Imperforate Anus / Anorectal Malformations
What Are Anorectal Malformations?
Anorectal malformations, including imperforate anus, are congenital defects in which the anus and rectum do not form properly. These abnormalities occur during fetal development and can range in severity from a missing anal opening to complex structural issues involving the rectum, urinary tract, or reproductive organs.
Imperforate anus is typically diagnosed at birth and requires surgical intervention to create or reconstruct the anal opening, allowing the child to pass stool normally. Prompt evaluation and a tailored surgical approach are essential to achieve good long-term outcomes.
Types and Associated Conditions
Anorectal malformations may include:
- Low-type anomalies – where the rectum ends close to the skin
- High-type anomalies – where the rectum ends higher in the pelvis and may connect to the urinary or reproductive system (fistula)
- Imperforate anus – no visible anal opening at birth
These conditions are often associated with other anomalies, including VACTERL association (vertebral, anal, cardiac, tracheoesophageal, renal, and limb abnormalities).
Signs and Symptoms
In most cases, anorectal malformations are identified during the newborn exam. Signs may include:
- Absent or misplaced anal opening
- Failure to pass stool within the first 24–48 hours
- Abdominal distension
- Passing stool through the urethra or vagina (in the presence of a fistula)
Diagnosis
Evaluation involves a combination of physical exam and imaging studies to determine the type and extent of the malformation:
- Abdominal X-rays or ultrasound
- Cross-table lateral radiograph to assess rectal pouch position
- MRI or contrast studies in complex cases
Treatment Options
The mainstay of treatment is surgery to create a functional anal opening and reposition the rectum. Surgical options include:
- Anoplasty – for low-type defects, usually performed shortly after birth
- Posterior sagittal anorectoplasty (PSARP) – a more extensive surgery for higher defects
- Temporary colostomy – may be needed before definitive repair to allow stool to pass safely
Long-term follow-up focuses on bowel management, continence, and monitoring for complications like constipation or soiling.
