Definition

Sacral agenesis is a rare congenital condition characterized by the partial or complete absence of the sacral portion of the spine. It falls under the spectrum of caudal regression syndrome (CRS), a disorder affecting the development of the lower spine and adjacent structures. The severity of the condition can vary, ranging from minor sacral hypoplasia to the complete absence of the sacrum and lumbar spine.

Causes and Risk Factors

The exact cause of sacral agenesis is not fully understood, but several factors have been associated with its development:

Maternal Diabetes Mellitus – One of the strongest risk factors, with a significantly higher incidence in infants born to mothers with pregestational or poorly controlled gestational diabetes.
Genetic Factors – Although most cases are sporadic, some familial cases have been reported, suggesting a possible genetic predisposition.
Vascular Disruptions – Abnormal blood supply to the developing caudal region during early fetal development may contribute to the condition.
Teratogenic Factors – Exposure to certain toxins or medications during pregnancy may increase the risk.

Symptoms and Clinical Features

The clinical presentation of sacral agenesis varies depending on the severity of the malformation and associated anomalies. Common features include:

Musculoskeletal abnormalities – Shortened trunk, limb deformities, hip dislocations, and clubfoot.
Neurological deficits – Impaired sensation and motor function in the lower extremities, leading to difficulty walking or complete paralysis.
Urological and gastrointestinal issues – Neurogenic bladder, incontinence, constipation, or anal atresia due to sacral nerve involvement.
Spinal deformities – Scoliosis, kyphosis, or lordosis may develop due to spinal instability.

Diagnosis

Sacral agenesis is diagnosed through a combination of:

Prenatal ultrasound – May detect spinal abnormalities as early as the first trimester.
X-ray and MRI – Essential for assessing the extent of sacral and spinal abnormalities.
Neurological and urological evaluations – Help determine the impact on bladder and bowel function.

Treatment and Management

There is no cure for sacral agenesis, but management focuses on improving function and quality of life:

Orthopedic interventions – Physical therapy, orthotics, and in severe cases, corrective surgeries for limb deformities.
Urological management – Catheterization, bladder augmentation, or other interventions to address incontinence.
Bowel management programs – Dietary changes, enemas, or surgical procedures to improve bowel function.
Spinal surgery – In cases with severe spinal instability or deformities.

Prognosis

The prognosis depends on the severity of the condition and the extent of associated complications. Many individuals with mild sacral agenesis can lead independent lives with proper medical care and rehabilitation, while more severe cases may require lifelong medical support.