The process of delivering the placenta is known as the third stage of labor, a phase that begins immediately after the baby is born. This stage concludes only when the placenta and its attached membranes are completely expelled from the uterus. Though often the shortest stage of labor, it involves major physiological change as the uterus must shrink significantly to prevent excessive bleeding.
The Typical Timeline and Process of Placental Delivery
For most individuals, the placenta is delivered relatively quickly, typically within 5 to 30 minutes following the baby’s arrival. Immediately after the birth, the uterus begins to contract vigorously, causing the placenta to shear away from the uterine wall. This separation initiates the process of expulsion.
The placenta can separate in one of two ways: the Schultze mechanism or the Duncan mechanism. The Schultze method, which occurs in the majority of cases, involves the placenta separating from the center first. It descends like an inverted umbrella with the fetal surface appearing first, containing the blood in a retroplacental clot and often resulting in less visible bleeding.
The alternative is the Duncan mechanism, where separation begins at the edges of the placenta. In this scenario, the placenta slides out sideways, with the maternal surface appearing first. This process is sometimes associated with more visible blood loss during delivery.
Regardless of the mechanism, healthcare providers monitor for three classic signs indicating that separation has occurred: a sudden gush of blood, the lengthening of the umbilical cord, and a change in the shape and position of the uterus.
Active Management vs. Expectant Management
The time it takes to deliver the placenta is largely influenced by the chosen approach for this third stage of labor. Care providers generally use one of two strategies: active management or expectant management. Active management is the most common approach and involves interventions designed to expedite delivery and reduce the risk of postpartum hemorrhage.
The first component of active management is the administration of a uterotonic drug, typically oxytocin, given immediately after the baby is born. This medication causes the uterus to contract strongly, helping the placenta separate quickly and aiding in closing off the blood vessels. The other components are controlled cord traction and massage of the uterine fundus after delivery. This active method can shorten the third stage considerably, often resulting in delivery within six minutes.
In contrast, expectant management, also referred to as physiological management, involves waiting for the placenta to detach and be expelled spontaneously without medical intervention. This approach typically includes delaying the clamping of the umbilical cord and relying on maternal effort and gravity. While this method is favored by some, it generally results in a longer third stage, sometimes lasting 30 minutes or more.
Understanding a Delayed or Retained Placenta
A delayed or retained placenta occurs when the organ fails to deliver completely within a set time frame, often defined as 30 minutes after birth. This is a serious complication because the failure of the placenta to separate and the uterus to contract properly leaves open blood vessels, leading to excessive bleeding. The primary danger is Postpartum Hemorrhage, a leading cause of maternal complications globally.
The failure of the placenta to deliver can stem from several underlying issues. Most commonly, this is uterine atony, where the uterine muscle loses its tone and cannot contract strongly enough. Another cause is an abnormally adherent placenta, such as in placenta accreta spectrum, where the organ has grown too deeply into the uterine wall.
When a retained placenta is diagnosed, immediate action is necessary to prevent significant blood loss. The primary intervention is manual removal of the placenta, a procedure performed by a clinician who inserts a hand into the uterus to detach and extract the organ. This procedure requires appropriate pain management. If medical interventions fail or if the bleeding is severe, procedures like uterine evacuation or the use of tamponade devices may be necessary.