Retained Products of Conception (RPOC) describes the presence of placental or fetal tissue that remains inside the uterus following the conclusion of a pregnancy. This can occur after a spontaneous miscarriage, a medically or surgically induced termination of pregnancy, or a full-term delivery. The continued presence of this tissue in the uterine cavity interferes with the body’s natural recovery process and can lead to complications requiring medical attention.
The Mechanism and Causes of Retained Tissue
The underlying cause of RPOC is the failure of the uterus to complete the process of tissue expulsion after the pregnancy ends. Normally, the muscular wall of the uterus contracts forcefully to detach and push out all contents, including the placenta and membranes. RPOC occurs when these contractions are insufficient or when the tissue is abnormally adhered to the uterine wall, leaving remnants behind.
RPOC occurs in three main contexts. The most common is following an incomplete miscarriage or spontaneous abortion, where the body does not fully expel the non-viable pregnancy tissue. The risk of RPOC is higher after second-trimester miscarriages compared to those in the first trimester.
The condition is also seen after medical or surgical termination of pregnancy, where a small amount of tissue can persist despite the procedure. Following a full-term delivery, RPOC involves the failure of the placenta to detach completely during the third stage of labor. A serious risk factor in this context is Placenta Accreta, where the placenta has grown too deeply into the uterine wall, making complete spontaneous separation impossible.
Risk factors for RPOC include advanced maternal age, a history of uterine scarring from previous surgeries like Cesarean sections or Dilation and Curettage (D&C), and certain placental abnormalities. The retained tissue acts as a foreign body, preventing the uterus from returning to its normal, non-pregnant state. This tissue can also become a site for bacterial growth, increasing the risk of infection.
Recognizing the Signs and Symptoms
The primary indication of RPOC is abnormal or persistent vaginal bleeding. While some bleeding is expected after any pregnancy event, RPOC-related bleeding is heavier than normal or continues long past the expected timeframe, sometimes lasting for weeks. This bleeding may include large blood clots and can lead to anemia due to significant blood loss.
Another common sign is persistent or worsening pelvic pain and cramping. The uterus attempts to contract to expel the retained tissue, causing discomfort that is often more intense than typical post-pregnancy or post-miscarriage cramping. This pain may feel like severe menstrual cramps or a constant ache in the lower abdomen.
Signs of infection, such as fever or chills, require immediate medical evaluation. Retained tissue can become infected, leading to endometritis, which is an infection of the uterine lining. An accompanying sign of this infection is a foul-smelling or unusually colored vaginal discharge.
Diagnostic Confirmation
When a patient presents with suggestive symptoms, medical professionals use specific diagnostic tools to confirm the presence of retained tissue. The diagnostic process begins with a physical examination and a review of the patient’s recent history, noting the timing and nature of the bleeding and pain. This initial assessment helps guide subsequent testing.
The primary diagnostic tool is the Transvaginal Ultrasound (TVUS), which provides detailed imaging of the uterine cavity. RPOC is suggested by the visualization of an echogenic or heterogeneous mass—tissue that appears brighter or mixed in texture—within the endometrial lining. While a thickened endometrial lining greater than 15 millimeters can raise suspicion, a distinct mass is a stronger indicator.
Blood tests play a supportive role, particularly monitoring the levels of human chorionic gonadotropin (hCG). This hormone is produced by placental tissue, and its failure to decline appropriately after the end of a pregnancy suggests that active tissue remains in the uterus. Doppler flow studies are sometimes used alongside TVUS to assess blood flow within the suspected mass.
Vascularity within the tissue mass on a Doppler study strongly supports the diagnosis of RPOC rather than a simple blood clot, which is avascular. This distinction is important because it helps the medical team differentiate retained tissue from normal post-pregnancy changes or blood clots, which often do not require intervention.
Treatment Pathways
The management of RPOC is tailored to the amount of retained tissue, the patient’s clinical stability, and the presence of infection. When the amount of retained tissue is small and the patient is clinically stable with minimal bleeding, Expectant Management may be appropriate. This approach involves watchful waiting, allowing the body a chance to expel the tissue naturally, often with serial monitoring via ultrasound.
Medical Management uses medications to stimulate uterine contractions and facilitate tissue expulsion. The drug misoprostol, a uterotonic agent, is commonly prescribed to help the cervix soften and the uterus contract rhythmically. This approach is often successful for managing smaller amounts of tissue and is preferred as a less invasive alternative to surgery.
Medical management may be less effective for larger tissue remnants or when the tissue is densely attached. It also carries the possibility of side effects like cramping, nausea, or heavy bleeding during expulsion. If medical management fails, or if the patient is experiencing heavy bleeding or signs of infection, Surgical Management is recommended.
The most common surgical procedure is Dilation and Curettage (D&C) or Suction Curettage, sometimes referred to as Evacuation of Retained Products of Conception (ERPC). The procedure involves gently widening the cervix and using a suction device or a curette to physically remove the tissue from the uterine lining. This offers the advantage of immediate and complete removal, which is important in cases of significant hemorrhage or active infection.
While D&C is highly effective, it carries risks, including uterine perforation, infection, or the formation of intrauterine scar tissue, known as Asherman syndrome. The risk of Asherman syndrome is related to the depth of the tissue removal and can impact future fertility. Newer techniques like hysteroscopic removal allow the retained tissue to be visualized and removed directly, potentially reducing the risk of damage to the surrounding healthy uterine lining.