What is an imperforate anus?

An imperforate anus is a birth defect that happens while your baby is still growing in the womb. This defect means that your baby has an improperly developed anus, and therefore can’t pass stool normally from their rectum out of their body.

According to the Cincinnati Children’s Hospital, about 1 out of every 5,000 babies has an imperforate anus or other malformation of the anus or rectum. It occurs more often in boys than girls. The rectum, bladder, and vagina of a female baby with an imperforate anus sometimes share one large opening. This opening is called a cloaca.

The condition develops in the womb during the fifth to seventh weeks of pregnancy. The cause is unknown. Many times babies with this condition also have other defects of the rectum.

Doctors usually can diagnose this condition shortly after birth. This is a very serious condition that requires immediate treatment. Most babies will need surgery to repair the defect. The outlook following surgery is very positive.

The signs of imperforate anus are usually obvious soon after birth. They include:

  • no anal opening
  • an anal opening in the wrong place, such as too close to the vagina
  • no stool in the first 24 to 48 hours of life
  • stool passing through the wrong place, such as the urethra, vagina, scrotum, or the base of the penis
  • a swollen abdomen
  • an abnormal connection, or fistula, between your baby’s rectum and their reproductive system or urinary tract

About half of all babies born with imperforate anus have additional abnormalities. Some of these may be:

  • kidney and urinary tract defects
  • abnormalities of the spine
  • windpipe, or tracheal, defects
  • esophageal defects
  • defects of the arms and legs
  • Down syndrome, which is a chromosomal condition associated with cognitive delay, intellectual disability, a characteristic facial appearance, and weak muscle tone
  • Hirschsprung’s disease, which is a condition involving missing nerve cells of the large intestine
  • duodenal atresia, which is an improper development of the first part of the small bowel
  • congenital heart defects

A doctor can usually diagnose an imperforate anus by performing a physical exam after birth. An X-ray of the abdomen and abdominal ultrasound can help reveal the extent of the abnormalities.

After diagnosing imperforate anus, your baby’s doctor should also test for other abnormalities associated with this condition. Tests used may include:

  • X-rays of the spine to detect bone abnormalities
  • spinal ultrasound looking for abnormalities in the vertebral body, or bones of the spine
  • echocardiogram looking for cardiac anomalies
  • MRI looking for evidence of esophageal defects such as formation of fistulae with the trachea, or windpipe

This condition almost always requires surgery. Multiple procedures are sometimes necessary to correct the problem. A temporary colostomy can also allow your baby time to grow before surgery.

For a colostomy, your baby’s surgeon creates two small openings, or stoma, in the abdomen. They attach the lower part of the intestines to one opening and the upper part of the intestines to the other. A pouch attached to the outside of the body catches waste products.

The type of corrective surgery needed will depend on the specifics of the defect, such as how far your baby’s rectum descends, how it affects the nearby muscles, and whether fistulas are involved.

In a perineal anoplasty, your baby’s surgeon closes any fistulas so that the rectum no longer attaches to the urethra or vagina. They then create an anus with normal positioning.

A pull-through operation is when your baby’s surgeon pulls the rectum down and connects it to the new anus.

To prevent the anus from narrowing, it may be necessary to stretch the anus periodically. This is called anal dilation. You may need to repeat this periodically for a few months. Your doctor can teach you how to perform this at home.

Your doctor will instruct you on how to perform anal dilations. These ensure that the anal opening is large enough to allow stool to pass.

Some children will experience problems with constipation. Toilet training may take a bit longer. Stool softeners, enemas, or laxatives may be necessary to relieve constipation later in life. Surgery can usually fix the abnormalities, and most children do very well.

A diet high in fiber and regular follow-up care throughout childhood are beneficial.