Placenta Accreta Spectrum Imaging And Multidisciplinary Planning

Placenta accreta spectrum (PAS) describes abnormal placental attachment and invasion into the uterine wall. The condition ranges from accreta, where chorionic villi attach abnormally, to increta and percreta, where invasion extends into the myometrium or beyond the uterus. It is an important cause of major obstetric haemorrhage and complex birth planning.

In Australia, the risk profile is familiar to obstetric, radiology, anaesthetic and neonatal teams. A previous caesarean birth combined with placenta praevia is a particularly important warning pattern, although PAS can occur without all classic risk factors. Care may involve a tertiary referral hospital in Sydney, Melbourne, Brisbane, Perth or another state-based centre, especially when imaging suggests deep invasion.

The safest pathway begins before labour or bleeding: identify risk, confirm the placental location, obtain expert imaging and coordinate a plan that is practical for the woman and the hospital. The scientific context of perinatal medicine is reflected in the FAOPS 2020 archive, which records the congress program, speakers and research interests surrounding maternal and newborn care.

Recognising Risk Before Symptoms Appear

The first assessment starts with the clinical history and a careful review of prior uterine surgery. Caesarean scars, previous placenta praevia, curettage, myomectomy and assisted reproductive technology may increase concern, although the strength of association varies. The number and location of previous caesarean deliveries should be documented alongside the current placental position.

Routine mid-trimester ultrasound should identify whether the placenta is low-lying or praevia and whether it overlies a uterine scar. A posterior placenta can be more difficult to assess than an anterior placenta, while a lateral or fundal location does not completely exclude abnormal invasion. If the placenta is close to a scar, the report should recommend targeted review rather than offering false reassurance.

Risk assessment also needs to account for access to care. A woman living in regional New South Wales, northern Queensland or Western Australia may need early referral because transfer time, weather and retrieval availability affect the safety margin. The local maternity network should clarify where advanced pelvic surgery, massive transfusion and neonatal intensive care are available.

Ultrasound As The First-Line Examination

Expert obstetric ultrasound is usually the primary imaging modality for suspected PAS. Transabdominal scanning can assess placental position and the relationship with the bladder, while transvaginal ultrasound may provide better views of the lower uterine segment and cervical region when clinically appropriate. A full bladder is not always necessary, and excessive distension can distort the anatomy.

Useful sonographic signs include placental lacunae with turbulent flow, loss or irregularity of the clear zone behind the placenta, thinning of the myometrium, interruption of the bladder wall interface and abnormal vessels crossing tissue planes. Bridging vessels, placental bulging and hypervascularity at the uterovesical interface can raise suspicion of more extensive invasion.

No single sign should determine management. Ultrasound performance depends on gestational age, placental position, operator expertise and image quality. Reports should describe the likely topography of disease rather than simply stating “accreta present” or “accreta absent.” A useful report may address anterior or posterior involvement, cervical extension, bladder interface changes and possible parametrial or lateral invasion.

Serial imaging can help when the initial result is uncertain. Review by a maternal-fetal medicine specialist or an experienced sonographer is valuable, particularly in a busy Australian public hospital where a general antenatal scan may not answer the surgical questions. Images and reports should travel with the patient if she is referred from a smaller maternity unit.

When Magnetic Resonance Imaging Adds Value

Magnetic resonance imaging (MRI) is an adjunct rather than a replacement for expert ultrasound. It may assist when the placenta is posterior, lateral or high in the uterus, when ultrasound findings are equivocal, or when the surgical team needs more information about suspected parametrial, cervical or bladder involvement. MRI can also help reconcile conflicting findings in a patient with a complex scar history.

The protocol should be designed for placental assessment, with appropriate sequences and experienced interpretation. Features may include dark intraplacental bands, uterine bulging, disrupted uteroplacental architecture, abnormal placental vessels and extension beyond the uterine serosa. MRI should describe anatomical relationships clearly, because the clinical value lies in planning rather than in assigning an isolated imaging grade.

Access varies across the country. A woman referred to a tertiary service in Melbourne or Sydney may have relatively straightforward access to specialist MRI, while a patient in rural South Australia or the Northern Territory may face travel, accommodation and scheduling issues. These practical factors should be incorporated into timing decisions without delaying urgent assessment when bleeding or labour occurs.

Imaging cannot reliably predict the exact volume of blood loss or guarantee that the bladder, ureters or bowel will be unaffected. It is most effective when interpreted alongside clinical risk, previous operative notes and the expertise available at the planned birth facility.

Building The Multidisciplinary Birth Plan

A suspected PAS birth should be planned by a team that matches the anticipated complexity. Core participants commonly include maternal-fetal medicine, an experienced obstetric surgeon, anaesthesia, transfusion medicine, neonatology, midwifery, radiology and theatre staff. Urology is important when bladder invasion is suspected, while interventional radiology, vascular surgery, colorectal surgery and intensive care may be consulted according to local capability.

The plan should specify the preferred hospital, timing of birth, senior decision-makers, operating theatre access and escalation arrangements. It should also record whether conservative management is being considered or whether planned caesarean hysterectomy is the likely approach. Any deviation from the plan should be based on the woman’s condition, her preferences and the team’s real-time assessment.

Communication with the patient is central. Discussions should cover the possibility of severe haemorrhage, transfusion, hysterectomy, urinary tract injury, premature birth, intensive care and neonatal admission. Fertility goals, religious or cultural considerations, consent for blood products and the presence of a support person need to be addressed early rather than during an emergency.

Australian hospitals should align the plan with state or territory protocols, local blood-bank capacity and retrieval pathways. In a private hospital, arrangements may need to include transfer to a public tertiary centre if the required surgical or neonatal resources are unavailable. The plan should be accessible in the electronic record and printed for ambulance or aeromedical transfer if necessary.

Preparing For Haemorrhage And Newborn Care

Blood-product planning is a practical component of PAS management. The team should confirm group and screen results, crossmatched red cells, plasma and platelets, rapid access to fibrinogen replacement and a massive transfusion protocol. Cell salvage, warming equipment, arterial monitoring and large-bore vascular access may be considered according to the anticipated risk and hospital policy.

Anaesthetic review before admission allows discussion of general versus regional techniques, arterial and central access, postoperative intensive care and the possibility of prolonged surgery. Theatre staff should prepare equipment for difficult pelvic dissection, urinary tract assessment and rapid haemorrhage control. A clear communication chain matters as much as the equipment itself.

Neonatal planning should include gestational age, corticosteroid timing, anticipated prematurity and the location of the neonatal intensive care unit. The broader perinatal literature also recognises the value of coordinated supportive care for newborns and families; relevant background on nonpharmacologic care approaches illustrates how neonatal teams can contribute beyond immediate medical procedures.

If birth is planned before term, the decision should balance maternal safety, bleeding risk and neonatal maturity. The neonatal team can explain respiratory support, feeding, parent-infant contact and likely length of stay. In Australia, this may mean arranging a place in a tertiary NICU and helping families manage travel from areas far from the capital city.

Turning Imaging Into A Safe Local Pathway

Imaging findings should lead to a documented management pathway, not a label that sits in the radiology report. A low-risk scan with no concerning signs may support usual surveillance, while a suspicious scan should prompt referral, expert review and multidisciplinary discussion. Indeterminate cases deserve a defined follow-up plan rather than being lost between routine appointments.

The timing of delivery is individualised, but an unplanned admission with vaginal bleeding, contractions or rupture of membranes should activate the same escalation process. The woman’s location, transport time, gestation, haemodynamic status and proximity to an equipped hospital all influence the response. Rural and remote services should know which tertiary centre to contact and how retrieval will be coordinated.

The comparison below summarises how common imaging and planning elements contribute to decision-making. It is a framework for discussion, not a substitute for specialist interpretation.

A high-quality plan remains flexible. It recognises that imaging estimates anatomy, while surgery reveals the operative situation. Regular review by the responsible team ensures that new bleeding, altered placental findings or changes in gestation are reflected in the plan.

For clinicians and services, the priority is a reliable pathway from detection to birth: skilled ultrasound, selective MRI, early referral, honest counselling and coordinated preparation. For patients, early specialist review can replace uncertainty with clear arrangements for travel, admission, surgery, blood support and newborn care. Contacting the relevant maternal-fetal medicine service or tertiary maternity unit early is the most important practical step when PAS is suspected.