Children's Hospital Colorado

Body-Stalk Anomaly

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 (the structure that is the connection between the mother and baby). Body-stalk anomaly is the rarest and most severe of fetal abdominal wall defects and is considered to be fatal.

Because a body-stalk anomaly diagnosis can be devastating for parents, it's important to detect the condition as early as possible. The Colorado Fetal Care Center is a national leader in diagnosing complex fetal conditions like body-stalk anomaly. We provide families with helpful resources throughout the process and are here for them every step of the way.

For patients

Body-stalk anomaly is a rare abdominal wall defect in which the abdominal organs develop outside of a baby's abdominal cavity and remain attached directly to the placenta. This condition is also accompanied by a short or non-existent umbilical cord. Due to the severity of the defects, this condition is almost always fatal for the fetus.

What causes body-stalk anomaly?

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, meaning that there likely is not a genetic cause. 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.

As a parent, receiving the news that your baby has any birth defect - especially one that threatens his or her life - can be devastating. If you are facing a body-stalk anomaly prognosis, receiving support from the best fetal care team is imperative to safeguarding your physical and emotional health.

Because body-stalk anomaly has no known treatments, the Colorado Fetal Care Center focuses treatment for this condition on counseling and support for the expectant mother and family. Once doctors have explained the body-stalk anomaly prognosis to expectant parents, they will have the option to terminate the pregnancy or allow it to proceed naturally, knowing the baby will live for only a short time after delivery.

For healthcare professionals

Body-stalk anomaly is a severe abdominal wall defect that results from abnormalities in the development of the cephalic, caudal and lateral embryonic body folds. This maldevelopment results in the absence or shortening of the umbilical cord with the abdominal organs lying outside the abdominal cavity and directly attached to the placenta (Shalev et al., 1995; Smrcek et al., 2003). Body-stalk anomaly was first described by Kermauner in 1906 in a newborn with an abdominal wall defect consisting of an amniotic sac that contained viscera; the anterior wall of the sac was directly attached to the placenta and there was no umbilical cord. Other than the references given in textbooks of pathology, body-stalk anomaly was not appreciated in the general obstetric literature until the report of Lockwood et al. in 1986.

After gastrulation, the embryo consists of a three layered, flat, oval germinal disk. The rapid growth of the embryo, especially along the sagittal axis causes the germinal disk to curve. Through circumferential folding, the embryo becomes cylindrical. As a result of this process, the body of the embryo closes, the body stalk forms and an intraembryonic coelom (peritoneal cavity) separates from an extraembryonic coelom (chorionic cavity) (Giacoia, 1992). The amniotic cavity, which is initially located dorsal to the germinal disk, grows rapidly and eventually encircles the fetus, obliterates the chorionic cavity and envelops the umbilical cord. The abnormality in the folding process prevents this obliteration of the chorionic cavity and formation of the umbilical cord. Without an umbilical cord, the fetus becomes directly attached to the placental chorionic plate. This body-stalk anomaly consists of a sac of amnion–mesoderm that contains the displaced abdominal organs (Giacoia, 1992).

Causes proposed for body-stalk defect include early amnion rupture with direct mechanical pressure and amniotic bands, vascular disruption of the early embryo or an abnormality in the germinal disk that leads to the formation of an anomalous amniotic cavity (Van Allen et al., 1987). In the early amnion-rupture theory, the abdominal wall and spinal defects could be secondary to the passage of the lower half of the fetal body into the coelomic cavity through the defect in the amniotic sac. The fetus has no room to move and remains practically attached to the placenta. Limb amputations and encephalocele could be secondary to the entrapment of the fetal skull and/or limbs in the coelomic cavity (Daskalakis et al., 1997). Alternatively, early generalized compromise of embryonic blood flow could lead to a failure of closure of the ventral body wall and persistence of the coelomic cavity (Van Allen et al., 1987). This could also lead to a rupture of an unsupported amnion and formation of amniotic bands.


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