Sacral Agenesis: Symptoms, Causes, Diagnosis and Treatment

Written by Medicover Team and Medically Reviewed by Dr NVS Vinay , Orthopedics

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1. Causes 2. Find a Doctor 3. Diagnosis 4. Treatment 5. FAQs

Sacral agenesis is a rare congenital disorder in which part or all of the sacrum-the triangular bone at the base of the spine-fails to develop before birth. The condition varies widely in severity and may affect the lower spine, pelvis, spinal cord, lower limbs, and the nerves controlling bowel and bladder function.

Sacral agenesis is considered part of the broader spectrum of caudal regression syndrome, although not all individuals with caudal regression syndrome have complete sacral agenesis. The condition is present at birth and can range from mild spinal abnormalities to significant physical disabilities. Early diagnosis and multidisciplinary management help improve mobility, independence, and quality of life.

What Are the Types of Sacral Agenesis?

Sacral agenesis is classified according to the extent of sacral and lower spinal involvement.

Partial Sacral Agenesis: Only part of the sacrum is absent. Symptoms are often milder and may include bowel or bladder dysfunction and mild orthopedic abnormalities.
Complete Sacral Agenesis: The entire sacrum is absent, often causing significant neurological, orthopedic, urinary, and gastrointestinal complications.
Sacral Agenesis Associated with Caudal Regression Syndrome: Some individuals also have abnormalities involving the lumbar spine, spinal cord, lower limbs, kidneys, gastrointestinal tract, or urinary system.

What Are the Symptoms of Sacral Agenesis?

The symptoms vary depending on the severity of the spinal abnormality and nerve involvement.

Abnormal curvature of the spine such as scoliosis or kyphosis
Partial or complete absence of the sacrum
Difficulty walking or standing
Weakness of the legs
Limb length discrepancy
Foot deformities such as clubfoot
Hip dislocation
Bowel dysfunction or constipation
Bladder dysfunction or urinary incontinence
Delayed motor development
Reduced sensation in the lower limbs

What Causes Sacral Agenesis?

The exact cause of sacral agenesis is not fully understood. Both genetic and environmental factors are believed to contribute to abnormal development of the lower spine during early pregnancy.

Genetic Factors

Rare genetic changes affecting early embryonic development may contribute to sacral agenesis in some individuals, although most cases occur sporadically.

Maternal Diabetes

Maternal diabetes is the strongest known risk factor. Poor blood sugar control during early pregnancy significantly increases the risk of caudal regression syndrome and sacral agenesis.

Developmental Factors

Disruption of normal development of the lower spine and spinal cord during the first few weeks of pregnancy can result in incomplete formation of the sacrum.

When to See a Doctor for Sacral Agenesis?

Sacral agenesis (Caudal Regression Syndrome) requires a multidisciplinary care team because it can affect the spine, nerves, urinary tract, bowel, and lower limbs. Treatment is individualised and is commonly coordinated by an Orthopaedic Surgeon, Pediatric Urologist, Neurosurgeon, and Paediatrician, with other specialists involved based on the child's specific needs.

Medical evaluation is recommended if an infant or child has abnormalities of the lower back, delayed motor development, bowel or bladder problems, leg weakness, or difficulty standing and walking. Early diagnosis allows timely treatment, coordinated specialist care, and reduces the risk of long-term complications.

You should see a doctor if you notice:

Delayed developmental milestones
Difficulty standing or walking
Persistent bowel or bladder control problems
Unequal leg length or foot deformities
Abnormal curvature of the spine

Seek immediate medical care if:

Sudden weakness or paralysis develops
Recurrent urinary tract infections occur with fever
Severe constipation or bowel obstruction develops
Loss of bladder or bowel control suddenly worsens

Early multidisciplinary care can improve mobility, urinary function, and overall quality of life.

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How Is Sacral Agenesis Diagnosed?

Diagnosis is based on clinical examination and imaging studies that evaluate the spine, spinal cord, and associated organs.

Prenatal ultrasound
Fetal MRI when needed
Physical examination after birth
X-rays of the spine and pelvis
MRI of the spine and spinal cord
CT scan for detailed bone evaluation
Neurological examination
Kidney and bladder ultrasound
Urodynamic studies to assess bladder function

How Is Sacral Agenesis Treated?

There is no cure for sacral agenesis. Treatment aims to improve mobility, preserve organ function, and maximize independence through multidisciplinary care.

Orthopedic Management

Correction of scoliosis or spinal deformities
Treatment of hip dislocation and limb deformities
Orthotic braces
Mobility aids such as walkers or wheelchairs when needed

Physical Therapy and Rehabilitation

Strengthening exercises
Balance and gait training
Stretching exercises
Occupational therapy for daily living skills

Bowel and Bladder Management

Clean intermittent catheterization
Medications for bladder control
Bowel management programs
Dietary modifications and laxatives when necessary

Surgical Treatment

Spinal surgery for severe deformities
Orthopedic procedures for lower limb abnormalities
Urological surgery when indicated

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What Are the Risk Factors for Sacral Agenesis?

Several factors have been associated with an increased risk of sacral agenesis.

Maternal diabetes, particularly poorly controlled diabetes
Genetic susceptibility
Early disturbances during fetal development
Rare chromosomal abnormalities

What Are the Complications of Sacral Agenesis?

The complications depend on the severity of spinal and nerve involvement.

Permanent mobility impairment
Chronic bowel dysfunction
Neurogenic bladder
Recurrent urinary tract infections
Kidney damage from urinary problems
Hip dislocation
Progressive scoliosis
Pressure sores due to reduced mobility
Reduced quality of life

Can Sacral Agenesis Be Prevented?

Most cases cannot be prevented because they result from abnormal fetal development. However, women with diabetes can reduce the risk by maintaining good blood sugar control before conception and throughout pregnancy. Regular prenatal care, healthy lifestyle habits, and early pregnancy monitoring may also help reduce the risk of congenital abnormalities.

Living With Sacral Agenesis

Living with sacral agenesis requires lifelong medical follow-up and individualized care. Many individuals achieve good independence through rehabilitation, assistive devices, bowel and bladder management programs, and orthopedic treatment. Regular follow-up with orthopedic surgeons, neurologists, urologists, rehabilitation specialists, and physical therapists helps manage complications and maintain the best possible quality of life. With early intervention and comprehensive support, many people with sacral agenesis can participate actively in school, work, and everyday activities.