Strangulation of the Umbilical Cord by Amniotic Bands: A Case Report
By Robert V. Reese, Jr., DO
ABSTRACT: Amniotic band syndrome is a collection of congenital malformations affecting mainly the limbs but may also affect the umbilical cord. Once thought to be rare at 1:100,000 deliveries; amniotic band syndrome is now reported to be 1:1200 to 1:15,000. Early amnion rupture leads to fibrous bands that entangle body parts of the fetus. Umbilical cord stricture and strangulation may occur leading to fetal demise. Prenatal ultrasound does not usually diagnose these bands. Diagnosis is made by examination of the placenta and membranes. There are reported cases that seem to be associated with amnioscentesis. In patients with a decreased fetal heart rate and a history of amnioscentesis; intensive ultrasound follow up is recommended to evaluate for amniotic bands.
Amniotic band syndrome (ABS) is an uncommon fetal malformation with increasing prevalence.3 Synonyms for ABS include: Congenital constriction band syndrome, Streeter’s dysphasia, ADAM (Amniotic Deformity Adhesion Mutilation) complex and fetal disruption complex.3
Strangulation of the umbilical cord by strands of torn amniotic membrane is a recognized cause
of asphyxia of the fetus at or
near term.8
A case report of fetal asphyxia caused by amniotic band strangulation of the umbilical cord is presented below.
Case Report
A 27-year old gravida 5, para 3, abortus 1, black female presented at 36 weeks estimated gestational age (EGA) with complaints of labor pains. Her antepartum course was remarkable for essential hypertension controlled with Labetalol. Ultrasound examinations at 20 weeks and 31 weeks had shown normal amniotic fluid and no fetal abnormalities. Two weeks prior to admission she had a normal fetal heart rate of 160 and slightly elevated blood pressure of 130/96. She stated that she had not been taking her blood pressure medications. There was no protein in her urine and no edema. On admission, she was having active contractions. Her blood pressure was 138/100. The cervix was 4 cm dilated. A fetal heart rate was recorded as 90. However, this was later determined to be a maternal heart rate and not a fetal heart rate. Due to the elevated blood pressure and suspected utero-placental insufficiency, the patient was taken to the OR for an emergency C-Section. A nonviable infant female was delivered, weighing 2,588 grams. Fetal autolysis was consistent with 72-120 hours of intrauterine death.
Gross examination of the placenta revealed the following: Placental mass was 530.3 grams. The umbilical cord had an abnormal insertion including multiple branches surrounded by amniotic bands. The cord inserted 3.0cm from the edge. The cord extending beyond the amnion, measured 26.0cm in length and up to 1.5cm in diameter. Many of the branches enveloped by the amniotic bands were extremely thin and measured 0.5cm in diameter. The portion of the umbilical cord beyond the amnion showed multiple areas of ischemia. There was a large placental hemorrhagic infarct measuring 7.0cm. These findings are pictured in images 1, 2 and 3.
Discussion
Amniotic band syndrome is not an anomaly as first described more than a century and a half ago, and appears to be rising. Once believed to have an incidence of 1:100,000, recent literature supports the incidence today as 1:1200 to 1:15,000 births.2 No distinct sex predilection has been determined. Nearly sixty percent of the cases have some sort of abnormal gestation history. Prenatal risk factors associated with amniotic band syndrome include prematurity (<37 weeks), low birth weight (<2500 g), maternal illness (during pregnancy), maternal drug exposure and maternal hemorrhage/trauma.3
Amniotic band syndrome occurs when the amnion ruptures and free floating bands encircle developing fetal parts. This can lead to amputation of digits and umbilical cord constriction.9 Although the disruptive defect resulting from amniotic bands may occur at any time during gestation, amnion rupture most likely occurs before 12 weeks’ gestation. Before that time, the amnion and chorion are completely separate membranes and as such it has been suggested that the amnion is vulnerable to rupture. Examination of the placenta and membranes is diagnostic. Aberrant bands or strands of amnion are noted.
Because the result of amnion rupture is external compression or disruption; internal anomalies do not occur. Hence the features evident by surface examination are usually the only abnormalities noted.5
There does not appear to be any association between ABS and genetic or chromosomal disorders.1 Karyotypes are virtually always normal, and the syndrome is almost always sporadic in nature.3
ABS is difficult to diagnose. Prenatal diagnoses are the exception rather than the rule. The detailed fetal visualization required to diagnose ABS is beyond the scope of routine obstetrical ultrasound examinations.2
Two main theories for the pathogenesis of ABS have been proposed. According to the exogenous theory, rupture of the amnion without rupture of the chorion causes the amnion to detach by the undermining action of the amniotic fluid emerging through an artificial hole. The outer surface of the amnion and the naked chorion produce amniotic bands that can entangle fetal parts.1
According to the endogenous theory, an early teratogenic insult occurs to the germ disk.1 Edmonds, in 1954, summarized the literature and proposed the concept of necrosis of Wharton’s Jelly, beginning near the fetus, creates torsion and fetal demise.7 Virgilio, in a more recent study, opposed this theory, pointing out that constriction may occur at any point in the cord.7
This hypothesis is supported in the case of this patient where constriction occurred near the placental insertion of the cord. While a definite pathogenesis for the formation of amniotic bands still remains to be established, it is apparent that premature rupture of the amnion must occur.4 It has been postulated that excessive fetal activities, long fingernails or toenails may contribute to this. Strangulation of the umbilical cord by strands of torn amniotic membrane is a recognized cause of asphyxia of the fetus at or near term.
Torpin (1968) found only 19 recorded cases.8 Velamentous Cord insertion is associated with an increased risk of fetal hemorrhage from the unprotected vessels as well as vascular compression and thrombosis.7 In the case of this patient, webs of amnion at the base of the cord apparently compromised circulation to the fetus.
Although the patient in this case did not have an amniocentesis; there is a report by Kanayama of umbilical cord constriction following an amniocentesis at 17 weeks.6 It is postulated that the Amniocentesis tore the amnion causing the amniotic band to occur. Kanayama also demonstrated reverse diastolic flow in the umbilical artery caused by the constriction. Rapid intervention with Cesarean section resulted in a favorable outcome in spite of the high rate of intrauterine fetal demise associated with this condition.6
Summary
Amniotic Band Syndrome can be difficult to diagnose. Ultrasound does not usually reveal it. As in this case, two ultrasounds were read as normal.
Even though the incidence of the condition is very low, obstetricians need to be aware of the possibility of umbilical cord constriction by an amniotic band.6 The presentation of a patient with decreased fetal heart rate and a history of amniocentesis must to be monitored closely. There is a high fetal death rate associated with this diagnosis. When the fetus is at a viable gestational age, immediate delivery may be indicated.6
When Intrauterine Demise does occur, amniotic band syndrome should be included as one of the possible etiologies. Thorough evaluation of the placenta and cord is necessary to rule out constriction of the cord by Amniotic bands. Although the finding of Amniotic Band Syndrome may not change the outcome identifying a definitive cause for the parents may provide a small measure of closure in the context of this tragic event.
Dr. Reese is a 1987 graduate of Oklahoma State University College of Osteopathic Medicine, Tulsa, Oklahoma. He became board certified in family medicine in 2002, and is currently in private practice in Fitzgerald, Georgia.
References:
| Microscopic Image #1 |
| Gross image of fetal surface showing abnormal umbilical cord insertion encased in amnion with multiple branches below the amnion |
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| Microscopic Image #2 |
| Gross image of umbilical cord and placenta is showing dusky discoloration of the umbilical cord suggestive to early ischemia. |
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