Non-Previa Placenta Accreta Spectrum in a Woman with Previous Cesarean Section: A Case Report and Review of Pathogenesis,Etiology,and Management Perspectives

Abstract

Introduction:

Placenta accreta spectrum (PAS) represents a significant contributor to maternal mortality, primarily as a result of severe postpartum hemorrhage. The most prominent risk factors associated with PAS are the placenta previa and a history of cesarean delivery. Nevertheless, a normal location of placenta does not exclude PAS, although this is underreported.

Case Report:

We report a G3P2L0 female who was booked with us since her first trimester and had two previous cesarean deliveries, but with no live issue. During her elective lower segment cesarean section at term with all routine preparations, the placenta did not separate with the routine prophylactic dose of oxytocin, even though placenta was placed fundally. Non-separation of the placenta with a well-contracted uterus led us to consider manual removal of the placenta; however, no plane of cleavage was felt or seen, raising a suspicion of the placenta accreta syndrome. As we were at a secondary care setup without any ICU and blood bank facility, given no postpartum hemorrhage, a decision to leave the placenta in situ was taken, and the patient was shifted to a tertiary care setup for observation. She underwent an emergency hysterectomy at the referral center.

Conclusion:

In non-previa PAS cases, guidelines for management, tools for early suspicion and management when encountered as a surprise, and research toward its pathogenesis have a long way to go. Conservative management, particularly in uterine body PAS and resource-limited settings, with leaving the placenta in situ, should be strongly considered.

Introduction

Placenta accreta spectrum (PAS) has become a major obstetrical challenge, with its incidence rising significantly over the past decade. It is a leading cause of maternal morbidity and mortality due to severe postpartum hemorrhage. PAS is classified by FIGO recently into grade 1 (placenta creta or adherenta), grade 2 (placenta increta), and grade 3 (placenta percreta) subtypes. ¹

Placenta previa and a history of cesarean section (CS) are considered the most significant risk factors for the development of PAS. ² Other risk factors include advanced maternal age (≥35 years), previous uterine surgery, previous uterine curettage, and multiparity. ³ ART (artificial reproductive techniques) was also considered a risk factor for PAS recently. ⁴

Current clinical guidelines recommend that all women with placenta previa and additional risk factors for PAS to undergo targeted screening between 20 and 24 weeks of gestation. ² Despite, a normal location of the placenta does not exclude PAS. PAS without placenta previa (also stated as “uterine body PAS”) is frequently encountered clinically, though there have been only a few comprehensive literature reports on this.

We report such a case of non-placenta previa PAS, which was suspected clinically during CS at a secondary care setup and managed. We want to refer this case as uterine body PAS cases, which are challenging to diagnose prenatally and can be encountered intraoperatively even in a resource-limited facility. As no guidelines exist for the management of such cases, no preparations can be made for the same in advance and this may be very difficult to manage for any obstetrician due to massive hemorrhage, which might be encountered.

Case Report

A 25-year-old G3P2L0 female was booked with us since her first trimester. She had had two previous cesarean deliveries, with no live issue. The first CS was done, for failed induction with premature rupture of membranes, delivering a healthy baby who expired at 1 year of age due to pneumonia, and the second one was done 2 years back, in view of a previous lower segment cesarean section (LSCS), not willing for vaginal birth after CS for a term intrauterine death (IUD) baby, the cause for IUD was unknown. Both CSs were uneventful without any intra- or postpartum complications and were done at the district hospital in Bihar state. No history of any other uterine surgery.

She was booked and followed up as high-risk precious pregnancy with us. In her antenatal follow-up, she was diagnosed with gestational diabetes mellitus (controlled on diet) and moderate anemia, which was corrected with an oral iron supplement. She had five ultrasounds performed by a radiologist throughout her ANC duration, including level I/II and growth scans. She also had a fetal echo at 24 weeks. All her ultrasounds reported the placenta as anterior and fundal, or upper segment.

She was posted for elective LSCS with all routine preparations. Intraoperatively, the bladder was high up and adhered to the previous scar site, which was dissected and pushed down. No abnormal vascularity on the anterior surface of the uterus or bladder. The previous uterine scar was thinned out and puckered. An incision was given on the lower uterine segment, and the baby was delivered as cephalic, cord clamped and cut. A routine prophylactic dose of injection oxytocin was given, after which the placenta did not separate. Although the placenta was placed fundally, the lower edge was just above the uterine scar. This edge was separated spontaneously for around 2 cm, and the posterior lower edge of the placenta was also separated for around 3 cm. When the rest of the placenta did not get separated with medical management and a well-contracted uterus, we considered manual removal of the placenta. However, no plane of cleavage was felt or seen, leading to suspicion of placenta accreta syndrome. Following this, the patient and her relatives were counseled, and they consented to the preservation of the uterus, knowing all the risks and the plan of management. As there was no active bleeding from the placental site, we partially resected and ligated already separated edges of the placenta, leaving the rest of the placenta in situ. The uterus and abdomen were closed in layers, and the surgery was concluded with an average blood loss of 400 ml. As we were at a secondary care setup without any ICU (intensive care unit) and blood bank facility, the patient was shifted to a tertiary care setup for observation and the need for intervention, if needed.

She was planned for an emergency hysterectomy in place of conservative management at our tertiary care center, with consent after repeat counseling. The hysterectomy was uneventful, and she received two units of PRBC during her postoperative stay. On a cut section of the uterus, the placenta was found densely adhered to an area of around 10 * 12 cm in the fundal region (Fig. 1). The patient recovered well and was discharged on postop day 5 with her postop Hb as 11.4 g/dL without any ICU stay or postoperative complication.

FIG. 1.

Cut section of hysterectomy specimen: Figure shows thinning of the overlying myometrium suggestive of invasive placenta.

The histopathology examination (HPE) report also showed it as the placenta accreta syndrome at the fundal area (grade 2—placenta increta as per the FIGO grading system) (Figures 2 and 3).

FIG. 2.

Histopathological examination showing FIGO grade 2 (placenta increta): Trophoblastic villi can be seen within myometrial muscular fibers.

FIG. 3.

Another histopathological picture showing trophoblastic: tissue away from uterine serosa.

Discussion

We want to discuss this case for the two challenges we encountered during management. First, is about the diagnosis of uterine body PAS cases and a different aspect of pathogenesis for such cases. Second, is about differing views on the management of PAS cases.

Uterine body PAS

Once considered a rare obstetric condition, PAS has become an increasingly prevalent complication of pregnancy, mainly attributable to the rising rate of cesarean deliveries. The incidence of PAS correlates strongly with the number of prior uterine surgeries, particularly CSs. In cases where the placenta is low-lying, the risk of PAS increases dramatically, from approximately 3% in women with no prior cesarean delivery to as high as 67% in those with four or more previous CSs. ²

However, as in our case, the patient has had two previous cesarean deliveries. But, as the placenta is upper segment or fundal, we did not suspect PAS probability in her or screened her for the same. Similarly, Rajkumar et al. encountered a placenta percreta in a primigravida female who was diagnosed as PAS after a failed attempt of manual removal of a fundally placed placenta during LSCS done for failed induction, leading to emergency hysterectomy, blood transfusion, and ICU stay. ³

Garg et al. also reported a P2L2 female who delivered with normal vaginal delivery at 37 weeks but failed to deliver the placenta. Following this, MRP (manual removal of placenta) was attempted, leading to severe hemorrhage that did not respond to medical management and was taken up for emergency laparotomy. On the cut section, placenta was seen adhered to the posterior wall, which was confirmed as the placenta increta on HPE later on. This female also needed a massive blood transfusion and postoperative ICU stay. ⁵

Ramadan et al. reported two cases, the first involving a primigravida who underwent an LSCS due to preterm premature rupture of membranes and fetal distress at 31 weeks’ gestation. Following delivery of the fetus, the placenta failed to deliver spontaneously. Upon exteriorization of the uterus, a prominent myometrial bulge was observed at the left fundal cornua, raising suspicion for PAS. The second was also a primigravida who had a second-trimester abortion at 17 weeks of gestation and failed to deliver the placenta but had no excessive bleeding. On USG (ultrasonogram), PAS was suspected, as the overlying myometrium is thinned out above the placental attachment. Both these cases were managed conservatively with good outcomes without any complications. ⁶

Dankher et al. also reported a P2L2A1 female with two previous CS deliveries with secondary severe hemorrhage following a spontaneous second-trimester abortion, and underwent an emergency subtotal hysterectomy. On the cut section, the placenta was adhered to the anterior and fundal area of the uterus and was reported as placenta increta on HPE later on. ⁷

All these case reports cited above highlight PAS in non-placenta previa cases, irrespective of their previous CS delivery status. These were also reported or stated as “uterine body PAS” in various case reports. ⁶ These cases highlighted that the normal location of the placenta does not exclude PAS. A placenta located in the uterine fundus can also be a PAS. Uterine body PAS can be easily missed on prenatal ultrasound and is mainly encountered during delivery as a retained placenta or hemorrhage during attempts of manual removal.

Assisted reproductive technology (frozen embryo transfer with HRT [hormone replacement therapy]) and a previous uterine procedure, including a previous cesarean section delivery, were strong risk factors for PAS without placenta previa. ⁴ Women with more than six previous cesarean deliveries exhibited an incidence of 4.7% for non-previa placenta accreta, compared to a significantly lower incidence of 0.03% in women with no prior cesarean sections. ³

PAS in the absence of placenta previa is associated with a lower risk of invasive placentation, reduced blood loss, and decreased likelihood of hysterectomy; however, it poses greater challenges for prenatal diagnosis compared to PAS cases complicated by placenta previa. ⁴

Histopathological examination of PAS typically reveals a complete or partial absence of the decidua basalis and impaired development of the fibrinoid layer (Nitabuch layer). This disruption permits abnormal invasion of the chorionic villi into the myometrium. Two principal theories have been proposed to explain the pathogenesis of PAS: one implicates the absence or deficiency of the decidua, often secondary to prior uterine surgery or instrumentation, which allows abnormal chorionic villous invasion; the other suggests unregulated penetration of chorionic villi driven by factors secreted by cytotrophoblasts. Cohen et al. demonstrated that cytotrophoblasts secrete factors promoting invasion, while the decidua appears to play a limited role in regulating cytotrophoblast invasion in vitro. This latter mechanism may particularly underlie non-previa PAS cases, where there is no history of uterine surgery, instrumentation, or congenital uterine anomalies. ⁸

In contrast, Garmi et al. demonstrated in vitro that a deliberate sharp incision of the decidua, simulating a CS, significantly enhanced the invasive potential of trophoblastic cells. Furthermore, complete reapproximation of the incised decidual edges in vitro appeared to restore the integrity of the decidua, thereby limiting the extent of trophoblastic invasion. ⁹ They suggested that placenta accreta does not arise through excessive trophoblast invasiveness or proliferation, and the absence of decidua is of more importance in the pathogenesis. But trophoblasts may also regulate their development at an unfavorable intramyometrial implantation site, i.e., scar site, by producing hyaluronic acid. ¹⁰

The role of surgical technique, indication, and stage of labor while performing CS are also stated as important factors in the etiopathogenesis of PAS as they affect the healing of the cesarean scar site. This is because, histologically, the lower uterine segment constitutes a part of the cervix and is characterized by a high collagen content, which increases progressively as you approach towards uterine cervix. ¹¹

Osser OV et al. conducted a transvaginal ultrasound examination of the cesarean scar after 6–9 months of cesarean to know defects, if any, and concluded that CS performed in advanced labor is associated with increased risk of CS site defects. ¹² Immunocytochemical analysis of wound defects after cesarean showed a complete absence of growth factors. The decidua fails to develop beneath the uterine incision due to the thinness of the uterine segment and its relatively poor blood supply; consequently, only the amniotic layer is present in this region. ¹¹

This underscores the potential role of surgical technique in mitigating these issues. Specifically, utilizing a higher incision in the lower uterine segment, referred to as a “short superior” incision, may offer a straightforward solution. Although precise anatomical landmarks for this area are not well defined, Shao et al. proposed that making the incision in the upper portion of the lower uterine segment, approximately 2–3 cm above the vesico-uterine serosa at the thicker, wider muscular region, can significantly reduce intraoperative blood loss, facilitate easier surgical repair, prevent bladder adhesions to the suture line, and decrease overall operative time. ¹³ At this anatomical level, the blood supply is maintained by both direct and anastomotic branches of the uterine arteries, which facilitates optimal healing and the appropriate release of growth factors. ¹¹

Conservative management of PAS

Uterine body PAS were difficult to diagnose antenatally, and hence planning and operating them at a tertiary care facility is difficult. As per our literature search, we only found reported case reports of uterine body PAS diagnosed or suspected when the placenta fails to separate after delivery of the baby in both normal or cesarean delivery. MRP in such cases will lead to massive hemorrhage, and some reported cases were also diagnosed after emergency lifesaving hysterectomy, even in primigravida patients. ³

Diagnosis and management in such cases, particularly in cases of vaginal delivery with retained placenta or even when encountered during CS done at a secondary care setup, are challenging. Whether to attempt MRP in cases of retained placenta in this era of PAS cases is also a big question. Perlman et al. stated that retained placenta should be reviewed for the presence of any high-risk factor for uterine body PAS, including previous uterine surgery, IVF (In vitro fertilization) conception, prior history of retained placenta, or any uterine anomaly. There is currently no uniform consensus regarding the optimal timing for diagnosing retained placenta during the third stage of labor in the absence of postpartum hemorrhage; in some cases, waiting up to 60 minutes before intervention may be considered. ¹⁴

Ramadan et al. reported that placenta accreta accounts for 8.5%–50% of cases of retained placenta. Without reliable imaging modalities, the duration of placental retention can help distinguish between an adherent normal placenta and PAS. A longer duration of retention favors true accreta, whereas spontaneous separation within 24 hours is usually associated with a normally adherent placenta.

Given the recent surge in PAS incidence, the routine use of MRP in all cases of retained placenta warrants re-evaluation. Even in the presence of significant postpartum hemorrhage, MRP may exacerbate bleeding when invasive forms of PAS are present. Because the diagnostic accuracy of sonography for non-previa PAS remains limited, it may be prudent to avoid MRP in patients with a high clinical risk of PAS. ⁶ Even when attempting MRP, if a clear separation plane between the placenta and uterine wall is particularly difficult to establish, PAS should be strongly suspected, and preparations must be made for potential massive hemorrhage and hysterectomy. ⁷ This approach was also adopted in our case.

Once performing a CS and encountering a retained placenta, we recommend exteriorizing the uterus and inspecting for signs of PAS. MRP should not be attempted, particularly if the plane of cleavage is not felt/seen, no postpartum hemorrhage, and in a resource-limited facility. In fact, conservative management with leaving the placenta in situ and observation and follow-up is also reported with good success rates. When conservative management is employed for PAS, it mandates meticulous and close observation of these patients for several months and counseling regarding unpredictable outcomes. ⁶

Other than this, several conservative surgical techniques have been reported. Mousa et al., reported conservative management with surgical resection of the invaded part of the uterine wall along with the PAS, followed by uterine reconstruction along with bilateral ligation of the uterine arteries at low and high levels. ¹⁵ Nguyen et al. reported using a helium plasma device to fulgurate placenta accreta in a case where the volume of adhered placenta was 12.76 cc out of a total placental volume of 466 cc. They observed adequate hemostasis of the retained placental bed with minimal blood loss and no complications and further suggested this technique as a safer alternative for the management of PAS—particularly focal PAS—thereby avoiding a cesarean hysterectomy. ¹⁶

These conservative surgical options can be considered in cases of focal PAS, i.e., where the placenta is adherent to the myometrium only in a small, localized area (such as near a previous uterine scar) and the major portion of the placenta still demonstrates a definable plane of cleavage. In our case, however, the major part of the placenta was adherent with only a small area separating; therefore, conservative surgical approaches were not applicable. In conclusion, the role of these conservative surgeries in uterine body PAS does not seem promising due to a larger area of adherence of the placenta and resection of the fundal area, and reconstitution can itself be quite tricky.

Although there is a lot of upcoming research and data on PAS, non-previa PAS is still unaddressed. Guidelines for management, tools for early suspicion and management when encountered as a surprise, and research toward its pathogenesis have a long way to go.

Conclusions

In conclusion, a normally placed placenta also does not rule out PAS. Previous cesarean delivery increases the risk of PAS with placenta previa as well as PAS in non-previa cases. In the case of a retained placenta, the time for spontaneous separation can be individualized. MRP in this era of PAS should be considered only if the cleavage plane is felt or seen. Conservative management, particularly in uterine body PAS and resource-limited settings, with leaving the placenta in situ, should be strongly considered.

Ethical Approval

No ethical approval required.

Informed Consent

Informed consent was obtained from patient to publish this case report.