Blood flow to the scarred gravid uterus at 22-24 weeks of gestation

Evaluation of Cesarean section scar using saline contrast sonohysterography in women with previous Cesarean scar pregnancy

OBJECTIVE

To evaluate Cesarean scar defects using saline contrast sonohysterography (SCSH) in women with a history of Cesarean scar pregnancy (CSP).

METHODS

A cohort of 38 non-pregnant women with a history of CSP treated with combined local and systemic methotrexate was investigated prospectively by SCSH. For the purpose of analysis, they were classified, according to the modified Delphi consensus criteria for CSP in early gestation, into three subgroups based on the depth of the gestational sac herniation in the midsagittal plane. Subgroup A included eight (21.1%) cases, in which the largest part of the gestational sac protruded towards the uterine cavity; Subgroup B included 20 (52.6%) cases, in which the largest part of the gestational sac was embedded in the myometrium; and Subgroup C included 10 (26.3%) cases, in which the gestational sac was located partially outside the outer contour of the cervix or uterus.

RESULTS

SCSH revealed that all women in Subgroup C had a uterine niche. The median niche length (P = 0.006) and depth (P = 0.015) were significantly greater in Subgroup C than in Subgroups A or B. The median residual myometrial thickness (RMT) was significantly lower in Subgroup C than in Subgroups A or B (P = 0.006).

CONCLUSIONS

Women with prior CSP who had a gestational sac protruding beyond the serosal line had a significantly greater niche length and depth, and lower RMT. This knowledge may guide individualized risk counseling. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Unexpected Dramatic Evolution of Placenta Increta: Case Report and Literature Review

Placental morbid adherence is a known risk factor for postpartum hemorrhage. The incidence of abnormal placental attachment has been increasing over the past few decades, mainly due to rising rates of cesarean deliveries, advanced maternal age, and the use of assisted reproductive technologies. Cesarean section is a significant risk factor for placenta increta, as it disrupts the normal architecture of the uterine wall, making it more difficult for the placenta to detach after delivery. We present the case of a woman who underwent a cesarean section at 28 weeks due to anterior placenta previa, accompanied by hemorrhage and rupture of membranes. Following the delivery, she experienced normal postoperative bleeding and was discharged home after five days. However, six weeks later, she presented with heavy bleeding, leading to the decision to perform a total hysterectomy. The levels of HCG were found to be low. The pathological examination of the specimens confirmed a diagnosis of placenta increta, as it revealed notable placental proliferation, necrotic villi, and placental invasion near the uterine serosa. Notably, we did not find any similar cases documented in the literature. Patients experiencing prolonged vaginal bleeding after childbirth and diagnosed with placenta accreta should be closely monitored through ultrasound examinations; abnormal proliferation of the placenta can occur, and prompt detection is crucial for appropriate management.

A Retrospective Cohort Study to Determine Whether the Previous Route of Delivery Affects the Uterine Artery Blood Flow

INTRODUCTION

 In our study, we aimed to investigate the effect of the previous delivery route on uterine artery pulsatility index (PI) and obstetric outcome. We aim to assess the effects of previous cesarean delivery (CD) and placental location on first- and second-trimester uterine artery Doppler indices as well as first-trimester pregnancy-associated plasma protein-A (PAPP-A) multiples of the median (MoM) levels in the subsequent pregnancy.

MATERIALS AND METHODS

 We designed a retrospective cohort study to collect the participants' clinical and uterine artery Doppler. Data regarding pregnant women's first- and second-trimester exams, who were referred to our maternal-fetal medicine unit, were collected from hospital records between June 2015 and December 2019.

RESULTS

 Uterine artery PI MoM values were not different between the cases with the anterior and non-anterior placental locations. No significant difference was found in the first- and second-trimester uterine artery PI MoM values by delivery route (p = 0.57). However, the intrauterine growth restriction rate was higher in the CD group (p < 0.001).

CONCLUSION

 In this study, we compared the uterine blood flow indices between the previous cesarean and vaginal delivery groups. We observed no significant difference between the patients with different delivery routes.

Placenta accreta spectrum ultrasound stage and fetal growth

OBJECTIVE

to evaluate fetal growth in pregnancies complicated by placenta accreta spectrum (PAS) and to compare fetal growth between cases stratified by ultrasound stage of PAS.

METHODS

This was a prospective multicenter cohort study of women diagnosed with PAS between January 2018 and December 2021. We grouped participants into cases by ultrasound stage (PAS stage 1-3) and controls (PAS0). Fetal growth centiles at three timepoints with median gestational ages of 21 ± 1 weeks (interquartile range [IQR], 20 ± 1-22 ± 0 weeks), 28 ± 0 weeks (IQR, 27 ± 0-28 ± 5 weeks), and 33 ± 0 weeks (IQR, 32 ± 1-34 ± 0 weeks) and birth weight centiles were compared between cases and controls and between those with PAS stratified by ultrasound stage.

RESULTS

A total of 53 women met inclusion criteria, with a mean age of 37 years (standard deviation, ±4.0 years) and body mass index of 27 kg/m² (standard deviation, ±5.8 kg/m² ). Median (IQR) fetal weight centiles were around the 50th centile at each timepoint, with no difference between groups. The incidence of small for gestational age (birth weight ≤ 10th percentile) and large for gestational age (birth weight ≥ 90th percentile) was 11.3% (n = 6) and 15.1% (n = 8), respectively, with no differences by ultrasound stage. The median birth weight centile was 64 (IQR, 26-85), with no differences between cases and controls or by ultrasound stage.

CONCLUSIONS

In our cohort, a diagnosis of PAS was not associated with fetal growth restriction.

Uterine artery Doppler indices throughout gestation in women with and without previous Cesarean deliveries: a prospective longitudinal case-control study

To determine whether a history of previous Cesarean delivery (CD) impacts uterine artery (UtA) Doppler indices throughout pregnancy. Women with and without CD (NCD) were prospectively enrolled for sequential assessments of the UtA mean/median pulsatility index (UtA-PI), resistance index (UtA-RI), and systolic/diastolic ratio (UtA-S/D) at 11-13 + 6, 14-19 + 6, 30-34 + 6, and 35-37 + 6 weeks' gestation. Data from 269/269, 246/257, 237/254, and 219/242 CD/NCD participants from each gestational period were available for analysis. Multiples of the median (MoMs) of UtA Doppler indices showed biphasic temporal (Δ) pattern; with an initial dropping until the second trimester, then a subsequent elevation until late in pregnancy (p < 0.05). The measurements and Δs of the UtA indices between CD and NCD were not different (p > 0.05). Mixed-effects modelling ruled out effects from nulliparity (n = 0 and 167 for CD and NCD, respectively) (p > 0.05). History of CD neither influenced the measurements nor the temporal changes of the UtA Doppler indices throughout pregnancy. The biphasic Δs of UtA Doppler indices added to the longitudinal data pool, and may aid in future development of a more personalized prediction using sequential/contingent methodologies, which may reduce the false results from the current cross-sectional screening.

Prospective Evaluation of the Ultrasound Signs Proposed for the Description of Uterine Niche in Nonpregnant Women

OBJECTIVES

To evaluate the new ultrasound-based signs for the diagnosis of post-cesarean section uterine niche in nonpregnant women.

METHODS

We investigated prospectively a cohort of 160 consecutive women with one previous term cesarean delivery (CD) between December 2019 and 2020. All women were separated into two subgroups according to different stages of labor at the time of their CD: subgroup A (n = 109; 68.1%) for elective CD and CD performed in latent labor at a cervical dilatation (≤4 cm) and subgroup B (n = 51; 31.9%); for CD performed during the active stage of labor (>4 cm).

RESULTS

Overall, the incidence of a uterine niche was significantly (P < .001) higher in women who had an elective (20/45; 44.4%) compared with those who had an emergent (21/115; 18.3%) CD. Compared with subgroup B, subgroup A presented with a significantly (P = .012) higher incidence of uterine niche located above the vesicovaginal fold and with a significantly (P = .0002) lower proportion of cesarean scar positioned below the vesicovaginal fold. There was a significantly (P < .001) higher proportion of women with a residual myometrial thickness (RMT) > 3 mm in subgroup A than in subgroup B and a significant negative relationship was found between the RMT and the cervical dilatation at CD (r = -0.22; P = .008).

CONCLUSIONS

Sonographic cesarean section scar assessment indicates that the type of CD and the stage of labor at which the hysterotomy is performed have an impact on the location of the scar and the scarification process including the niche formation and RMT.

Placenta accreta spectrum-a catastrophic situation in obstetrics

Placenta accreta is a significant obstetric complication in which the placenta is completely or focally adherent to the myometrium. The worldwide incidence of placenta accreta spectrum (PAS) is increasing day by day, mostly due to the increasing trends in cesarean section rates. The accurate and timely diagnosis of placenta accreta is important to improve the feto-maternal outcome. Although standard ultrasound is a reliable and primary tool for the diagnosis of placenta accreta, the absence of ultrasound findings does not preclude the diagnosis of placenta accreta. Therefore, clinical evaluation of risk factors is equally essential for the prediction of abnormal placental invasion. Pregnant women with a high impression or established diagnosis of placenta accreta should be managed by a multidisciplinary team in a specialist center. Traditionally, PAS has been managed by an emergency obstetric hysterectomy. Previously, few studies suggested a satisfactory success rate of conservative management in well-chosen cases, whereas few studies recommended delayed hysterectomy to reduce the amount of bleeding. The continuously increasing trends of PAS and the challenges for its routine management are the main motives behind this literature review.

Effect of previous cesarean sections on second-trimester uterine artery Doppler

AIM

In this study, we investigated the effects of previous cesarean sections on uterine artery Doppler indices.

METHODS

This prospective cohort study included 153 healthy pregnant women between 18 and 24 weeks of gestation. Seventy-three pregnant women without previous cesarean sections (control group) and 80 pregnant women with previous cesarean sections (study group) were compared in terms of uterine artery Doppler indices.

RESULTS

The mean uterine artery pulsatility index (PI) MoM value was 1.18 ± 0.40 in the study group and 1.07 ± 0.35 in the control group (P = 0.046). The number of patients with uterine artery PI values above 95 percentile was 18 (22.5%) in the study group and 5(6.8%) in the control group (P = 0.007). The mean gestational age at birth was significantly lower in the study group (38.2 ± 1.3 vs. 39 ± 1.0, P < 0.001). There was no significant difference between the mean PI, resistance index (RI) and systolic/diastolic (S/D) ratio values of the uterine artery (P = 0.16, 0.11, 0.08, respectively). When the comparison was made with the number of previous cesarean sections, all three index values of the patients who had had more than two cesarean sections were found to be significantly higher.

CONCLUSION

The Doppler flow indices of the uterine artery significantly increased in patients with more than two previous cesarean sections. When evaluating uterine artery Doppler indices in pregnant women with a history of previous cesarean sections, these factors should be considered.

Impact of placenta previa with placenta accreta spectrum disorder on fetal growth

OBJECTIVES

To evaluate fetal growth in pregnancies complicated by placenta previa with or without placenta accreta spectrum (PAS) disorder, compared with in pregnancies with a low-lying placenta.

METHODS

This was a multicenter retrospective cohort study of singleton pregnancies complicated by placenta previa with or without PAS disorder, for which maternal characteristics, ultrasound-estimated fetal weight and birth weight were available. Four maternal-fetal medicine units participated in data collection of diagnosis, treatment and outcome. The control group comprised singleton pregnancies with a low-lying placenta (0.5-2 cm from the internal os). The diagnosis of PAS and depth of invasion were confirmed at delivery using both a predefined clinical grading score and histopathological examination. For comparison of pregnancy characteristics and fetal growth parameters, the study groups were matched for smoking status, ethnic origin, fetal sex and gestational age at delivery.

RESULTS

The study included 82 women with placenta previa with PAS disorder, subdivided into adherent (n = 35) and invasive (n = 47) PAS subgroups, and 146 women with placenta previa without PAS disorder. There were 64 controls with a low-lying placenta. There was no significant difference in the incidence of small-for-gestational age (SGA) (birth weight ≤ 10^th percentile) and large-for-gestational age (LGA) (birth weight ≥ 90^th  percentile) between the study groups. Median gestational age at diagnosis was significantly lower in pregnancies with placenta previa without PAS disorder than in the low-lying placenta group (P = 0.002). No significant difference was found between pregnancies complicated by placenta previa with PAS disorder and those without for any of the variables. Median estimated fetal weight percentile was significantly lower in the adherent compared with the invasive previa-PAS subgroup (P = 0.047). Actual birth weight percentile at delivery did not differ significantly between the subgroups (P = 0.804).

CONCLUSIONS

No difference was seen in fetal growth in pregnancies complicated by placenta previa with PAS disorder compared with those without and compared with those with a low-lying placenta. There was also no increased incidence of either SGA or LGA neonates in pregnancies with placenta previa and PAS disorder compared with those with placenta previa with spontaneous separation of the placenta at birth. Adverse neonatal outcome in pregnancies complicated by placenta previa and PAS disorder is linked to premature delivery and not to impaired fetal growth. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Endometrium-free uterine closure technique and abnormal placental implantation in subsequent pregnancies

BACKGROUND

Abnormal placentation can result in massive hemorrhage, which is the leading cause of severe maternal morbidities and mortality in its management. Over the past 50 years, the incidence of placenta previa (PP), abnormal implantation of the placenta, and cesarean scar pregnancy have continued to rise. This coincides with the well-documented parallel rise in the rate of cesarean deliveries, the performance of multiple repeat cesarean deliveries and the adoption of newer uterine closure techniques. However, no studies have examined the role of uterine closure techniques in abnormal placentation in women with a history of a prior cesarean delivery.

OBJECTIVE

To assess the practicality of one specific uterine closure technique at cesarean delivery and to evaluate the relationship between previous cesarean delivery and subsequent development of abnormal implantation of the placenta, as well as neonatal and other perioperative outcomes after receiving an endometrium-free uterine closure technique.

METHODS

This retrospective observational study considered cesarean deliveries (n = 727) and subsequent vaginal births after cesarean delivery (n = 109) among total deliveries (n = 4496) performed in private practice at NYU Langone Health from 1985 to 2015. All cesarean deliveries were performed using the endometrium-free uterine closure technique. The primary outcome was the incidence of abnormal implantation of the placenta in subsequent pregnancies. The secondary outcomes were neonatal and maternal complications, specifically postoperative hemoglobin and hematocrit concentration losses. The association between independent variables and outcomes were evaluated using mixed-effect regression models.

RESULTS

In contrast to published data, independent of the number of repeat cesarean deliveries, the presence of 26 (3.1%) PPs and of 366 (43.8%) anterior placentas, there were no patients with abnormal implantation of the placenta in a cesarean scar, neither prenatally nor at delivery. Maternal hemorrhage, postoperative and neonatal complications did not reach clinical significance. The statistical analysis revealed that, when compared with women who had fewer repeat cesarean deliveries using endometrium-free uterine closure technique, those with the most had a lesser risk of forming PP and less blood loss, as measured by both hematocrit and hemoglobin evaluation.

CONCLUSION

In this retrospective cohort study, the exclusion of the endometrium during the endometrium-free uterine closure technique was associated with fewer placental abnormalities in subsequent pregnancies and reduced life-threatening maternal morbidity for future cesarean deliveries.

Pathophysiology of Placenta Accreta Spectrum Disorders: A Review of Current Findings

Current findings continue to support the concept of a biologically defective decidua rather than a primarily abnormally invasive trophoblast. Prior cesarean sections increase the risk of placenta previa and both adherent and invasive placenta accreta, suggesting that the endometrial/decidual defect following the iatrogenic creation of a uterine myometrium scar has an adverse effect on early implantation. Preferential attachment of the blastocyst to scar tissue facilitates abnormally deep invasion of trophoblastic cells and interactions with the radial and arcuate arteries. Subsequent high velocity maternal arterial inflow into the placenta creates large lacunae, destroying the normal cotyledonary arrangement of the villi.

Placenta accreta spectrum: pathophysiology and evidence-based anatomy for prenatal ultrasound imaging

Placenta accreta spectrum is a complex obstetric complication associated with high maternal morbidity. It is a relatively new disorder of placentation, and is the consequence of damage to the endometrium-myometrial interface of the uterine wall. When first described 80 years ago, it mainly occurred after manual removal of the placenta, uterine curettage, or endometritis. Superficial damage leads primarily to an abnormally adherent placenta, and is diagnosed as the complete or partial absence of the decidua on histology. Today, the main cause of placenta accreta spectrum is uterine surgery and, in particular, uterine scar secondary to cesarean delivery. In the absence of endometrial reepithelialization of the scar area the trophoblast and villous tissue can invade deeply within the myometrium, including its circulation, and reach the surrounding pelvic organs. The cellular changes in the trophoblast observed in placenta accreta spectrum are probably secondary to the unusual myometrial environment in which it develops, and not a primary defect of trophoblast biology leading to excessive invasion of the myometrium. Placenta accreta spectrum was separated by pathologists into 3 categories: placenta creta when the villi simply adhere to the myometrium, placenta increta when the villi invade the myometrium, and placenta percreta where the villi invade the full thickness of the myometrium. Several prenatal ultrasound signs of placenta accreta spectrum were reported over the last 35 years, principally the disappearance of the normal uteroplacental interface (clear zone), extreme thinning of the underlying myometrium, and vascular changes within the placenta (lacunae) and placental bed (hypervascularity). The pathophysiological basis of these signs is due to permanent damage of the uterine wall as far as the serosa, with placental tissue reaching the deep uterine circulation. Adherent and invasive placentation may coexist in the same placental bed and evolve with advancing gestation. This may explain why no single, or set combination of, ultrasound sign(s) was found to be specific for the depth of abnormal placentation, and accurate for the differential diagnosis between adherent and invasive placentation. Correlation of pathological and clinical findings with prenatal imaging is essential to improve screening, diagnosis, and management of placenta accreta spectrum, and standardized protocols need to be developed.

Doppler Assessment of Uterine Blood Flow in Pre-eclampsia: A Review

Doppler ultrasonography plays an ever-increasing role in obstetric imaging. Although commonly purported to assess blood flow, most studies in this area report purely on velocimetric parameters, rather than true volumetric flow. This review article highlights the physiological importance of this distinction, and reports on a literature review of uterine artery Doppler interrogation in the context of pre-eclampsia, which identified only four original research papers that attempted to assess blood flow. Attention is needed for true volumetric flow assessment in pre-eclampsia research, which may permit a more complete conceptualisation of the pathogenesis and haemodynamic consequences of this condition.