NEW YORK (Reuters Health) – Training delivery ward personnel in manual assistance techniques in the crowning stage of labor significantly decreases the occurrence of anal sphincter tears, a Norwegian interventional program shows.

The researchers note in the October issue of Obstetrics & Gynecology that there has been a gradual increase in the incidence of obstetric anal sphincter tears over the past 40 years in Norway.

“Our nationwide project shows that it is possible to reverse the rising trend of anal sphincter tears in the noninstrumental as well as in the instrumental deliveries,” Dr. Jouko Pirhonen told Reuters Health by email. “You have to make small changes in (previous) clinical practice during the last stage of delivery. This does not cost anything but the change in attitudes is not easy because the increment of tears has taken several decades.”

Dr. Pirhonen, with the University Hospital of North Norway in Tromso, and colleagues conducted an interventional study with four hospitals to see if it could be expanded to multiple centers.

Labor ward staff — nurses, midwives and physicians — had to attend 2 or 3 days of tutorials focusing on four factors: communication between the delivering woman and the birth assistants, perineal support, a delivery position allowing visualization of the perineum, and indications for episiotomy. “Generally, the physicians had an easier time to accept the need for improvement than midwives did,” Dr. Pirhonen commented.

The aim was “to reintroduce the midwives and doctors to the traditional method of assisting delivery of the neonate during the final part (crowning) of the second stage of delivery, a procedure commonly used in Norway before the 1980s.” the authors explain.

“The manual support of perineum described in the present article is the most important factor in aim to decrease the number of tears,” Dr. Pirhonen pointed out.

The procedure involves the birth assistant pressing the head of the neonate to control the speed of crowning, while supporting the perineum with the other hand. Then, when the neonate’s chin can be grasped, the head is slowly eased through the vaginal introitus until the perineal ring can finally be pushed under the neonate’s chin.

The rate of anal sphincter tears at the four centers decreased from 4-5% to 1-2% over the course of the study. Of note, the rate of grade 4 tears decreased by 63.5%.

The frequency of episiotomy increased in two hospitals but remained unchanged in the other two. “If the physicians and midwives use an adequate type of episiotomy just on indication, the incidence of sphincter tears will further decrease,” Dr. Pirhonen said.

The authors conclude, “As a result of our project, the number of anal sphincter ruptures in participating delivery clinics is now close to the levels seen during the late 1960s. Therefore, we advise other hospitals to introduce an interventional program as described here aimed at reducing the morbidity of this serious complication of vaginal delivery.”

Obstet Gynecol 2010;116:901-908.