Chronic Inflammation in Preterm PROM May Lead to Cell Death in the Chorion

OB/GYN News, Oct 15, 1999 by Mitchel L. Zoler

TORONTO -- Destruction of the chorion in women who are diagnosed with preterm premature rupture of membranes and chorioamnionitis may be due to cell death triggered by inflammation.

A natural process of cell death, apoptosis, was more common in the chorion laeve of women with chorioamnionitis than in chorions taken from control women without chorioamnionitis, Dr. Amy P. Murtha reported at the annual meeting of the Infectious Diseases Society for Obstetrics and Gynecology

"Women with preterm premature rupture of membranes [PROM] may have a chronic inflammatory response that leads to cell death in the chorion and preterm labor," suggested Dr. Murtha, who is a maternal-fetal medicine physician at Duke University in Durham, N.C.

To test this hypothesis, fetal membrane specimens were obtained from 29 women who were diagnosed with preterm PROM.

The specimens were fixed with formalin, embedded in paraffin, and examined histologically for chorioamnionitis. The specimens were also analyzed using a specific staining technique to flag cells that had undergone apoptosis.

Twenty of the membrane specimens showed evidence of chorioamnionitis and contained an average of 3.5% apoptotic nuclei.

The other nine specimens had no evidence of chorioamnionitis and contained a mean of 1.9% apoptotic nuclei, a statistically significant difference, Dr. Murtha said at the meeting, which was also sponsored by the American College of Obstetricians and Gynecologists.

"We conclude that apoptosis is accelerated in the chorion laeve of women with preterm PROM and histologic chorioamnionitis," she said.

Fetal membrane specimens were taken from another 18 women with preterm PROM but were excluded from the main analysis because these women lacked a chorion laeve.

Of these specimens, 16 (89%) showed histologic evidence of moderate or severe chorioamnionitis, she said at the meeting.

Although the amnion was intact in these 16 specimens, "the chorion was destroyed and replaced by inflammatory cells," she said.

"This supports the hypothesis that inflammation accelerates cell death, either by apoptosis or necrosis, and destroys the chorion laeve," Dr. Murtha said.