there is no anus in the normal anus position, as long as the baby is born, you can find the perineum.

(1) High or levator ani muscle deformity: about 40% of anorectal malformations, boys are more common than girls, this kind of sick child is slightly sunken in the normal anal position, darker color, but no anus, sick children crying When you use it hard, the depression does not bulge outward. There is no impact when you touch it with your fingers. The X-ray examination of the airflow at the end of the rectum is above the shame line. Whether it is a boy or a girl, there is often a fistula, but because the fistula is thin. Almost all have intestinal obstruction symptoms, the rectal end position is higher, above the levator ani muscle, the innervation of the pelvic muscle is often defective, and often accompanied by spinal and upper urinary tract malformations, girls often accompanied by vaginal fistula, more open in The posterior vaginal wall of the vagina, such a child with genital dysplasia, is naive, urinary sputum is almost seen in boys, girls are rare, venting from the external urethra and meconium is the main symptom of rectal urinary fistula, from the There is meconium in the external urethra or meconium mixed in the urine. It is not possible to distinguish between bladder spasm or urethra spasm. However, if you carefully observe the urination of the sick child, sometimes you can find obvious differences. When the bladder is paralyzed, the meconium enters the bladder and mixes with urine. , In the whole process of urination, the urine of the sick child is green, and the last part of the urine is darker. At the same time, the gas trapped in the bladder can be discharged. Because of the absence of sphincter control, the feces often flow out from the fistula, which may cause genital tract infections, such as compression of the bladder. In the area, meconium and gas are discharged more. When not urinating, due to the control of the bladder sphincter, no gas is discharged. When the rectal urethra is paralyzed, only a small amount of meconium is discharged at the beginning of urination, and it is not mixed with urine. Urine is transparent, because there is no sphincter control, and the venting from the external urethra has nothing to do with urinary movement. These symptoms are important for the diagnosis of urinary sputum, but because the thickness of the fistula is different, or it is often blocked by sticky meconium. The degree of occurrence is not the same, or even does not appear at all. Therefore, it is necessary to routinely check the presence of meconium in the urine of the sick child. A urine test is negative, and the presence of urinary fistula cannot be excluded. It must be checked several times. Some cases may be According to the X-ray photograph, the urethra cystography, the gas or liquid level in the bladder was diagnosed, and the contrast agent was filled in the mouth or into the rectum to confirm the diagnosis.

(2) Median malformation: about 15%, this type of malformation used to be classified as high malformation by some people, while others are classified as low malformation, innocent blind end of the urethral ball sponge muscle, or vagina Near the lower end, the puborectalis muscle surrounds the distal rectum. The fistula is open to the urethral bulb, the lower vagina or the vestibule. The appearance of the anus is similar to the high malformation. It can also be defecation from the urethra or vaginal. Through the fistula into the rectum, touch the anus with your finger to touch the top of the probe. On the X-ray photograph, the air bubble at the end of the rectum is located below the shaman's tail line. The girl's rectal vestibule is more common than the vaginal fistula. The vestibular vestibular fossa, also known as the scaphoid fossa, has a large pupil, can maintain normal bowel movements, can develop normally, and has incontinence only during loose stools. For example, the rectum of the rectal vestibule is very narrow, and its clinical manifestations Similar to the various low-position malformations that open in the genital area, however, by inserting the probe through the fistula, the probe travels toward the cephalad rather than to the dorsal side. Because of the frequent fecal outflows during infancy, such as poor care, often in the vestibular vestibule Casual, can cause vaginitis or ascending infection, anorectal stenosis is a rare deformity, stenosis involving the anus and lower rectum, may be confused with anal stenosis, fistula angiography can determine the diagnosis.

(3) low or levator ani muscle deformity: about 40% of anorectal malformation, caused by the late development of the embryo, the rectum, anal canal and sphincter develop normally, the rectal end position is lower, below the I line, this kind Most of the deformities have a fistula, but less common with other malformations. Some clinical manifestations have depressions in the normal anal position. The anal canal is completely occluded by a diaphragm. The diaphragm is sometimes thin, and it can be seen in the anal canal. Meconium is dark blue. When the sick child is crying, the diaphragm bulges outward obviously. When touched with a finger, it has obvious impact. It has obvious contraction to the stimulus. Some anal membranes are broken, but not complete. The caliber is only 2 ~ 3mm, difficulty in defecation, thinning of the note, like the toothpaste, some anus is normal, but the position is forward, between the normal anus and the scrotum root or the posterior labia, called the perineal anus, generally no clinical symptoms. There is no need for treatment. Many low-grade malformed children are accompanied by anal skin fistulas, which are filled with meconium and dark blue. The fistula is open to the perineum or more to the scrotal suture or the ventral side of the penis. Any part of the girl's hidden meconium is not easy to see, but if the probe is inserted from the mouth, it will go straight down the skin. In the girl, many low-position deformities have an opening in the genital area near the joint of the labia. Some of them have a similar appearance to the normal anus. They are called the vestibular anus or the genital anus. The anus outside the anus is a variation of the anal diaphragm. In the anal vestibule, the intestine has passed through the puborectal muscle, and the end of the anal canal communicates with the vestibule through a small fistula. In clinical practice, the fistula is different from the rectal vestibular fistula. For the probe inserted into the fistula, the probe is slightly moved to the dorsal side instead of the head side, and the probe tip is easily touched by a finger touching the normal anal point.

(4) Rare malformations: There are also some rare malformations, such as the girl's perineal fissure, a wet epithelial fissure between the anus and the vaginal vestibule, and a rectal vestibule with a normal anus. The cloaca is deformed, the vulva develops in a naive form, the labia majora is thin, and only one opening is seen, and the urine is discharged from the mouth.

Pediatric congenital rectal anus deformity examination

1. Peripheral blood: When there are symptoms of infection and systemic poisoning, peripheral blood leukocytes, neutrophils increase, and there may be a decrease in the number of platelets.

2. Blood biochemistry: concurrent dehydration, acidosis, routine check blood sodium, potassium, chlorine, calcium, blood pH, urea nitrogen, creatinine and so on.

3. Urine routine examination: There is meconium in the urine of the sick child. The purpose of the examination is to clarify the following questions: 1 Anatomy and type of deformity. 2 nerve development. 3 The developmental state of the internal and external sphincters and levator ani muscles. 4 What are the deformities?

4. X-ray examination: Accurately determine the height of rectal atresia, with or without urinary fistula, X-ray examination is indispensable, and some cases can be diagnosed according to X-ray photographs of gas or liquid level in the bladder. It is pointed out that the intestinal lumen Calcification is also the basis for the diagnosis of rectal urinary fistula. Urinary tract angiography, contrast agent can only fill the mouth of the mouth, there is a diverticulum-like shadow, and there are few contrast agents into the rectum. The fistula in the urethral membrane is thick. The metal urinary catheter can be inserted into the rectum along the posterior wall of the urethra. The fistula can be used to determine the diagnosis. The inverted lateral X-ray film is still used today. The method is to invert the child 24 hours after birth, and the anal crypt is sticky. A small typeface, the distance between the typeface and the blind end of the inflatable rectum before the iliac crest is the height of the atresia, from the lower edge of the pubic symphysis to the tailbone line, that is, the upper edge of the puborectal muscle is called the pubic line, and the airway at the end of the rectum is visible on the X-ray picture. The shadow is located below the shaman's tail line, and the air shadow is higher than the shame line, which is a high position deformity, but the X-ray photograph results sometimes have errors.

(1) Check too early (within 24 hours after birth), the gas swallowed by the baby has not reached the rectum.

(2) The inversion time is too short and the gas has not reached the rectum.

(3) X-ray injection angle is not suitable or exposed when the baby exhales.

(4) There is a child with a rectal blind end that can not be filled can cause illusion, so there is no need to use the inverted film method, but the use of fistula angiography can determine the direction of the fistula, the length and the level of the rectal end, the patella flat: in the high anus Children with rectal malformation often have tibial deformity, sacral nerve and sphincter dysplasia, especially those with vertebral body below the second vertebrae. The postoperative recovery is worse, so it is meaningful for the child to make this examination.

5. Computerized tomography (CT): can show the developmental state and trend of the levator ani muscle group, can also be used as a reference for postoperative follow-up. CT shows normal pediatric puborectal muscle like a soft tissue mass, the front is fixed to the pubis, Backward and connected to both sides of the rectum and the posterior wall, the internal and external sphincters form an oval mass, which is difficult to separate. Children with different types of anorectal malformations have different CT findings, such as rectal urethra and puborectalis. Around the urethra and rectal blind end, the anal sphincter is located just below the perineum.

6. B-type ultrasonic inspection: no time limit, no special preparation before inspection, the method is safe and simple, the measured data is reliable, less error than X-ray, repeatable, and the child has little pain.

7. Magnetic resonance (MRI): In the application of anorectal malformation, it can observe the changes of the muscles around the anus, and at the same time can judge the type of deformity and the presence or absence of deformity of the appendix. The changes of the perianal muscles can be observed from three aspects. In order to obtain a clear image, a sedative can be given to the sedative before the examination, and a marker is placed in the anal crypt. If necessary, the gas is filled into the rectal blind end through the mouth to make the image clearer.

Diagnosis and diagnosis of congenital rectal anus deformity in children

diagnosis

1. Medical history and physical examination: the diagnosis of typical anal atresia is not difficult. After the birth, there is no anal opening in the perineum. The diagnosis is confirmed. The lower anal occlusion is dark blue film at the anus crypt or the intermittent brown line along the perineal scrotum. (caused by storage of meconium), or an external impulse with increased abdominal pressure at the anus, no upper symptoms without high anus, rectal bladder spasm and rectal urethra fistula, mixed urine in the urine, rectal perineum, vestibule The sputum and vaginal fistula can flow out of the fetus at the perineum, the scapular fossa or the hymen.

2. Auxiliary examination: The type of deformity and coexisting deformity are confirmed by auxiliary examination.

Through the clinical features and auxiliary examination, the diagnosis of congenital anorectal malformation is not difficult. It is important to determine the height of rectal atresia, the relationship between the rectal end and the rectal muscle, and the presence or absence of urinary fistula and spinal deformity. Etc., related to the formulation and prognosis of the treatment plan.

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