Koru Hospital Placenta Accreta Spectrum (PAS) Center is a multidisciplinary treatment center specializing in the management of abnormal placental adhesion disorders, which are among the most severe complications of pregnancy. With our high-risk pregnancy experience and surgical equipment, we implement protocols that ensure the highest level of safety for both mother and baby.
What is Placenta Accreta Spectrum?
Placenta accreta spectrum (PAS) is a group of conditions describing the abnormally deep attachment or invasion of the placenta into the uterine wall. In a normal pregnancy, the placenta detaches spontaneously from the uterine wall after birth. In PAS cases, this detachment does not occur, leading to a risk of uncontrolled hemorrhage.
The incidence of PAS has increased significantly in recent years in parallel with the rise in cesarean section rates. According to current data, one PAS case is observed in approximately every 500-700 births.
PAS Classification
- Placenta accreta: Placental villi attach to the surface of the myometrium but do not invade the muscle layer. It is the most common type.
- Placenta increta: Placental villi penetrate into the myometrial muscle layer.
- Placenta percreta: Placental villi completely penetrate the myometrium and invade the serosa and adjacent organs (bladder, bowel). It is the most severe form.
Risk Factors
The most significant risk factor for the development of PAS is the combination of a previous cesarean section and placenta previa. Risk factors are listed as follows:
- Repeat cesarean section: The risk of PAS increases exponentially with each additional cesarean section (3% after 1 cesarean, up to 40% after 3 or more)
- Placenta previa: Especially placenta previa located over a cesarean scar carries the highest risk
- History of uterine surgery: Myomectomy, curettage, uterine septum resection
- Advanced maternal age: Increased risk over the age of 35
- Multiparity: History of multiple pregnancies
- Asherman syndrome and endometrial damage
- Assisted reproductive techniques (IVF) pregnancies
Prenatal Diagnosis and Imaging
Diagnosing PAS before birth is life-saving as it allows for planned surgical intervention. Diagnostic methods applied in our center include:
Ultrasonography
Transvaginal and transabdominal ultrasonography is the primary imaging method for PAS diagnosis. Ultrasound findings evaluated by our experienced perinatology specialists include:
- Loss of the retroplacental clear zone: Disappearance of the hypoechoic area between the placenta and the myometrium
- Lacunar structures: Irregular vascular spaces within the placenta ("Swiss cheese" appearance)
- Myometrial thinning: Decrease in uterine wall thickness under the placenta
- Bladder-uterus interface irregularity: Signs of bladder wall invasion in percreta cases
- Increased subplacental vascularity: Abnormal vascularization shown by Color Doppler
Magnetic Resonance Imaging (MRI)
Pelvic MRI provides complementary information to ultrasonography, especially in cases with posterior placental placement and for assessing the depth of invasion. MRI holds critical diagnostic value in cases of suspected parametrial invasion, bladder involvement, and percreta.
Multidisciplinary Team and Planning
The key to success in PAS management is a multidisciplinary team approach and detailed prenatal planning. Our PAS team consists of the following specialists:
- Perinatology (maternal-fetal medicine) specialist - Team coordinator
- Gynecologic oncology specialist - Radical surgery experience
- Urology specialist - Bladder and ureteral surgery
- Vascular surgery specialist - Major vessel control
- Interventional radiology - Intraoperative embolization and balloon occlusion
- Anesthesiology - Massive transfusion protocol management
- Neonatology - Premature infant care
- Blood bank and transfusion medicine specialist
- Intensive care team
Prenatal Preparation Protocol
After a PAS diagnosis is confirmed, the preparation steps implemented in our center are:
- Detailed information session and informed consent process with the patient and family
- Antenatal corticosteroid administration (for fetal lung maturation)
- Blood typing, cross-match, and preparation of blood products (minimum 6 units of erythrocyte suspension)
- Correction of iron deficiency anemia during the prenatal period
- Scheduling the operation date (usually 34-36 weeks of gestation)
- Coordination of intensive care bed and neonatal intensive care unit
Surgical Management
Cesarean Hysterectomy
In the majority of PAS cases, the planned surgical approach is cesarean hysterectomy (removal of the uterus after the delivery of the baby). Critical stages of the operation include:
- Providing a wide surgical field with a vertical skin incision
- Delivery of the baby through a uterine incision away from the placenta (fundal hysterotomy)
- Leaving the placenta in situ - Placental detachment is not attempted
- Systematic devascularization and total or subtotal hysterectomy
- Partial cystectomy or segmental bowel resection if there is adjacent organ invasion
Conservative Surgical Approaches
In selected patients who wish to preserve their fertility, uterus-sparing surgery may be considered. In this approach, the placenta is left in situ, and methotrexate therapy or one-step conservative surgery may be applied. The conservative approach can only be safely performed under appropriate indications and in experienced centers.
Interventional Radiology Support
In our center, the interventional radiology team accompanies the surgery during PAS procedures. Techniques applied include:
- Internal iliac artery balloon occlusion: Temporary vessel occlusion to reduce blood loss during surgery
- Uterine artery embolization: Hemorrhage control in conservative approaches
- Aortic balloon occlusion: Last-resort hemorrhage control in percreta cases
Hemorrhage Management and Massive Transfusion
Average blood loss in PAS surgery can range between 2000-5000 ml. Our center activates the massive transfusion protocol as a standard:
- Preparation of the cell saver (intraoperative blood salvage) system
- Transfusion of erythrocytes, fresh frozen plasma, and platelet suspensions in a 1:1:1 ratio
- Use of fibrinogen concentrate and tranexamic acid
- Real-time coagulation monitoring with thromboelastography (TEG)
- Serial monitoring of hemoglobin, lactate, and base deficit
Postoperative Care
After PAS surgery, patients are closely monitored in the intensive care unit. Points of focus in postoperative follow-up include:
- Hemodynamic stabilization and hemorrhage monitoring
- Thromboembolic prophylaxis (low molecular weight heparin)
- Evaluation of urinary system integrity (if bladder resection was performed)
- Wound care and infection surveillance
- Emotional support and psychological counseling after hysterectomy
Risk Assessment for Subsequent Pregnancies
In patients who underwent conservative management and preserved their uterus, the risk of recurrence of PAS in subsequent pregnancies is high. These patients' pregnancies must be followed as high-risk pregnancies by a perinatology specialist. Placental localization and signs of invasion should be monitored via ultrasonography from the early stages of pregnancy.
Within the Koru Hospital Placenta Accreta Spectrum (PAS) Center, our expert staff aims to achieve the safest surgical outcomes while protecting maternal and infant health in high-risk pregnancies.