NEW YORK (Reuters Health) – Pregnant women who’ve had abnormal cervical tissue removed with a loop electrosurgical procedure (LEEP) are not at increased risk for preterm delivery, a retrospective study suggests.
The 2006 consensus guidelines for management of cervical intraepithelial neoplasia (CIN) indicate that this procedure does increase the risk for adverse pregnancy outcomes. And the 2009 guideline for cervical cytology screening has cut back and delayed the recommended schedule, partly to avoid unnecessary interventions that could be harmful. (See Reuters Health report of November 20, 2009.)
However, researchers at the University of Texas Southwestern Medical Center in Dallas question whether “characteristics intrinsic to the woman undergoing LEEP might be associated with the adverse pregnancy effects rather than the procedure itself.”
Their study population included 241,701 women, all with singleton pregnancies, who gave birth at Parkland Hospital between 1992 and 2008. Five hundred eleven had LEEP before the index pregnancy and 842 had LEEP after the pregnancy. The mean interval from LEEP to subsequent pregnancy was 113 weeks, but 11% had an interval of no more than 90 days.
Lead author Dr. Claudia L. Werner and co-investigators note that clinicians did not modify prenatal care or surveillance for patients with a history of LEEP.
In the March issue of Obstetrics and Gynecology, the researchers report that the proportion of women delivering at 36 weeks or less was 7% in the general population, 7% among women who had LEEP prior to the pregnancy, and 9% among those who had LEEP after the pregnancy (p = ns). There was also no significant association between LEEP and perinatal mortality.
Recent studies on this topic have had conflicting results, Dr. Werner’s team points out. Two of three meta-analyses published between 2003 and 2008 suggest that LEEP does increase the risk of preterm birth.
The authors note that their study did not include information on potential confounders, such as substance use or prior preterm births, or data on LEEP depth, amount of excised tissue, or the degree of neoplasia.
They conclude, “LEEP cannot definitively be implicated as a cause of preterm birth.”
“I think the risk of premature birth is related more to the reasons that women get abnormal pap smears that lead to LEEP,” Dr. Jay Iams, an obstetrician at Ohio State University in Columbus, told Reuters Health. He explained that LEEP is performed to treat CIN that is often related to sexually transmitted viral infections, such as human papillomavirus. “People with these infections also have an increased risk for preterm birth.”
For women who’ve had any cervical procedure, Dr. Iams provides no extra surveillance other than using “ultrasound to check their cervix once or twice before 22 weeks’ gestation.”
Dr. Alan G. Waxman of the University of New Mexico, Albuquerque, who headed up the committee that developed the 2009 American College of Obstetrics and Gynecology guidelines, told Reuters Health that almost all the literature after 2003 shows an increased risk of preterm birth associated with LEEP.
“That’s why we recommend conservative surveillance for younger women,” he said. “But I’m delighted that Dr. Werner’s group is adding more evidence to what is a growing body of knowledge.”
According to Dr. Waxman, “some studies show that the extent of LEEP makes a difference, especially if it is a centimeter or more in depth,” which may account for the research team’s findings. “There may also be population differences.”
He advises that physicians should “be cognizant that most literature does show increased risk of preterm birth and should take that into account when weighing the risks and benefits of doing excision procedures.”
Obstet Gynecol 2010;115:605-608.