Pre-delivery digital exams may increase in utero bacterial levels

June 28, 1999

Columbus, Ohio -- Digital cervical examinations during labor increase the risk of vaginal bacteria entering the cervix and the uterus and causing harm to the newborn, new research at Ohio State University suggests.

While many bacteria are harmless, increased amounts of certain bacteria may be of concern to women who have ruptured fetal membranes when they go through childbirth.

Potentially harmful bacteria may enter the ruptured membranes and cause inflammation of the sacs that surround the fetus. These bacteria, such as the infection-causing Enteroccocus species, may then be passed along to the baby during birth.

Researchers examined 35 pregnant women and found that the amounts of vaginal bacteria that have gotten into the cervix and uterus nearly doubled in 28 patients (80 percent) after a digital exam. Doctors use digital examination -- inserting a gloved finger into the vagina and cervix -- during labor to determine how much the cervix of a pregnant woman has dilated.

"Previous studies have linked digital examination and intrauterine infection, but none has shown with certainty that digital exams introduce bacteria into the cervix and uterus," said Wayne Trout, assistant professor of obstetrics and gynecology at Ohio State.

The research appears in a recent issue of the American Journal of Obstetrics and Gynecology.

The researchers studied 35 women with reported ruptured membranes who had come to the labor and delivery suite at Ohio State University Medical Center. All women were at 34 weeks' gestation or greater.

"At this point, delivery is routine in women with confirmed rupture of membranes," Trout said.

Each woman underwent a routine sterile speculum exam to diagnose the rupture of the chorion and amnion -- the sacs that encase the fetus during its development. Membranes were ruptured in 25 of the patients and intact in 10. While women with intact membranes have little reason to worry about vaginal bacteria causing an infection in the cervix or uterus, these same bacteria can cause chorioamnionitis -- the inflammation of the sacs surrounding the fetus -- in a woman with ruptured membranes. Bacteria in the amniotic fluid could be taken in by the fetus and may cause pneumonia or other diseases.

The researchers looked at cultures taken during the initial speculum exam to determine the types and amounts of bacteria residing in the cervix. Immediately after the initial speculum exam, each woman underwent a digital cervical exam, followed by a second speculum exam.

To ensure that the sterile speculum exams did not introduce bacteria into the cervix, five patients underwent two speculum exams without the intervening digital exam. "There were no increases in bacterial growth or amount of organisms in the second culture," Trout said. Unlike the digital exam, the speculum rests only in the vagina.

The number of bacteria isolated before and after the digital exam rose from an average of 2.8 different types of organisms to 4.4 different types of organisms. Twenty-one of the 25 patients with ruptured membranes and seven of the 10 patients with intact membranes had greater growth or a larger variety of organisms after the digital exams.

"Increased growth and greater numbers of isolated organisms both indicated the introduction of vaginal organisms into the cervix," Trout said.

Most of the bacteria were benign, yet several potentially pathogenic organisms were isolated from the cultures, such as Group B Streptococcus (GBS). GBS is the "number one cause of neonatal meningitis -- infection of the tissue lining of the brain," Trout said. The other potentially harmful bacteria, such as Bacteriaceae and E. coli, could cause chorioamnionitis.

Trout said he and his colleagues routinely withhold digital exams in women whose fetal membranes rupture before 34 weeks. He also warns doctors against performing digital exams in certain women who carry 34 weeks or longer.

"Doctors should not digitally examine a woman who is both close to her delivery date and has ruptured membranes," he said.
-end-
Trout co-authored this study with Hytham Imseis, now in private practice in Asheville, N.C., and Steven Gabbe, now a professor and chair of the department of obstetrics and gynecology at the University of Washington in Seattle.

Contact: Wayne Trout, 614-293-8000; Trout.2@osu.edu
Written by Holly Wagner, 614-292-8310; Wagner.235@osu.edu

Ohio State University

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