Retained Placenta: A Clinical Review and Supportive Information for Maternal Health

Abstract

Retained placenta, a postnatal complication wherein the placenta is not expelled from the uterus within the expected time frame after childbirth, presents significant risks to maternal health. This condition, although relatively uncommon, requires prompt recognition and intervention to prevent serious outcomes such as postpartum haemorrhage, infection, and future fertility issues. The causes are multifactorial and may include uterine atony, abnormal placental adherence such as placenta accreta spectrum disorders, or a trapped placenta due to cervical constriction. Complications can be immediate or delayed, with long-term effects on reproductive and overall maternal health. Management strategies range from pharmacological interventions and manual removal to surgical procedures like dilation and curettage (D&C), each with its own potential complications. This paper aims to provide an overview of the causes, complications, and current clinical approaches to the management of retained placenta. Additionally, it explores emerging concerns regarding overlooked or underdiagnosed secondary complications. By raising awareness among healthcare providers and informing patients, this review supports timely diagnosis, appropriate management, and better outcomes for affected individuals.

Key Terms and Definitions

• Retained Placenta
  A clinical condition in which the placenta or fragments of placental tissue remain within the uterus beyond 30 minutes after the delivery of the baby. It is a recognised obstetric emergency that may result in significant maternal morbidity if not managed promptly.
• Placenta Accreta Spectrum (PAS) Disorders
  A group of conditions characterised by abnormal adherence of the placenta to the uterine wall. It includes:

• Placenta accreta: the placenta attaches too deeply to the uterine wall without penetrating the muscle.
• Placenta increta: the placenta invades the uterine muscle.
• Placenta percreta: the placenta penetrates through the entire uterine wall and may attach to surrounding organs.
• Uterine Atony
  A failure of the uterus to contract effectively after delivery, which can contribute to the retention of the placenta and is a leading cause of postpartum haemorrhage.
• Trapped Placenta
  A condition where the placenta detaches from the uterine wall but cannot be expelled due to closure or constriction of the cervix.
• Manual Removal of Placenta (MROP)
  A medical procedure where the placenta is physically removed by hand, usually under anaesthesia, when it fails to deliver spontaneously.
• Postpartum Haemorrhage (PPH)
  Excessive bleeding following childbirth, typically defined as blood loss of more than 500ml after vaginal delivery or more than 1000ml after caesarean section. Retained placenta is a significant contributor to PPH.
• Dilation and Curettage (D&C)
  A surgical procedure involving the dilation of the cervix and the removal of tissue from the uterine lining. It is sometimes employed when manual removal is incomplete or unsuccessful.
• Uterotonic Agents
  Medications, such as oxytocin or misoprostol, used to stimulate uterine contractions in order to facilitate placental expulsion or control bleeding.
• Endometritis
  An infection of the uterine lining, which can occur as a complication of retained placenta, particularly if placental fragments are left in situ.
• Fertility Implications
  Potential impacts on future reproductive health, including increased risk of abnormal placentation in subsequent pregnancies or uterine scarring from surgical interventions.

Introduction

The third stage of labour, involving the delivery of the placenta following the birth of the baby, is a critical period requiring close clinical observation and timely intervention. In typical cases, the placenta separates from the uterine wall and is expelled within 30 minutes. However, when this process fails, the condition is termed a retained placenta, an obstetric complication that can lead to life-threatening outcomes if not promptly addressed.

The incidence of retained placenta varies globally, with higher prevalence reported in settings with limited access to skilled birth attendants and emergency obstetric care. In the United Kingdom, retained placenta affects approximately 2–3% of vaginal deliveries, although incidence rates may be higher among certain risk groups, including women with a history of caesarean section, uterine surgery, or previous retained placenta.

Several underlying causes have been identified, including uterine atony, abnormal placental adherence such as placenta accreta spectrum (PAS) disorders, and mechanical obstruction such as a trapped placenta. While many cases are resolved with pharmacological or manual intervention, others may necessitate surgical procedures, each carrying associated risks and long-term implications.

Despite advancements in obstetric care, retained placenta remains a significant contributor to postpartum haemorrhage (PPH), maternal infection, and, in severe cases, maternal mortality. Furthermore, delayed or improper management can lead to chronic reproductive complications, emotional distress, and increased healthcare utilisation.

This paper aims to provide a comprehensive analysis of retained placenta, examining its causes, immediate and delayed complications, and available management strategies. It also addresses lesser-known or under-recognised outcomes, offering guidance for improved clinical decision-making and patient support. Through a balanced synthesis of current clinical guidelines and evidence-based practice, this review aspires to equip both healthcare professionals and affected individuals with the knowledge necessary to ensure safer childbirth experiences.

Aetiology and Risk Factors

The aetiology of retained placenta is multifactorial, encompassing both physiological and pathological mechanisms that prevent complete separation and expulsion of the placenta following childbirth. Understanding these underlying causes is essential for timely diagnosis, risk stratification, and appropriate clinical intervention. Broadly, retained placenta can be classified into three principal types, each associated with distinct aetiological features and risk profiles:

1. Placenta Adherens

This occurs when the uterus fails to contract sufficiently during the third stage of labour, resulting in the placenta remaining loosely attached to the uterine wall. Uterine atony—the inability of the uterus to contract effectively—is the most common cause of placenta adherens. This condition may be transient or associated with uterine fatigue following prolonged labour, induction of labour, or overdistension of the uterus due to multiple gestation or polyhydramnios.

2. Trapped Placenta

A trapped placenta arises when the placenta has completely separated from the uterine wall but fails to exit the uterus due to mechanical obstruction. Common causes include closure of the cervix before expulsion or cervical constriction due to inappropriate use of uterotonic agents such as oxytocin. Trapped placenta may also result from anatomical anomalies or scarring of the cervix following previous obstetric or gynaecological procedures.

3. Placenta Accreta Spectrum (PAS) Disorders

In PAS disorders, the placenta abnormally adheres to or invades the uterine wall, preventing normal separation. This spectrum includes:

• Placenta accreta: Superficial attachment to the myometrium
• Placenta increta: Deeper invasion into the myometrium
• Placenta percreta: Infiltration through the uterine wall, potentially involving adjacent organs (e.g., bladder)

These conditions are often associated with uterine scarring, most commonly from prior caesarean section, myomectomy, or dilation and curettage procedures.

Additional Contributing Risk Factors

Several maternal, obstetric, and iatrogenic factors have been implicated in the increased risk of retained placenta. These include:

• Previous Retained Placenta: Strong predictor of recurrence in subsequent deliveries
• Advanced Maternal Age: Women over the age of 35 are at increased risk
• Preterm Delivery/Premature Birth: Higher likelihood of incomplete placental separation
• Induced or Augmented Labour: Use of prostaglandins and oxytocin may affect natural expulsion
• Prolonged Third Stage of Labour: Greater than 30 minutes without placental delivery increases the risk of complications
• Multiparity: Repeated stretching and thinning of the uterine wall may affect contractility
• Chorioamnionitis: Intrauterine infection can compromise placental separation
• Placental Abnormalities: Accessory lobes, velamentous cord insertion, or succenturiate lobes may complicate delivery
• Obesity and High Body Mass Index (BMI): Associated with altered hormonal milieu and increased obstetric risk

Early identification of these risk factors during antenatal care enables pre-emptive planning, including active management of the third stage of labour and access to emergency obstetric support where needed.

Detailed Analysis of Complications

The retention of placental tissue following childbirth poses both immediate and delayed threats to maternal health, necessitating a comprehensive understanding of its multifaceted complications. These complications can be classified temporally into acute (immediate) and chronic (delayed or hidden) sequelae, each associated with varying degrees of morbidity and long-term reproductive impact.

1. Immediate Complications

a. Postpartum Haemorrhage (PPH)
Postpartum haemorrhage is the most common and life-threatening immediate consequence of retained placenta. It is defined as blood loss exceeding 500 mL after vaginal delivery or 1,000 mL after caesarean section. Retained placental fragments impede effective uterine contraction, thereby contributing to uterine atony and subsequent haemorrhage. If not managed promptly with uterotonics, uterine massage, or surgical intervention, PPH may progress to hypovolaemic shock, disseminated intravascular coagulation (DIC), multiorgan failure, and maternal death.

b. Endometritis and Sepsis
The persistence of necrotic placental tissue within the uterine cavity provides a fertile medium for bacterial proliferation. This can result in endometritis, characterised by uterine tenderness, fever, offensive lochia, and elevated inflammatory markers. In severe cases, infection may ascend to systemic circulation, culminating in puerperal sepsis, which remains a leading cause of maternal morbidity and mortality globally. Progression to septic shock requires aggressive antibiotic therapy, fluid resuscitation, and, in some cases, critical care support.

2. Delayed and Hidden Complications

a. Asherman’s Syndrome
Asherman’s Syndrome, or intrauterine adhesions, may develop following surgical evacuation procedures such as dilation and curettage (D&C) used to manage retained placental fragments. The resulting endometrial scarring can disrupt normal menstruation (hypomenorrhoea or amenorrhoea), cause chronic pelvic pain, and lead to infertility or recurrent pregnancy loss. Hysteroscopic adhesiolysis is often required for diagnosis and treatment.

b. Secondary Postpartum Haemorrhage
Secondary or late-onset postpartum haemorrhage typically occurs between 24 hours and 6 weeks postpartum. It often results from residual placental tissue acting as a nidus for infection or interfering with uterine involution. Women may present with prolonged vaginal bleeding, anaemia, or signs of systemic infection. Diagnosis may be confirmed through pelvic ultrasonography, and management includes antibiotics and surgical evacuation when necessary.

c. Future Obstetric Complications
Women with a history of retained placenta are at significantly increased risk of recurrence in subsequent pregnancies. Furthermore, surgical interventions to remove retained tissue may predispose to abnormal placental implantation disorders, particularly placenta accreta spectrum (PAS). The incidence of PAS is markedly higher in women with prior uterine surgery, and such conditions often necessitate complex obstetric care, including planned caesarean hysterectomy to control haemorrhage.

d. Psychological and Emotional Sequelae
While often under-recognised, the psychological burden of complications arising from retained placenta should not be overlooked. Women may experience postpartum depression, anxiety, or post-traumatic stress, particularly in the context of emergency interventions or maternal-infant separation during recovery. Multidisciplinary follow-up and mental health support are recommended components of holistic postpartum care.

Management and Treatment Approaches

The effective management of retained placenta and its associated complications necessitates a stratified and evidence-based approach. Treatment modalities are determined by the type and extent of placental retention, the haemodynamic status of the patient, and the presence of complications such as haemorrhage or infection. Management typically falls into two categories: medical therapy and procedural or surgical intervention. Each modality carries potential risks and complications which must be judiciously weighed against anticipated benefits.

1. Medical Management

a. Uterotonic Agents (e.g., Oxytocin, Misoprostol)
Uterotonic medications represent the cornerstone of first-line medical management in cases of retained placenta, with the primary objective of stimulating sustained and effective uterine contractions to promote placental separation and expulsion.

• Oxytocin is typically administered via intravenous or intramuscular routes, initiating myometrial contractility and promoting haemostasis.
• Misoprostol, a synthetic prostaglandin E1 analogue, may be delivered orally, sublingually, or rectally to augment uterine tone and reduce the risk of haemorrhage.

Associated Complications and Adverse Effects of Oxytocin and Misoprostol Drugs:

• Uterine Hyperstimulation (Tachysystole): Excessive or uncoordinated contractions may result in uterine rupture, especially in women with prior uterine surgery.
• Cardiovascular Stress: Tachycardia, hypotension, or chest discomfort may occur in predisposed individuals.
• Gastrointestinal Reactions: Misoprostol is frequently associated with nausea, vomiting, diarrhoea, and abdominal cramping.
• Febrile Response: Transient pyrexia, chills, and shivering are common misoprostol-related side effects.
• Incomplete Expulsion: Despite adequate contraction, placental remnants may persist, necessitating surgical intervention.

b. Nitroglycerin Administration
Sublingual or intravenous nitroglycerin may be employed in specific clinical scenarios where the placenta becomes trapped behind a constricted internal cervical os or in cases of uterine entrapment. The drug acts as a smooth muscle relaxant, facilitating manual or spontaneous placental delivery by reducing uterine and cervical tone.

Associated Complications and Adverse Effects:

• Profound Hypotension: Vasodilation may lead to abrupt and significant blood pressure reduction, compromising maternal perfusion.
• Reflex Tachycardia: A compensatory response to hypotension, which may exacerbate cardiac strain.
• Neurological Symptoms: Headache, dizziness, and flushing are frequent due to cerebral vasodilation.
• Syncope or Collapse: Rare but dangerous in haemodynamically unstable patients.

c. Antibiotic Therapy
The use of broad-spectrum antibiotics—whether prophylactically or therapeutically—is crucial in preventing or managing infectious complications associated with retained placental tissue, particularly following manual or surgical evacuation.

Associated Complications and Adverse Effects:

• Antibiotic Resistance: Overuse or inappropriate empirical selection may contribute to resistant microbial strains.
• Gastrointestinal Disturbances: Nausea, diarrhoea, and abdominal discomfort are common, particularly with broad-spectrum regimens.
• Allergic Reactions: Ranging from mild rash to anaphylaxis; necessitates thorough allergy screening.
• Clostridium difficile Infection: A serious healthcare-associated infection that may result in pseudomembranous colitis, requiring targeted therapy.
• Masking of Sepsis: Inadequate or indiscriminate use without clinical monitoring may obscure signs of systemic infection, delaying definitive intervention.

2. Manual and Surgical Interventions

In cases where medical management is insufficient or unsuccessful in facilitating placental expulsion, manual or surgical interventions are indicated. These approaches require expert clinical judgement and are performed under appropriate anaesthesia to minimise discomfort and complications. The goal is to ensure complete placental removal, control postpartum haemorrhage, and prevent infection.

a. Manual Removal of Placenta (MROP)
Manual removal of the placenta is typically performed when there is a failure of spontaneous placental expulsion or when pharmacological agents are ineffective. This procedure involves the operator manually detaching the placenta from the uterine wall under anaesthesia, generally performed in a controlled environment such as an operating theatre.

Associated Complications and Adverse Effects:

• Uterine Perforation: In rare cases, aggressive or poorly executed manual removal may result in uterine perforation, leading to severe bleeding or damage to the uterine wall.
• Infection Risk: Manual removal significantly increases the risk of introducing bacterial pathogens into the uterine cavity, leading to endometritis or more severe pelvic infections.
• Postpartum Haemorrhage: Despite being a method of placental expulsion, the manual approach can inadvertently damage the uterine vessels, contributing to significant haemorrhage.
• Emotional Trauma: Given the invasive nature of the procedure, patients may experience psychological distress or trauma, particularly if informed consent and emotional support are inadequate.

b. Dilation and Curettage (D&C)
D&C is a surgical procedure used to remove remaining placental tissue or fragments from the uterine cavity. It involves dilating the cervix and scraping the uterine lining with a curette. D&C is typically performed under general or regional anaesthesia.

Associated Complications and Adverse Effects:

• Uterine Perforation and Injury: Similar to manual removal, D&C carries a risk of perforating the uterine wall, potentially causing organ damage.
• Cervical Laceration: The procedure requires cervical dilation, which may result in lacerations, particularly in women with a history of cervical trauma or difficult deliveries.
• Infection and Sepsis: Introduction of pathogens during the procedure may lead to pelvic infections, endometritis, or more severe sepsis if not promptly treated.
• Asherman’s Syndrome: The mechanical action of D&C can cause scarring of the endometrial lining, increasing the risk of intrauterine adhesions and subsequent menstrual irregularities or infertility.
• Increased Risk of Future Placental Abnormalities: Women who undergo multiple D&Cs may experience an elevated risk of placental abnormalities in future pregnancies, such as placenta accreta.

c. Hysteroscopy
Hysteroscopy is a minimally invasive procedure that uses a thin, flexible telescope (hysteroscope) to visualise the uterine cavity. It can be performed to remove retained placental fragments or to assess the uterine cavity for any abnormalities following childbirth.

Associated Complications and Adverse Effects:

• Uterine Perforation: Though less common than in D&C, uterine perforation remains a risk, especially when navigating the uterine cavity.
• Infection: As with any invasive procedure, hysteroscopy can introduce infections if aseptic technique is not rigorously maintained.
• Fluid Imbalance: In cases where the procedure involves the infusion of fluids into the uterine cavity (e.g., saline or glycine), there is a risk of fluid overload, particularly if excessive amounts are absorbed into the bloodstream, potentially leading to water intoxication or electrolyte imbalance.
• Failed Tissue Removal: Although less invasive than D&C, hysteroscopy may fail to remove all retained tissue, necessitating further surgical intervention.

d. Hysterectomy
Hysterectomy, the surgical removal of the uterus, is considered a last-resort intervention for cases where placenta accreta, percreta, or increta (abnormal placental attachment) occurs, particularly when there is uncontrolled haemorrhage. It is typically reserved for cases where the placenta cannot be safely removed, and bleeding cannot be controlled by other methods.

Associated Complications and Adverse Effects:

• Haemorrhage: The most significant risk during hysterectomy is severe bleeding, requiring transfusion or the use of haemostatic agents.
• Infection: Postoperative infections such as pelvic abscesses or endometritis are possible, particularly if proper sterile techniques are not employed.
• Organ Injury: The procedure may inadvertently damage nearby organs, including the bladder, ureters, or intestines, especially in the presence of extensive adhesions.
• Anaesthesia Complications: As with any major surgery, risks associated with anaesthesia include respiratory or cardiac complications, particularly in high-risk individuals.
• Psychological Impact: The irreversible nature of hysterectomy can lead to significant psychological distress, particularly for women who wish to retain their fertility. Psychological support and counselling are critical following this intervention.
• Long-term Recovery and Morbidity: Recovery from hysterectomy is prolonged, and women may experience physical and emotional challenges, particularly related to the loss of reproductive function.

These interventions, while crucial in managing retained placenta, carry inherent risks that must be carefully balanced against the need for effective placental expulsion. The clinical decision-making process should involve shared decision-making, comprehensive counselling, and continuous post-procedural monitoring to mitigate complications and promote recovery.

Hidden Complications and Long-Term Effects

While immediate clinical interventions for retained placenta are often successful, there exists a significant risk of under-recognised and delayed sequelae which may impact the individual’s physical, reproductive, and psychological wellbeing. These consequences frequently go unaddressed due to their insidious onset or misattribution to unrelated postpartum changes, thus necessitating careful monitoring and holistic postnatal care.

1. Chronic Pelvic Pain

Persistent pelvic discomfort following retained placenta may be attributed to intrauterine adhesions, unresolved infection, or scarring from surgical procedures such as dilation and curettage (D&C). Chronic pain may interfere with daily functioning, sexual health, and quality of life.

• Pathophysiology: Nerve sensitisation, pelvic floor dysfunction, and uterine scarring.
• Clinical Implication: May require multidisciplinary management, including physiotherapy, analgesia, and in some cases, surgical intervention.

2. Menstrual Irregularities and Fertility Concerns

Disruption of the endometrial lining and subsequent development of intrauterine adhesions (Asherman’s Syndrome) can lead to irregular or absent menstruation (oligomenorrhoea or amenorrhoea) and compromised fertility.

• Mechanism: Post-surgical damage or infection impairs the normal regenerative process of the endometrium.
• Long-Term Consequences: Subfertility or infertility, increased risk of abnormal placentation in future pregnancies (e.g., placenta previa or accreta spectrum disorders).

3. Psychological Distress

The emotional impact of a traumatic childbirth experience compounded by retained placenta and its management can have profound psychological consequences. Individuals may develop:

• Postpartum Depression: Feelings of sadness, hopelessness, and detachment, potentially impairing maternal-infant bonding.
• Postpartum Anxiety: Excessive worry, panic attacks, and difficulty sleeping or relaxing.
• Post-Traumatic Stress Disorder (PTSD): Re-experiencing the traumatic event, avoidance behaviours, and hyperarousal.
• Contributing Factors: Emergency interventions, pain, fear of mortality, and inadequate postnatal psychological support.
• Recommendations: Early psychological screening, referral to perinatal mental health services, and access to counselling and peer support networks.

These hidden complications necessitate an integrated model of postpartum care that extends beyond immediate clinical management, encompassing long-term surveillance, reproductive health support, and psychological wellbeing. This ensures a comprehensive recovery trajectory for the birthing individual and safeguards future maternal health.

Recommendations for Clinical Practice and Prevention

To ensure optimal maternal outcomes and mitigate both immediate and long-term sequelae associated with retained placenta, a structured, multidisciplinary, and anticipatory approach to prevention, diagnosis, and management is imperative. The following recommendations are proposed based on current clinical evidence, international guidelines, and best practice standards.

1. Antenatal Risk Stratification and Preparedness

• Comprehensive Obstetric History: Early identification of women at increased risk—such as those with prior retained placenta, caesarean section, uterine anomalies, or assisted conception—should prompt individualised birth planning.
• Enhanced Monitoring in High-Risk Pregnancies: Intrapartum planning should include readiness for active management of the third stage of labour, availability of surgical facilities, and multidisciplinary team coordination.

2. Skilled Management of the Third Stage of Labour

• Active Management Protocols: Administration of uterotonic agents (e.g., oxytocin) immediately following delivery significantly reduces the incidence of retained placenta and postpartum haemorrhage.
• Time-Conscious Assessment: A placenta not expelled within 30 minutes postpartum should trigger immediate evaluation and potential escalation to manual or surgical removal, in accordance with NICE guidelines.

3. Prompt Intervention and Evidence-Based Management

• Medical Therapies: Where clinically appropriate, initiate pharmacological agents (oxytocin, misoprostol, nitroglycerin) to facilitate uterine contraction and cervical relaxation, thereby avoiding unnecessary surgical intervention.
• Manual and Surgical Techniques: When pharmacological methods fail, manual removal under anaesthesia should be undertaken by experienced practitioners. Dilation and curettage or hysteroscopy must be cautiously performed to minimise uterine trauma and adhesion formation.
• Post-Procedural Monitoring: Vital signs, uterine tone, and bleeding status must be meticulously monitored post-removal to detect early signs of complications.

4. Infection Prevention and Antibiotic Stewardship

• Prophylactic and Therapeutic Use: Broad-spectrum antibiotics should be administered where there is evidence of infection or invasive intervention. Strict aseptic technique must be observed during all procedures.

5. Long-Term Follow-Up and Reproductive Counselling

• Menstrual and Fertility Assessment: Patients should undergo follow-up to evaluate menstrual recovery, detect symptoms of intrauterine adhesions, and assess reproductive function.
• Future Pregnancy Planning: Those with prior retained placenta must be counselled regarding potential recurrence and may benefit from consultant-led antenatal care in subsequent pregnancies.

6. Psychological and Emotional Support

• Screening for Mental Health Sequelae: Routine postnatal assessments should include screening for depression, anxiety, and trauma symptoms.
• Access to Support Services: Referral pathways to perinatal mental health services, psychological counselling, and peer support groups should be established as standard practice.

7. Institutional and Policy-Level Improvements

• Standardised Protocols and Training: Health institutions must adopt evidence-based protocols and ensure all maternity staff are trained in the timely recognition and management of retained placenta.
• Data Collection and Auditing: Regular audit of cases involving retained placenta should be used to evaluate outcomes, identify areas for improvement, and inform clinical governance.

By implementing these best practices, healthcare providers can significantly reduce the burden of retained placenta, enhance maternal safety, and promote holistic recovery encompassing physical, reproductive, and psychological health.

Conclusion

Retained placenta remains a significant obstetric complication, associated with considerable maternal morbidity and, in severe cases, mortality. The condition encompasses a complex interplay of aetiological factors, from abnormal placental implantation and uterine atony to uterine anomalies and procedural risks. The immediate consequences, such as postpartum haemorrhage and sepsis, can be life-threatening without swift and skilled intervention. Furthermore, delayed recognition and suboptimal management may lead to chronic gynaecological sequelae, compromised future fertility, and psychological distress.

This paper underscores the importance of a proactive, multidisciplinary approach, encompassing antenatal risk stratification, prompt postpartum assessment, evidence-based medical and surgical management (considering all risks), and comprehensive long-term follow-up. Particular attention must be given to both physical and psychosocial outcomes, recognising that recovery from retained placenta extends beyond the acute clinical episode.

To ensure optimal care and reduce the incidence of preventable complications, including the use of drugs and medications that carry serious health problems, healthcare systems must invest in training, protocol development, and integrated care pathways. Patient education, emotional support, and continuity of care are equally essential in safeguarding maternal health and dignity.

Addressing retained placenta demands not only clinical excellence but a compassionate and holistic commitment to women’s reproductive wellbeing across the continuum of care.