Abdominal wall defects constitute a broad spectrum of congenital malformations due to abnormal development of the fetal abdominal wall. As a result of the defect present, they affect a number of gastrointestinal organs and can also have effects on other systems like the pulmonary system. Currently there is no fetal intervention for these defects, however, the main stay for their management is post natally once the baby is born.
Types of Abdominal Wall Defects
Is due to failure of the caudal aspect of the abdominal wall to form. These babies have defects involving the bladder, abdominal wall, perineum (the area between the anus and the scrotum or vulva), genitals and pelvis. In this condition, the bladder is exposed through the defect in the abdominal wall and is seen protruding from the body, which can affect muscular, neurological and urinary function if not treated.
In addition to malformations of the abdominal wall, babies with bladder exstrophy have abnormal muscle and pelvic hip bones. The genitals can also be deformed and the muscles surrounding the bladder and urethra fail to function properly. Without normal muscle and neurological function, future incontinence – the inability to control urination – is at risk without surgery.
What causes it?
This condition occurs in as few as 1 in 50,000 live births. However, a family history makes it more likely. Children born to a parent with bladder exstrophy have about a 1-in-70 chance of having it, and if parents have one child with this condition, they have a 1-in-100 chance of having another child with it.
Recent studies also suggest that children born as the result of fertility treatments are 7 times more likely to have bladder exstrophy than those conceived without fertility assistance. Males are five times more likely than females to be diagnosed with bladder exstrophy.
In some cases, bladder exstrophy is detected from a routine prenatal ultrasound. In other cases, it isn’t diagnosed until birth, when physicians can clearly see the exposed bladder.
Prenatally, ultrasound and MRI together often assist in making this diagnosis.
At birth, the diagnosis of bladder exstrophy is made when:
- Part of the bladder extends out beneath the umbilical cord
- In male babies, the penis is short and wide with the tip of the penis split in the middle
- In females, the mons pubis (the rounded mass of fatty tissue lying over the pubic bones), clitoris and labia are separated, and the opening of the vagina or anus may be pushed more towards the abdomen
The treatment for fetal bladder exstrophy is different with each child.
Babies born with this condition generally receive at least one bladder exstrophy surgery, but most children require multiple operations. The first priority is to close the bladder, the back of the urethra and the pelvic bones, while ensuring that the internal organs are enclosed within the abdomen. Surgeons also rebuild the external sex organs and fix the bladder so it can provide urinary continence.
The number of surgeries depends on the details of each case, but physicians often follow a phased approach to bladder exstrophy surgery. This means they start at birth by closing the bladder and pelvis and repair the urethra and genitals later in infancy. Then, when a child is ready for potty training and his or her bladder is large enough, physicians perform the bladder exstrophy surgery necessary for continence (usually around age 4).
Reconstructive surgery to correct the defects associated with bladder exstrophy have positive results, with most patients achieving functional use of their bladder, urethra, pelvic bones and genitals by potty-training-age. Even in more complex cases that require longer-term management, reconstructive surgery can allow patients to reach puberty with successful results.
Body-stalk anomaly is a severe abdominal wall defect that results in the absence or shortening of the umbilical cord. In this condition, the abdominal organs lie outside the abdominal cavity and attach directly to the placenta. Body-stalk anomaly is the rarest and most severe of fetal abdominal wall defects and is considered to be fatal.
What causes it?
While the cause of body-stalk anomaly is unknown, theories include early rupture of the amnion (the sac encasing the fetus) along with amniotic band constriction due to that rupture. Disruption of the embryo’s vascular system or an abnormality in the fertilized egg are also potential causes.Body-stalk anomaly has been associated with cocaine usage and younger mothers but is mostly considered to occur randomly. It is not believed to run in families, and because it is believed to occur randomly, no future pregnancies should be affected by this anomaly.
Body-stalk anomaly is usually diagnosed by prenatal ultrasound in either the first 10-14 weeks of pregnancy or at approximately 16-20 weeks of pregnancy, depending on when a patient has an ultrasound performed. Malformed abdominal structures are usually visible on the images, as are abnormalities of the head, arms and legs.
Because the condition is almost always fatal, it’s important to detect it as early as possible to give parents the option of early termination. After diagnosis, some parents may choose to allow the pregnancy to proceed without interruption.
Cloacal exstrophy represents a spectrum of rare anomalies that prevent normal development of a baby’s lower abdominal wall resulting in exposure of the intestines, and bladder. Babies with cloacal exstrophy may also have an imperforate anus, which means the opening to the anus is missing or blocked. There are also a number of other defects associated with this condition, which may require extensive intervention and reconstruction before and after birth.
Because a baby’s organs can be exposed and there is an imperforate anus, this condition can be very life-threatening during and after pregnancy. However, in the past two decades, reconstructive surgery has provided incredible outcomes for babies with cloacal exstrophy.
This is a rare birth defect that affects approximately 1 in every 200,000 to 400,000 births. Babies with the condition are born with a single common channel connecting the rectum, vagina and urinary tract. Part of the large intestine usually develops outside of the abdominal cavity, with the bladder connected to it on either side, in halves. Because the colon is connected to the bladder, urine and stool can mix and there is often no anus. The penis and clitoris are usually split in two and girls may have more than one vaginal opening. Infants born with cloacal exstrophy can also have spinal abnormalities.
What causes it?
Cloacal exstrophy occurs as an isolated event without a recognized cause. There is a higher incidence of cloacal exstrophy in families in which one member is affected as compared with the general population. However, there’s no evidence to suggest that anything done by expectant parents leads to the condition.
In some cases, cloacal exstrophy is detected from a routine prenatal ultrasound. In other cases, it isn’t diagnosed until birth, when physicians can clearly see the exposed organs. Once diagnosed, additional tests are used to confirm the details of each case and to design a treatment plan. These tests may include:
- Fetal magnetic resonance imaging (MRI)
- Computerized tomography (CT) after the baby is born
- Endoscopy (inserting an instrument to view the inside of an organ)
- Abdominal ultrasound (using sonography to view internal organs and assess blood flow)
Cloacal exstrophy is treated through an individualized surgical repair after birth, usually in stages to address each defect. This requires an in-depth treatment plan to be created for your child’s specific needs. The extent of cloacal exstrophy surgery required for your baby depends on the type and severity of his or her abnormalities.
In most cases, surgeons perform multiple operations over the course of several years. This approach, referred to as staged reconstruction, usually begins in the first days of life with the highest-priority procedure. Physicians usually repair the bladder, create a colostomy (an opening in the colon with an attached “bag” that allows stool to pass) and repair the abdominal wall defect.
Babies with ectopia cordis are born with their hearts partially or completely outside of their bodies. There are usually other organ structures that also develop abnormally. Ectopia cordis often coexists with additional heart defects as well as abdominal wall defects.
There are four ectopia cordis classifications or “types” based on the position of the heart:
- Cervical (3% of cases)
- Thoracic (64% of cases)
- Thoracoabdominal ectopia (18% of cases)
- Abdominal ectopia (15%)
What causes it?
Ectopia cordis is extremely rare, affecting around one in 126,000 births. The cause of ectopia cordis is unknown, but males tend to be affected more often than females. There has not been a reported case of recurrence of ectopia cordis in a sibling.
This condition is often diagnosed by ultrasound and can occur as early as the first trimester. If not discovered during pregnancy, it becomes obvious as soon as the baby is born.
Ectopia cordis treatment varies based on your child’s specific needs.
When a baby is diagnosed with this severe birth defect in utero, the mother can opt to terminate the pregnancy, as the ectopia cordis survival rate is around 10%. There are currently no fetal interventions (surgery) options while the baby is in utero.
Gastroschisis is a hole in the abdominal wall, which allows a baby’s intestines to protrude outside of the abdominal cavity. Gastroschisis is almost always located immediately to the right of the insertion of the umbilical cord. The hole can also be much larger, which may also cause the stomach, liver or other organs to be exposed.
What causes it?
In most babies, the cause of gastroschisis is unknown. However, recent research has indicated that certain factors can increase the likelihood of having a baby with the condition. Those factors include young mothers (under 20 years of age) and smoking tobacco, drinking alcohol or using recreational drugs during pregnancy.There are also reports that gastroschisis can occur again within the same family. Some research estimates that gastroschisis can recur in future pregnancies about 4% of the time.
Most cases of gastroschisis are diagnosed during routine ultrasounds. In addition, second trimester maternal serum alpha–fetoprotein (MSAFP) screening has shown a connection between elevated MSAFP levels and gastroschisis. The diagnosis of abdominal wall defects during the first trimester is difficult because it is normal for the bowel to protrude or push into the base of the umbilical cord. This is why the most reliable ultrasounds occur after 14 weeks of pregnancy, when the bowel should be entirely enclosed in the abdomen.
Gastroschisis is treated with surgery after birth, at which time the intestines are placed back in the baby’s belly. There are no fetal interventions available at this time.
The extent of surgery required for your baby depends on how much of the intestines or additional organs lie outside of his or her body at birth and if there is an associated atresia or blockage in the intestine. There are 2 main approaches for closure of gastroschisis; primary repair, where the protruded organs are returned to the abdomen and the muscle closed. The alternative approach is delayed closure after placement of the organs in a pre-formed silp bag.
Babies with gastroschisis often need additional treatment during this process, including:
- Intravenous nutritional supplementation
- Antibiotics to prevent infection
- Careful body temperature monitoring
An omphalocele is a birth defect where abdominal organs protrude from the belly and lie exposed outside the abdomen. The organs, usually the intestines and liver, are covered in a thin sac. Associated abnormalities can include a smaller-than-normal abdominal cavity or lungs, organ damage or infection (especially if the sac holding the intestines ruptures).
The abdominal wall with an omphalocele fails to develop properly, leaving the abdominal contents covered by a thin membrane. The size and severity of this condition ranges from small, with only part of the intestines protruding, to large, with entire and multiple organs remaining outside of the abdomen.
The incidence of omphalocele ranges from approximately 1 in 4,000 to 1 in 7,000 live births. There is an increased risk of stillbirth in babies with this condition, which is why we strive for early diagnosis and observation.
What causes it?
The defect is thought to be caused by an abnormality that occurs during the process of body infolding in the embryo at 3 to 4 weeks of pregnancy. While no specific cause is known, omphalocele has been associated with advanced maternal age.
Studies also show that several factors can increase the likelihood of having a baby with omphalocele. Women who are obese or overweight prior to pregnancy are more likely to have a baby with omphalocele, as are women who drink alcohol, smoke cigarettes or take certain kinds of anti-depressants during pregnancy.
Omphalocele is often detected from a routine prenatal ultrasound. The condition can also trigger abnormal results on prenatal blood screening tests.
Omphalocele treatment plans depend on the number of organs involved and how much of those organs remain outside of the belly at birth. If only parts of the intestines are protruding, surgeons return them to the abdomen soon after birth and close the opening in the abdominal wall. If the omphalocele is large with multiple organs exposed, or there are associated respiratory problems, physicians usually take a phased approach. In the most severe cases, doctors will take time to allow the body to grow skin over the membrane. Ace wraps can then be used to develop space to accommodate the organs, with repair of the defect occurring at 1-2 years of age. Currently, there are no fetal (in utero) interventions offered to treat omphalocele.
Pentalogy of Cantrell
Pentalogy of Cantrell is a rare and severe abdominal wall defect that consists of five abnormalities:
- Midline abdominal wall defect, covered by a thin membrane
- Defect of the lower sternum
- Deficiency of the anterior diaphragm
- Defect in the diaphragmatic pericardium, where the heart meets the diaphragm
- Various heart defects
Not every case has all five factors, with the majority featuring just a few. Some babies born with the condition also have associated anomalies, like cleft lip or cleft palate.
In Pentalogy of Cantrell, the heart is oriented more vertically in the chest and there usually are sometimes, but not always, defects within the heart (referred to as intracardiac anomalies). The most common defect is a hole in the wall between the two lower chambers of the heart (referred to as the ventricles) that is called a ventricular septal defect. The hands and spine are also commonly abnormal in this condition.
What causes it?
Pentalogy of Cantrell is thought to occur randomly, although African Americans and males may be more likely to develop pentalogy of Cantrell. The condition is thought to occur between 1 in every 65,000 births or as low as 1 in every 200,000 births.
In some cases, there might be a genetic component. A genetic cause means the baby’s chromosomes (considered to be the baby’s “blueprint”) are abnormal. Whatever the underlying cause, the result is that certain key steps in the first few weeks of conception did not occur normally. It is important to understand that the mother did nothing to cause this condition.
Pentalogy of Cantrell is usually detected from a routine prenatal ultrasound after about 12 weeks. If not discovered during pregnancy, it’s visible as soon as the baby is born.
At this time, there are no fetal interventions for pentalogy of Cantrell, which means all treatment will have to wait until your child is delivered
*diagnostic information provided courtesy of our partners at Colorado Fetal Care Center
The Fetal Health Foundation is a parent-founded non profit helping families experiencing a fetal syndrome diagnosis.