What is OEIS (Omphalocele, Exstrophy of the bladder, Imperforate anus, Spinal defects) syndrome?

OEIS Syndrome: A Comprehensive Overview

OEIS syndrome is a rare congenital malformation complex characterized by Omphalocele, Exstrophy of the bladder, Imperforate anus, and Spinal defects that requires early multidisciplinary management to address multiple organ system involvement and improve quality of life and survival outcomes. 1

Definition and Key Components

OEIS syndrome is a severe birth defect that includes:

• Omphalocele: Abdominal wall defect with protrusion of abdominal organs
• Exstrophy: Typically bladder exstrophy or cloacal exstrophy
• Imperforate anus: Absence of a normal anal opening
• Spinal defects: Including spina bifida, meningomyelocele, and other vertebral anomalies

Epidemiology and Etiology

• OEIS complex is extremely rare
• Etiology involves a single localized defect in early mesoderm development that contributes to:
  • Infraumbilical mesenchyme
  • Cloacal septum
  • Caudal vertebrae 2
• Some evidence suggests OEIS complex may share pathogenic mechanisms with limb body wall complex (LBWC), representing a continuous spectrum of abnormalities 3

Clinical Presentation and Associated Anomalies

OEIS syndrome presents with multiple congenital anomalies:

1. Gastrointestinal system:

   • Omphalocele (abdominal wall defect)
   • Imperforate anus
   • Potential colonic agenesis 4
   • Possible presence of multiple appendices 4

2. Genitourinary system:

   • Bladder exstrophy or cloacal exstrophy
   • Ambiguous genitalia
   • Hydroureter
   • Potential kidney abnormalities including glomerulocystic kidney disease 4
   • Neurogenic bladder dysfunction 5

3. Neurological system:

   • Spinal defects (spina bifida)
   • Meningomyelocele, particularly at the lumbosacral junction 4
   • Terminal myelocystocele (rare) 6

4. Musculoskeletal system:

   • Nonunion of pubic symphysis 4
   • Potential lower limb defects, which can be severe 2
   • Possible club foot (congenital talipes equinovarus) 3

Diagnosis

Prenatal Diagnosis

Prenatal ultrasound can detect OEIS complex with findings including:

• Abdominal wall defect (omphalocele)
• Spina bifida
• Hydroureter
• Kidney abnormalities 4
• Lower extremity abnormalities

Fetal MRI provides superior soft-tissue visualization and can better characterize:

• Neural tube defects
• Position of the conus medullaris
• Associated anomalies 5, 6

Early prenatal diagnosis is crucial for:

• Appropriate counseling of families
• Planning for multidisciplinary perinatal management 2
• Consideration of delivery planning

Postnatal Diagnosis

Postnatal evaluation includes:

• Physical examination
• Radiographic studies (X-ray)
• Pelvic MRI
• Renal ultrasound to assess for hydronephrosis and other complications 5
• Urodynamic testing to assess bladder function 5

Management

Management of OEIS complex requires a multidisciplinary approach involving:

1. Surgical interventions:

   • Repair of abdominal wall defect
   • Colostomy for imperforate anus
   • Urological reconstruction
   • Neurosurgical repair of spinal defects
   • Potential nephrectomy in cases with severe kidney disease 4

2. Urological management:

   • Assessment and management of neurogenic bladder
   • Monitoring for urinary tract infections
   • Prevention of upper urinary tract damage
   • Potential need for intermittent catheterization 5

3. Neurological management:

   • Repair of meningomyelocele
   • Monitoring for tethered cord
   • Assessment of neurological function

4. Long-term follow-up:

   • Monitoring renal function
   • Urodynamic testing
   • Assessment of lower extremity function
   • Management of bowel function

Prognosis and Outcomes

• Long-term survival can be achieved with successful corrective surgery
• Quality of life is significantly impacted by:
  • Severity of associated malformations
  • Presence of large meningomyelocele
  • Severity of limb defects 2
• Neurogenic bladder dysfunction can lead to complications including:
  • Urinary tract infections
  • Hydronephrosis
  • Potential renal damage if not properly managed 5

Special Considerations

• OEIS complex may have overlapping features with body stalk anomaly/limb body wall complex 3
• The umbilical cord may be absent, with umbilical vessels embedded in an amniotic sheet connecting the anterior body wall defect to the placenta 3
• Prenatal detection of an abdominal wall defect with multiple midline defects should prompt genetic investigation and counseling 7

Early diagnosis and coordinated multidisciplinary care are essential to optimize outcomes for infants with this complex condition.