What Is Caudal Regression Syndrome?


Caudal regression syndrome is a disorder that affects the development of the fetus in the uterus. This disease affects your child's bones, kidneys, and gastrointestinal tract. Children with this syndrome may have difficulty urinating and pooping. Treatment is usually symptomatic and includes surgery.2

Understanding Caudal Regression Syndrome

The general phrase "caudal regression syndrome" refers to a rare, complex condition marked by aberrant growth of the lower (caudal) end of the spine. The spinal column is made up of several little bones in the spine called vertebrae. The cervical spine, which consists of the vertebrae just below the skull, the thoracic spine, which includes the vertebrae in the chest region, and the lumbar spine, which includes the vertebrae in the lower back, are the three segments that make up the spinal column. 

The lumbar region of the spine and the pelvis are connected by a bone structure with a triangle form called the sacrum. The sacrum is made up of five fused vertebrae. The tailbone, or coccyx, protrudes from the end of the sacrum. Infants with caudal regression syndrome are at risk for developing the sacrum and coccyx abnormally (sacral and coccyx agenesis), as well as lumbar spine anomalies.1

According to a case report,5  Caudal Regression syndrome affects 0.1-0.25:10,000 of healthy births. However, it affects one in 350 babies of diabetic moms, an increase of almost 200 times. With this syndrome, the orthopaedic, gastrointestinal, genitourinary, and cardiac defects are frequently observed.

Causes of Caudal Regression Syndrome

Caudal regression syndrome in a newborn can be brought on by a variety of genetic and environmental factors, such as:

  1. Diabetes: The birthing parent has a diabetes diagnosis. Changes to the parent’s blood glucose levels and metabolism can affect fetal development.
  2. Mesoderm: The mesoderm is the middle layer of tissue in a growing embryo and is made up of a collection of cells that are in charge of constructing the skeleton and internal organs of the foetus. Genetic modifications may have an impact on the mesoderm's development around day 28 of pregnancy.
  3. Abdominal artery anomaly: An artery is a tube that carries blood from your heart to other regions of your body. The artery that supplies blood to the lower half of the body of a growing foetus is facing in a different direction than that part of the body, preventing blood flow there.
  4. Genetic mutation: This disorder can be brought on by changes to your genes that take place during conception (when the egg and sperm meet), more specifically genetic mutations in the HLXB9 or the VANGL1 gene.

Caudal regression syndrome can occasionally occur suddenly or randomly for unknown reasons. To find out more about the potential origins of this illness and how it affects neonates, research is still being conducted.


The following are examples of caudal regression syndrome symptoms that can impair how your child's bones grow:

  1. Their lower spine's (vertebrae) bones either don't exist or have unusual shapes.
  2. Where their vertebrae didn't entirely shut around their spinal cord, a fluid-filled sac develops close to it.
  3. Scoliosis, the curvature of their spine.
  4. little hipbones.
  5. irregular chest shape, which makes breathing difficult.
  6. Dimpled and flat buttocks.
  7. They have very little sensation in their lower body.
  8. Infants with caudal regression syndrome may have an unnatural stance that might impact how they walk. This is due to the underdevelopment of the bones in their legs.

This might comprise:

  1. Your child should stand with their legs bent in the "frog" position, with their knees turned outward and their feet parallel to their hips.
  2. ​​Your youngster has clubfeet, or inward-facing feet.
  3. Calcaneovalgus: The upward and outward rotation of your child's feet.

Diagnosis and Treatment of Caudal Regression Syndrome

During a prenatal ultrasound, your healthcare practitioner may be able to detect caudal regression syndrome before your kid is born. During this test, they will check for symptoms of the illness that influence the development of your child's lower half.

Your provider may offer additional testing after your kid is born to discover more about the extent of their disease. Imaging tests, such as an X-ray or an MRI, may be performed to check the impact of the illness on your child's bones and organs.2

The precise symptoms that each person experiences as a result of caudal regression syndrome are targeted for treatment. The coordinated efforts of a group of professionals may be necessary throughout treatment. It may be necessary to carefully and thoroughly organise a child's therapy with the help of paediatricians, neurosurgeons, neurologists, urologists, orthopedists, orthopedist surgeons, cardiologists, kidney specialists (nephrologists), and other medical professionals.3

Each kid with caudal regression syndrome receives treatment based on their symptoms and needs, which may vary. Possible treatments include:

  1. surgery to treat your child's skeletal system or other bone-related ailments.
  2. surgery to enhance the genitalia, organs, urinary system, and/or bowels of your child.
  3. Symptom-relieving medications.
  4. breathing assistance provided by a ventilator.
  5. employing prostheses, assisted mobility equipment, or braces to help your child move.

As they develop, your kid might require more surgeries to treat their issues. Your kid may need to begin therapy with drugs or surgery soon after birth or in the first few months of life, depending on their symptoms.To ensure that kids with caudal regression syndrome achieve their full potential, early intervention is crucial. Physical therapy, psychological counselling, and other medical, social, and/or occupational services could all be helpful.

Disorders with similar symptoms to Caudal Regression Syndrome

A rare congenital condition known as sirenomelia, or "mermaid syndrome," has symptoms similiar to Caudal Regression Syndrome. It is characterised by abnormalities of the lower spine and lower limbs. Leg fusion, either partial or total, is the disorder's defining feature. Agenesis, the absence or underdevelopment (agenesis) of one or both kidneys, genitourinary abnormalities, gastrointestinal abnormalities, and anomalies of the lumbar sacral spine and pelvis are other possible malformations. Infants who are affected might not have one foot, have no feet, or have both feet that are rotated externally.The majority of sirenomelia cases happen intermittently, seemingly at random.


Caudal Regression Syndrome (CRS) is a rare disorder affecting fetal development, characterized by lower spinal, skeletal, and organ abnormalities. Children with CRS can experience challenges with urination and defecation. The spine consists of cervical, thoracic, and lumbar segments, with a sacrum connecting to the pelvis. CRS can cause abnormal development of these areas, leading to complications. The syndrome affects approximately 0.1-0.25:10,000 healthy births, but the risk increases in babies of diabetic mothers. Causes include genetic and environmental factors, maternal diabetes, mesoderm abnormalities, abdominal artery anomalies, and genetic mutations. Symptoms range from spine and bone abnormalities to organ defects.

Diagnosis involves prenatal and postnatal methods like ultrasounds, X-rays, and MRIs. Treatment is usually multidisciplinary and tailored to the individual's symptoms. Surgical interventions address skeletal and organ issues, while supportive therapies improve quality of life. Early intervention is crucial for the best outcomes.

CRS has similarities with sirenomelia or "mermaid syndrome," characterized by leg fusion and lower limb abnormalities. Both conditions involve spinal, genitourinary, and gastrointestinal anomalies. Sirenomelia is rare and often occurs randomly.


  1. Caudal regression syndrome: MedlinePlus Genetics [Internet]. [cited 2023 Aug 24]. Available from: https://medlineplus.gov/genetics/condition/caudal-regression-syndrome/
  2.  Cleveland Clinic [Internet]. [cited 2023 Aug 24]. Caudal regression syndrome (Sacral agenesis): symptoms & causes. Available from: https://my.clevelandclinic.org/health/diseases/23425-caudal-regression-syndrome
  3. Caudal regression syndrome - symptoms, causes, treatment | nord [Internet]. [cited 2023 Aug 26]. Available from: https://rarediseases.org/rare-diseases/caudal-regression-syndrome/
  4. Sen K, Patel M. Caudal regression syndrome. Med J Armed Forces India [Internet]. 2007 Apr [cited 2023 Aug 26];63(2):178–9. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4925436/
  5. Tortori-Donati P, Fondelli MP, Rossi A, Raybaud CA, Cama A, Capra V. Segmental spinal dysgenesis: neuroradiologic findings with clinical and embryologic correlation. American Journal of Neuroradiology [Internet]. 1999 Mar 1 [cited 2023 Aug 26];20(3):445–56. Available from: https://www.ajnr.org/content/20/3/445
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Tehreem Iman

Bachelor of Science - BS, Clinical/Medical Laboratory Science/Research and Allied Professions, University of Sharjah

I am a dedicated undergraduate student pursuing a Medical Laboratory Sciences degree at the prestigious University of Sharjah. I have been a member of the American Academy of Developmental Medicine and Dentistry Newsletter, where I honed my medical writing skills and gained significant experience in conducting interviews. I have promoted cancer awareness as an Overseas Ambassador for the esteemed Shaukat Khanum Memorial Cancer Hospital and Research Centre. In addition, a rewarding internship at the World Wide Fund For Nature and committed community work have helped me to advance my practical expertise.

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