What Is Caudal Regression Syndrome?

Medically Reviewed by Dan Brennan, MD on February 20, 2024
3 min read

Caudal regression syndrome is an anal-rectal congenital disorder. It is also known as caudal dysplasia or sacral syndrome. It impacts the normal formation of the lower (caudal) half of the body. It can often lead to impairments of the gastrointestinal system. People with caudal regression syndrome may have twisting in the intestines, blockage of the anus, and other digestive system irregularities.

The causes of caudal regression syndrome are not yet well understood. Causes may be a mix of environmental and genetic factors. Some of the most common causes are believed to include:

  • Genetics. It is thought that caudal regression syndrome is a genetic disorder.
  • Mother’s health. Doctors believe that high blood sugar and metabolic imbalances affect the development of the fetus, especially if the mother’s diabetes is poorly managed. However, caudal regression can also happen when the mother doesn’t have diabetes. The connection between the two is still being studied. 
  • Developmental disturbances. If there are issues or trauma to the uterus around a month into the pregnancy, these events may disrupt the development of the baby’s skeletal, gastrointestinal, and urinary systems. 
  • Blood vessel abnormality. Some people believe caudal regression syndrome could be a result of reduced blood flow. It is thought that this blockage of crucial oxygen and nutrients brought to the fetus by blood could result in developmental issues.
  • Embryonic abnormalities.  The mesoderm is the middle of three tissue layers present in the early stages of the embryo (a developing baby in the earliest weeks of pregnancy). The mesoderm plays a massive role in the formation of many of the structures that are affected by caudal regression syndrome. Therefore, some scientists believe that caudal regression happens because there is a disturbance to the mesoderm.

Here are the major markers of caudal regression syndrome:

  • Irregularities in the bones of the lower spine. In caudal regression syndrome, the bones in the lower spine can be distorted or missing. These irregularities will also be reflected in the spinal cord. 
  • Incomplete closure at the base of the spine. The vertebrae (bones around the spinal cord) may also be missing. Instead, these vertebrae may end up in a skin-covered, fluid-filled sac located on your back, along with thicker patches of skin at the base of your spine. 
  • Scoliosis. Another spinal condition that occurs in caudal regression is an abnormal curving of the spine or scoliosis. The curvature can affect the structure of the chest and cause breathing issues. 
  • Irregular bones in the lower parts of the body. People with caudal regression syndrome have smaller hips and flatter buttocks. Your leg bones may be shaped in irregular ways. Some people find that their knees point out to the side or that their feet point either inward or outward. Other people may have limited feeling in their lower limbs. 
  • Irregular kidneys. Sometimes kidneys are missing or fused together. The tubes that carry liquid from the kidneys to the bladder can also be duplicated. These irregularities can cause infection or kidney failure. 
  • Bladder functions. If you have caudal regression syndrome, your bladder can be positioned through your abdominal wall. You may have damage to the nerves in your bladder and difficulty controlling urination. 
  • Genital differences. In males, the urethra (the tube that lets urine pass out of the body) can be placed underneath the penis, or the testicles can remain undescended. Females may have a strange connection between their vagina and rectum. In addition, some people may not have developed their genitalia. 
  • Additional symptoms. If you have caudal regression syndrome, you may also experience constipation and other irregularities with urination or elimination.  

Caudal regression treatment is dependent on the person and their specific symptoms. It will often be carried out by a team of physicians, including:

  • Pediatricians
  • Neurosurgeons
  • Neurologists
  • Urologists
  • Orthopedists
  • Orthopedic surgeons
  • Cardiologists
  • Kidney specialists

Infants born with caudal regression syndrome will need a broad spectrum of treatment. They may need surgeries and intensive therapies. Some surgeries might be done early on to treat urological, spinal, cardiac, anal, or limb issues. These children may also need to take medication specifically for urological problems.

Caudal regression syndrome must be treated as swiftly as possible. Children with caudal regression syndrome may need ongoing physical therapy, psychiatric support, and other supportive services.