Prediction of scar integrity and vaginal birth after caesarean delivery

Definition of large niche after Cesarean section based on prediction of postmenstrual spotting: Chinese cohort study in non-pregnant women

OBJECTIVE

A large niche after Cesarean section (CS) is associated with long-term complications, of which postmenstrual spotting is associated positively with the size of the niche. However, the diagnosis of a large niche in the literature is inconsistent and the definition is largely subjective. The aim of this study was to generate a definition for a large niche in non-pregnant women based on the presence of postmenstrual spotting.

METHODS

Women who had undergone CS in our hospital between January 2012 and June 2017 were selected randomly from our database, contacted by telephone and subsequently examined between January 2016 and June 2020. Eligible for inclusion were non-pregnant women who had their last CS more than 1 year earlier and agreed to undergo transvaginal sonography (TVS). All participants underwent examination of their CS scar by TVS (two-dimensional color Doppler) during the midfollicular phase. Niche depth, length, width, residual myometrial thickness (RMT), adjacent myometrial thickness (AMT) and ratio of niche depth/AMT were recorded. Women diagnosed with a niche, defined as an indentation at the site of the CS with a depth of at least 2 mm, were classified into two groups (symptomatic or asymptomatic) according to whether they experienced postmenstrual spotting. Logistic regression analysis was used to establish the best cut-off values for the niche parameters to predict postmenstrual spotting. A new definition was generated based on the niche parameters with the highest area under the receiver-operating-characteristics (ROC) curve (AUC) for the prediction of postmenstrual spotting.

RESULTS

A total of 727 women who had a CS > 1 year earlier underwent TVS examination, of whom 263 were diagnosed with a niche (prevalence of 36.2%). Of these, 160 women experienced postmenstrual spotting and 103 were asymptomatic. The three variables with the highest AUC for prediction of postmenstrual spotting were niche depth/AMT ratio (AUC, 0.798; 95% CI, 0.745-0.852), niche depth (AUC, 0.731; 95% CI, 0.668-0.795) and RMT (AUC, 0.683; 95% CI, 0.618-0.748). Based on the best cut-offs according to ROC-curve analysis, a large niche was defined as: niche depth ≥ 0.50 cm, RMT ≤ 0.21 cm or niche depth/AMT ratio ≥ 0.56. The prevalence of a large niche according to this definition was 22.4% (163/727). The new definition had a specificity of 61.17% (95% CI, 52.34-70.41%) and sensitivity of 76.87% (95% CI, 70.28-84.16%) for a large niche.

CONCLUSION

This study has provided a new definition for a large niche after CS. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Safety and feasibility of trial of labor in pregnant women with cesarean scar diverticulum

OBJECTIVE

Literature on trial of labor after cesarean section (TOLAC) in women with isthmoceles is scarce because of complications associated with the procedure. This study investigated TOLAC's safety and feasibility in patients with isthmoceles.

METHODS

The study group comprised 34 pregnant women with isthmoceles who vaginally delivered. The control group comprised 102 pregnant women without isthmoceles who vaginally delivered during the same period. Scar diverticula were measured using color Doppler ultrasonography; between-group delivery outcomes were compared.

RESULTS

Of the study group patients, 27/34 had isthmoceles diagnosed by ultrasound before pregnancy. Nineteen (70.37%) of these patients had mild defects and eight (29.63%) had moderate defects. The scar diverticula's mean length, depth, and width were 1.05 ± 0.62, 0.54 ± 0.28, and 1.20 ± 0.70 cm, respectively. The residual muscle layer's mean thickness was 0.27 ± 0.07 cm. The mean diverticulum depth/residual muscular thickness ratio was 2.39 ± 2.58. The duration of the first stage of labor was significantly shorter and the neonatal weight was significantly lower in the study group than control group.

CONCLUSION

Successful vaginal delivery is possible for women with mild and moderate isthmoceles. Further large-scale studies are needed to improve TOLAC's safety in pregnant women with isthmoceles.

Comparison of the lower uterine segment in pregnant women with and without previous cesarean section in 3 T MRI

BACKGROUND

Prenatal risk stratification of women with previous cesarean section (CS) by ultrasound thickness measurement of the lower uterine segment (LUS) is challenging. There is a wide range of proposed cutoff values and a valuable algorithm for selection before birth is not available. Using 3 T magnetic resonance imaging (MRI), we aimed to identify possible shortcomings of the current protocols used for birth selection after CS. Therefore, we evaluated anatomic and morphologic differences of the LUS and its thickness in patients with CS and those without. Possible impact factors on LUS thickness were studied.

METHODS

We retrospectively analyzed 3 T MRI scans of 164 pregnant women in their second or third trimester, with (patient group, n = 60) and without previous CS (control group, n = 104). Sagittal T2-weighted images were studied. Normal findings of the LUS in MRI, reliability of MRI measurements, as well as factors influencing LUS thickness were assessed. MRI findings were compared to intraoperative findings.

RESULTS

MRI provided good intra- (ICC 0.872) and fair inter-rater reliability (ICC 0.643). The relationship of the LUS and the cesarean scar to the surrounding anatomical structures and also its morphology varied strongly in patients and controls. Scar identification was possible in only 9/60 (15.0%) patients. The LUS was thinner in patients (1.9 ± 0.7 mm) than in controls (2.7 ± 1.3 mm). An LUS thinning up to 1 mm was observed in 23% of women without a previous CS and in 34% of women with normal intraoperative findings. Suspicion of a uterine dehiscence (LUS thickness < 1 mm) was only found in the patient group (5/59 (8.5%)) and was intraoperatively confirmed. In controls, LUS thickness was influenced by fetal weight, gestational age and amniotic fluid amounts.

CONCLUSION

Variability in anatomy, thickness and morphology seem to limit common prenatal LUS imaging diagnostics. Therefore, we consider that diagnostic protocols must be re-evaluated and imaging should be adjusted to the individual patient conditions. Due to its independency of ultrasound limitations, an additional MRI might be useful for altered anatomy and impaired ultrasound conditions. An LUS thinning up to 1 mm might be a normal finding and should be further investigated as reference value.

Sonographic evaluation of surgical repair of uterine cesarean scar defects

BACKGROUND

The aim of the study was to assess the clinical outcomes of surgical repair of uterine cesarean scar defects with sonography (US).

METHODS

Seven nonpregnant women with history of cesarean section and a large uterine scar defect were enrolled. The surgical repair was performed by minilaparotomy. The US assessment of the uterine scar was performed using a standardized approach at baseline, then at a first visit 2-3 days following the surgical intervention (V1) and at a follow-up visit 3 months later (V2). Residual myometrial thickness (RMT), width, and depth of the scar defect were measured.

RESULTS

The mean RMT increased significantly from 1.9 mm at baseline to 8.8 mm at V1 and 8.0 mm at V2. No intraoperative complications were observed. Postmenstrual spotting and abdominal pain reported preoperatively resolved after the operation.

CONCLUSIONS

A surgical repair procedure for an incompletely healed uterine cesarean scar is effective in increasing RMT thickness, decreasing the depth of the scar, and reducing symptoms related to the cesarean section scar defect. Further studies on post-repair pregnancy outcomes are required to evaluate whether the procedure affects the rate of cesarean scar pregnancy, morbidly adherent placenta, and/or uterine scar dehiscence and rupture. The repair of a cesarean scar defect is recommended only for symptomatic women. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:455-460, 2017.

Standardized ultrasonographic approach for the assessment of risk factors of incomplete healing of the cesarean section scar in the uterus

OBJECTIVE

To identify factors related to the healing of a Cesarean uterine incision using the standardized ultrasonographic approach of scar assessment in the non-pregnant uterus.

STUDY DESIGN

Measurements of the uterine scar were taken from 409 women with a history of at least one low transverse cesarean section (CS) with a single layer uterine closure. Residual myometrial thickness (RMT), width (W) and depth (D) of the triangular hypoechoic scar niche, D/RMT ratio and clinical characteristics were analyzed. For statistical analysis, the Mann-Whitney U test, chi-square test, Spearman's rank correlation coefficient, ANOVA test, and logistic regression were used.

RESULTS

268 women presented with a scar defect. RMT values were significantly correlated with the number of CSs (R=-0.17) and uterus retroflection (R=-0.15). The presence of a scar defect was significantly associated with lower RMT values (R=-0.33), greater gestational age (R=0.10), and younger maternal age (R=-0.11). The mean RMT value was significantly smaller in women with CSs performed in the second stage of labor (0.62) when compared to women with CSs in the first stage of labor (0.97) or without cervical dilatation (0.91).

CONCLUSION

A standardized approach of CS scar assessment in the non-pregnant uterus helps to identify women at risk of long-term complications of CS.

Cesarean section scar measurements in non-pregnant women using three-dimensional ultrasound: a repeatability study

OBJECTIVE

To evaluate intra- and inter-observer agreement in measurements of the cesarean scar niche and the residual myometrial thickness (RMT) using 3-dimensional (3D) transvaginal ultrasonography.

STUDY DESIGN

Fifty-eight uterine 3D volumes from women with deep cesarean scar niches were evaluated. 3D volumes were obtained six to fifteen months after a primary cesarean section. Evaluation of the 3D volume was performed in a standardized multiplanar view. Two observers independently obtained RMT, cesarean scar niche depth (D), length (L), width (W), and myometrium adjacent to the scar (M). Differences within and between observers were expressed in mm and were evaluated according to the Bland-Altman method including the calculation of limits of agreement (LOAs).

RESULTS

The intra-observer LOAs in mm were as follows: RMT: -3.7 to 4.0; D: -2.2 to 2.6; L: -3.6 to 4.2; W: -4.0 to 3.7; and M: -3.4 to 4.5. The inter-observer LOAs in mm were as follows: RMT: -3.2 to 4.1; D: -3.3 to 2.2; L: -3.4 to 4.2; W: -3.2 to 4.1; and M: -4.1 to 3.2.

CONCLUSIONS

In non-pregnant women, we found rather wide limits of agreement measuring the cesarean section scar niche and myometrium using 3D volumes. Whether 3D transvaginal ultrasonography provides clinical advantages compared to 2D TVU needs clarification.

Trial of Labor After Cesarean Section Among Women with Unique Lower Segment Scarred Uterus and Fetal Weight >3500 g: Prognostic Factors for a Safe Vaginal Delivery

OBJECTIVE

To evaluate outcome of trial of labor after cesarean section (TOLAC) with fetal weight >3500 g.

MATERIALS AND METHODS

This retrospective descriptive study was carried out between March 1, 2012, and February 28, 2015. Medical and obstetrical records of women with birth weight (BW) >3500 g admitted in the labor ward with advanced labor or admitted in early labor but with underestimated fetal weight >3500 g were analyzed. Main variables analyzed included maternal parity, vaginal delivery prior to TOLAC, the BW and the integrity of the uterine scar.

RESULTS

Mean BW was 3789.3 g. Out of 36 women, 75 % had a successful TOLAC. Women who delivered vaginally before TOLAC had a higher success rate than women who never delivered vaginally (94.1 vs. 63.1 %, P < 0.044).

CONCLUSION

Successful TOLAC with birth weight >3500 g can be observed among women, especially among those admitted in advanced labor or with successful vaginal delivery prior to the current TOLAC.

Prediction of uterine dehiscence using ultrasonographic parameters of cesarean section scar in the nonpregnant uterus: a prospective observational study

BACKGROUND

Every year 1.5 million cesarean section procedures are performed worldwide. As many women decide to get pregnant again, the population of pregnant women with a history of cesarean section is growing rapidly. For these women prediction of cesarean section scar performance is still a serious clinical problem.

METHODS

Starting in 2005, the study included 308 nonpregnant women with a history of low transverse cesarean section. The following ultrasonographic parameters of the cesarean section scar in the nonpregnant uterus were assessed: the residual myometrial thickness (RMT) and the width (W) and the depth (D) of the triangular hypoechoic scar niche. During 8 years of follow-up, 41 of these women were referred to our department for delivery. In all cases, a repeat cesarean section was performed and the lower uterine segment was assessed. Two independent statistical methods namely the logit model and Decision Tree analysis were used to determine the relation between the appearance of the cesarean section scar in the nonpregnat state and the performance of the scar in the next pregnancy.

RESULTS

The logit model revealed that the D/RMT ratio showed significant correlation with cesarean section scar dehiscence (P-value of 0.007). Specifically, a D/RMT ratio value greater than 1.3035 indicated that the likelihood of dehiscence was greater than 50%. The Decision Tree analysis revealed that a diagnosis of dehiscence versus non-dehiscence could be based solely on one criterion, a D/RMT ratio of at least 0.785. The sensitivity of this method was 71%, and the specificity was 94%.

CONCLUSIONS

Assessment of the cesarean section scar in the nonpregant uterus can be used to predict the occurrence of scar dehiscence in the next pregnancy.