Introduction
The fetal abnormality known as body-stalk anomaly is a highly uncommon defect of the abdominal wall, wherein the organs within the abdomen develop outside of the cavity and remain directly attached to the placenta. This condition is often accompanied by a short or absent umbilical cord and is typically fatal for the fetus due to the severity of the defects. It is considered to be the most severe and rarest of all fetal abdominal wall defects.
The reported prevalence of this uncommon malformation syndrome is 0.12 cases per 10,000 births, encompassing both live and stillbirths. However, a recent multicenter study examining 106,727 fetuses at 10 to 14 weeks of gestation revealed an incidence rate of 1 per 7,500 pregnancies. This disparity in incidence rates implies that this particular malformation could potentially contribute to a substantial number of spontaneous abortions in the first trimester of pregnancy. Consequently, the true incidence of this anomaly may be underestimated.
What Is a Body Stalk Anomaly?
Body stalk anomaly is a term used to describe a pattern of severe defects that, in most reported cases, are incompatible with life. This condition should be suspected when a significant abdominal defect, along with abnormalities in the axial skeleton like kyphosis or scoliosis, are observed and a short or absent umbilical cord is found. Ultrasound can detect body stalk defects at the end of the first trimester of pregnancy. It is also important to consider other pathologies that impact the abdominal wall, such as gastroschisis, omphalocele, bladder exstrophy, cloacal exstrophy, and the OEIS complex (omphalocele, exstrophy of cloaca, imperforate anus, and spinal defects).
What Causes a Body Stalk Anomaly?
The etiology of body-stalk anomaly remains uncertain, although several theories have been proposed. These theories encompass the possibility of an early rupture of the amnion, accompanied by the subsequent constriction of the amniotic band. Additionally, disruptions in the vascular system of the embryo or abnormalities within the fertilized egg have also been suggested as potential causes.
While body-stalk anomaly has been linked to cocaine usage and younger maternal age, it is predominantly considered to occur sporadically. There is limited evidence to support a hereditary component, indicating that a genetic cause is unlikely. Given its presumed random occurrence, it is improbable that future pregnancies will be affected by this anomaly.
Potential causes of body-stalk anomaly include the early rupture of the amnion, which exerts direct mechanical pressure, and the presence of amniotic bands. Vascular disruptions during the early stages of embryonic development or abnormalities within the germinal disk may also contribute to this condition. Defects in genes associated with embryogenesis may play a role in the development of body-stalk anomaly.
What Are the Signs of Body-Stalk Anomaly?
The occurrence of the defect arises when the abdominal wall fails to form during the developmental stage of the fetus. Consequently, the abdominal organs of the baby, including the intestines and liver, are positioned externally to the body and directly attached to the placenta.
This condition is associated with multiple severe fetal malformations, which encompass:
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Limb defects.
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Deformity of the spine, known as kyphoscoliosis, where the spine exhibits curvature both sideways and front-to-back.
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Neural tube defects that involve abnormalities in the brain, spinal cord, or spine.
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Craniofacial defects.
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Malformation of the chest wall.
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Absence or extreme brevity of the umbilical cord.
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Incomplete development of the lungs referred to as pulmonary hypoplasia.
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Malformations of the urinary organs, including the kidneys and bladder, as well as the genitals.
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Intestinal atresia, characterized by complete blockage or closure of the intestines.
How Is Body-Stalk Anomaly Diagnosed?
Prenatal ultrasound is typically used to diagnose a body stalk anomaly during the initial 10 to 14 weeks or around 16 to 20 weeks of pregnancy, depending on the timing of the ultrasound. The images obtained from the ultrasound often reveal malformed abdominal structures, as well as abnormalities in the head, arms, and legs.
Given the high fatality rate associated with this condition, early detection is crucial to provide parents with the choice of terminating the pregnancy at an early stage. Following diagnosis, certain parents may opt to continue with the pregnancy without any intervention.
A diagnosis of body stalk anomaly is established when a minimum of two out of the three defects listed below are observed:
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A defect in the thoracic (chest) or abdominal wall.
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Defects in the limbs.
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Encephalocele, characterized by the protrusion of a portion of the brain through a skull opening, accompanied by facial clefts.
Additionally, the ultrasound may reveal severe spinal curvature and a shortened umbilical cord. Accurate diagnosis plays a crucial role in distinguishing body-stalk anomaly from other treatable abdominal wall defects, such as gastroschisis and omphalocele.
How Is Body Stalk Anomaly Managed?
Receiving the news that their child has a birth defect, especially one as potentially fatal as a body-stalk anomaly, can be extremely upsetting. It is critical to seek support from a highly skilled fetal care team to ensure the well-being of both physical and emotional health. Because there are no known treatments for a body-stalk anomaly, the focus of treatment is on counseling and support for the expecting mother and her family. Following a detailed explanation of the body stalk anomaly prognosis by medical professionals, pregnant parents will be given the option of terminating the pregnancy or allowing it to develop naturally, even though the baby's life will be short after birth.
Can a Baby Survive With a Body-Stalk Anomaly?
The body-stalk anomaly is distinguished by severe abnormalities that leave the fetus incapable of survival, most commonly due to pulmonary hypoplasia. When this birth defect occurs during pregnancy, the result is frequently a miscarriage, early termination, or stillbirth. In rare situations, the infant may survive for a short time after birth.
Conclusion
Body stalk abnormality is a serious disorder that is frequently fatal. The majority of affected fetuses do not survive to full term, and those that do are frequently stillborn or die soon after birth. Ultrasonography can be used for prenatal diagnosis, and depending on the severity of the defect, doctors can provide various options and counseling to the parents.
