What are the key concerns and management strategies for Placenta Percreta?

Placenta Percreta: Pathophysiology and Clinical Implications

Pathophysiologic Mechanism

Placenta percreta represents the most severe form of placenta accreta spectrum, characterized by abnormal trophoblast invasion completely through the myometrium and uterine serosa, often extending into adjacent organs such as the bladder. 1

The underlying pathophysiology involves:

• Defective endometrial-myometrial interface at the site of prior uterine scarring, leading to failure of normal decidualization 1
• This defect allows abnormally deep placental anchoring villi and trophoblast infiltration beyond the normal boundaries of placental attachment 1
• The placenta penetrates through the full thickness of the uterine wall and may invade the bladder, bowel, or other pelvic structures 2

Critical Risk Factors

The most significant risk factor is prior cesarean delivery combined with placenta previa 1:

• With placenta previa alone (no prior cesarean): 3% risk of accreta spectrum 1
• Placenta previa + 1 prior cesarean: 11% risk 1
• Placenta previa + 2 prior cesareans: 40% risk 1
• Placenta previa + 3 prior cesareans: 61% risk 1
• Placenta previa + 4+ prior cesareans: 67% risk 1

Additional risk factors include advanced maternal age, multiparity, prior uterine surgeries or curettage, and Asherman syndrome 1

Life-Threatening Complications

Placenta percreta carries the highest risk of catastrophic hemorrhage, maternal mortality, and adjacent organ damage within the accreta spectrum. 1

Hemorrhagic Complications

• Median blood loss of 3,500 mL when percreta is removed at time of primary cesarean delivery 1
• 100% transfusion rate with immediate hysterectomy 1
• 42% massive transfusion rate (>10 units) with immediate removal 1
• Attempting placental removal triggers profuse, life-threatening hemorrhage 1

Organ Involvement

• Bladder invasion is the most common extra-uterine site, requiring potential cystotomy or bladder resection 1, 2
• Ureteral injury risk necessitates collaboration with urologic or gynecologic oncology surgeons 1
• Bowel involvement may occur in severe cases 1

Maternal Mortality and Morbidity

• Increased maternal death rates compared to normal placentation 1
• One reported maternal death from methotrexate toxicity and septic shock in expectant management 1
• Risk of severe complications including hemorrhagic shock, multiorgan failure, infection, and thromboembolic events 1
• Potential for Sheehan syndrome (postpartum pituitary necrosis) from hypoperfusion 1

Optimal Management Strategy to Minimize Mortality

The American College of Obstetricians and Gynecologists recommends planned cesarean hysterectomy at 34-36 weeks gestation with placenta left in situ, performed at a Level III/IV maternal care center by a multidisciplinary team. 1, 3

Delivery Timing

• Schedule delivery at 34 0/7 to 35 6/7 weeks gestation to balance neonatal outcomes against maternal hemorrhage risk 1, 3
• Do not wait beyond 36 0/7 weeks as approximately 50% require emergent delivery for hemorrhage after this point 1, 3

Surgical Approach

• Never attempt placental removal - this causes catastrophic hemorrhage 1, 3
• Deliver fetus through uterine incision that avoids the placenta when possible 1
• Ligate umbilical cord close to placenta and proceed directly to hysterectomy 3
• Total hysterectomy usually required due to lower uterine segment bleeding 1

Alternative: Delayed Interval Hysterectomy

For placenta percreta specifically, delayed interval hysterectomy (median 41 days post-cesarean) significantly reduces blood loss and transfusion requirements compared to immediate hysterectomy. 1

This approach demonstrates:

• 900 mL blood loss at cesarean delivery + 700 mL at delayed hysterectomy versus 3,500 mL with immediate removal 1
• 46% transfusion rate with no massive transfusions (>4 units) versus 100% transfusion rate with immediate removal 1
• Reduced organ damage: no bladder resections required 1
• However, this remains investigational and should only be considered at experienced centers with extensive counseling 1, 3

Critical Pitfalls to Avoid

• Never attempt manual placental removal - this is the single most dangerous action 1, 3
• Never deliver at facilities without massive transfusion capability 3
• Never delay delivery beyond 36 weeks in stable patients 3
• Methotrexate is not recommended due to unproven benefit, maternal toxicity risk, and one reported death 1, 3
• Routine prophylactic iliac artery balloon occlusion is not recommended due to lack of proven benefit and risk of arterial complications 1

Postoperative Vigilance

Intensive care monitoring is essential given risks of:

• Ongoing hemorrhage requiring reoperation or interventional radiology 1
• Fluid overload from massive resuscitation 1
• Renal failure, liver failure, disseminated intravascular coagulation 1
• Unrecognized ureteral, bladder, or bowel injury 1
• Pulmonary embolism (including potential amniotic fluid embolism with intact abnormal placenta) 4