Жатыр қабырғасына плацентаның қалыптан тыс жабысуы

Placenta accreta occurs when all or part of the placenta attaches abnormally to the myometrium (the muscular layer of the uterine wall). Three grades of abnormal placental attachment are defined according to the depth of attachment and invasion into the muscular layers of the uterus:
Accreta – chorionic villi attached to the myometrium, rather than being restricted within the decidua basalis. Increta – chorionic villi invaded into the myometrium. Percreta – chorionic villi invaded through the perimetrium (uterine serosa). Because of abnormal attachment to the myometrium, placenta accreta is associated with an increased risk of heavy bleeding at the time of attempted vaginal delivery. The need for transfusion of blood products is frequent, and surgical removal of the uterus (hysterectomy) is sometimes required to control life threatening bleeding. Rates of placenta accreta are increasing. As of 2016, placenta accreta affects an estimated 1 in 272 pregnancies.

An important risk factor for placenta accreta is placenta previa in the presence of a uterine scar. Placenta previa is an independent risk factor for placenta accreta. Additional reported risk factors for placenta accreta include maternal age and multiparity, other prior uterine surgery, prior uterine curettage, uterine irradiation, endometrial ablation, Asherman syndrome, uterine leiomyomata, uterine anomalies, and smoking. The condition is increased in incidence by the presence of scar tissue i. e. Asherman's syndrome usually from past uterine surgery, especially from a past dilation and curettage, (which is used for many indications including miscarriage, termination, and postpartum hemorrhage), myomectomy, or caesarean section. A thin decidua can also be a contributing factor to such trophoblastic invasion. Some studies suggest that the rate of incidence is higher when the fetus is female. Other risk factors include low lying placenta, anterior placenta, congenital or acquired uterine defects (such as uterine septa), leiomyoma, ectopic implantation of placenta (including cornual pregnancy). Pregnant women above 35 years of age who have had a caesarian section and now have a placenta previa overlying the uterine scar have a 40% chance of placenta accreta.

The placenta forms an abnormally firm and deep attachment to the uterine wall. There is absence of the decidua basalis and incomplete development of the Nitabuch's layer. There are three forms of placenta accreta, distinguishable by the depth of penetration. Type Fraction Description Placenta accreta 75–78% The placenta attaches strongly to the myometrium, but does not penetrate it. This form of the condition accounts for around 75% of all cases. Placenta increta 17% Occurs when the placenta penetrates the myometrium. Placenta percreta 5–7% The highest risk form of the condition occurs when 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 urinary bladder.

Treatment may be delivery by caesarean section and abdominal hysterectomy if placenta accreta is diagnosed before birth. Oxytocin and antibiotics are used for post surgical management. When there is partially separated placenta with focal accreta, best option is removal of placenta. If it is important to save the woman's uterus (for future pregnancies) then resection around the placenta may be successful. Conservative treatment can also be uterus sparing but may not be as successful and has a higher risk of complications.

The reported incidence of placenta accreta has increased from approximately 0.8 per 1000 deliveries in the 1980s to 3 per 1000 deliveries in the past decade. Incidence has been increasing with increased rates of caesarean deliveries, with rates of 1 in 4,027 pregnancies in the 1970s, 1 in 2,510 in the 1980s, and 1 in 533 for 1982–2002. In 2002, ACOG estimated that incidence has increased 10 fold over the past 50 years.