gynecology and obstetrics
Fetal Presentation, Position, and Lie (Including Breech Presentation)
Breech presentation
There are several types of breech presentation. Frank breech:The fetal hips are flexed, and the knees extended (pike position). Complete breech:The fetus seems to be sitting with hips and knees flexed. Single or double footling presentation:One or both legs are completely extended and present before the buttocks. Breech presentation makes delivery difficult ,primarily because the presenting part is a poor dilating wedge. Having a poor dilating wedge can lead to incomplete cervical dilation, because the presenting part is narrower than the head that follows. The head, which is the part with the largest diameter, can then be trapped during delivery. Additionally, the trapped fetal head can compress the umbilical cord if the fetal umbilicus is visible at the introitus, particularly in primiparas whose pelvic tissues have not been dilated by previous deliveries. Umbilical cord compression may cause fetal hypoxemia. Predisposing factorsfor breech presentation include Preterm Labor None Multifetal Pregnancy None Uterine abnormalities Fetal anomalies If delivery is vaginal, breech presentation may increase risk of Umbilical cord prolapse Birth Injuries None Perinatal death It is best to detect abnormal fetal lie or presentation before delivery. During routine prenatal care, clinicians assess fetal lie and presentation with physical examination in the late third trimester. Ultrasonography can also be done. If breech presentation is detected, external cephalic version can sometimes move the fetus to vertex presentation before labor, usually at 37 or 38 weeks. This technique involves gently pressing on the maternal abdomen to reposition the fetus. A dose of a short-acting tocolytic (terbutaline0.25 mg subcutaneously) may help. The success rate is about 50 to 75%. For persistent abnormal lie or presentation, cesarean delivery is usually done at 39 weeks or when the woman presents in labor. 