Quantify abnormal cord coiling. (Decreasing Liability Risk).

SAN FRANCISCO -- Abnormal cord coiling should be quantified, Dr. Geoffrey A. Macbin said at a meeting on antepartum and intrapartum management sponsored by the University of California, San Francisco.

"Very few obstetricians know that cord coiling can and should be quantified though it is well established in the scientific literature," said Dr. Macbin, a fetal and genetic pathologist at the Northern California Region of Kaiser Permanente in Oakland.

The normal umbilical cord coil is one coil per 5 cm. Both over-coiling and undercoiling can contribute to fetal demise, difficult labor, and chronic problems such as intrauterine growth retardation, he said.

In a study published in 2000, Dr. Machin and fellow researchers found that in 1,329 cases referred to placental pathology departments, overcoiing and undercoiing were clinically correlated with fetal demise (in 37% and 29% of cases, respectively), fetal intolerance to labor (14% and 21%), intrauterine growth retardation (10% and 15%) and chorioamnionitis (10% and 29%) (Pediatr. Dev. Pathol. 3[5]:462-71, 2000).

Overcoiled cords squeeze the thinwalled umbilical vein out of shape and may cause the stroma to collapse and buckle, leading to stenosis and thrombosis. Thrombi can also embolize to the brain, resulting in damage and abnormalities such as cerebral palsy.

Undercoiled cords do not have enough osmotic pressure to keep them open and they often buckle, cutting off the umbilical vein, Dr. Machin said at the meeting.

The umbilical cord coil pattern is established in the first trimester when the fetus has adequate amniotic fluid in which to rotate. Afterward, the cord continues to grow but doesn't change its coil pattern.