SWARAJ HOSPITAL & RESEARCH INSTITUTE

BOLANGIR, ODISHA  •  OBSTETRICS & GYNAECOLOGY CLINICAL PATHWAY SERIES

Clinician Reference Infographic

Placenta Accreta Spectrum

Placenta accreta spectrum is a major cause of life-threatening bleeding that can be anticipated. This guide covers definitions and grades, risk factors, ultrasound and MRI diagnosis, antenatal planning, the planned operation, and the unexpected case and aftercare, using the ACCRETA approach.

🎯 AT A GLANCE — PLACENTA ACCRETA SPECTRUM

Placenta accreta spectrum (PAS) is an abnormally adherent or invasive placenta because the decidua is deficient, so the placenta grows into or through the uterine wall and cannot separate normally after birth

The leading cause of massive obstetric haemorrhage, peripartum hysterectomy, and maternal intensive care admission

The main risk factor is a previous caesarean section with a placenta previa or low-lying placenta; incidence is rising with the caesarean rate

Prenatal diagnosis by expert ultrasound (with MRI when needed) lets the team plan: a planned caesarean hysterectomy at about 34–36 weeks in a centre with blood, intensive care, and a multidisciplinary team gives far better outcomes than an unplanned emergency

The cardinal rule: do not try to pull out an adherent placenta

Think of it in every woman with a previous caesarean and a low or anterior placenta — ask the sonologist to look specifically

🚨 ACT NOW IF

Previous caesarean (especially two or more) with placenta previa or a low anterior placenta — refer for expert PAS ultrasound and a specialist centre

Antepartum bleeding in a woman with suspected PAS — admit, cross-match, call the senior team, and arrange transfer

Placenta does not separate after birth, or heavy bleeding when removal is attempted — stop pulling, call for help, and resuscitate

Haematuria, abdominal pain, or a bulging bladder area — suspect bladder invasion

Uterine scar pregnancy in the first trimester (gestational sac low in the scar) — early specialist referral

🗺️ THE PATHWAY AT A GLANCE

1 · SuspectPrevious caesarean or uterine surgery with a low or anterior placenta

2 · ScanExpert ultrasound at 18–24 weeks, repeat at about 28–32 weeks, MRI if unclear

3 · ReferTo a centre with a PAS team, blood bank, and intensive care

4 · PrepareCorrect anaemia, counsel, plan blood and cell salvage, steroids

5 · DeliverPlanned caesarean hysterectomy at about 34–36 weeks (earlier if bleeding)

6 · RecoverIntensive care, clot prevention, counselling, contraception

STEP 1 · WHAT IT IS — the spectrum and the grades

🔬 DEFINITIONS AND GRADES

Term	Details
Placenta accreta (FIGO grade 1)	Villi attach to the myometrium without invading it (no decidua between them); the commonest type
Placenta increta (grade 2)	Villi invade into the myometrium
Placenta percreta (grade 3)	Villi penetrate the serosa (3a), invade the bladder (3b), or other pelvic organs and tissues (3c)
Why it happens	Scar tissue, a thin lower segment, or damaged endometrium means poor decidua, so trophoblast invades deeper
How common	Rare before the 1980s (about 1 in 2,500) and now reported at roughly 1 in 300–700 deliveries, rising with caesarean rates; Indian figures vary by centre

STEP 2 · WHO IS AT RISK — find the woman before the bleeding

⚠️ RISK FACTORS

Factor	Details
Previous caesarean with previa	Risk of PAS rises with the number of caesareans: about 3% after one, 11% after two, 40% after three, and over 60% after four or more (classic series, from memory)
Placenta previa or low-lying placenta	Even without a scar, previa carries a small risk; an anterior placenta over a scar is the highest-risk site
Other uterine surgery	Myomectomy, dilatation and curettage, hysteroscopic surgery, endometrial ablation, previous manual removal, and uterine infection; Asherman syndrome
Other factors	Assisted reproduction (IVF), advanced maternal age, high parity, smoking, short interval after caesarean, hypertensive disease
Previous PAS	High risk of recurrence (reported around 20–30%, from memory)

Every unnecessary primary caesarean raises the risk of PAS in later pregnancies — the best prevention is a safe vaginal birth where possible

STEP 3 · DIAGNOSIS — scan in the right woman, by the right person

📡 ULTRASOUND AND MRI

Tool	Signs and notes
Who to scan	Anyone with a previous caesarean or uterine surgery and a low or anterior placenta; assess the placental site at every anomaly scan
Best time	First-trimester scan for a scar pregnancy; detailed scan at 18–24 weeks, repeat in the third trimester; use transabdominal and transvaginal views
Grey-scale signs	Loss of the clear retroplacental zone, thinned or absent myometrium (under 1 mm), irregular placental lacunae ('Swiss cheese'), bulging of the placenta into the bladder, interrupted bladder wall
Colour Doppler signs	Marked hypervascularity between the placenta and bladder, bridging vessels crossing the myometrium, turbulent lacunar flow
Accuracy	Good in expert hands (sensitivity around 90% in reported series); a normal scan reduces but does not remove the risk
MRI	Adds information when ultrasound is unclear, for posterior placentas, or to map parametrial and bladder invasion; gadolinium is not needed
Cystoscopy	Only if bladder invasion is suspected, by a urologist
Do not	Do a vaginal examination in a woman with previa; use serum markers (such as alpha-fetoprotein) alone to diagnose PAS

STEP 4 · ANTENATAL PLANNING — get her to the right place with the right supplies

🏥 PLAN THE BIRTH

Topic	Details
Refer early	To a centre with a multidisciplinary PAS team: senior obstetrician, gynaecological surgeon, urologist, anaesthetist, intensive care, blood bank, neonatologist, and interventional radiology
Counsel	Explain the risk of haemorrhage and hysterectomy, the loss of fertility, the blood transfusion, the chance of a preterm baby; document consent for hysterectomy
Optimise	Treat anaemia with iron (oral or intravenous); aim for a haemoglobin of at least 11 g/dL; stop smoking
Avoid	Sexual intercourse and vaginal examination (if previa); travel far from the centre in late pregnancy
Admission	Consider admission or staying near the hospital from about 32–34 weeks, especially with a history of bleeding or living far away
Antenatal steroids	Betamethasone or dexamethasone if birth is planned before 37 weeks (per local protocol)
Timing	Planned delivery at about 34 0/7 to 35 6/7 weeks (American guidance) or 35 to 36+6 weeks (UK guidance) when stable; earlier for bleeding, contractions, or rupture of membranes
Blood	Valid group and screen, cross-match of at least 4–6 units with plasma, platelets, and cryoprecipitate on standby; cell salvage if available; massive transfusion protocol ready

STEP 5 · THE OPERATION — one planned attempt, done well

🔪 CAESAREAN HYSTERECTOMY

Step	Details
Set-up	Daytime, fully staffed theatre; two large intravenous lines, arterial line, warming, tranexamic acid, antibiotics; regional or general anaesthesia by the anaesthetist
Incision	Midline vertical skin incision for access; consider ureteric stents or placing balloon catheters where the team and equipment are available
Uterine incision	Through the fundus or the upper segment, away from the placenta (not through it); locate the placenta with ultrasound before opening
Deliver the baby	Hand the baby to the neonatal team; clamp the cord; do not remove the placenta and do not give routine oxytocin until it is clear the placenta will not be removed
Hysterectomy	Leave the placenta in place; close the uterine incision and proceed to hysterectomy (total, if the lower segment or cervix is involved); dissect the bladder carefully; divide the vessels early
Control of bleeding	Pelvic devascularisation (uterine and internal iliac artery ligation), balloon occlusion of the internal iliac or aorta (interventional radiology), packing, tamponade balloon, damage-control surgery if unstable
Injuries	Bladder, ureter and bowel injuries are common in percreta; involve the urologist and repair them
Alternatives in selected women	Leave the placenta in place and follow up (risk of bleeding, infection, and clots; hysterectomy later may be needed), or a one-step conservative operation (such as the triple-P procedure) in expert centres; methotrexate is not recommended

STEP 6 · WHEN IT IS NOT EXPECTED — emergency plan and aftercare

🆘 UNEXPECTED PAS AND AFTERCARE

Situation	Action
Placenta will not separate or bleeds heavily after attempted removal	Stop pulling, call the senior obstetrician, anaesthetist, and blood bank; resuscitate, give uterotonics and tranexamic acid, and start massive transfusion if needed
If bleeding is controlled	Leave the placenta in place, close, and transfer to a PAS centre (with blood and an escort) if the facility lacks resources
If bleeding is severe	Compress the aorta, apply tamponade or packing, and proceed to hysterectomy with the most experienced surgeon available
Intensive care	Watch for haemorrhage, coagulopathy, infection, kidney injury, and fluid overload
Clots and infection	Give antibiotics and low molecular weight heparin when bleeding is controlled; mobilise early
The mother	Counsel on grief and loss of fertility; iron; review before discharge and at 6 weeks
The baby	Often preterm, so neonatal care and early breastfeeding support (see the premature newborn sheet)
Future pregnancy	After conservative management, advise reliable contraception and early specialist care in a future pregnancy

⚠️ COMMON PITFALLS

Not looking for PAS in a woman with a previous caesarean and a low placenta

Relying on a scan by someone not trained in PAS, or assuming a normal scan excludes it

Pulling on the placenta or attempting manual removal

Delivering at night or in a unit without blood, intensive care, or a surgeon when a planned delivery was possible

Waiting for term and meeting the bleeding unprepared

Cutting through an anterior placenta instead of using a fundal or upper segment incision

Missing bladder and ureteric injury

Not counselling or taking consent for hysterectomy beforehand

Memory Aid

ACCRETA

Seven steps for placenta accreta spectrum.

A

Anticipate — previous caesarean plus a low or anterior placenta

C

Confirm — expert ultrasound at 18–24 weeks, MRI if unclear

C

Centre — refer to a unit with blood, intensive care, and a team

R

Ready — correct anaemia, cross-match, cell salvage, tranexamic acid

E

Elective — planned delivery at about 34–36 weeks

T

Team — obstetrician, urologist, anaesthetist, radiologist, neonatologist

A

Avoid pulling — leave the placenta, hysterectomy, or a conservative plan

Remember: suspect early, scan expertly, plan the birth, and never pull the placenta.

Swaraj Hospital & Research Institute · Department of Obstetrics & Gynaecology, Bolangir, Odisha

Clinician-facing summary drawn from memory of Royal College of Obstetricians and Gynaecologists (RCOG), American College of Obstetricians and Gynecologists (ACOG) and Society for Maternal-Fetal Medicine (SMFM), International Federation of Gynecology and Obstetrics (FIGO), and International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) guidance; no source was read for this sheet. No Government of India document was read. Incidence, risk percentages, scan accuracy, blood requirements, and timing of delivery vary between guidelines and centres; thresholds, intervals and regimens vary between guidelines — follow local protocol and involve a senior obstetrician in any high-risk case.