Imperforate Anus: Definition, Causes, Symptoms, Diagnosis, Treatment and Prognosis

It is a defect that is present at birth (congenital).

In anorectal malformations , there may be skin covering the area where the anus should be, and that skin may be several inches thick or just a thin membrane.

The opening of the anus may be narrow or it may be completely absent.

Anal atresia occurs when the intestine does not form properly while the fetus is developing. It is not known what causes the intestine to not form properly.

Most babies with anal atresia develop some type of abnormal connection (fistula) between the anus and the urethra, between the anus and the area between the urethra and the anus (the perineum), between the anus and the vagina, or, in rare cases, between the anus and the bladder.

Anal atresia usually occurs along with other birth defects such as defects of the spine, heart, kidneys, and extremities.

Affected babies may also have a tracheoesophageal fistula and esophageal atresia.

Babies with anal atresia do not have a normal bowel movement after birth. An intestinal obstruction ends up coming if the defect is not treated.

Causes of imperforate anus

An imperforate anus is one of many congenital conditions that can affect the way the rectum forms.

In normal prenatal development, the lower intestinal system and the urinary system begin as one structure and separate during the first trimester of pregnancy.

Anus imperfect is a congenital malformation resulting from the interruption or abnormalities in the embryological development of the anus, rectum and urogenital tract.

For unknown reasons, this separation does not occur in children born with an imperforate anus, resulting in a variety of possible differences in anatomy, including the urogenital tract, such as:

  • A baby’s anal opening can move from its normal location and beyond the control of the sphincter muscles.
  • The anus may not connect to the rectum.
  • There may not be any opening where the anus should be.
  • The rectum can connect to the urinary system, joining the penis in boys or the vagina in girls.
  • In more advanced cases, the bladder and rectum are connected in a way that causes problems with the passage of urine and stool.

These abnormalities occur in approximately one in every five thousand live births.

They are closely related to defects in the spine, heart, kidneys, esophagus, pelvis, and arm bones, a group of abnormalities known as VACTERL syndrome.


  • There is no anal opening present at birth.
  • Anal opening in the wrong place.
  • The baby does not have the first stool between 24 and 48 hours after birth.
  • Stool that is excreted through the vagina, penis, scrotum, or urethra.
  • Tight and swollen stomach.
  • There is no bowel control by the age of 3 years.

Diagnosis of the imperfect year

Its diagnosis in the prenatal period is rare and the percentage of death is high. And it is common for the child born with an imperfect anus to have additional abnormalities such as vertebral abnormalities and anal atresia.

Those who survive the malformation should undergo anorectal reconstruction surgery after 6 months of age.

Imperforate anus is usually not detected until after birth, when a baby does not pass stool after feeding, or when someone notices an abnormality in the opening of the rectum.

A prenatal ultrasound or magnetic resonance imaging showing intestinal obstruction and dilation of the intestines may be suggested.

Babies are examined by ultrasound and contrast X-rays of the rectum and urinary system to show the anatomy.


In mild to intermediate cases, pediatric surgeons reposition the rectum in its correct location or construct one for a child born without an opening.

Depending on the circumstances, the surgery can be performed between birth and three months of age.

If, for example, a baby does not have an opening where the anus should be and there are no other serious birth defects, surgery may be done during the first week of life.

Surgeons use natural body tissue to build, rebuild, or reposition the anus and rectum where they belong, allowing stool to pass normally.

If a baby has a complicated anatomy, one of the first surgeries may be an ostomy, an opening created that diverts stool into a bag outside the body by bringing a portion of the intestine to the surface.

Creating an ostomy offers surgeons time to decide the best approach and timeline for repairing the anatomy.

Other more life-threatening conditions can be cared for, if needed, and babies given more time to grow before any reconstructive surgery.

During this wait, we watch the baby closely to confirm that body waste is moving normally through the intestines to the ostomy.

The most complicated cases cannot be treated until a child is at least one year old.

Males may have undescended testicles or a malformation of the penis. Girls may have a cervix and an unformed uterus, or two halves of a uterus that do not form as a complete organ.

These babies often require pediatric general surgeons to repair the rectum and intestinal tract, and pediatric urologists to reconstruct the genitalia and urinary tract.

Before the anorectal reconstruction surgery, the colostomy is performed (surgical opening in the abdominal region that connects the large intestine with the external environment for the elimination of stool).

The colostomy will be closed when the anorectal reconstruction surgery is done and is properly healed.


The most prevalent consequences after corrective surgery are fecal incontinence and constipation.

Treatment is generally long and requires a multiprofessional team due to the complexity of the case.

The physiotherapist is one of the professionals who must compose the rehabilitation team of the patient who underwent imperforate anus correction surgery, work on the surgical scar, promoting a training of the pelvic floor muscles, especially the levator ani muscle, in the adequacy of bladder and intestinal function.

The results depend on the severity of the child’s condition at birth.

In mild cases of imperforate anus, children can have permanent bowel control without help.

Children with intermediate abnormalities can take bowel medications to thicken their stools and help their natural continence.

Dietitians can also be contacted to help children maintain a diet that keeps their stools in a proper texture, allowing it to pass easily through the colon.

After the child is old enough to participate in his or her own care and hygiene, enemas may be introduced to help achieve optimal bowel control.

For some children and their families, surgery can be the beginning of a lifelong journey.

Even after treatment, babies born with significant differences in their anatomies are less likely to have full control of their bowels and bladder when they are past potty training age.

In the most severe cases, children may need intensive treatment to lead a normal life, without worrying about fecal dirt.

Once children are old enough to assist in their own care, they sometimes benefit from a secondary surgery called a continent appendicostomy procedure for antegrade enemas.

The procedure has been used successfully in the treatment of fecal incontinence or constipation in children with anorectal dysfunction and other underlying diseases, this allows children to adopt a predictable regimen that keeps them empty during the day by flushing the colon each night.

To perform the procedure, surgeons borrow the end of the appendix and it is inserted through a small incision that is made in the area under the incision site of a standard appendectomy, constructing a tube with access to the colon.

A silicone catheter is inserted up to the cecum. This tube is infused with water, which irrigates the colon from below and cleans the stool out of the body.

After discharge, parents are taught the intermittent catheterization technique, and over time each child learns to take care of himself.