I. Definition
Anal atresia, also known as low-grade anorectal atresia, is caused by abnormal development of the primitive anus and failure to form an anal canal, resulting in inaccessibility of the rectum to the outside world.
Etiology
Due to the developmental disorder of the primitive anus, the anal canal is not recessed inward. The rectum is basically normal, with its blind end at the edge of the urethral bulbospongiosus muscle or near the lower end of the vagina, and the puborectal muscle wraps around the distal end of the rectum. The perineum is often hypoplastic and flat, and the anal area is covered by intact skin. It may be combined with urethral bulb, lower vaginal segment, or vestibular fistula.
III. Diagnostic points
The child is born without meconium excretion and soon develops vomiting, abdominal distension and other symptoms of bitter intestinal obstruction. On local examination, the perineum is flat in the center and the anal area is partially covered by skin. In some cases, there is a small concavity with obvious pigmentation and radiating wrinkles, and stimulation of the area reveals a contraction response of the circular muscle. In some cases, there is a small depression with obvious pigmentation and radiating wrinkles.
IV. Differential diagnosis
1, congenital intestinal atresia.
2.Intestinal stenosis.
3.Intestinal obstruction.
V. Treatment
Once diagnosed, surgical treatment should be chosen according to the situation.
1, low type combined with rectal navicular fistula, rectal skin fistula, anal stenosis and thick fistula can be first dilated, dilator gradually increased to ensure normal defecation, to be 6-12 months later according to the situation to decide to take anal transposition or shaping surgery.
2, low anus without fistula or fistula is too thin to maintain defecation, perineal anoplasty is feasible.
3.Sacral perineal anorectoplasty is feasible for intermediate anorectoplasty.
4, high anus, the general condition of the child is poor, combined with serious congenital anomalies, such as congenital heart disease, esophageal atresia, etc., or due to technical difficulties, in order to ensure a good defecation function after surgery, colostomy should be performed first. If the situation is good, sacral perineal anoplasty or abdominal sacral perineal anoplasty is feasible.
VI. Grading and treatment guidelines
Grading: high deformity, medium deformity, low deformity
Guidelines for diagnosis and treatment: see the fifth treatment point.
VII. Admission criteria
Once diagnosed, clinical examination: postnatal perineum without anus or with only one trace and no meconium discharge, admission is allowed.
VIII. Special critical pointers
1.Birth time more than 3 days;
2, dehydration, infectious shock;
3, systemic sepsis.
IX. Consultation criteria
1.No bowel movement after birth;
2, perineal anal agenesis.
X. Complications and management
1.Anal stricture;
2.Urethral injury;
3.Bladder injury;
4.Fistula recurrence;
5.Anal incontinence;
6.Retraction of rectum;
7.Perianal infection;
8.Mucosal ectopia;
9.Anal sphincter injury.
XI. Talking points
Secondary diseases such as megacolon may be operated again; postoperative anal stricture, perianal infection, rectal retraction, fecal incontinence, fistula recurrence, urethral injury.
XII. Discharge criteria
The child has normal bowel movements, eats milk well, no abdominal distension, vomiting, and the perianal wound or fistula wound heals well.
XIII. Discharge instructions
(1) Keep the anus clean, wipe the feces after each bowel movement and take a bath;
(2) It must be emphasized that anal dilation should be started 2 weeks after surgery, once a day for 3 months, after which it can be reduced to once every other day or 3 days depending on the situation, and dilated until half a year, with regular postoperative outpatient review.
1. Diagnosis.
Clinical examination: the diagnosis can be determined by the absence of anus or only a trace in the perineum after birth and the absence of meconium discharge.
2.Auxiliary examination.
Complete examination: blood routine, blood type, routine urine and stool, liver and kidney function, electrolytes, coagulation function, nine items before transfusion, inverted X-ray, ultrasound (anal crypt to blind end of rectum); if the general condition of the child is good and conditions allow, cardiac ultrasound and abdominal ultrasound can be completed to exclude other organ malformations.
3.Pre-operative preparation
(1) Determine the location of the blind end of the rectum: inverted x-ray, which should be taken 12-24 hours after birth; ultrasound examination of the distance from the blind end of the rectum to the anal crypt.
(2) Preoperative comprehensive examination to understand whether the child is combined with other malformations, such as serious congenital malformations, which can also be life-threatening.
(3) Preoperative catheterization and urinalysis should be performed.
(4) Preoperative infection should be prevented by giving broad-spectrum antibiotics, metronidazole, and vitamin K1 10mg intramuscularly to newborns.
(5) Pay attention to warmth before surgery, and pay special attention to the occurrence of sclerosis when the temperature is low.
(6) Pre-operative gastric tube.
4. Choice of surgical method
(1) The low type combined with rectal navicular fistula, rectal skin fistula, anal stenosis and thick fistula can be dilated first, and the dilator can be gradually increased to ensure normal defecation, and after 6-12 months, the anal transposition or shaping can be decided according to the situation.
(2) For low anus without fistula or fistula that is too small to maintain defecation, perineal anoplasty is feasible.
(3) Sacroperineal anoplasty is feasible for intermediate anorectal.
(4) In the case of high anus, the general condition of the child is poor, combined with serious congenital anomalies, such as congenital heart disease, esophageal atresia, etc., or due to technical difficulties, in order to ensure good defecation function after surgery, colostomy should be performed first. If the situation is good, sacral perineal anoplasty or ventral sacral perineal anoplasty is feasible.
5.Postoperative precautions
(1) If the child’s abdominal distension disappears and the bowel movement is smooth, he can eat breast milk after 6 hours;
(2) Keep the anus clean, wipe the feces after each bowel movement and take a bath;
(3) It is important to emphasize that anal dilatation should be started 2 weeks after surgery, once a day for 3 months, after which it can be reduced to once every other day or 3 days depending on the situation, and dilated until half a year, and regular postoperative outpatient review.