Imperforated Anus (Anal Atresia)

• Riverside College, Inc. aims to be the home of 21st Century Global Leaders and Professionals

Imperforated Anus (Anal Atresia)

• It is defined as a stricture or the absence of the anus.
• It refers to a range of anorectal abnormalities from a membranous separation to the complete absence of the anus.
• The outward appearance of a child with this condition can be misleading regarding the true complexity of the malformation.

Statistics and Incidence

• Occurs in 1 out of 5000 live births.
• More common in males than in females.
• May occur as an additional complication of spinal cord disorders, as they arise from the same germ layer.

Etiology

• The cause is unknown or idiopathic.
• Believed to be due to the abnormal development of the rectum during embryo formation.
• During the 7th week of intrauterine life, the upper bowel elongates to pouch and combines with a pouch that invaginates from the perineum.
• If the membrane between the two surfaces of the bowel does not dissolve where these two sections meet, an imperforated anus results.

Germ Layers

• Formed during gastrulation and are present by two weeks.
• Include endoderm, mesoderm, and ectoderm.
• In humans, the germ tissues are the basis of all tissues and organs.

Primitive Gut Tube Development

• Develops during weeks 3-4 by incorporating the yolk sac during craniocaudal and lateral folding of the embryo.
• Divided into 3 distinct sections.
• These sections give rise to different parts of the digestive system.
• The foregut gives rise to the esophagus, stomach, liver, gallbladder, bile ducts, pancreas, and proximal duodenum.
• The midgut develops into the distal duodenum, jejunum, ileum, cecum, appendix, ascending colon, and proximal 2/3 of transverse colon.
• The hindgut becomes the distal 1/3 of the transverse colon, descending colon, sigmoid colon, and the upper anal canal.

Gut Tube Development and Abnormalities

• By week 6, proliferation of the epithelial lining of the gut tube results in obliteration of the lumen.
• During week 8, the central cells then degenerate and the tube is recanalized.
• Abnormalities in this process can result in stenosis, atresia, and duplications.

Diagnosis

• X-rays or sonograms may reveal the disorder.
• Prenatal ultrasounds may show signs suggesting an imperforated anus.
• The infant may be positioned in a slightly head-down position to allow swallowed air to rise to the end of the blind pouch of the bowel.
• Estimating the distance between the intestines and the perineum helps determine the extent of correction needed.
• Diagnosed at birth upon inspection of the newborn's anal region, revealing the absence of an anus.
• Absence of stool within 24 hours, with evident abdominal distention, is a diagnostic indication.
• Follow-up assessment includes checking if the baby is defecating.
• If not, a urine specimen should be collected and examined for the presence of meconium.
• The rectal-bladder fistula or rectovaginal fistula must be observed

Risk Factors

• VACTERL Syndrome is a risk factor.
• CHARGE Syndrome is a risk factor.
• Environmental Factors can cause this.
• Currarino Syndrome increases the chances.
• Townes-Brocks Syndrome may cause it.
• Parental exposure to nicotine prenatally can be a factor.
• Prenatal alcohol intake can increase the chances.
• Prenatal intake of caffeine may be a risk.
• Prenatal intake of illicit drugs is a dangerous factor.
• Occupational hazards are a risk.
• Being overweight or obese and having diabetes are prenatal risks.

Signs and Symptoms

• The anus opening is missing or not in the usual place.
• In girls, it may be near the vagina.
• Swollen belly or abdomen.
• No passage of stool within a day or two after birth.
• Passing stool through another opening, like the urethra in boys or the vagina in girls.

Potential Complications

• Constipation in the future.
• Bladder control problems.
• Bowel control problems.
• Problems with sexual function.

Medical Management: Diet

• NPO (nothing by mouth) before surgery.
• NGT (nasogastric tube) with low intermittent suction for decompression to relieve pressure.
• Maintain fluid and electrolytes with IV (intravenous) fluids or TPN (total parenteral nutrition).
• Avoid high-residue foods to lessen the bulk of stools, such as unrefined rice, grains, fruits, vegetables, and fruits with peels.

Medical Management: Activity

• Children with anorectal malformations are often otherwise healthy.
• Activity limitations are usually related only to the period around surgical procedures.

Surgical Management

• Includes colostomy, pull-through surgery, and posterior sagittal anorectoplasty (PSARP).

Colostomy

• Neonatal colostomy may be performed in children with malformation complexity or associated comorbidity.
• Colostomy can be closed traditionally after healing and postoperative dilations have achieved the desired size.

Pull-Through Surgery

• Primary neonatal pull-through without colostomy is used in boys with recto-urinary fistulas, in girls with cloaca or vestibular fistula, and in those who do not have a fistula when the rectal pouch is further than 1 cm.

Posterior Sagittal Anorectoplasty (PSARP)

• Used in fistulas and closed rectal pouches on lateral pelvic radiography.

Nursing Management

• Take the temperature in the tympanic, rather than the rectal area post-surgery.
• There should be no enemas or suppositories.
• Administer stool softeners as ordered.
• Place the diaper under, not on, the infant.
• Irrigate with saline after each bowel movement.
• Place the infant on a supine or side-lying position after surgery, rather than prone.
• Perform rectal dilation once or twice a day for a few months to ensure proper patency by inserting a cot-covered finger in the rectum.