Placenta Percreta

Placenta Percreta 

Definition:

Placenta Percreta is a term given to the most severe but least common form of the spectrum of abnormal villous placenta adherence/implantation. It carries serious maternal as well as fetal risks.

Epidemiology:

It accounts for 5-7% of all abnormal placental villous implantation/adherence. The incidence is thought to be increasing presumably due to the increased practice of Caesarean sections (which is a risk factor). Though this form of abnormal villous adherence is rare compared to the others.

Pathogenesis:

It is characterised by transmural extension of placental tissue across the myometrium with serosal breach i.e the placenta penetrates the entire myometrium to the uterine serosa (invades through entire uterine wall).This variant can lead to the placenta attaching to other organs such as the rectum or bladder. 
Placental invasion of the myometrium is related to a thinned decidual endometrium at the site of implantation and this can happen for a number of reasons.

Risk Factors:

Risk Factors are same for other types of abnormal placenta villous adherence.
Known Risk Factors of Placenta Percreta include;

• Placenta Previa
• Prior cesarean section
• Uterine anomalies
• Previous uterine surgery
• Dilation and curettage(D&C)
• Myomectomy
• Maternal age greater than 35 years
• Multiparity

Diagnosis:

Ultrasound

Ultrasound may identify:

• Protrusion of placental tissue beyond the outer confines of the uterine myometrium
• Increased vascularity between serosa and adjacent structures such as the bladder or rectum.

MRI is usually an adjunct to the diagnosis.

Complications:

• Uterine Rupture
• Catastrophic peri-partum haemorrhage

Treatment and Prognosis:

Surgical intervention has been the most common favorable choice of treatment in most cases. However bleeding during intervention is a serious concern especially in situation where adjacent organs such as bladder or bowel in involved. In these circumstances, conservative management is preferred. Embolisation techniques have also been considered in selected cases.