Indicated preterm birth for placenta accreta

[French survey on the management strategy for placenta accreta spectrum]

OBJECTIVE

Placenta accreta belongs to placenta accreta spectrum and is defined by an adhesion or even invasion of the placental villi in the myometrium. The main risk factor is a history of cesarean section. Its incidence is increasing following an increase in the cesarean section rate in recent years and the cause of severe maternal morbidity (hemorrhage, transfusions, hysterectomy). Treatment can be radical by cesarean section-hysterectomy or conservative with an attempt at uterine preservation. American, English, Canadian and international recommendations have been established but there are no French recommendations to date. The objective of this study was to investigate management strategy for placenta accreta in type III maternity hospitals in France.

MATERIALS AND METHODS

An anonymous questionnaire was sent by email to the obstetrics referents of the university hospital centers in France with type III maternity.

RESULTS

Forty-eight centers were approached, with a participation rate of 77%.

CONCLUSION

The management of placenta accreta spectrum in France is relatively heterogeneous on several points such as multidisciplinary management, evaluation by placental MRI, preoperative urological evaluation, treatment adopted as first-line, cesarean section-hysterectomy or conservative treatment, therapeutic strategy according to the placental invasion. However, the literature is currently poor, which may explain divergent treatment.

Complicated placenta accreta spectrum: identifying a high-risk cohort

OBJECTIVE

To assess differences in the perioperative complication rate between patients with placenta accreta spectrum (PAS) with and without complicating factors.

METHODS

This retrospective cohort study included subjects who underwent cesarean hysterectomy with histology-proven PAS between 23 0/7 and 42 0/7 weeks gestational age (GA) from 1 July 2008 to 11 April 2017. Perioperative outcomes were compared between those with uncomplicated PAS and "complicated PAS," defined as PAS subjects who experienced ≥2 bleeding episodes, preterm premature rupture of membranes (PPROM), or premature contractions requiring tocolysis.

RESULTS

Overall, 26 complicated PAS and 27 uncomplicated PAS cases were compared; no difference in the rate of perioperative complications was identified. An increased proportion of complicated PAS cases required blood product transfusion before delivery: 2 (40%), 3 (27.3%), and 2 patients (20%) for those with PPROM, preterm contractions, and ≥2 bleeding episodes respectively, compared to patients with uncomplicated PAS, having no transfusions (p = .001). Time of delivery was earlier for patients with complicated compared to uncomplicated PAS (median GA 30.9 [Q1 = 27.9; Q3 = 31.9] and 34.9 [Q1 = 32.1; Q3 = 35.7], p < .001). Median birthweights were lower (p < .0144) and maternal length of stay longer (p < .0012) for complicated PAS.

CONCLUSION

Patients with complicated PAS were not at higher risk for perioperative complications but were associated with earlier delivery, required more antenatal blood transfusions, and had a longer LOS.

Bioengineering Approaches for Placental Research

Research into the human placenta's complex functioning is complicated by a lack of suitable physiological in vivo models. Two complementary approaches have emerged recently to address these gaps in understanding, computational in silico techniques, including multi-scale modeling of placental blood flow and oxygen transport, and cellular in vitro approaches, including organoids, tissue engineering, and organ-on-a-chip models. Following a brief introduction to the placenta's structure and function and its influence on the substantial clinical problem of preterm birth, these different bioengineering approaches are reviewed. The cellular techniques allow for investigation of early first-trimester implantation and placental development, including critical biological processes such as trophoblast invasion and trophoblast fusion, that are otherwise very difficult to study. Similarly, computational models of the placenta and the pregnant pelvis at later-term gestation allow for investigations relevant to complications that occur when the placenta has fully developed. To fully understand clinical conditions associated with the placenta, including those with roots in early processes but that only manifest clinically at full-term, a holistic approach to the study of this fascinating, temporary but critical organ is required.

Triple P with T-shaped lower segment suture; an effective novel alternative to hysterectomy in morbidly adherent anterior placenta previa

PURPOSE

To evaluate the efficacy and safety of the Triple-P procedure as a conservative method in women with morbidly adherent placenta (MAP).

MATERIALS AND METHODS

A prospective trial conducted on 20 women performing elective cesarean sections (CS) at 37 weeks for anterior placenta previa accreta or increta. All women were young aged with low parity and previous CS deliveries. Triple-P procedure involved delivery of the fetus through a uterine incision placed above the upper border of the placenta, bilateral uterine arteries ligation immediately after delivery of the fetus followed by placental nonseparation and myometrial excision with reconstruction of the uterine wall in a T-shaped manner. The study outcome measures included duration of surgery, amount of intra and postoperative blood loss, Percentage of hemoglobin (Hb %) reduction, the need to perform hysterectomy and postoperative complications.

RESULTS

Mean duration of surgery was 58 ± 1.8 min, mean intraoperative blood loss was 1.3 ± 0.3 l, mean postoperative blood loss was 180 ± 94 ml and mean Hb % reduction was 1.5 ± 0.1 g/dl. Only one case necessitated hysterectomy for severe bleeding.

CONCLUSION

Triple-P procedure is a novel effective weapon that can replace hysterectomy in suitable women with MAP, especially in young patients with low parity.

Coagulopathy in surgical management of placenta accreta spectrum

BACKGROUND

One of the major complications of the placenta accreta spectrum (PAS) is the development of coagulopathy. The detection, prevention and prompt treatment of coagulopathy may be lifesaving.

OBJECTIVE

Our objective was to study selected factors associated with coagulopathy in the management of PAS by a well-established multidisciplinary team.

STUDY DESIGN

This is a retrospective review of all patients with pathologically proven PAS (including placenta accreta, increta or percreta) who underwent surgery by our multidisciplinary team between January 2011 and February 2017. Coagulopathy in this setting was defined as a platelet count of <100,000/mm³, international normalized ratio >1.5, and/or fibrinogen <300 mg/dL based on institutional protocols developed by our Division of Transfusion Medicine & Coagulation. The outcomes of those patients with and without coagulopathy were compared with appropriate adjustments. Receiver operating characteristics curves (ROCs) were constructed to assess the ability of select variables to discriminate between women with and without coagulopathy, and the area under the curves (AUCs) were calculated.

RESULTS

Of 123 singleton patients with PAS, 37 (30.1%; 95%CI 22.1-39.0) developed coagulopathy and 86 (69.9%; 95%CI 61.0-77.9) did not. Baseline patient demographic characteristics did not differ significantly between these groups. Estimated blood loss (median and Inter-quartile range) was 2100cc (1800, 400) and 1400 (1000, 2500) in the presence and absence of coagulopathy, respectively (P < 0.01). The overall number of units of red blood cells (RBC) transfused was greatest in the coagulopathy group [3 (2, 9) vs. 1 (0, 4); P < 0.01]. Univariate regression analysis confirmed the association between coagulopathy and (i) the number of units of RBC's transfused, and (ii) the estimated blood loss. ROC curves showed that an estimated blood loss ≥ 1500 mL had the best discriminating power. Depth and/or severity of placental invasion were not associated with coagulopathy in patients with PAS.

CONCLUSIONS

Coagulopathy in patients with PAS undergoing hysterectomy is strongly associated with blood loss and replacement. It may be prudent to establish protocols that aggressively monitor for, and treat, coagulopathy when EBL exceeds 1500 mL in such surgeries, prior to the development of clinical coagulopathy which if uncorrected may lead to massive blood loss.

Outcomes of Planned Compared With Urgent Deliveries Using a Multidisciplinary Team Approach for Morbidly Adherent Placenta

OBJECTIVE

To compare outcomes between planned and urgent cesarean hysterectomy for morbidly adherent placenta managed by a multidisciplinary team.

METHODS

This is a retrospective case-control study of women with singleton pregnancies with antenatally suspected and pathologically confirmed morbidly adherent placenta who underwent cesarean hysterectomy between January 1, 2011, and February 30, 2017. Timing of delivery was classified as either planned (delivery at 34-35 weeks of gestation) or urgent (need for urgent delivery as a result of uterine contractions, bleeding, or both). The primary outcome variable was composite maternal morbidity. Logistic regression analysis was used to evaluate risk factors for urgent delivery.

RESULTS

One hundred thirty patients underwent hysterectomy. Sixty (46.2%) required urgent delivery. Composite maternal morbidity was identified in 34 (56.7%) of the urgent and 26 (37.1%) of the planned deliveries (P=.03). Fewer units of red blood cells and fresh frozen plasma were transfused in the planned delivery group (red blood cells, median interquartile range 3 [0-8] versus 1 [0-4], P=.02; fresh frozen plasma, median interquartile range 1 [0-2] versus 0 [0-0], P=.001). Rates of low Apgar score and respiratory distress syndrome were higher in the urgent compared with the planned delivery group (5-minute Apgar score less than 7, 34 [59.6%] versus 14 [23.3%], P<.01; respiratory distress syndrome, 34 [61.8%] versus 16 [27.1%], P<.01). A history of two or more prior cesarean deliveries was an independent predictor of urgent delivery (adjusted odds ratio 11.4, 95% CI 1.8-71.1).

CONCLUSION

Women with morbidly adherent placenta requiring urgent delivery have a worse outcome than women with planned delivery. Women with morbidly adherent placenta and two or more prior cesarean deliveries are at increased risk for urgent delivery. In such women, scheduling delivery before the standard 34- to 35-week timeframe may be reasonable.

Increased incidence of respiratory distress syndrome in neonates of mothers with abnormally invasive placentation

BACKGROUND

The incidence of abnormally invasive placentation (AIP) is increasing. Most of these pregnancies are delivered preterm. We sought to characterize neonatal outcomes in AIP pregnancies.

METHODS

In this retrospective case-control study (2006-2015), AIP neonates (n = 108) were matched to two controls each for gestational age, antenatal glucocorticoid exposure, sex, plurity, and delivery mode. Medical records were reviewed for neonatal and maternal characteristics/outcomes. Univariate and multivariate Poisson regressions were performed to determine relative risk ratios (RR).

RESULTS

There were no mortalities. All neonatal outcomes were similar except for respiratory distress syndrome (RDS), which affected 37% of AIP neonates (versus 21% of controls). AIP neonates required respiratory support (64.8% vs. 51.9%) and continuous positive airway pressure (53.7% vs. 42.1%) for a longer duration. Univariate regression yielded elevated RRs for RDS for AIP (RR 1.78, 95% CI 1.24-2.54), placenta previa (RR = 1.94, 95% CI 1.36-2.76), and placenta previa with bleeding (RR 2.29, 95% CI 1.36-3.86). One episode of bleeding had a RR of 2.43 (95% CI 1.57-3.76), 2 or more episodes had a RR of 2.95 (95% CI 1.96-4.44), and bleeding/abruption as the delivery indication had a RR of 2.57 (95% CI 1.82-3.64). A multivariate regression stratifying for AIP and evaluating the combined and individual associations of AIP, bleeding, placenta previa, and GA, resulted in elevated RRs for placenta previa alone (RR 2.16, 95% CI 1.15-4.06) and placenta previa and bleeding (RR 1.69, 95% CI 1.001-2.85).

CONCLUSIONS

The increased incidence of RDS at later gestational ages in AIP is driven by placenta previa. AIP neonates required respiratory support for a longer duration than age-matched controls. Providers should be prepared to counsel expectant parents and care for affected neonates.

Pilot Study of Intra-Aortic Balloon Occlusion to Limit Morbidity in Patients with Adherent Placentation Undergoing Cesarean Hysterectomy

Objective  We study whether using an intra-aortic balloon (IAB) during cesarean hysterectomy decreases delivery morbidity in patients with suspected morbidly adherent placentation. Study Design  This is a retrospective cohort study of deliveries complicated by suspected abnormal placentation between 2009 and 2016 comparing maternal and neonatal outcomes with an IAB placed prior to cesarean hysterectomy versus no IAB. The primary outcome included quantified blood loss (QBL). Results  Thirty-five cases were reviewed, 16 with IAB and 19 without IAB. No difference was seen in median QBL between the two groups (1,351 vs. 1,397 mL; p  = 0.90). There were no significant differences in overall surgical complications (19% IAB, 21% no IAB; p  = 0.86), bladder complications (12 vs. 21%; p  = 0.66), intensive care unit admissions (12 vs. 26%; p  = 0.41), surgical duration (2.9 vs. 2.8 hour; p  = 0.83), or blood transfusions (median 2 vs. 2; p  = 0.27) between the two groups. There was one groin hematoma at the balloon site that was managed conservatively. There were no complications involving thrombosis or limb ischemia in the IAB group. Conclusion  While we did not detect statistically significant differences, larger studies may be warranted given the potential for extreme morbidity in these cases. This study highlights the potential use of an IAB in the management of these cases.

Society for Maternal-Fetal Medicine (SMFM) Consult Series #44: Management of bleeding in the late preterm period

Third-trimester bleeding is a common complication arising from a variety of etiologies, some of which may initially present in the late preterm period. Previous management recommendations have not been specific to this gestational age window, which carries a potentially lower threshold for delivery. The purpose of this document is to provide guidance on management of late preterm (34 0/7-36 6/7 weeks of gestation) vaginal bleeding. The following are Society for Maternal-Fetal Medicine recommendations: (1) we recommend delivery at 36-37 6/7 weeks of gestation for stable women with placenta previa without bleeding or other obstetric complications (GRADE 1B); (2) we do not recommend routine cervical length screening for women with placenta previa in the late preterm period due to a lack of data on an appropriate management strategy (GRADE 2C); (3) we recommend delivery between 34 and 37 weeks of gestation for stable women with placenta accreta (GRADE 1B); (4) we recommend delivery between 34 and 37 weeks of gestation for stable women with vasa previa (GRADE 1B); (5) we recommend that in women with active hemorrhage in the late preterm period, delivery should not be delayed for the purpose of administering antenatal corticosteroids (GRADE 1B); (6) we recommend that fetal lung maturity testing should not be used to guide management in the late preterm period when an indication for delivery is present (GRADE 1B); and (7) we recommend that antenatal corticosteroids should be administered to women who are eligible and are managed expectantly if delivery is likely within 7 days, the gestational age is between 34 0/7 and 36 6/7 weeks of gestation, and antenatal corticosteroids have not previously been administered (GRADE 1A).

Multidisciplinary team learning in the management of the morbidly adherent placenta: outcome improvements over time

BACKGROUND

Morbidly adherent placenta (MAP) is a serious obstetric complication causing mortality and morbidity.

OBJECTIVE

To evaluate whether outcomes of patients with MAP improve with increasing experience within a well-established multidisciplinary team at a single referral center.

STUDY DESIGN

All singleton pregnancies with pathology-confirmed MAP (including placenta accreta, increta, or percreta) managed by a multidisciplinary team between January 2011 and August 2016 were included in this retrospective study. Turnover of team members was minimal, and cases were divided into 2 time periods so as to compare 2 similarly sized groups: T1 = January 2011 to April 2014 and T2 = May 2014 to August 2016. Outcome variables were estimated blood loss, units of red blood cell transfused, volume of crystalloid transfused, massive transfusion protocol activation, ureter and bowel injury, and neonatal birth weight. Comparisons and adjustments were made by use of the Student t test, Mann-Whitney U test, χ² test, analysis of covariance, and multinomial logistic regression.

RESULTS

A total of 118 singleton pregnancies, 59 in T1 and 59 in T2, were managed during the study period. Baseline patient characteristics were not statistically significant. Forty-eight of 59 (81.4%) patients in T1 and 42 of 59 (71.2%) patients in T2 were diagnosed with placenta increta/percreta. The median [interquartile range] estimated blood loss (T1: 2000 [1475-3000] vs T2: 1500 [1000-2700], P = .04), median red blood cell transfusion units (T1: 2.5 [0-7] vs T2: 1 [0-4], P = .02), and median crystalloid transfusion volume (T1: 4200 [3600-5000] vs T2: 3400 [3000-4000], P < .01) were significantly less in T2. Also, a massive transfusion protocol was instituted more frequently in T1: 15/59 (25.4%) vs 3/59 (5.1%); P < .01. Neonatal outcomes and surgical complications were similar between the 2 groups.

CONCLUSION

Our study shows that patient outcomes are improved over time with increasing experience within a well-established multidisciplinary team performing 2-3 cases per month. This suggests that small, collective changes in team dynamics lead to continuous improvement of clinical outcomes. These findings support the development of centers of excellence for MAP staffed by stable, core multidisciplinary teams, which should perform a significant number of these procedures on an ongoing basis.

Morbidly Adherent Placenta: Its Management and Maternal and Perinatal Outcome

OBJECTIVES

The aim of the study was to identify the risk factors predisposing to morbidly adherent placenta and to study the different modes of management and the obstetric and neonatal outcome of these patients.

METHODS

This was a retrospective cum prospective observational study conducted in the Department of Obstetrics and Gynaecology in a tertiary care referral hospital in Mumbai from January 2012 to November 2014.

RESULTS

The incidence of morbidly adherent placenta was 1.32 per 1000 pregnancies with patient profile comprising second gravida in the age group 26-28 years; 90 % of the patients in this study had previous Caesarean section and co-existing placenta praevia was diagnosed in 63 %. Fifty-three per cent of the women delivered between 35 and 38 weeks and 40 % had elective deliveries. Caesarean section was the mode of delivery in 90 % of the patients. Prophylactic balloon placement in the internal iliac artery followed by classical Caesarean section, uterine artery embolization and post-operative methotrexate was done in 27 % which preserved the uterus and was associated the blood loss of 1000-2000 mL.

CONCLUSION

Antenatal diagnosis of morbidly adherent placenta allows for multidisciplinary planning in an attempt to minimize potential maternal or neonatal morbidity and mortality.

Placenta accreta spectrum: accreta, increta, and percreta

Placenta accreta can lead to hemorrhage, resulting in hysterectomy, blood transfusion, multiple organ failure, and death. Accreta has been increasing steadily in incidence owing to an increase in the cesarean delivery rate. Major risk factors are placenta previa in women with prior cesarean deliveries. Obstetric ultrasonography can be used to diagnose placenta accreta antenatally, which allows for scheduled delivery in a multidisciplinary center of excellence for accreta. Controversies exist regarding optimal management, including optimal timing of delivery, surgical approach, use of adjunctive measures, and conservative (uterine-sparing) therapy. We review the definition, risk factors, diagnosis, management, and controversies regarding placenta accreta.

Estimating the Radiation Dose to the Fetus in Prophylactic Internal Iliac Artery Balloon Occlusion: Three Cases

Background. Although radiation exposure is of great concern to expecting patients, little information is available on the fetal radiation dose associated with prophylactic internal iliac artery balloon occlusion (IIABO). Here we estimated the fetal radiation dose associated with prophylactic IIABO in Caesarean section (CS). Cases. We report our experience with the IIABO procedure in three consecutive patients with suspected placenta previa/accreta. Fetal radiation dose measurements were conducted prior to each CS by using an anthropomorphic phantom. Based on the simulated value, we calculated the fetal radiation dose as the absorbed dose. We found that the fetal radiation doses ranged from 12.88 to 31.6 mGy. The fetal radiation dose during the prophylactic IIABOs did not exceed 50 mGy. Conclusion. The IIABO procedure could result in a very small increase in the risk of harmful effects to the fetus.

Maternal morbidity in patients with morbidly adherent placenta treated with and without a standardized multidisciplinary approach

OBJECTIVE

The purpose of this study was to test the hypothesis that a standardized multidisciplinary treatment approach in patients with morbidly adherent placenta, which includes accreta, increta, and percreta, is associated with less maternal morbidity than when such an approach is not used (nonmultidisciplinary approach).

STUDY DESIGN

A retrospective cohort study was conducted with patients from 3 tertiary care hospitals from July 2000 to September 2013. Patients with histologically confirmed placenta accreta, increta, and percreta were included in this study. A formal program that used a standardized multidisciplinary management approach was introduced in 2011. Before 2011, patients were treated on a case-by-case basis by individual physicians without a specific protocol (nonmultidisciplinary group). Estimated blood loss, transfusion of packed red blood cells, intraoperative complications (eg, vascular, bladder, ureteral, and bowel injury), neonatal outcome, and maternal postoperative length of hospital stay were compared between the 2 groups.

RESULTS

Of 90 patients with placenta accreta, 57 women (63%) were in the multidisciplinary group, and 33 women (37%) were in the nonmultidisciplinary group. The multidisciplinary group had more cases with percreta (P = .008) but experienced less estimated blood loss (P = .025), with a trend to fewer blood transfusions (P = .06), and were less likely to be delivered emergently (P = .001) compared with the nonmultidisciplinary group. Despite an approach of indicated preterm delivery at 34-35 weeks of gestation, neonatal outcomes were similar between the 2 groups.

CONCLUSION

The institution of a standardized approach for patients with morbidly adherent placentation by a specific multidisciplinary team was associated with improved maternal outcomes, particularly in cases with more aggressive placental invasion (increta or percreta), compared with a historic nonmultidisciplinary approach. Our standardized approach was associated with fewer emergency deliveries.

Risk factors for unscheduled delivery in patients with placenta accreta

OBJECTIVE

Patients with suspected placenta accreta have improved outcomes with scheduled delivery. Our objective was to identify risk factors for unscheduled delivery in patients with suspected placenta accreta.

STUDY DESIGN

This was a cohort study of women with antenatally suspected placenta accreta. Women who delivered prior to a planned delivery date were compared with women who had a scheduled delivery. Data were analyzed using a Student t test, χ(2), logistic regression, and survival analyses. Variables included in the analyses were episodes of antenatal vaginal bleeding, preterm premature rupture of membranes (PPROM), uterine contractions, prior cesarean deliveries, interpregnancy interval, parity, and patient demographic factors. A value of P < .05 was considered significant.

RESULTS

Seventy-seven women with antenatal suspicion for placenta accreta were identified. Thirty-eight (49.4%) had an unscheduled delivery. Demographics were similar between groups. Unscheduled patients delivered earlier (mean 32.3 vs 35.7 weeks, P < .001) and were significantly more likely to have had vaginal bleeding (86.8% vs 35.9%, P < .001) and uterine activity (47.4% vs 2.6%, P < .001). Each episode of antenatal vaginal bleeding was associated with an increased risk of unscheduled delivery (adjusted odds ratio, 3.8; 95% confidence interval, 1.8-7.8). Risk of earlier delivery was even greater when associated with PPROM (P < .001).

CONCLUSION

Among women with suspected placenta accreta, those with antenatal vaginal bleeding were more likely to require unscheduled delivery. This risk increases further in the setting of PPROM and/or uterine contractions. These clinical factors should be considered when determining the optimal delivery gestational age for women with placental accreta.

Prenatal diagnosis of abnormally invasive placenta reduces maternal peripartum hemorrhage and morbidity

OBJECTIVE

Abnormally invasive placenta (AIP) poses diagnostic and therapeutic challenges. We analyzed clinical cases with confirmed placenta increta or percreta.

DESIGN

Retrospective case series.

SETTING

Multicenter study.

POPULATION

Pregnant women with AIP.

METHODS

Chart review.

MAIN OUTCOME MEASURES

Prenatal detection rates, treatment choices, morbidity, mortality and short-term outcome.

RESULTS

Sixty-six cases were analyzed. All women and all but three fetuses survived; 57/64 women (89%) had previous uterine surgery. In 26 women (39%) the diagnosis was not known before delivery (Group 1), in the remaining 40 (61%) diagnosis had been made between 14 and 37 weeks of gestation (Group 2). Placenta previa was present in 36 women (54%). In Groups 1 and 2, 50% (13/26) and 62% (25/40) of the women required hysterectomy, respectively. In Group 1 (unknown at the time of delivery) 69% (9/13) required (emergency) hysterectomy for severe hemorrhage in the immediate peripartum period compared with only 12% (3/25) in Group 2 (p = 0.0004). Mass transfusions were more frequently required in Group 1 (46%, 12/26 vs. 20%, 8/40; p = 0.025). In 18/40 women (45%) from Group 2 the placenta was intentionally left in situ; secondary hysterectomies and infections were equally frequent (18%) among these differently treated women. Overall, postpartum infections occurred in 11% and 20% of women in Groups 1 and 2, respectively.

CONCLUSIONS

AIP was known before delivery in more than half of the cases. Unknown AIP led to significantly more emergency hysterectomies and mass transfusions during or immediately after delivery. Prenatal diagnosis of AIP reduces morbidity. Future studies should also address the selection criteria for cases appropriate for leaving the placenta in situ.

Morbidly adherent placenta: evaluation of ultrasound diagnostic criteria and differentiation of placenta accreta from percreta

OBJECTIVES

To evaluate the diagnostic accuracy of two-dimensional (2D) gray-scale and color Doppler and three-dimensional (3D) power Doppler sonographic criteria for morbidly adherent placenta (MAP), and to identify criteria to help distinguish placenta accreta from placenta percreta.

METHODS

We enrolled 187 patients with placenta previa and history of uterine surgery and performed transabdominal and transvaginal ultrasound examination for early detection of MAP. With 2D gray-scale transabdominal and transvaginal ultrasonography, we investigated loss/irregularity of the echolucent area between the uterus and the placenta ('clear space'), thinning or interruption of the hyperechoic interface between the uterine serosa and the bladder wall and the presence of turbulent placental lacunae with high-velocity flow (>15 cm/s). Using transabdominal 3D power Doppler, we evaluated the hypervascularity of the uterine serosa-bladder wall interface and irregular intraplacental vascularization. Ultrasound findings were reviewed against the final diagnosis made during Cesarean section (CS).

RESULTS

MAP was detected on CS in 41 patients. All of them had an anterior placenta previa (34 major and seven minor) and had undergone at least one previous CS. The evaluated sonographic criteria showed good diagnostic performance; in MAP patients at least two out of five criteria were detected, with at most one of the criteria present in patients without MAP. Loss/irregularity of clear space used as a single criterion was responsible for the most false positives, demonstrating a low positive predictive value. Irregular intraplacental vascularization with tortuous confluent vessels affecting the entire width of the placenta, and hypervascularity of the entire uterine serosa-bladder wall interface, were only detected, on 3D power Doppler, in cases of placenta percreta.

CONCLUSIONS

The reviewed ultrasound criteria may be useful for the prenatal diagnosis of MAP and to differentiate between placenta accreta and placenta percreta; 3D power Doppler techniques were an important aid in the diagnosis.