Placenta accreta in the department of gynaecology and obstetrics in Rabat, Morocco: case series and review of the literature

Placenta accreta spectrum disorders is a rare pathology but the incidence has not stopped to increase in recent years. The purpose of our work was the analysis of the epidemiological profile of our patients, the circumstances of diagnosis, the interest of paraclinical explorations in antenatal diagnosis and the evaluation of the evolutionary profile. We hereby report a case series spread over a period of one year from 01/01/2015 to 01/01/2016 at the Gynaecology-Obstetrics department of the University Hospital Center IBN SINA of Rabat where we identified six cases of placenta accreta. We selected patients whose diagnosis was confirmed clinically and histologically. The major risk factors identified were a history of placenta previa, previous caesarean section, advanced maternal age, multiparity. 2D ultrasound and magnetic resonance imaging (MRI) allowed us to strongly suspect the presence of a placenta accreta in a pregnant woman with risk factor(s) but the diagnosis of certainty was always histological. Placenta accreta spectrum disorders were associated with a high risk of severe postpartum hemorrhage, serious comorbidities, and maternal death. Leaving the placenta in situ was an option for women who desire to preserve their fertility and agree to continuous long-term monitoring in centers with adequate expertise but a primary elective caesarean hysterectomy was the safest and most practical option. Placenta accreta spectrum disorders is an uncommon pathology that must be systematically sought in a parturient with risk factors, to avoid serious complications. In light of the latest International Federation of Gynecology and Obstetrics (FIGO) recommendations of 2018, a review of the literature and finally the experience of our center, we propose a course of action according to whether the diagnosis of the placenta is antenatal or perpartum.


Introduction
The 2018 International Federation of Gynecology and Obstetrics (FIGO) consensus described the placenta accreta spectrum disorders by three categories: first, the adherent placenta accreta when the villi simply adhere to the myometrium; second the placenta increta, when the villi invade the myometrium; and third the placenta percreta, when villi invade the full thickness of the myometrium including the uterine serosa and sometimes adjacent pelvic organs [1]. Its incidence has been rising in recent years and this appears to correlate with the increase of caesarean section rates.
Major risk factors are a history of placenta previa, previous caesarean section, advanced maternal age, multiparity and a history of endouterine maneuvers [2]. The diagnosis may be antenatal, based primarily on obstetrical ultrasound, Doppler ultrasound and magnetic resonance imaging (MRI), but may be discovered after a failed delivery. The diagnosis of certainty is histological; it is mainly posed per-partum in front of the absence of cleavage zone between the placenta and the myometrium thus making delivery difficult or impossible [3]. The first-line treatment has long been hysterectomy, but current advances in surgical and hemostatic techniques have improved the prognosis in postpartum hemorrhage allowing us to experiment a conservative treatment. This conservative treatment must be applied with caution and in a suitable infrastructure and would allow the preservation of subsequent fertility as well as the reduction of morbidity and maternal-fetal mortality [3]. Placenta accreta spectrum disorders is associated with a high risk of severe postpartum hemorrhage, serious comorbidities, and maternal death.
According to World Health Organization, the main cause of maternal death is severe bleeding (mostly bleeding after child birth) which is why these disorders have become a public health problem [4]. It is therefore essential that obstetricians be up-to-date to properly manage patients by following the latest recommendations from learned societies.

Methods
We hereby report a case series spread over a period of one year from  After ten days of favorable evolution, she left the hospital. accreta on 155 670 births with an incidence rate of 1/2 510 births or 0.0398% [5]. This lower incidence in Morocco can be explained by the fact that screening is more effective in developed countries than in low-and middle-income countries. The only certainty is that the incidence of placenta accreta has increased dramatically in a few decades, and it was shown that this was likely correlated to the increasing rate of cesarean delivery [7]. Furthermore, the widespread use of ultrasound including looking for signs of placental accretisation in patients with a scarred uterus, alone represents an essential factor in the increased incidence of this disease. This trend is not expected to change in the coming years given the current obstetrical practices regarding cesarean indications such as breech presentation, twin pregnancies and scarred uteri. This is why it is important to identify women at risk in order to establish an appropriate management.

Risk factors: several risk factors have been reported in the literature
but the one that comes up most often is the occurrence of caesarean section. In a 20-year retrospective study, Wu et al. [2] studied the risk factors for placenta accreta in a population of 121 cases compared to a control population. It is evident from these data that one of the major risk factors for placenta accreta is cesarean section, especially their number. Indeed they showed that the rate of occurrence of this anomaly increases with the number of previous cesarean sections, multiplying by 3 or 4 when there are 2 or more antecedents compared to a single caesarean section [2]. The second risk factor found in the literature is placenta praevia. Miller et al. [5] reported an incidence rate of 1/68 000 births or 0.0015% in the absence of any risk factor to nearly 10% of births in patients with a low-lying placenta. Indeed, the low insertion of the placenta exposes to an invasion accreta, because of the topography of the placental insertion in a place (uterine isthmus and internal cervix orifice) where the functional quality of the decidua is lacking [5]. In addition, the authors of a recent study warn practitioners that within the patients with placenta previa: placental attachment to the incision site and full placenta previa further increase the risk of accretion [8]. Other less significant risk factors could be identified including: advanced maternal age, multiparity, endometritis or any endo-uterine gesture favoring an abnormality in the reconstruction of the endometrium, such as curettage, myomectomies or metroplasty [9]. Moreover, in a study published by Alanis et al. it was found that among the 15% of women who had a subsequent pregnancy after a placenta accreta, 18% recidivated [10]. patients. An MRI was performed to confirm the ultrasound images.
This low proportion of antenatal diagnosis is in agreement with the studies, in particular that of Clouqueur et al. [3]: only 6 of 21 patients have benefited from an antenatal diagnosis. That was also the case in O'brien et al.'s study [11], where only 50% of the 109 cases of placenta percreta were diagnosed prenatally. This difficulty in diagnosing placentas accreta during the prenatal period can be explained by the high frequency of risk factors. In point of fact, it is difficult to perform an effective screening on a large population with this type of complementary examinations. The diagnosis is made mainly in the presence of the association of placenta previa and a cicatricial uterus. In our series, concerning the patients who benefited from an antenatal diagnosis, 3 of 3 presented this association. In the Clouqeur et al. study [3] this association represents 5 out of 6 patients. From our results, it seems that Doppler ultrasound is effective to diagnose placenta accreta in a population at risk; this is consistent with the literature. Chou et al.'s study [12] of 64 cases of placenta accreta, evaluating the efficacy of Doppler ultrasound in the antenatal diagnosis of placenta accreta in a population at risk (previous caesarean section and placenta previa) found a good specificity (96.8%) and a good negative predictive value (95.3%).

Ultrasound signs
The presence of intra-placental lacunaes: intraplacental lacunae were found in our 3 cases that benefited from a prenatal diagnosis.
According to these results, the intraplacental deficiencies are thus a predictive sign of placenta accreta, which is in agreement with the study of Yang et al. [13], which finds a specificity of 78.6% and a sensitivity of 86.9% in the presence of gaps. It is thus considered as the most reliable sign in the diagnosis of placenta accreta.
Finberg et al. [14] have established a classification in 4 stages: Stage 0: no lacunae. Stage 1: 1 to 3 small sized lacunas. Stage 2: 4 to 6 bigger lacunaes with irregularities. Stage 3: more than 6 lacunaes occupying all the placental thickness. Finger et al. [14] were able to show that the positive predictive value of this criterion increases with stage.
Interruption of the hyperechoic zone at the interface of the uterine serosa and the bladder: according to Palacios et al.'s study [15], the interruption of this limit is a specific but insensitive sign. Other authors found that some aspects of bulging towards the bladder may be visible and are predictive of a placenta accreta [16]. We found this interruption in our fourth patient where the diagnostic of placenta percreta was made.
Thinning of the myometrium next to the bladder: some authors such as Finberg et al. [14] showed that a thickness of less than 1 mm would be a predictive measure of accreta. This thinning was objectified in the doppler of our second patient.  [18], which concluded that MRI could visualize better the degree of placental invasion and thus identify better placentas percreta and their relationship to the bladder.
Therapeutic management: placenta accreta spectrum disorders is a high-risk situation for severe post-partum bleeding and its complications such as disseminated intravascular coagulation, haemostasis hysterectomy, surgical wounds of the ureters and the bladder, multi-organ failure or even maternal death; especially in the case of placenta percreta [11]. Finally, the failure of these measures imposes hemostasis hysterectomy. The two decision tree diagrams summarize the actions to be taken in both cases ( Figure 5, Figure 6).

Conclusion
Placenta accreta spectrum disorders is a rare pathology but the incidence has not stopped to increase in recent years. This trend is probably correlated to the increase of caesarean sections and certain risk factors such as the history of placenta previa, advanced maternal age and uterine surgery with mucosal erosion. This disease is burdened with heavy transfusion morbidity and a significant mortality.
2D ultrasound and MRI can strongly guide the presence or absence of an accreta in a pregnant woman with risk factor(s) of placenta accreta.
The improvement of prenatal diagnosis allows an optimization of the care. According to the latest recommendations, leaving the placenta in situ is an option for women who desire to preserve their fertility and agree to continuous long-term monitoring in centers with adequate expertise. But a primary elective caesarean hysterectomy is the safest and most practical option for most low-and middle-income countries where diagnosis, follow-up and additional treatments are not available.

What is known about this topic
• The placenta is a rare but increasing pathology mainly because of the increased number of caesareans; • The presumptive diagnosis is ultrasonographic or at the MRI but it is only histology that confirms it; • The choice of the management strategy depends mainly on the anatomical type of the placenta encountered and the subsequent desire for fertility of the patient.

What this study adds
• The combination of a previous caesarean section with a low inserted placenta should always makes us suspect a placenta accreta • A primary elective caesarean hysterectomy is the safest and most practical option for most low-and middle-income countries where diagnosis, follow-up, and additional treatments are not available.