Anal and rectal malformations in neonates

Introduction to neonatal anorectal and rectal malformations The incidence of anal and rectal malformations (malformationofanusandrectumofnewborn) was 0.75 in the neonatal period, accounting for the first place in the digestive tract malformation. Boys have a little more to see, have a certain family relationship, often see a low intestinal obstruction, seriously affecting the lives of children. basic knowledge The proportion of the disease: 0.075% (the incidence of the disease in certain age groups is 0.075% (the incidence of other malformations accounted for 30% to 50%)) Susceptible population: newborn Mode of infection: non-infectious Complications: intestinal obstruction

Causes of neonatal anorectal and rectal malformations

(1) Causes of the disease

This disease is the result of obstacles in normal embryonic development. The earlier the embryo developmental disorder occurs, the higher the position of anorectal malformation. The cause of developmental disorders is not very clear, such as some unfavorable factors (drugs, machinery, blood supply). Malformations can occur in disorders, etc., and are also related to genetic factors, with a family history of 1%.

At the end of the third week of the embryo, the terminal end of the intestine is swollen and communicates with the anterior allantoic sac to form a cloaca. The tail end of the cloaca is closed by a layer of epithelial cell membrane of the ectoderm, called the cloaca membrane, separated from the body, located at the 4th week. The mesodermal folds between the cloaca and the hindgut are formed and grow to the caudal side, and at the same time, the inner side of the cloaca is filled with the inner side of the cloaca to form a fold and grow into the cavity. These constitute the urinary rectal septum, and the cloaca is divided into two parts, the former. Forming the genitourinary system, the latter develops into the rectum, and the gap in the middle gradually shrinks. It is called the cloaca, and the primitive perineum appears at the 7th weekend, so that the anterior part of the cloaca develops into the urinary genital membrane, and the posterior part develops into the anal membrane. Anal, bulging left and right anal nodules, growing in the direction of the abdomen, around the end of the intestine, a depression in the center of the nodule, later evolved into an anus, the anus of the embryo in the 8th week and the hindgut, the anorectal malformation is mostly in the embryo 7th ~ At 8 weeks, the tail was abnormally developed or blocked, such as the anal membrane and the original anus did not penetrate, forming an anal atresia, cloaca and primitive perineal dysplasia, forming various urinary tracts. Fistula between the system and the colonization rectally, in addition to developmental defects combined tail fistula, urethral stricture can also be complicated, sacral and sacral nerve defect and the like.

(two) pathogenesis

Can be divided into 4 types (Ladd and Gross classification):

1. Anal stenosis: the rectum and anus are intact, but there are varying degrees of anal stenosis or stenosis at the anorectal junction.

2. Anal membrane type closure: the anus skin and the rectum are not penetrated, there is a membrane septum, which is a low anal atresia.

3. Anorectal hypoplasia: there is only one depression in the anus, and there is a considerable distance between the rectum and the anal depression, which is a high anal atresia.

4. Rectal atresia: The shape of the anus is normal, there is an anal canal, but the distance between the anal canal and the rectum is different, which is less common.

The atresia can be simple atresia or combined with various fistulas. The incidence of fistula is about 50%, especially for girls. Boys can have rectal bladder spasm, rectal urethral fistula and rectal epiglottis, and girls can have rectal vagina., rectal vestibular palsy and rectum will be sputum 3 kinds.

Often combined with other malformations, the incidence of 30% to 50%, and often multiple deformities, the most common are genitourinary malformations and other parts of the digestive tract malformation.

The international classification method is based on the lateral position of the pelvic inverted position, taking the pubic symphysis to the appendix joint line, marked as PC line (pubic tail bone line), representing the levator ani muscle plane, observing the relationship between the rectal blind end and the PC line, rectal blindness The end of the PC line, for the levator musculotype (lower type), above the PC line, for the levator levator type (high type); located in the PC line plane, for the levator ani muscle type (middle position type) .

Neonatal anal and rectal malformation prevention

The cause of the disease has not yet been fully elucidated. The genetic counseling work should be done well, and all the health care work during pregnancy should be done. The preventive measures should be based on birth defects, and the 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, treponema pallidum, HIV) and reproductive system examination (such as screening for cervical inflammation). General medical examinations (such as blood pressure, electrocardiogram) and asking about the family history of the disease, personal medical history, etc., do a good job in genetic disease counseling.

Pregnant women should avoid harmful factors as far as possible, including away from smoke, alcohol, drugs, radiation, pesticides, noise, volatile 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 examination, 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 be treated, how to prognose, etc., and take practical measures for diagnosis and treatment.

Neonatal anorectal and rectal malformation complications Complications, intestinal obstruction

Low intestinal obstruction, water and electrolyte balance disorder, seriously affecting the lives of children, often combined with fistula formation, according to statistics, newborn males in addition to perineal sputum with rectal urethra is more common, and women in addition to perineal sinus rectal scaphoid Mainly sputum, the incidence of fistula formation without anus was only about 5% of the entire case.

Neonatal anal and rectal malformations common symptoms intestinal atresia dehydration rectal stenosis intestinal stenosis intestinal perforation urethral fistula

Due to the large number of types, the clinical manifestations are different, and the symptoms are different. Most of the children have no anus. If you examine the perineum carefully, you can find that the symptoms are mainly low intestinal obstruction. Most cases gradually develop symptoms after birth. Anorectal atresia, no meconium discharge after birth, abdominal expansion, vomiting after eating, spit out for milk, containing bile and fecal samples, symptoms progressively worsened, and dehydration, electrolyte imbalance, can cause intestinal perforation and other mergers Symptoms, death within 1 week, anorectal stenosis and combined fistula may vary greatly depending on the thickness and position of the fistula. The general boy has no anus combined with rectal posterior urethral fistula, more common fistula, intestinal obstruction symptoms More obvious, and can have symptoms such as meconium or gas in the urine. In the urethra, diapers are contaminated with a small amount of meconium, and there is no hole in the anus. Many of them can be found early and treated. If they are not treated promptly, they can be repeated. Occurrence of urethritis, anorectal stenosis and girls with low rectal vaginal fistula, fistula is more coarse, can pass the fistula defecation, the symptoms of intestinal obstruction are unknown It is obvious that after several months, due to the addition of complementary foods, the stool becomes thick and thick, and the symptoms of intestinal obstruction appear. Due to frequent bowel movements, feces accumulate in the colon to form hard dung stones, or secondary megacolon, most of which affect growth and development. Can also cause vaginitis or ascending infection, check the anus, common hip flat circle, shallow gluteal groove, no hole in the anus or only one trace, low deformity, the diagnosis can touch the blind end of the rectum.

Examination of neonatal anal and rectal malformations

1. Urine examination: There are clear meconium or microscopic examination of squamous epithelial cells, which are formed by rectal urethral fistula and rectal bladder.

2. Blood examination: white blood cells and neutrophils increase when there is infection; when there is anemia, the hemoglobin concentration decreases, and the red blood cell count decreases.

3. Blood biochemical examination: there may be water and electrolyte disorders, blood sodium, potassium, chlorine, calcium, magnesium and blood pH, creatinine should be checked.

The diagnosis of congenital anorectal malformation is not difficult clinically, but the main reason is how to correctly determine the height of the atresia, the relationship between the blind end of the rectum and the puborectal muscle, and the presence or absence of urinary fistula and skeletal deformity.

1. X-ray inverted position film examination: X-ray examination is an indispensable diagnostic measure. Wangensteen and Ricc first described the X-ray inverted position film method in 1930 to understand the distance between the gas shadow of the rectum and the skin of the perineum. The deformed position has been used for more than half a century, and Stephens proposed the connection of the inverted lateral slice from the midpoint of the pubic bone to the appendix joint, the PC line (pubococoygeal line), which is equivalent to the pubic bone. The posterior position of the rectal ring, Kelly added a description, the same as the lateral position, the shadow of the newborn ischial ridge is like a comma ",", at its upper end (point I) as a parallel line parallel to the PC line, here is equivalent In the central fiber plane of the puborectal muscle, embracing the rectum or fistula or surrounding the cloaca, vaginal or urethra, Smith proposed a high position above the PC line, a median position between the PC line and the I point, and a line below the I point is a low position deformity. This is important for determining the treatment and choosing the surgical method. At the 1970 Melbourne International Pediatric Surgery Conference, it was agreed that this X-ray judgment method is correct and is now internationally available. Identification method.

(1) Operation method: The operation method of inverting the lateral slice is to put the child in the lower position of the head for 5 to 10 minutes after the birth of the child, and gently massage the abdomen by hand to make the gas fully enter the rectum, which is equivalent to normal in the perineum. A metal opaque marker is fixed on the skin of the anus, and the child's legs are inverted for 3 minutes. The X-ray center is perpendicular to the lap, and the injection point is pubic symphysis. The patient is exposed when inhaling, and the inverted side position is taken. sheet.

(2) Reason for the error: It should be noted that this method also has certain errors, which may be due to:

1 Within 24 hours after birth, the gas swallowed by the baby has not reached the rectum.

2 is too short when inverted.

3 The blind end is filled with sticky meconium, and the air is not easy to reach.

4X line injection angle is not suitable or exposed when the baby exhales.

2. Ultrasound examination: In recent years, the blind end of the perineal rectum puncture and suction to determine the distance between the blind end of the rectum and the skin has been rarely used. Ultrasound can accurately measure the distance between the blind end of the rectum and the skin of the anus. Chongqing Medical University used to be in 1985. Try B ultrasound to diagnose 15 cases of congenital anorectal malformation. They believe that the advantage is that there is no damage. The position of the blind end is not restricted according to the echo image of meconium. It does not need to be inverted, and the error is smaller than the X-ray examination.

3. Sputum tube angiography: combined with fistula but difficult to diagnose, can be used for fistula angiography, with iodized oil for lateral position radiography.

4. Urethral cystography: visible contrast agent filled with fistula or into the rectum, can determine the diagnosis, this method is not easy for newborns, positive for a diagnosis, negative can not be excluded.

5. X-ray abdominal plain film examination: Simultaneously finding the gas or liquid level in the bladder on the X-ray film is a simple and reliable method for diagnosing urinary fistula. Others such as fistula angiography and urethral cystography are also often used for diagnosis.

6. X-ray pelvic anterior and posterior: About 45% of neonates with rectal malformation have abnormal humeral dysplasia, and this change is closely related to the function of defecation later. Therefore, the anterior and posterior pelvis should be taken at the same time. According to the proportion of the development of the tibia, this is helpful for the pediatric surgeon to judge the prognosis.

The uppermost point of the two babies of the newborn is A and A', the B and B' points are the outermost edge of the atlas, the AA' is parallel with the BB' line, and the tail is C, and the C point is parallel to The C line of the BB' line, see Figure 5, the average tibia rate of normal children (BC: AB) = 0.7 ~ 0.8, on the contrary, in the case of severe anorectal malformation, the rate of tibia development is even less than 0, the ratio of low and defecation The prognosis of the function is positive, so the tibia rate is an indicator of the prognosis of anorectal malformation. The Currarino triad is a special type of humeral deformity, which can be associated with anal stenosis and anterior sacral mass (eg lipoma, anterior tibiofibular ridge) Membrane bulging, etc., Xinhua Hospital affiliated to Shanghai Second Medical University reported 2 cases in 1998.

7. CT scanning and magnetic resonance imaging: the technique of non-invasive has been gradually applied. Krasna et al. (1988) believe that the X-ray inverted lateral slices proposed by Wangensteen and Rice have been used for more than 50 years, and their correctness is only 72%. The CT scan can be used to understand the position of the rectal blind bag in the anal deformity. In 4 cases, the correctness is high, the time and body position are not affected, and the bone mark in the X-ray film is clear.

Diagnosis and diagnosis of neonatal anorectal and rectal malformations

Diagnostic criteria

According to the shape of the anus, combined with the fistula, the initial diagnosis is not difficult, but the type of deformity needs to be further examined.

1. Clinical examination: after the birth, there is no anus or only a trace of the perineum, no meconium discharge, the diagnosis can be confirmed, there is a membrane septum between the anus skin and the rectum, when the child crying or the abdominal pressure increases, the anus is seen External bulging, and sometimes visible meconium can be seen through the skin. For example, there is a certain distance between the blind end of the rectum and the skin. The fingertip can be placed on the anal mark. When the child is crying, if the finger has a shock. , indicating that the distance is relatively close, otherwise most of the high-level atresia, combined with perineal or vaginal fistula, can be probed into the fistula, turn the tip to the anus side, touch the finger at the anus, if you can touch the probe, you can estimate the distance between them ( The puncture and suction method can also be used to measure the depth of the needle tip when the meconium is extracted to determine the distance between the blind end and the skin. The perineum and vestibular sacral examination can be seen, and the size of the fistula can be measured, such as meconium. Excreted in the hymen, it is vaginal fistula, rectal bladder spasm and rectal urethra fistula, urine can be diagnosed with feces.

2. X-ray examination: The commonly used method is the inverted side method, which must be checked 24 hours after birth. The air can be reached for about 20 hours after swallowing. Otherwise, the blind end is estimated to be too high. The blind end of the rectum is located in the PC. The upper line is the high position, the lower one is the lower type, under the PC line, but still above the M line (the 2/3 of the ischial tuberosity and the line connecting the PC line with the lower 1/3 junction). Bit type.

Differential diagnosis

Identification of intestinal obstruction caused by other causes, confirmed by clinical features and auxiliary examination.

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