Anal Agenesis - Causes, Symptoms, Diagnosis, and Treatment

What Is Anal Agenesis?

Anal agenesis is a problem or birth defect that occurs in an unborn during the developing stages of pregnancy. These are also known as anorectal malformations. In these conditions, the anus and rectum do not develop properly, which form the lower part of the digestive tract.

Anorectal- ano means anus. This consists of the opening end of the large intestine. The stool passes through the anus when the bowel movement occurs. Rectal means rectum, which is also a part of the large intestine which lies just above the anus. Normally, the bowel movement and stool pass from the large intestine to the rectum and then to the anus. Muscles present in the anal area help to control when bowel movement occurs. Nerves in the area help in sensing the need for a bowel movement. Nerves also stimulate muscle activity.

What Problems Occur Along With Anal Agenesis?

Along with anorectal malformation, severe issues occur like:

• Covered anal opening with tissue or membrane.

• Disconnected anus and rectum.

• Narrow anal passage.

• The connected rectum to part of the urinary tract or reproductive system happens through the fistula, a passage connected with it.

• Anal agenesis can cause problems with the baby’s bowel movements. Treatment depends on the types of malformations that have affected the baby.

What Causes Anal Agenesis?

The causes of anal agenesis in an unborn baby growing in the mother’s womb fairly start occurring at an early stage of pregnancy.

The lower part of the large intestine and the urinary tract starts as one large mass of cells. During the first three months of gestation, certain steps of developing structures happen. There are steps where the anus and rectum break away from the urinary tract and form proper separate structures. Due to certain malformation unknown causes, the steps of developing structures do not happen as they should normally. In most cases, the cause is unknown.

What Are the Risk Factors That Lead to Anal Agenesis?

Anal agenesis may be seen with other genetic syndromes and congenital problems that also show up at birth. They are:

• Digestive system problems.

• Down syndrome.

• Spinal problems.

• Urinary tract problems.

• Townes-brocks syndrome (this syndrome includes problems with ears, arms, legs, anus, and kidneys).

What Are the Signs and Symptoms of Anal Agenesis?

The signs and symptoms of anal agenesis cause problems that affect a child’s bowel movements. Most malformations are found before the newborn leaves the hospital. If it is not diagnosed in the hospital, the symptoms include:

• Stool from the vagina.

• Urine from the anus.

• Lack of stool.

• Trouble having a bowel movement.

• Constipation.

How Is the Diagnosis Made for Anal Agenesis?

Diagnosis of anal agenesis is made on a routine physical examination of the newborn. The healthcare provider examines the baby’s anus and sees if it opens normally or if any abnormality is present at the site of the anal opening. Other imaging tests are done that include:

• CT Scan (Computed Tomography): Tests that use X-rays and a computer to make images of tissues of the body that include muscles, fat, organs, and bones.

• Abdominal Ultrasound: High-frequency sound waves and a computer are used to create images of tissues, organs, and blood vessels.

• Abdominal X-rays: Test to take images of bones, organs, and tissues.

• MRI (Magnetic Resonance Imaging): A test that uses a magnetic field and radio waves to record images of tissues and organs.

• Lower Gastrointestinal Series or Barium Enema: Test that checks the large intestine, rectum, and lower part of the small intestine. A chalky, metallic fluid (barium) is injected into the rectum as an enema. An X-ray of the belly or lower abdomen would show narrowed areas called blockages, strictures, and other problems.

• Upper Gastrointestinal Series or Barium Swallow: Test that checks organs of the upper digestive tract, which includes the esophagus, stomach, and duodenum. Metallic, chalky barium fluid is swallowed, followed by X-rays taken to check the digestive tract.

What Is the Treatment Provided for Anal Agenesis?

Treatment depends on the child’s symptoms, general health, and age. It also depends on how severe the condition is. Most babies require surgery to correct the problems. The type and number of surgeries vary from baby to baby. This depends on the unique malformation the baby has. In cases of narrow anal passages, surgery may not be required. This procedure is known as anal dilation, which helps to stretch anal muscles so stool can pass through. In cases with anal membranes, surgery to remove the membrane is done.

In cases of lack of fistula or presence of fistula series of surgeries are done to repair the problem. The surgeries like:

• Colostomy: Large intestine is divided into two sections with the procedure colostomy. The upper section leads the stool through the opening and then into the collection bag. The lower section lets mucus produced by the intestines collect in collection bags. A colostomy does not damage a child’s digestion or growth of the child.

• Closing The Colostomies: This surgery is done later, about two to three months from the diagnosis. The child who undergoes surgery will not be able to eat food for a few days of surgery which leads to the healing of the intestine. Initially, stools pass often as days pass. Less often and more solid stools. This causes constipation. A high-fiber diet helps with constipation.

• Attaching The Rectum To The Anus: Colostomies stay in place after the surgery; the surgery is often done in the first few days of life. Without being infected by the stool, the area can heal soon, and the rectum and anus are joined. But stool leaves the body through the colostomies until they are closed by the surgery. After surgeries, anal dilation helps with regular bowel movements.

Conclusion:

Anal agenesis includes a broad spectrum of defects that involve the lower portion of the intestine and the urogenital tracts. Children with these malformations have an imperforate anus because of the missing anal opening. The spine and urogenital tract are also involved. Anal agenesis with RVF (rift valley fever) is a rare anomaly. Careful clinical examination, along with distal colostogram, endoscopy, and preoperative EUA (examination under anesthesia), would help in planning the management of the agenesis.