Imperforate anus is a birth defect where the anus has no opening or is blocked. According to the National Library of Medicine (NLM), this abnormality is present in about one of every 5,000 births, occurring more often in boys than girls. (NLM, 2011) In female infants, imperforate anus is typically characterized by the rectum, bladder and vagina sharing one large opening. This opening is called a cloaca (pronounced cloh-AIK-uh)
The condition develops in utero during the fifth to seventh weeks of pregnancy. The cause is unknown. This condition often happens in conjunction with other defects of the rectum.
Diagnosis is usually made shortly after birth. This is a very serious condition that requires immediate treatment. Most infants 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 and include:
- no anal opening
- anal opening in the wrong place (like too close to the vagina)
- no stool in the first 24 to 48 hours of life
- stool passing through the wrong place (urethra, vagina, scrotum, base of penis)
- swollen abdomen
- an abnormal connection (fistula) between the rectum and the reproductive system or urinary tract
According to the Cincinnati Children’s Hospital (CCH), about half of all babies born with imperforate anus have additional abnormalities. (CCH, 2010) Some of these may be:
- kidney and urinary tract defects
- abnormalities of the spine
- windpipe (tracheal) defects
- esophageal defects
- defects of the arms and legs
- Down syndrome (a chromosomal condition associated with cognitive delay, intellectual disability, a characteristic facial appearance, and weak muscle tone)
- Hirschsprung’s disease (blockage of the large intestine)
- duodenal atresia (the first part of the small bowel is not properly developed)
- congenital heart defects
This is a very serious medical condition that needs prompt attention. The inability to pass stools can cause constipation, abdominal pain, and bowel obstruction. Infection can occur when stools pass through the urinary tract due to a fistula.
A physical exam after birth is generally enough to make a diagnosis. Imaging tests can confirm the problem and reveal the extent of the abnormalities. These may include:
- X-rays of the abdomen
- abdominal ultrasound
After the diagnosis of imperforate anus, your 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 vertebral body (bones of the spine) abnormalities
- echocardiogram looking for cardiac anomalies
- magnetic resonance imaging (MRI) looking for evidence of esophageal defects such as formation of fistulae with the trachea (wind pipe)
Surgery is almost always required. Multiple procedures are sometimes needed to correct the problem. If necessary, a temporary colostomy is used to allow an infant time to grow before surgery.
For a colostomy, the surgeon creates two small openings (stoma) in the abdomen. The lower part of the intestines is attached to one and the upper part of the intestines to the other. A pouch attached to the outside of the body catches waste products.
The exact type of corrective surgery will depend on the specifics of the defect, such as how far the infant’s rectum descends, how the nearby muscles are affected, and whether there are fistulas involved.
In a procedure called a perineal anoplasty, any fistulas that are found will be closed so that the rectum is no longer attached to the urethra or vagina. An anus will be created in the normal positioning.
When the rectum is pulled down and connected to the new anus, the procedure is called a pull-through operation.
To prevent the anus from narrowing, it may be necessary to periodically stretch the anus (anal dilations). This will be repeated periodically for a few months. Healthcare providers can teach parents how to perform this at home.
Within a few weeks of surgery, parents will be instructed on how to perform anal dilations to ensure that the anal opening is large enough to allow stool to pass. Some children will experience problems with constipation, and toilet training may take a bit longer. Stool softeners, enemas, or laxatives may be necessary to relieve constipation later in life. However, most of the time, surgery can fix the abnormalities and most children do very well. A high-fiber diet and regular follow-up care throughout childhood are recommended.