Limb Body Wall Complex



 



What Is Limb Body Wall Complex?

The Medical Definition of LBWC:
Limb-body wall complex (LBWC) is a rare fetal polymalformation of uncertain etiology, but has been regarded as sporadic in nature with a low recurrence risk. (1)



 






What Does This Actually Mean?
This means that Limb Body Wall Complex is a:   1) rare fetal polymalformation- the rare multi-deformity of a fetus     2) of uncertain etiology- they don't know exactly what causes it    3) but has been sporadic in nature- it doesn't happen very often, and is scattered over different areas   4) with a low recurrence risk-  it usually won't happen to the same family twice.

In layman's terms, Limb Body Wall Complex is usually defined as consisting of 2 of the following 3 fetal anomalies:

1) Thoraco-abdominoschisis or abdominoschisis (gatsroschisis or omphalocele)

2) Limb Defects (club foot, missing limbs, etc.)

3) Cranio-facial defects (cleft lip/palate, encephalocele, exencephaly, etc.)

Other common anomalies associated with LBWC are:

Short Umbilical Cord, Congenital Scoliosis, Horseshoe Kidneys, and Spina Bifida



There have been two types of LBWC identified: (2)

Type 1, "placentocranial adhesion phenotype" which consists of craniofacial defects, and can present with the fetal face fused with the placenta.

Type 2, "placentoabdominal adhesion phenotype" which consists of abdominal, spinal, extremity, and genital defects, and which can present with a short umbilical cord, or no umbilical cord at all.



What Causes Limb Body Wall Complex?
 
There is no known cause of LBWC. There are a number of theories regarding what causes it, the most popular being:

The “amnion rupture theory”. (3)
Here is a series of illustrations that shows how an embryo begins to form:
The illustration on Day 19 will help explain the amnion rupture in simple terms.
The amniotic sac is comprised of the chorion and the amnion. The chorion is the outer membrane if the amniotic sac and the amnion the inner.  The chorion is part of the placenta and the amnion is what holds all of the amniotic fluid, as well as the fetus.
The amnion rupture theory posits that in a very early stage of development, the amnion surrounding your baby ruptured, and stringy, sticky, fibrous bands of amnion became “entangled” with the embryo, and caused a disruption in how the embryo was forming. 

The second theory is the "germ disc" theory.(4)


In the beginning, your baby was a zygote. A zygote is formed when an egg is fertilized. After 5 days, the human zygote turns into a blastocyst.
The blastocyst consists of two cell types; the inner cells will form the fetus and the outer cells will form the placenta. About 9 days after fertilization, the blastocyst implants itself into the endometrium (lining of the uterus). When that implantation happens, hormones are secreted that signal to your body that you are pregnant.

The second week after conception the blastocyst separates into three layers. The outside layer, the ectoderm, will form the skin, hair, sweat glands, tooth enamel, salivary glands, and all the nervous tissue, including the brain. The middle layer, or mesoderm, will form the muscles, bones, blood, circulatory system, teeth, connective tissues and kidneys. The inner layer, the endoderm, will form most of the internal organs (stomach, intestines, liver, lungs, heart, and so on). This is called the germ disc.

When this portion of embryonic formation is disrupted- for whatever reasons, the capacity for multiple, massive deformities of the fetus are inevitable.


Can/will this happen again in subsequent pregnancies?

 
Because Limb Body Wall Complex is most likely caused by an external disruption, rather than a congenital malformation, the risk to future pregnancies has been classified as “negligible”. At this time, there is no known genetic cause for LBWC.

 (1) Journal of Maternal Fetal Neonatal Medicine: The official journal of European Association of Perinatal Medicine, The Federation of Asia and Oceana Perinatal Societies, The International Society of Perinatal Obstetricians 2002 Aug;12(2):132-7. Limb-body wall complex: a case series.Luehr B, Lipsett J, Quinlivan JA.
Department of Obstetrics and Gynaecology, Flinders Medical Centre, Adelaide, Australia.

(2) Russo R, D'Armiento M, Angrisani P, Vecchione R: Limb body wall complex: a critical review and a nosological proposal. Am J Med Genet 1993, 47(6):893-900

(3) Torpin, 1965

(4)  germ disc defect with early embryonic maldevelopment [Streeter, 1930; Herva et al., 1984; Bamforth, 1992]

(For future reference, theories other than amnion rupture and germ disc defect which have been suggested as a cause for LBWC):
(a) vascular disruption [Van Allen, 1987] and


(b) disturbance of the embryonic folding process [Hartwig et al. 1989, 1991].
Information about the formation of embryos:
http://bms.brown.edu/pedisurg/Fetal/Seminar/Syllabus%20pages/3_Embyrology.pdf