How should I manage a patient with a known history of cesarean sections presenting with suspected placenta accreta spectrum?

For a patient with a known history of caesarean sections who is presenting with suspected placenta accreta spectrum (PAS), the management involves a series of diagnostic steps, specialist referral, and multidisciplinary planning for birth.

Initial Assessment and Referral:

• If a routine 20-week ultrasound scan shows placenta praevia or a low-lying placenta in a woman with a previous caesarean scar (or other uterine surgery scar), a greyscale ultrasound scan with colour doppler should be performed to assess for placenta accreta ¹.
• This specialized scan should be conducted around 28 weeks, but no later than 29 weeks, by a senior clinician experienced in diagnosing placenta accreta ¹.
• If placenta accreta is suspected following this greyscale ultrasound scan with colour doppler, the woman or pregnant person should be referred to a specialist placenta accreta spectrum centre for comprehensive care and ongoing management ¹. A specialist centre is defined as a maternity service with an appropriate multidisciplinary team, access to adult intensive care, level 3 neonatal care, and blood products ¹.

Further Investigations and Discussions:

• An MRI scan may be considered to complement ultrasound findings, particularly for a posterior placenta, when planning ongoing surgical management of PAS ¹. It is important to discuss with the patient what to expect during an MRI, that it can help clarify the degree of invasion, and that while current experience suggests it is safe, there is a lack of evidence about any long-term risks to the baby ¹.
• A senior obstetrician should discuss birth options with the woman, including the timing of birth, potential operative interventions (such as the possibility of hysterectomy), and the need for blood transfusion ¹. It should be explained that placental adherence problems are a relevant risk with multiple caesarean births ¹.

Planning and Management of Birth:

• When planning a caesarean birth for suspected PAS, the multidisciplinary team must agree on which other healthcare professionals need to be consulted or present (e.g., specialists in gynaecological surgery, interventional radiology, colorectal surgery, urology, or vascular surgery, depending on the nature of the PAS) and define the responsibilities of each team member ¹.
• During a planned caesarean birth for suspected PAS, a consultant obstetrician, a consultant gynaecologist, and a consultant anaesthetist must be present in the operating theatre ¹. A paediatric or neonatal registrar or consultant should also be present to provide immediate care for the baby ¹. A haematology registrar or consultant should be available for advice ¹.
• Ensure a critical care bed is available for the woman and a critical care neonatal cot for the baby, although emergency surgery should not be delayed while waiting for a bed ¹. Sufficient cross-matched blood and blood products must be readily available if acceptable to the woman ¹.

Protocols and Emergency Care:

• Specialist placenta accreta spectrum centres and their supporting local maternity units should develop protocols for the diagnosis, assessment, and management of PAS across their network ¹. These protocols should also cover the care and management of PAS identified late in pregnancy or during labour, including how specialist units can support emergency care in local maternity units ¹.