Early prediction of placenta accreta spectrum in women with prior cesarean delivery using transvaginal ultrasound at 11 to 14 weeks

The effect of uterine closure technique on cesarean scar niche development after multiple cesarean deliveries

OBJECTIVES

To use saline infusion sonohysterography (SIS) to evaluate the effect of uterine closure technique on niche formation after multiple cesarean deliveries (CDs).

METHODS

Patients with at least one prior CD were evaluated for niche via SIS. Subgroups of any number repeat CD (>1 prior), lower-order CD (<4 prior), and higher-order CD (≥4 prior) were analyzed, stratifying by hysterotomy closure technique at last cesarean preceding imaging; techniques included Technique A (endometrium-free double-layer closure) and Technique B (single- or double-layer routine endo-myometrial closure). Niche defects were quantified (depth, length, width, and residual myometrial thickness). The primary outcome was clinically significant niche, defined as depth >2 mm. Statistical analysis was performed using chi-square, ANOVA, t-test, Kruskal-Wallis, and multiple logistic regression, with p-values of <0.05 were statistically significant.

RESULTS

A total of 172 post-cesarean SIS studies were reviewed: 105 after repeat CDs, 131 after lower-order CDs, and 41 after higher-order CDs. Technique A was associated with a shorter interval to imaging and more double-layer closures. Technique B was associated with more clinically significant niches across all subgroups, and these niches were significantly longer and deeper when present. Multiple logistic regression demonstrated a 5.6, 8.1, and 11-fold increased adjusted odds of clinically significant niche following Technique B closure in the repeat CD (p<0.01), lower-order CD (p<0.001), and higher-order CD (p=0.04) groups, respectively.

CONCLUSIONS

While multiple CDs are known to increase risk for niche defects and their sequelae, hysterotomy closure technique may help to reduce niche development and severity.

Placenta Accreta Spectrum and Postpartum Hemorrhage

Placenta accreta spectrum is a group of disorders involving abnormal trophoblastic invasion to the deep layers of endometrium and myometrium. Placenta accrete spectrum is one of the major causes of severe maternal morbidity, with increasing incidence in the past decade mainly secondary to an increase in cesarean deliveries. Severity varies depending on the depth of invasion, with the most severe form, known as percreta, invading uterine serosa or surrounding pelvic organs. Diagnosis is usually achieved by ultrasound, and MRI is sometimes used to assess invasion. Management usually involves a hysterectomy at the time of delivery. Other strategies include delayed hysterectomy or expectant management.

Expectant management of placenta accreta after a mid-trimester pregnancy loss: a case report and a short review

Objectives

Placenta accreta spectrum (PAS) disorders are a significant cause of maternal morbidity and mortality. Traditionally women with PAS are offered surgery, while expectant management is still considered investigational.

Case presentation

We present a case of expectant management of PAS after pregnancy loss at 19-weeks. PAS was suspected at sonography and confirmed by MRI. Patient was offered expectant management to preserve fertility. This consisted of leaving the placenta in situ, followed by in- and out-patient clinical and sonographic examinations and blood tests. After five weeks placental detachment occurred without major complications.

Conclusions

Our report suggests that expectant management could be a safe option in selected cases of PAS after mid-trimester pregnancy loss. We recommend expectant management should be offered in referral centers for PAS.

Diagnosing early scar pregnancy in the lower uterine segment after cesarean section by intracavitary ultrasound

BACKGROUND

Early scar pregnancy (CSP) in the lower uterine segment after cesarean section is a type of ectopic pregnancy that can cause major complications if left untreated. Transabdominal ultrasound is a common procedure but is influenced by external factors. Thus, intracavitary ultrasound may have better diagnostic efficiency for CSP.

AIM

To assess the value of intracavitary ultrasound for diagnosing CSP in the lower uterine segment after cesarean section.

METHODS

Patients diagnosed with CSP in our hospital from October 2019 to April 2021 were recruited. Transabdominal and intracavitary ultrasound examinations were performed to compare the diagnostic differences for CSP and its types.

RESULTS

Sixty-three patients were diagnosed during the study period. The diagnostic accuracy for CSP was higher in intracavitary ultrasound (96.83%) than in transabdominal ultrasound (84.13%) (P < 0.05). The missed diagnosis and misdiagnosis rates did not differ among the ultrasound types (intra: 0.00% and 3.17%; trans: 4.76% and 11.11%, respectively; P > 0.05). For the diagnostic rates for the CSP types, the rates for gestational sac (100.00% vs 90.48%), heterogeneous mass (93.75% vs 75.00%), and part of the uterine cavity (80.00% vs 60.00%) were higher in intracavitary ultrasound than in transabdominal ultrasound, but the difference was not statistically significant (P > 0.05). For gestational sac CSP patients, intracavitary ultrasound showed that the gestational sac was located in the lower uterine segment scar with abundant peripheral blood flow; the distance between the gestational sac and the serosal layer was 2.42 ± 0.50 cm. Intracavitary ultrasound for heterogeneous mass CSP patients indicated that the mass mainly occurred in the lower anterior uterine wall, protruding into the bladder, and was surrounded by abundant internal and peripheral blood flow; the distance between the mass and serosal layer was 1.79 ± 0.30 cm. For CSP type partly located in the uterine cavity, the gestational sac was partly located in the lower uterine cavity and partly in the scar with abundant internal and peripheral blood flow; the distance between the gestational sac and the serosal layer was 2.29 ± 0.28 cm.

CONCLUSION

Intracavitary ultrasound had a higher diagnostic accuracy and application value for diagnosing CSP than transabdominal ultrasound, with reduced risk of missed diagnoses and misdiagnosis, thereby preventing delayed treatment.

Impact of introducing cell-free DNA screening into clinical care on first trimester ultrasound

OBJECTIVE

First-trimester ultrasound is an important component of prenatal care. We investigated the impact of introducing cell-free DNA (cfDNA) aneuploidy screening into routine care, on performance of first-trimester ultrasound.

METHODS

Retrospective study of patients who had prenatal care at a tertiary referral center. We compared the performance of any first-trimester ultrasound between three different aneuploidy screening protocols, used consecutively during the study period: (1) combined first-trimester screening (FTS); (2) FTS and cfDNA offered together; (3) patients requested to choose between FTS and cfDNA. Secondary outcomes included performance of nuchal translucency (NT), aneuploidy screens and diagnostic genetic procedures.

RESULTS

The number of patients undergoing first-trimester ultrasound remained similar with the second protocol but decreased in the third (68.7% vs. 40.9%, OR 0.32, 95% CI 0.25-0.4, p < 0.001). Diagnostic procedures decreased between protocol 1 and 2 (7.6% vs. 4.4%, OR 0.59, 95% CI 0.37-0.93, p = 0.02) while NT scans decreased between protocol 2 and 3 (6.8% vs. 1.3%, OR 0.18, 95% CI 0.09-0.4, p < 0.001). The rate of FTS decreased over the study period and less women had cfDNA when they had to choose one method (p < 0.001).

CONCLUSIONS

Introducing cfDNA screening as an alternative to FTS, resulted in fewer patients receiving ultrasound in the first-trimester.

Lower uterine segment scar assessment at 11-14 weeks' gestation to screen for placenta accreta spectrum in women with prior Cesarean delivery

OBJECTIVES

To validate prospectively transvaginal ultrasound assessment of the lower uterine segment (LUS) scar at the time of first-trimester screening in women with previous Cesarean section (CS) and to determine its feasibility and accuracy in stratifying women according to the risk for placenta accreta spectrum (PAS) disorder.

METHODS

Women with a history of CS were recruited between 11 + 0 and 13 + 6 weeks' gestation and underwent LUS scar assessment using transvaginal ultrasound. A standardized midsagittal plane, which included the cervicoisthmic canal (CIC), the uterine scar and the placental site, was obtained. The scar was described in terms of its size (narrow or dehiscent) and its location in relation to the CIC (within or above), with each LUS scar classified into one of four groups based on these features. Placental location was assessed and classified as high- or low-lying. Women were stratified according to the risk of PAS, based on the relationship between the scar location and placental site. Women were considered high risk when the scar was above the CIC and the placenta was low-lying (i.e. when the placenta was overlying an exposed scar) and low risk when the scar was within the CIC and/or the placenta was high. High-risk patients were followed up at 20 weeks and 28-30 weeks for the development of PAS. Maternal demographics, detailed obstetric history and obstetric outcome were collected.

RESULTS

First-trimester transvaginal ultrasound was offered to 535 women with prior CS during the study period. A LUS scar was visualized in 79.9% (401/502) of those who agreed to undergo the examination. At this scan, the LUS scar was above the CIC in 9.0% (36/401) of women, but only 5.7% (23/401) additionally had a low-lying placenta overlying the scar. Of these 23 high-risk women, two were found to have PAS on the mid-trimester screening scan and one was noted to have placental adherence during evacuation following mid-trimester termination of pregnancy. On the first-trimester scan, 94.3% (378/401) of women were at low risk of PAS. This screening protocol yielded a positive likelihood ratio of 21.33 (95% CI, 13.02-34.96), sensitivity of 100% (95% CI, 29.24-100%), specificity of 95.31% (95% CI, 92.39-97.35%), positive predictive value of 16.7% (95% CI, 5.8-39.2%) and negative predictive value of 100% (95% CI, 98.4-100%). On multivariable regression analysis performed to identify confounding variables associated with a LUS scar above the CIC, only maternal body mass index ≥ 30 kg/m² was significant (odds ratio (OR), 2.42 (95% CI, 1.04-5.39); P = 0.03). Although there was a trend towards an increased risk of a LUS scar above the CIC in women with prior elective prelabor CS (OR, 1.72 (95% CI, 0.80-3.68)), this association did not reach statistical significance.

CONCLUSIONS

Routine transvaginal ultrasound assessment of the location of the LUS scar and placenta at the time of first-trimester screening between 11 + 0 and 13 + 6 weeks' gestation in women with prior CS is a feasible and effective tool to identify those at risk of subsequent development of PAS disorder. A finding of placental implantation over an exposed LUS scar seems to be cardinal in predicting the risk of PAS disorder in women with prior CS, with an excellent negative predictive value. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Clinical Analysis of Improved Particle Swarm Algorithm-Based Magnetic Resonance Imaging Diagnosis of Placenta Accreta

The magnetic resonance imaging (MRI) image processing capabilities were investigated based on the improved particle swarm optimization (IPSO) algorithm, and the clinical application analysis of MRI images in the diagnosis of placenta accreta (PA) was evaluated in this study. The MRI uterine images were detected on the basis of IPSO. Besides, the clinical data of 89 patients with PA were selected and collected, who were diagnosed by clinical cesarean section surgery and pathological comprehensive diagnosis in hospital from January 2018 to July 2020. Then, all of them underwent the ultrasound (US) and MRI examinations, and the differences of sensitivity, specificity, and accuracy between MRI and US under IPSO in the diagnosis of PA were compared, as well as the differences in the diagnosis of adhesive, implantable, and penetrated PA. The results showed that the difference in detection between IPSO-based MRI images and US images was not statistically substantial (p > 0.05), but the number of initial detections was higher than the number of US examination. MRI examination had higher sensitivity and specificity in the diagnosis of PA during pregnancy, especially for implantable PA, compared with US examination (p < 0.05). In conclusion, MRI images based on the improved particle swarm optimization algorithm showed a good application effect in the diagnosis of placental implantation diseases, which was worthy of further promotion in clinical practice.