Duncan's Method

DUNCAN'S METHOD (Duncan), separation of the placenta from the uterine wall, described by Duncan in 1875. With this method, no retroplacental hematoma forms, as separation begins at the lower edge and is accompanied by the outward discharge of blood. After separating, the placenta descends into the vagina with its lower edge. The membranes maintain their normal position, i.e., the placenta does not turn inside out. The question of which method occurs more frequently—Schultze's or Duncan's—was vigorously debated by obstetricians. Since the placenta could change its position while passing through the vagina, a number of authors (including Duncan himself) attempted to resolve this question by performing an internal examination immediately after delivery; others, by exposing the cervix with specula, observed which part of the placenta first appeared at the external os. It turns out that a placenta that has separated in the uterus according to Duncan's method often changes its position in the vagina: the membranes extending from the lower edge of the placenta, due to their stronger attachment, are held back, and the placenta begins to turn inside out in the vagina; ultimately, having separated according to Duncan's method, the afterbirth exits the vagina with its firm side forward, thereby simulating Schultze's method. Most obstetricians adhere to the view that both methods—Schultze's and Duncan's—are normal. It is accepted that the decisive factor is the site of placental attachment, namely: with low attachment, Duncan's method is more frequently observed, while with attachment in the fundus, Schultze's method occurs. In recent times, the question has been further studied with the aid of X-rays. Wamekros, by injecting the placenta through the umbilical cord immediately after delivery, took a series of photographs on which both methods of separation could be observed; in the majority of cases, separation still occurred according to Duncan's method: in the vagina, the placenta often changed its position.