What Is an Imperforate Anus?

Imperforate anus, also referred to as an anorectal malformation, is a rare birth defect that includes the absence of a normal anal opening, meaning there is no opening at the end of the digestive tract where the anus is normally located. The diagnosis is usually made shortly after birth by a routine physical examination. The exact cause of anorectal malformations is unknown.

The degree of severity varies greatly from child to child, and there are numerous scenarios of how the anatomy can form. Normally, the rectum connects to the anal opening, where stool exits the body. There are several types of abnormalities and symptoms that can occur with imperforate anus, each of which can affect the child’s ability to have bowel movements.

  • A membrane is covering the anal opening
  • Anal opening is in an abnormal location
  • Rectum is not connected to the anus and ends in a blind pouch, with no anal opening
  • Rectum is connected to either the urinary tract or reproductive system, with no anal opening

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What Causes Imperforate Anus?

Imperforate anus is a type of anorectal malformation that affects approximately one in 5,000 babies. The exact cause is unknown.

How Is Imperforate Anus Evaluated?

The diagnosis of an imperforate anus is made by physical exam following delivery. Although the diagnosis of imperforate anus can be made by a physical examination, physicians may recommend additional tests to identify the specific type of imperforate anus. Additional tests may also be ordered to evaluate conditions associated with imperforate anus. Children who have an imperforate anus may also have other congenital anomalies. A commonly used acronym, VACTERL, describes the associated problems that infants with imperforate anus may have:

  • Vertebral defects
  • Anorectal malformation
  • Cardiac anomalies
  • Tracheoesophageal fistula
  • Esophageal atresia
  • Renal (kidney) anomalies
  • Limb anomalies

Tests for evaluation of imperforate anus and any associated anomalies may include:

  • X-rays
    • Help locate the lesion and position of the anorectal malformation
    • Evaluate for a possible esophageal abnormality
    • Evaluate the bones of the spine and limbs
    • Evaluate for an abnormal connection of the rectum
  • Ultrasound
    • Identify any problems of the kidneys and genitourinary tract
    • Evaluate the spinal cord
  • MRI 
    • Evaluate pelvic anatomy
    • Evaluate the spine
  • Echocardiogram
    • Evaluate the heart

How Is an Imperforate Anus Treated?

In the Comprehensive Congenital Colorectal Program1, both medical and surgical therapies are offered for the management of anorectal malformations. Treatment options for anorectal malformations depend on the specific type of abnormality. Pediatric surgeons and urologists work with a team of specialists, including gastroenterologists, nephrologists, neurosurgeons, nutritionists, and wound care/ostomy specialists to provide comprehensive care for each patient.

Surgical treatment of infants with imperforate anus depends upon the anatomy of the malformation.

  • A low imperforate anus can be repaired, quickly after birth, by a procedure called a perineal anoplasty.
  • For a high imperforate anus, a colostomy, an operation to divert the path of stool, is usually done. The infant with a high lesion is therefore given time to grow until definitive repair can be done with a pull-through operation, in which the rectum is "pulled down" and sewn into a newly made anal opening in the perineum. After surgery, the newly formed anus needs to be dilated regularly for several months until a soft, mature scar is obtained. The colostomy can then be closed.

Currently, the multidisciplinary team at McGovern Medical School at UTHealth is investigating the use of sacral nerve stimulators in treating fecal incontinence and constipation. This treatment involves implanting a device that delivers mild electrical pulses to the pelvic nerves and has been successful when used in conjunction with other therapies.

What Is the Long-Term Outlook for Children After Repair of Imperforate Anus?

Patients with a history of imperforate anus could develop a spectrum of long-term conditions. Patients could struggle with constipation, have difficulty with incontinence, or grow to develop normal stooling patterns.

The most important prognostic feature is the severity of the imperforate anus (high or low) and the presence or absence of associated spinal abnormalities. Children with a low lesion, especially those who require only a perineal anoplasty, often grow to have normal stooling patterns. These patients can suffer from constipation and are usually treated with a medication program.

Children with spinal abnormalities of the lower sacrum and a high imperforate anus frequently do not have normal bowel continence or function. These patients are helped by a bowel management program with dietary changes, medications and regular enemas.

How Do You Toilet Train Children With Imperforate Anus?

The affiliated pediatric specialists at the Texas Pediatric Colorectal Program1 recognize that potty training your child with an anorectal malformation can be difficult. The child may lack the normal nerve and muscle control required to control his or her bowel movements, which leads to the problem of fecal incontinence. The Bowel Management Program can help these children achieve bowel control and avoid future accidents.

Why Choose Children’s Memorial Hermann Hospital?

At Children’s Memorial Hermann Hospital, we understand the challenges associated with a child diagnosed with an anorectal malformation. Anorectal malformations and their associated anomalies can impact multiple areas of life, including nutrition, bowel and bladder control, kidney function, and even sexual function. The multidisciplinary and collaborative team at the Texas Pediatric Colorectal Program will perform a thorough evaluation and discuss with the patient’s family to determine the best treatment options and therapies for your child.

The affiliated team tailors the health care plan to each individual patient. Our multidisciplinary approach has specialized expertise to help children with anorectal malformations have a high quality of life. Patients with complex anorectal malformations confront medical challenges from birth and into adulthood.

1 Located within the UT Physician Professional Building in the Texas Medical Center, the Texas Pediatric Colorectal Program is affiliated with Children’s Memorial Hermann Hospital and the physicians at McGovern Medical School at UTHealth.

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If you have any questions, use the online tool below to help us connect with you. To refer a patient or schedule an appointment, please contact our clinic using the information below.

  • UT Physicians Pediatric Specialists 
    Texas Medical Center

    6410 Fannin St., Suite 500
    Houston, Texas 77030
    Phone: (832) 325-6516
  • UT Physicians Pediatric Surgery
    Texas Medical Center

    6410 Fannin St., Suite 950
    Houston, Texas 77030
    Phone: (832) 325-7234

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