Risks associated
with PAS

Placenta accreta spectrum covers a range of clinical conditions where the placenta is imbedded too deeply into the lining of the womb.

Heavy bleeding

  • Bleeding at the time of placenta accreta surgery is common, and over half of women will lose more than a litre of blood
  • Approximately 50% of  women will need a blood transfusion
  • Because the risk of bleeding is high, a cell saver is used for all women having surgery for placenta accreta. A cell saver is a special machine which is used to collect your own blood during the surgery. The blood is then given back to the woman during and after the surgery. This reduces the risk of needing a blood transfusion from a blood donor.

Damage to organs close to the womb

  • The most common complication of surgery for placenta accreta is injury to the bladder. This is sometimes necessary to fully remove the placenta in severe cases where the bladder is very stuck to the front of the womb. If the bladder is injured during the surgery, the surgical team will fix the bladder with a suture and a catheter is left in for around 10 days. After 10 days, an x-ray is performed to check the bladder has healed. The bladder is injured in approximately 4 out of 10 cases.
  • In some cases, where the placenta is invaded very deeply into the womb, the ureters (tubes which carry urine from the kidney to the bladder) are at risk of being injured. This is because the ureters lie very close the womb. To reduce the risk of injury, a small stent may be placed in the ureter to protect the ureters during the surgery. If a ureter is damaged during surgery this often means another surgery at a later date. This is a less common complication, and happens in approximately 5-10% of cases.  
  • Damage to the bowel is very rare in placenta accreta.
  • Although ovaries are conserved in almost all cases, if there is excessive bleeding it may be necessary to remove one or both ovaries. This is very rare.

Developing a blood clot in the leg or the lung

  • Women after placenta accreta surgery are at risk of getting a blood clot in the leg (deep venous thromboembolism) or in the lung (pulmonary embolism).
  • The medical team will assess each woman’s risk of developing a clot and advise blood thinning medication after the birth. These are injections which often need to be given for 6 weeks.
  • Women should wear TED stockings while in the hospital and for 6 weeks after going home.


  • Wound infections, chest infection and infections from intravenous catheters or central lines can occur.
  • An abscess or collection can form in the pelvis, which may need drainage. This is usually done under ultrasound guidance.
  • An infection is treated with antibiotics, which may be given as a tablet at home, or if women are more unwell, may mean coming into hospital to get antibiotics from a drip.

Hysterectomy and loss of fertility

  • If women have had a hysterectomy, they will no longer be able to carry a pregnancy in the future.


  • Older studies suggest a 7% risk of death, however early diagnosis and planned delivery with an experienced team has reduced this risk, with current estimates of a less than 1% risk of death.
  • There is a higher risk if placenta accreta spectrum is not diagnosed during the pregnancy.

For Baby

  • Many women with placenta accreta will give birth to their baby a few weeks before the due date.
  • When a baby is born early, they may need to be cared for in a neonatal intensive care unit for a few days or weeks after depending on how many weeks before the due date they are born .
  • The most common problems for babies born early will be breathing and feeding difficulties.