*University of New Mexico, School of Medicine, Division of Maternal  Fetal Medicine, Dept. of Obstetrics and Gynecology, 2211 Lomas Blvd, NE, Albuquerque, NM 87131-5286. Ph: 505-272-6907; Fax: 505-272-6385. *Captain  MC USNR. The opinions presented are not the opinions of the United States Navy. §Dept. of Radiology, Vanderbilt University.

Synonyms: Congenital absence or aplasia of the umbilical cord, limb-body-wall complex, body-stalk anomaly, cyllosomas, tethered fetus syndrome.

Definition: Severe anterior abdominal wall defect consisting of a sac of amnion-mesoderm that contains the displaced abdominal organs.

Prevalence: The incidence is estimated to be 0.7:10,000 births¹.

Etiology: There have been no chromosome defects identified with this anomaly. Three possible etiologic mechanisms have been proposed: 1) mechanical obstruction secondary to compression by amniotic bands, 2) abnormalities of the germ disk, and  3)  vascular disruption of the fetoplacental circulation¹.

Pathogenesis: Results from a failure of cephalic, caudal, and lateral body folds to fuse, and the failure to form an umbilical cord.

Associated anomalies: Abdominal wall defects, diaphragmatic hernia, ectopia cordis, sternal cleft, intracardiac defects, extrophy of the bladder, imperforate anus, intestinal and colonic agenesis, neural tube defects, skeletal defects, hypoplastic kidney, single umbilical artery, absent external genitalia².

Differential diagnosis: Similar defects are found in the short umbilical cord syndrome. This syndrome is a complex of omphalocele, exstrophy of the bladder, imperforate anus and spinal defects. However, an umbilical cord is present and there is a male predominance in contrast to a female predominance in body stalk anomaly^1,3-5.

Prognosis: Uniformly fatal.

Recurrence risk: Unknown, but is probably less than one percent.

Management: Since this anomaly is incompatible with life, pregnancy termination should be considered when ultrasonic findings are identified.

MESH Abdominal-Wall-embryology, abnormalities; Ectoderm-physiology; Abnormalities,-Multiple-etiology BDE 2957 ICD9 759.9 CDC 759.900

Introduction

Body stalk anomaly is one of the most dramatic anomalies that may affect a fetus. The diagnosis is usually simple, provided that it is considered. We present here three cases that illustrate the appearance at various stages of development.

Case 1

A 23-year-old Hispanic woman G₂P₁₀₀₁ was referred to the University of New Mexico Hospital Obstetrical Ultrasound unit at twelve weeks four days gestation for a second opinion because of suspected abdominal wall defects. The following findings were identified on examination: a nuchal fold, spinal dysraphism, and the heart, liver, and intestines lying outside the abdominal cavity. These findings were consistent with body stalk anomaly. The patient"s past history was significant in that her first child was born with tracheo-esophageal fistula, imperforate anus, absence of left thumb, dysplastic left kidney, and polydactyly on the left foot. This infant was delivered at 35 weeks, weighed 1570g and was diagnosed with VATER syndrome. After extensive counseling, the patient elected to have a pregnancy termination. Ultrasonographic findings were confirmed by pathologic examination of the aborted fetus.

Figure 2: Longitudinal view of the fetus. The thorax (blue arrow)

Case 2

A 22-year-old white female G₁P₀ was referred to the Department of Radiology, Division of Ultrasound, Vanderbilt University Medical Center, for a routine scan at 22 weeks. The ultrasound examination demonstrated multiple abnormalities as follows (fig. 3-5): absent abdominal wall, with liver and bowel floating outside the abdomen, collapsed chest, severe scoliosis, hydrocephalus, no visible umbilical cord, and a few strands of membranes floating in the amniotic fluid. The suggested diagnosis was body stalk anomaly. Past medical history was unremarkable and the patient denied the use of cigarettes, ethanol or drugs. The pregnancy was terminated by prostaglandin induction. All defects observed by prenatal ultrasound were confirmed during autopsy (fig. 6). Additional anomalies were noted, including a perimembranous ventricular septal defect, rocker bottom feet, low set ears, micrognathia and left renal agenesis. The fetus demonstrated a 46XY karyotype.

Figure 3: The spine is extremely curved.

Figure 4: The abdominal  wall is not visible.

Figure 5: The great vessels outside the fetus.

Figure 6: X-ray, front and back view of the fetus.

Case 3

A 32-year-old white woman G₃P₀₀₀₂ was found to have a triplet gestation at 6 weeks by ultrasound. Follow-up at 18 weeks revealed that one of the triplets presented a large abdominal wall defect with herniation of the gastro­intestinal tract and liver. The heart was found at the edge of the chest. No umbilical cord for this fetus could be visualized (fig. 7-8).

Figure 7: The affected fetus (top) and a normal triplet (below).

Figure 8: The short umbilical vein close to exteriorized bowel.

A presumptive diagnosis of body stalk anomaly was made. After extensive counseling and due to the fatal nature of this disorder, the patient elected to have selective termination of this fetus. This was accomplished by guiding a 20 gauge needle using sterile technique and local anesthesia to the fetal heart and injecting KCl. Two weeks later she began complaining of low grade fever and body aches. Urinary tract infection was diagnosed. Rupture of the membranes followed, with spontaneous loss of the three fetuses. Karyotyping revealed a 46 XY fetus. No autopsy was performed (fig. 9-10).

Figure 9: The fetus after delivery.

Figure 10: Close-up view of the open abdomen.

Discussion

Three cases of body stalk anomaly are presented, the first one of  which was diagnosed at twelve weeks four days of gestation. This patient was referred for a second opinion ultrasound because of suspected fetal anomalies. The fetus had multiple congenital anomalies confirmed by pathologic examination of the aborted fetus.

 The three cases illustrate the gross and bizarre abnormalities found with this entity, which are further discussed below.

Synonyms

Body stalk anomaly is also referred to as congenital absence of the umbilical cord and limb-body wall complex.

Definition

Body stalk anomaly is a severe abdominal wall defect caused by  the failure to form a body stalk and is characterized by the absence of an umbilical cord².

Prevalence

The incidence of body stalk anomaly is not known but is  estimated to be 0.7 in 10,000 births.

Etiology

The etiology of this anomaly is not clear. Chromosome defects have not been identified, but there is a female predominance. Three etiologic mechanisms have been suggested:

·        mechanical obstruction secondary to compression by amniotic bands,

·        abnormalities in the germ disk or

·        vascular disruption of the fetoplacental circulation.

The vascular disruption etiology is supported by two cases presented by Viscarello et al. in which  there was a history of cocaine abuse during the first trimester of pregnancy¹. Cocaine"s vasospastic properties are believed to result in vascular disruption and thereby are teratogenic.

Pathogenesis

From a flat oval germ disk, cephalic, caudal, and lateral infoldings create a cylindrical embryo. This infolding occurs at 22 to 28 days following conception^5,6,7.  These foldings separate the intra-embryonic coelom from the extra-embryonic coelom (fig. 11). The amniotic cavity which was dorsal to the germ disk enlarges to encircle the embryo and obliterate the chorionic cavity. The body of the embryo closes and a body stalk (destined to become the umbilical cord) is formed. The amnion and chorion fuse at the umbilicus⁸.  The faulty invagination process prevents the obliteration of the chorionic cavity and the formation of the umbilical cord. A wide-based cylinder is formed, bounded on one side by the fetal retroperitoneal space and the chorionic plate of the placenta at the other end. The sac-like walls, consisting of amnion and fetal mesoderm, contain the abdominal organs⁵.

Figure 11: In body stalk anomaly (right), the lateral, cranial and

Associated anomalies

The maldevelopment of the cephalic, caudal and two lateral folds result in the distinctive anomalies found in body stalk anomaly. A predominantly cephalic defect results in a constellation of anomalies known as pentalogy of Cantrell. It is characterized by an upper midline omphalocele, anterior diaphragmatic hernia, ectopia cordis, sternal cleft and intracardiac defects. In a predominantly caudal defect, one finds a hypogastric omphalocele, exstrophy of the bladder, imperforate anus, partial colonic agenesis and various degrees of intestinal atresias. Other anomalies found include skeletal defects (lordosis and scoliosis), thought to be caused by fetal compression, defects of the chest wall, pericardium, liver, lungs, hypoplastic kidney, and single umbilical artery2,4.

Differential diagnosis

Body stalk anomaly can be distinguished from the short umbilical cord syndrome by the absence of an umbilical cord and the  preponderance of 46,XX karyotype. In the short umbilical cord syndrome, the umbilical cord is present and there is a preponderance of 46, XY karyotype.

Prognosis

The anomaly is uniformly fatal. Intrauterine demise is associated with placenta abruption. Since the fetus is attached to the placenta, birth must occur with delivery of the fetus and placenta simultaneously.

Recurrence risk

The risk of recurrence is not known.  Since this anomaly is rare compared to other abdominal wall defects such as omphalocele and gastroschisis, the recurrence risk is probably less than one percent and similar to that of isolated omphalocele.

Management

In one report, the diagnosis was established at 18 weeks³. In this report the diagnosis was made at 12 weeks. Since this anomaly can be diagnosed in early pregnancy and because it is incompatible with life, termination of pregnancy should be considered when the ultrasound findings are identified. Even if the diagnosis is made in late second or early third trimester, interruption of pregnancy should be an option. If the pregnancy is continued, the patient should be counseled that extrauterine survival is impossible, therefore any intervention for fetal distress can be avoided. A history of cocaine use in the first trimester should alert the sonographer to look for anterior abdominal wall malformations as well as other anomalies.

References

1. Viscarello RR, Ferguson DD, Nores J, et al:  Limb-body wall associated with cocaine abuse:  Further evidence of cocaine"s tetratogenicity.  Obstet Gynecol 80:523-526, 1992.

2. Mann L, Ferguson-Smith MD, Desai M, et al:  Perinatal assessment of anterior abdominal wall defects and their prognosis.  Prenat Diagn 4:427-435, 1984.

3. Jauniaux E, Vyas S, Finlayson C, et al:  Early sonographic diagnosis of body stalk anomaly.  Prenat Diagn 10:127-132, 1990.

4. Giacoia GP:  Body stalk anomaly:  Congenital absence of the umbilical cord.  Obstet Gynecol 80:527-530, 1992.

5. Lockwood CJ, Scioscia AL, Hobbins JC:  Congenital absence of the umbilical cord resulting from maldevelopment of embryonic body folding.  Am J Obstet Gynecol, 155:1049-1051, 1986.

6. Lockwood C:  Identifying abdominal wall defects. Contemporary Obstetrics and Gynecology,  February 1986.

7. Schmidt W, Yarkoni S, Grelin ES, et al:  Sonographic visualization of physiologic anterior abdominal wall hernia in the first trimester.  Obstet Gynecol 69: 911-915, 1987.

8. Crelin ES: Development of gastrointestinal tract.  Clinical symposia, CIBA.