OEIS Syndrome, also known as cloacal exstrophy, is a rare and complex birth defect affecting multiple body systems. This congenital condition, present at birth, involves malformations of the lower abdominal wall, intestines, and urinary and reproductive systems. It is highly uncommon, occurring in approximately 1 in 200,000 to 400,000 live births, and often requires extensive medical intervention and long-term care.
Understanding OEIS Syndrome
OEIS Syndrome is an acronym for Omphalocele, Exstrophy, Imperforate anus, and Spinal defects. An omphalocele occurs when abdominal organs protrude through the umbilical cord area, covered by a translucent membrane. This can range from a small portion of the intestine to larger organs like the liver and spleen.
Exstrophy, specifically cloacal exstrophy, means the bladder is open and separated into two halves, exposed on the lower abdominal wall. The colon and rectum may also be open and divided, often with a segment of the rectum positioned between the exposed bladder halves. Urine drains directly from the ureters onto the exposed bladder plates.
Imperforate anus means the anal opening has not formed properly. In some cases, the colon may connect to other structures like the urethra, bladder, or vagina through an abnormal passage called a fistula. Spinal defects, the final component, can vary in severity and often include spina bifida, an incomplete closure of a section of the spine and its surrounding membranes.
Recognizing the Signs
The signs of OEIS Syndrome are observable at birth. These include:
An omphalocele, where abdominal organs visibly protrude from the belly, often encased in a sac.
Exposed bladder and intestines in the lower abdomen, appearing as open, flat plates. The bladder halves are typically separated, with the large intestine often exposed between them.
The absence of a normal anal opening (imperforate anus).
Genital abnormalities, such as a flat, short, or split penis in males, or a split clitoris and additional vaginal openings in females.
Spinal abnormalities, like spina bifida, which may appear as an opening in the lower back where the spinal cord or its membranes are visible.
Widely separated pelvic bones.
How OEIS Syndrome Develops
OEIS Syndrome arises from a disruption during the early stages of fetal development, specifically around 4 to 8 weeks of gestation. This disruption involves the normal embryonic migration and folding of the lower abdominal wall structures. The exact cause is often unknown, and it is considered a sporadic event, meaning it occurs randomly rather than being inherited.
The condition may result from a defect in early embryonic development, such as a failure of mesodermal migration. This can lead to the premature rupture of the cloacal membrane. While genetic and environmental factors are not fully understood, the condition is not linked to anything a parent did or did not do during pregnancy.
Diagnosis and Management
OEIS Syndrome can be detected before birth through prenatal ultrasound, typically in the second trimester (17-30 weeks). Ultrasounds may reveal the bladder or intestines outside the abdominal wall, widely separated pelvic bones, or a low-sitting umbilical cord. A fetal MRI may also be recommended for more detailed images of fetal organs.
Following birth, a physical examination confirms the diagnosis. Additional imaging tests, such as abdominal X-rays, ultrasounds of the kidneys and urinary structures, and spinal ultrasounds or MRIs, are performed to evaluate the full extent of the condition. An echocardiogram may also be conducted to check for heart defects.
Management involves a multidisciplinary approach with a team of specialists, including pediatric surgeons, urologists, orthopedists, and neonatologists. Treatment requires a series of surgical interventions, often staged over several years, to correct the anatomical defects. Initial surgeries focus on placing organs back into the abdominal cavity, closing abdominal and spinal openings, and creating a temporary colostomy for stool elimination. Subsequent procedures may involve realigning pelvic bones, reconstructing the bladder and genitals, and creating an anal opening, potentially through a “pull-through” surgery. Long-term supportive care is also provided for associated issues related to bladder and bowel function and mobility.