Placenta Accreta - What Are The Treatment Options Available?

Placenta accreta is the term used for morbid adherence of the placenta to the uterine wall. Such abnormal adherence is particularly likely to occur over scar tissue. Given a caesarean section rate of approximately 40% these days, it is not surprising that there is an increasing incidence of placenta accreta. The danger with this condition is post partum exsanguination as adherent placenta is retained, preventing uterine wall contraction. Dr Michael van der Griend a member of Invivo's Medical Advisory Panel looks at this dangerous problem.

Case History

Mrs J aged 41 has two children, both born via caesarean section. An ultrasound at 19 weeks, a standard test in pregnancies, revealed a low lying, anterior placenta. A repeat ultrasound performed at 34 weeks confirmed the diagnosis of placenta accreta. Mrs J would like to know what treatment options are available.

Diagnosis

An ultrasound characteristically reveals blood filled lacunae and a loss of interface between placenta and decidua. Doppler and MRI may have a role in confirming diagnosis.

Management

Traditional management involves hysterectomy in some form, with inevitable subsequent infertility. To avoid this, there is a conservative option, with significant risks of which the patient should be made aware.

Conservative Option

After delivery, the placenta is left in utero with no attempt being made to remove it. In an effort to avoid infection, broad spectrum antibiotics are prescribed. Methotrexate has been used in the belief that this drug acts on rapidly dividing cells such as trophoblast. But as the placenta is not rapidly dividing this view is disputed. Conservative treatment gives unpredictable results. Infection and massive secondary haemorrhage may occur.

Surgical Management

Total abdominal hysterectomy is the mainstay of treatment. The placenta should not be detached as massive hemorrhage ensues.

• The surgery is ideally performed electively at 37 weeks gestation involving a multidisciplinary approach with anaesthetists, haematologists, gynaecological oncologists all involved in care.
• Vertical skin and uterine incisions facilitate exposure. The uterine incision is oversewn after delivery of the baby and hysterectomy is performed. As the lower segment is often involved by adhesions and tissue planes are very vascular, a subtotal hysterectomy is not appropriate. The risk of bladder trauma is high and some authors advocate the use of modified catheters capable of inflating and deflating to more readily identify anatomy.

Staged Delivery with Uterine Embolisation

Sheaths with balloon catheters are placed in the common femoral arteries. Then midline laparotomy and uterine incisions as discussed above are performed, the baby is delivered and the uterus closed.

If anaesthetic conditions are stable, selective embolisation to the uterus and placental bed is performed prior to hysterectomy - if unstable, balloon catheters are inflated and hysterectomy performed.

This procedure produces a significant reduction in blood loss, and the need for blood products and ICU admission.

Although Levine found no difference in the final outcome when embolisation was performed, interventional radiology, pre-and intra-operatively, significantly reduce operation time.

Conclusion

With caesarean section incidence rising, so will the incidence of placenta accreta. With a general incidence of 1 in 2500 pregnancies most institutions will see at least one accreta per year. A woman who has had 2 prior caesarean sections has a 1 in 200 risk of accreta, making it essential that proper warnings be given.

Careful and thorough preoperative counseling about the risks of conservative management is essential.

When surgical intervention is planned, not only is it necessary to discuss likely need for blood transfusion and ICU admission, but all the standard risks of surgery including significant bladder or ureteric trauma need to be spelled out. Patients contemplating a further pregnancy after two or more previous caesarean sections should also be warned about the rare but dangerous conditions of placenta accreta.

Dr. Michael van der Griend
Obstetrician & Gynaecologist
Invivo Medical Advisor

REFERENCES

1. Levine A.B., Kuhlman K., Bonn J. Placenta Accreta: Comparisons of cases managed with and without Pelvic Artery Balloon Catheters. J. Matern Fetal Med. 1999;8: 173-6
2. Oyelese Y.,and Smulian J.S., Placenta Previa, Placenta Accreta and Vasa Previa Obstet. Gynaecol. 2006;107: 927-41