A retained placenta (RP) is a serious obstetric complication defined by the failure of the placenta to completely deliver after childbirth. This organ, which provided oxygen and nutrients to the baby, must detach and exit the uterus to allow the blood vessels at the attachment site to seal off. If all or part of the placenta remains inside the uterus, it prevents the muscle from contracting fully, creating a high risk of life-threatening bleeding and infection. Immediate medical attention is required, as the timing of removal is directly linked to the mother’s safety.
Defining When Placental Retention Occurs
The clinical definition of the third stage of labor determines how long a placenta can be retained. The third stage begins immediately after the baby is born and ends when the placenta is fully expelled from the uterus. This stage is typically managed actively with medication to encourage uterine contractions.
Under active management, a retained placenta is diagnosed if the organ has not delivered within 30 minutes of the baby’s birth. This 30-minute benchmark is used because the risk of excessive blood loss, or postpartum hemorrhage (PPH), significantly increases afterward. If a patient chooses a physiological management approach without immediate medication, the time limit may be extended to 60 minutes, provided the mother is stable.
Failure to deliver the placenta within these critical timeframes indicates that the natural mechanism of separation and expulsion has failed. Prolonging the time past these limits without intervention increases the risk of severe blood loss, which is the primary danger. Although a placenta can technically be retained for hours or even days, the medical community defines the condition within the first 30 to 60 minutes to trigger immediate intervention.
Identifying the Immediate Warning Signs
The most immediate sign of a retained placenta is excessive postpartum hemorrhage (PPH), characterized by heavy vaginal bleeding that does not slow down. This bleeding often includes large blood clots as the uterus struggles to control the blood flow from the open vessels. The uterus may also feel soft and boggy, rather than firm and contracted, because the retained tissue prevents the muscle fibers from clamping down.
If a small piece of placental tissue remains undetected after delivery, symptoms can appear days or even weeks later. These delayed signs are often linked to infection or secondary hemorrhage. Symptoms of infection include a fever, abdominal pain, and a foul-smelling vaginal discharge.
The patient may also experience persistent cramping or pain as the uterus attempts to expel the remaining fragments. Heavy, bright red bleeding or a sudden rush of blood occurring 10 to 12 days postpartum is another sign of retained fragments. Any of these delayed symptoms require immediate medical evaluation, as they indicate the uterine cavity is not healing properly.
The Critical Risks and Types of Retained Placenta
The primary danger associated with a retained placenta is massive postpartum hemorrhage, which can lead to significant blood loss requiring emergency transfusions. The retained tissue acts like a physical barrier, preventing the uterus from shrinking and compressing the blood vessels. If not addressed promptly, this uncontrolled bleeding can become life-threatening.
Infection is the second major risk, particularly if the placental tissue remains for an extended period. The retained tissue serves as an ideal culture medium for bacteria, leading to endometritis (an infection of the uterine lining). This infection can progress to a systemic infection if the bacteria enter the bloodstream.
Retained placenta is categorized into three main types based on the underlying cause.
Placenta Adherens
The most common is Placenta Adherens, where uterine contractions are not strong enough to shear the placenta away from the uterine wall. The placenta remains loosely attached to the inner lining of the uterus.
Trapped Placenta
A Trapped Placenta occurs when the organ separates from the uterine wall but the cervix closes too quickly, trapping the detached placenta inside the uterus. This type of retention is caused by a mechanical obstruction rather than a failure of separation.
Placenta Accreta Spectrum
The most severe type is related to the Placenta Accreta Spectrum, where the placenta has grown too deeply into the muscular wall of the uterus. Because the tissue is abnormally embedded, it cannot detach naturally, making manual removal difficult and often resulting in severe bleeding. This condition may necessitate a hysterectomy to stop the hemorrhage and save the mother’s life.
Necessary Medical Intervention and Removal Procedures
Upon diagnosis, the first steps involve confirming the presence of retained tissue, often through a vaginal examination or ultrasound scan. Initial non-invasive attempts to encourage expulsion include emptying the bladder, which can obstruct contractions, or administering oxytocin to stimulate stronger uterine contractions. Breastfeeding may also be encouraged, as it naturally releases oxytocin and promotes uterine contraction.
If these methods fail, the primary treatment is the physical removal of the retained tissue. This is often achieved through Manual Removal of Placenta (MRP), performed by an obstetrician. The doctor inserts a hand into the uterus to detach and remove the placenta or fragments. This procedure is typically done in an operating theater with adequate pain relief, such as an epidural or spinal anesthetic, and carries a risk of infection, so prophylactic antibiotics are often given.
For a Trapped Placenta, nitroglycerin may be used to temporarily relax the cervix and lower uterine segment, allowing the trapped organ to pass. If retention is due to deeply embedded fragments or is part of the Placenta Accreta Spectrum, more extensive surgical intervention may be required. This can involve a dilation and curettage (D&C) to scrape the uterine lining or, in the most extreme cases of Accreta, an emergency hysterectomy to control bleeding.