Imperforate Anus Nursing Care Management and Study Guide

What is Imperforate Anus?

When the anus is malformed, the associated muscles and nerves usually share a similar degree of malformation. The affected organs sit deep in the pelvis and are not well visualized through abdominal incisions, which made repair difficult for early surgeons.

Pathophysiology

The embryogenesis of these malformations remains unclear.

• The rectum and anus are believed to develop from the dorsal portion of the hindgut, or cloacal cavity, when lateral ingrowth of mesenchyme forms the urorectal septum in the midline.
• This septum separates the rectum and anal canal dorsally from the bladder and urethra. The cloacal duct is a small communication between the two portions of the hindgut.
• Downgrowth of the urorectal septum is believed to close this duct by 7 weeks' gestation. During this time the ventral urogenital portion acquires an external opening; the dorsal anal membrane opens later.
• The anus develops by fusion of the anal tubercles and an external invagination (the proctodeum) that deepens toward the rectum but is separated from it by the anal membrane. This membrane should disintegrate at 8 weeks' gestation.
• Interference with anorectal development at varying stages produces a range of anomalies, from anal stenosis, incomplete rupture of the anal membrane, or anal agenesis, to complete failure of the upper cloaca to descend and failure of the proctodeum to invaginate.

Statistics and Incidences

Anorectal malformations occur in approximately 1 newborn per 5000 live births (StatPearls, 2023).

• Anorectal and urogenital malformations are rarely fatal, although some associated anomalies (cardiac, renal) can be life-threatening.
• Intestinal perforation or postoperative septic complications in a newborn with imperforate anus can result in mortality or severe morbidity.
• Malformation-related morbidity stems from associated malformations of rectal motility, anorectal innervation, and sphincteric musculature. The most common is constipation; most children have mild malformations that commonly cause constipation for reasons that remain unclear.
• The most severe forms of malformation-associated morbidity are fecal and urinary incontinence.
• No known racial predilection has been reported.
• A slight male predominance is reported, roughly 1.2 to 1 (StatPearls, 2023).
• Most children with an anorectal malformation are identified on routine newborn physical examination.

Clinical Manifestations

Newborns with imperforate anus are usually identified on the first physical examination.

• Absence of stool. No passage of stool within a day or two of birth.
• Passing stool through other openings. The infant may pass stool through another opening, such as the urethra in boys or the vagina in girls.
• Swollen belly. Unable to pass stool, the newborn develops a swollen belly.
• Absence of anal opening. The anal opening is missing or out of its usual place; in girls this may be near the vagina.

Assessment and Diagnostic Findings

• Laboratory studies. CBC count, blood typing and screening, and serum electrolyte levels should be measured in all children with imperforate anus who require operation. Urinalysis should be performed to detect a rectourinary fistula in all cases where the diagnosis cannot be made on physical examination alone.
• Sacral radiography. Two views of the sacrum, posteroanterior and lateral, should be obtained before surgery to measure sacral ratios and to look for sacral defects, hemivertebrae, and presacral masses.
• Abdominal ultrasonography. Used specifically to examine the genitourinary tract and look for other masses. Hydronephrosis, hydrocolpos, presacral mass, abdominal mass, or similar findings can profoundly affect management.
• Spinal ultrasonography or MRI. All children with any form of anorectal malformation, even minor ones, should be screened for spinal malformations. These lesions can be diagnosed with ultrasonography before ossification of the spine.
• Lateral pelvic radiography at 24 hours. Children who cannot be diagnosed on physical examination alone traditionally underwent invertography (holding the baby upside down and using lateral radiography to see the level of gas in the distal rectum). A more humane approach is to wait 24 hours after birth to allow maximal pelvic pouch distension, then use cross-table lateral pelvic radiography with a radio-opaque marker on the anal dimple, with the child prone and hips slightly raised.
• MRI. All children with sacral defects on plain radiographs should undergo spine ultrasonography to rule out associated malformations such as meningocele, meningomyelocele, teratoma, or mixed lesions.
• CT scanning. CT scanning presently plays no role in the routine evaluation of anorectal malformations.

Medical Management

• Nothing by mouth. Newborns with imperforate anus should not be fed and should receive intravenous hydration.
• Neonatal colostomy. Performed in children not amenable to primary pull-through, either because of malformation complexity (any urinary fistula in boys; vestibular fistula or cloaca in girls; no fistula in either sex but >1 cm from perineal skin) or associated comorbidity.
• Primary neonatal pull-through without colostomy. Many pediatric surgeons opt for primary pull-through in children with perineal fistulas (or no fistulas) and close (<1 cm) rectal pouches on 24-hour lateral pelvic radiography.
• Posterior sagittal pull-through with a colostomy. Used in boys with rectourinary fistula (bulbar, prostatic, or bladder-neck), in girls with cloaca or vestibular fistula, and in either sex with no fistula when the rectal pouch is further than 1 cm on 24-hour lateral prone abdominal radiography.
• Colostomy closure. Once the wound has fully healed and postoperative dilations have reached their goal (the neoanus is at the desired size), the colostomy may be closed in traditional surgical fashion.
• Diet. After the obstruction is relieved by colostomy, primary pull-through, or dilation, children need no special diet. They should avoid constipating foods such as the bananas, rice, applesauce, and toast (BRAT) diet, and should be encouraged toward high-fiber and laxative foods (whole-grain foods and bread, dairy, fruits, vegetables, greasy foods, spicy foods).
• Activity. Children with anorectal malformations are often otherwise healthy. Activity limits usually apply only around their surgical procedures.

Pharmacologic Management

• Antibiotic prophylaxis. Urinary prophylaxis mitigates the risk of urinary infection and urosepsis in children with risk factors such as urinary fistula, vesicoureteral reflux, or continent diversion.
• Laxatives. Common laxatives include senna products, milk of magnesia, and propylene glycol solutions (eg, MiraLax, GlycoLax).

Nursing Management

Nursing Assessment

• History. Prenatal ultrasonography is often normal, though polyhydramnios or intraabdominal cysts may suggest an imperforate anus with associated hydrocolpos or hydronephrosis.
• Physical exam. Newborns are usually identified on the first physical examination. Malformations missed on initial exam are often discovered within 24 hours, when the newborn shows distention, fails to pass meconium, and a more thorough examination is performed.

Nursing Diagnoses

• Fluid volume deficit related to excessive loss through vomiting.
• Impaired skin integrity related to the colostomy.
• Risk for infection related to surgical procedures.

Nursing Care Planning and Goals

• Maintain adequate hydration with moist mucous membranes, good skin turgor, and adequate capillary refill.
• Maintain stable vital signs.
• Achieve adequate urine output.
• Achieve dry, damage-free skin around the colostomy.
• Absence of infection.

Nursing Interventions

• Avoid infection. Teach caregivers to keep the area around the colostomy clean with soap and water and to diaper the baby in the usual way. Monitor white blood cell (WBC) count. Wash hands, and teach the patient and significant other to wash hands before contact and between procedures.
• Protect skin integrity. A protective ointment helps shield the skin around the colostomy. Monitor the impaired site at least once daily for color changes, redness, swelling, warmth, pain, or other signs of infection, and use sterile dressing technique during wound care.
• Restore balanced fluid volume. Give parenteral fluids as prescribed. Consider an IV fluid challenge with immediate infusion for patients with abnormal vital signs. Teach family members to monitor both intake and output at home.

Evaluation

• Maintained adequate hydration with moist mucous membranes, good skin turgor, and good capillary refill.
• Maintained stable vital signs.
• Achieved adequate urine output.
• Achieved dry, damage-free skin around the colostomy.
• Absence of infection.

Documentation Guidelines

• Individual findings, including contributing factors, interactions, nature of social exchanges, and specifics of individual behavior.
• Intake and output.
• Signs of infection.
• Cultural and religious beliefs and expectations.
• Plan of care.
• Teaching plan.
• Responses to interventions, teaching, and actions performed.
• Attainment or progress toward the desired outcome.

Frequently Asked Questions

How common is imperforate anus? Anorectal malformations occur in about 1 in 5000 live births, with a slight male predominance of roughly 1.2 to 1 (StatPearls, 2023).

How is imperforate anus usually found? Most cases are caught on the first newborn physical exam, when the anal opening is absent, displaced, or the infant fails to pass meconium within the first day or two of life.

Does every baby need surgery? Most do. Repair ranges from a primary neonatal pull-through for low malformations with a close rectal pouch to a staged approach with a protective colostomy first for higher or more complex defects.

What is a colostomy for in this condition? A neonatal colostomy diverts stool and protects the surgical site while a higher or more complex malformation is repaired in stages. It is closed later, once the wound heals and dilations reach their goal.

What feeding is allowed before surgery? The newborn is kept nothing by mouth and given intravenous fluids until the obstruction is relieved by colostomy, pull-through, or dilation.

What are the long-term concerns after repair? Constipation is the most common issue. The most severe outcomes are fecal and urinary incontinence, which are more likely with higher malformations and associated sacral or spinal defects.