Can third-trimester assessment of uterine scar in women with prior Cesarean section predict uterine rupture?

Prenatal Detection and Conservative Management of Uterine Scar Dehiscence in Patient with Previous Uterine Rupture and Multiple Surgeries-A Case Report

Uterine rupture is a rare and life-threatening condition. It usually occurs in patients with uterine scars (most commonly for a previous myomectomy or caesarean section), but it can also affect an unharmed uterus. This complication is more frequent in the third trimester and during delivery. There is not yet a recognised method of prediction of uterine rupture and the ultrasound features still need a consensus. In this article, we have reported a case of uterine dehiscence diagnosed by a pelvic ultrasound and magnetic resonance (MRI) at 24 weeks of gestation. The finding was confirmed intraoperatively at the caesarean section at 29 weeks of gestation. The 40-year-old patient has had a previous pregnancy complicated by uterine rupture at 22 weeks of gestation, following six previous abdominal surgeries for stage IV endometriosis, diffuse and nodular adenomyosis, and pelvic adhesion syndrome. The early detection of uterine dehiscence allowed us to prolong the pregnancy and perform a subsequent fertility-sparing surgery, reducing maternal and neonatal morbidity and mortality. Our case report proves that women with severe endometriosis/adenomyosis are at a high risk of uterine rupture and scar dehiscence. The antenatal ultrasound can describe a uterine dehiscence (even in asymptomatic patients) and prevent complications.

Imaging of Acute Abdominopelvic Pain in Pregnancy and Puerperium-Part I: Obstetric (Non-Fetal) Complications

Acute abdominopelvic pain in pregnant and postpartum patients presents clinical and therapeutic challenges, often requiring quick and accurate imaging diagnosis. Ultrasound remains the primary imaging investigation. Magnetic resonance imaging (MRI) has been shown to be a powerful diagnostic tool in the setting of acute abdominal pain during pregnancy and puerperium. MRI overcomes some drawbacks of US, avoiding the ionizing radiation exposure of a computed tomography (CT) scan. Although CT is not usually appropriate in pregnant patients, it is crucial in the emergency evaluation of postpartum complications. The aim of this article is to provide radiologists with a thorough familiarity with the common and uncommon pregnancy and puerperium abdominal emergencies by illustrating their imaging appearances. The present first section will review and discuss the imaging findings for acute abdominopelvic pain of obstetric (non-fetal) etiology.

Change of the residual myometrial thickness during pregnancy in women who underwent laparoscopic niche resection compared with controls without niche surgery: a prospective comparative cohort study

BACKGROUND

Reduced residual myometrial thickness before and during pregnancy is associated with uterine rupture or dehiscence after vaginal birth after cesarean delivery. Laparoscopic niche resection performed in case of gynecologic symptoms has shown to increase residual myometrial thickness 6 months after surgery.

OBJECTIVE

This study aimed to evaluate the change in residual myometrial thickness from baseline value before pregnancy to the third trimester of pregnancy in women with and without laparoscopic niche resection and evaluate niche presence, niche size during pregnancy vs before pregnancy, and obstetrical outcomes, including uterine rupture and dehiscence in both study groups.

STUDY DESIGN

This was a prospective cohort study conducted in an academic medical center. Of note, 2 groups of pregnant women with a previously diagnosed niche were included: (1) women with a large symptomatic niche (residual myometrial thickness of <3 mm) followed by laparoscopic niche resection (LNR group) and (2) women with a niche without niche resection because of minimal symptoms or a residual myometrial thickness of ≥3 mm diagnosed before current pregnancy (expectant group). Participants underwent a transvaginal ultrasound at 12, 20, and 30 weeks of gestation. Changes in residual myometrial thickness and changes in niche measurements over time were analyzed with linear mixed models.

RESULTS

A total of 100 women were included, 61 in the LNR group and 39 in the expectant group. The change in residual myometrial thickness from baseline value before niche resection to the third trimester of pregnancy was +2.0 mm in the LNR group vs -1.6 mm in the expectant group (P<.001). Residual myometrial thickness decreased from the first trimester of pregnancy onward in both groups. Although residual myometrial thickness was thinner at baseline in the LNR group, it was thicker in the LNR group than in the expectant group during all trimesters: 3.2 mm (P<.001) in the first trimester of pregnancy, 2.5 mm (P<.001) in the second trimester of pregnancy, and 1.8 mm (P=.001) in the third trimester of pregnancy. Uterine dehiscence was reported in 1 of 50 women (2%) in the LNR group and 7 of 36 women (19%) in the expectant group (P=.007) and was related to the depth of niche-to-residual myometrial thickness ratio before pregnancy (after niche resection) and residual myometrial thickness in the second trimester of pregnancy. No uterine rupture was reported. Most patients received a scheduled cesarean delivery in both groups. There was more blood loss during subsequent cesarean delivery in the LNR group than in the expectant group.

CONCLUSION

Here, laparoscopic niche resection resulted in an increased residual myometrial thickness during a subsequent pregnancy. Moreover, a lower number of dehiscence was found in the LNR group than in the expectant group without niche surgery. Per-section blood loss was higher in the LNR group than in the expectant group. In general, laparoscopic niche resection is performed to improve gynecologic symptoms. Currently, there is no evidence to support a laparoscopic niche resection to improve obstetrical outcomes, but the trend toward more uterine dehiscence encourages further research.

Intrapartum ultrasound measurement of the lower uterine segment thickness in parturients with previous scar in labor: a cross-sectional study

Background

There is a lack of reliable methods to estimate the risk of uterine rupture or dehiscence during a trial of labor in women with previous cesarean sections. This study aimed to assess the lower uterine segment and myometrial thickness by ultrasonography in women with previous cesarean sections during labor and assess their association with the uterine defect.

Methods

A cross-sectional study was conducted on 161 women in the active phase of labor having one previous cesarean section. The study was conducted et al.-Azhar University Hospital, Assiut City, Egypt, from March 2018 to March 2019. Ultrasound measurements of lower uterine segment thickness and myometrial thickness were conducted by vaginal and abdominal ultrasound by two observers. The correlation of both thicknesses with the uterine defect was analyzed.

Results

Uterine defects were reported in 42 women (25.9%), uterine rupture in four women (2.5%), and dehiscence in 38 women (23.5%). The uterine defects were not associated with maternal factors (maternal age, gestational age at labor, body mass index, birth weight, interpregnancy, and inter-delivery interval). Receiver operating curve analysis demonstrated that lower uterine segment thickness was linked with uterine defect, with an area under the curve of 60% (95% CI, 51–70%, P = 0.044). Myometrial thickness was also linked to the uterine defect, with an area under the curve of 61% (95% CI, 52–71%, P = 0.025). Full lower uterine segment thickness of 2.3 mm and myometrial thickness of 1.9 mm were the cutoff value with the best combination of sensitivity and specificity for the uterine defect. Lower uterine segment thickness (OR = 0.49, 95%CI 0.24–0.96) and myometrial thickness (OR = 0.44, 95%CI 0.20–0.94) were significantly associated with the uterine defect. Lower uterine segment thickness (OR = 0.41, 95%CI 0.22–0.76) and myometrial thickness (OR = 0.33, 95%CI 0.16–0.66) were also significantly associated with cesarean section delivery.

Conclusion

A lower uterine segment thickness of 2.3 mm and myometrial thickness of 1.9 mm during the first stage of labor are associated with a high risk of uterine defects during a labor trial. These measurements during labor can have a practical application in deciding the mode of delivery in women with previous cesarean sections and might reduce uterine rupture.

Complications of Caesarean delivery part 1: Early complications

Introduction

With the rise in Caesarean deliveries, complications related to the procedure are increasingly encountered. Sonography has an indispensable role in the assessment of these complications and is often the first-line investigation of choice.Topic Description: Part 1 of this pictorial review summarises the early complications unique to and associated with Caesarean deliveries.

Discussion

Acute haemorrhagic complications include retained products of conception, subfascial and bladder flap haematomas and, rarely, postpartum uterine dehiscence or rupture and iatrogenic vascular complications. Infective complications include puerperal and wound infections. Key sonographic features of these conditions are illustrated. Pitfalls, mimics, limitations and indications for cross-sectional imaging are discussed.

Conclusion

Sound knowledge of the sonographic features of common early complications of Caesarean delivery will facilitate accurate diagnosis, timely management and improved patient outcomes.

Transvaginal Sonographic Evaluation of Cesarean Section Scar Niche in Pregnancy: A Prospective Longitudinal Study

Background and Objectives: To investigate the prevalence of a Cesarean section (CS) scar niche during pregnancy, assessed by transvaginal ultrasound imaging, and to relate scar measurements, demographic and obstetric variables to the niche evolution and final pregnancy outcome. Materials and Methods: In this prospective observational study, we used transvaginal sonography to examine the uterine scars of 122 women at 11⁺⁰–13⁺⁶, 18⁺⁰–20⁺⁶ and 32⁺⁰–35⁺⁶ weeks of gestation. A scar was defined as visible on pregnant status when the area of hypoechogenic myometrial discontinuity of the lower uterine segment was identified. The CS scar niche (“defect”) was defined as an indentation at the site of the CS scar with a depth of at least 2 mm in the sagittal plane. We measured the hypoechogenic part of the CS niche in two dimensions, as myometrial thickness adjacent to the niche and the residual myometrial thickness (RMT). In the second and third trimesters of pregnancy, the full lower uterine segment (LUS) thickness and the myometrial layer thickness were measured at the thinnest part of the scar area. Two independent examiners measured CS scars in a non-selected subset of patients (n = 24). Descriptive analysis was used to assess scar visibility, and the intraclass correlation coefficient (ICC) was calculated to show the strength of absolute agreement between two examiners for scar measurements. Factors associated with the CS scar niche, including maternal age, BMI, smoking status, previous vaginal delivery, obstetrics complications and a history of previous uterine curettage, were investigated. Clinical information about pregnancy outcomes and complications was obtained from the hospital’s electronic medical database. Results: The scar was visible in 77.9% of the women. Among those with a visible CS scar, the incidence of a CS scar niche was 51.6%. The intra- and interobserver agreement for CS scar niche measurements was excellent (ICC 0.98 and 0.89, respectively). Comparing subgroups of women in terms of CS scar niche (n = 49) and non-niche (n = 73), there was no statistically significant correlation between maternal age (p = 0.486), BMI (p = 0.529), gestational diabetes (p = 1.000), smoking status (p = 0.662), previous vaginal delivery after CS (p = 1.000) and niche development. Uterine scar niches were seen in 56.3% (18/48) of the women who had undergone uterine curettage, compared with 34.4% (31/74) without uterine curettage (p = 0.045). We observed an absence of correlation between the uterine scar niche at the first trimester of pregnancy and mode of delivery (p = 0.337). Two cases (4.7%) of uterine scar dehiscence were confirmed following a trial of vaginal delivery. Conclusions: Based on ultrasonography examination, the CS scar niche remained visible in half of the cases with a visible CS scar at the first trimester of pregnancy and could be reproducibly measured by a transvaginal scan. Previous uterine curettage was associated with an increased risk for uterine niche formation in a subsequent pregnancy. Uterine scar dehiscence might be potentially related to the CS scar niche.

Cervical and Lower Uterine Parameter Ultrasound and Elastographic Parameters for the Prediction of a Successful Induction of Labor

PURPOSE

 The prediction of successful induction of labor (IOL) has been the subject of a series of studies. The predictive role of cervical sonographic and elastographic parameters has been controversially discussed. Lower uterine segment (LUS) thickness and strain values have not been discussed yet in this regard.

MATERIALS AND METHODS

 A prospective cohort study was performed to examine the predictive power of Bishop score parameters, sonographic cervical length (CL), cervical funneling, cervical strain values, LUS thickness and its strain values regarding successful IOL within 24 hours and intervals to onset of labor, ROM and delivery of the fetus. A p-value of < 0.05 was considered statistically significant.

RESULTS

 135 patients were examined. A cervical length of 25 mm, the presence of cervical funneling and digital shorter cervix was significant for the prediction of successful induction of labor (IOL) within 24 hours. There was weak correlation between the functional CL and the onset of labor (r² = 0.10) and ROM (r² = 0.13). There was also a weak correlation between the cervical funnel width and the time interval to the onset of labor (r² = 0.25), ROM (r² = 0.23) and delivery of the fetus (r² = 0.22). Cervical elastography, LUS thickness and strain values were not significant for the prediction of a successful IOL.

CONCLUSION

 We were able to show that cervical structural changes at the level of the internal os, i. e., shortening through funneling, may be the determining factor for successful IOL.

Third trimester ultrasound. A long-standing debate

Third trimester ultrasound has long been in obstetrics a topic of debate. This issue is framed in a historical debate on the effectiveness of routine obstetrical ultrasound and two opposing trends originated in America and Europe, respectively. Primary function of this ultrasound has been to detect fetal growth restriction, but no study has shown evidence of improving perinatal outcomes. Other secondary functions are detection of fetal abnormalities or evaluation of fetal presentation, and they have also shown no evidence. Despite the continuous appearance of works in this regard, health policies of both american and european trends have not been modified. Future seems to show a prolongation of the stalemate. Those health systems with a universal third trimester policy should propose an optimization of the test, in order to improve the benefits and obtain data for future studies that could resolve this longstanding debate.

Evaluation of the uterine scar stiffness in women with previous Cesarean section by ultrasound elastography: A cohort study

PURPOSE

To evaluate by means of elastography if the quantitative assessment of the cesarean scar elasticity is feasible using as reference the surrounding intact myometrium and to investigate if the cesarean scar stiffness is influenced by the clinical characteristics of the previous cesarean delivery.

METHODS

Prospective study including women with a previous Cesarean Section (CS) ≥ 37 weeks' gestation performed 12-15 months before. By transvaginal ultrasound two regions of interest (ROI) were selected: uterine scar (Region 1) and surrounding myometrium (Region 2). Strain index (SI) for each ROI was calculated and the Strain Ratio (SR) was defined as Region 1 SI/Region 2 SI. The primary outcome was to compare SR among women who were grouped in accordance to presence of previous vaginal delivery, CS during labor, type of suture or pyrexia during post-partum. The secondary outcome of this study was to evaluate the correlation between SR and maternal, neonatal and labor characteristics.

RESULTS

68 women were included. The mean SR was 1.8 ± 0.7 thus indicating an increased stiffness of the uterine scar compared to the surrounding myometrium. No significant differences were found in terms of SR according to presence of previous VD, CS during labor, type of suture or pyrexia during post-partum period. Strain Ratio was not correlated to maternal characteristics nor to labor and neonatal outcome.

CONCLUSIONS

Evaluation of uterine scar stiffness is feasible by using elastography. The stiffness of the uterine scar is higher than that of the surrounding myometrium and is not correlated to maternal and labor characteristics.

Development of a Novel Nomogram for Predicting Placenta Accreta in Patients With Scarred Uterus: A Retrospective Cohort Study

Objective: The aim of this study was to develop a nomogram to predict the risk of placenta accreta in scarred uterus patients in China.

Methods: We retrospectively analyzed 8,371 singleton pregnancies with scarred uterus at Shengjing Hospital, affiliated with China Medical University. Two thirds of the patients were randomly assigned to the training set (n = 5,581), and one third were assigned to the validation set (n = 2,790). Multivariate logistic regression was performed by using the training set, and the nomogram was developed. Discrimination and calibration were performed by using both the training and validation sets.

Results: The multivariate logistic regression model identified number of previous cesarean section, number of vaginal bleeding, medication during pregnancy, and placenta previa as covariates associated with placenta accreta. A nomogram was developed to predict the risk of placenta accreta in the training set with a Harrell's C-index of 0.93 and 0.927 in the training set and validation set, respectively. Calibration of the nomogram predicted placenta accreta corresponding closely with the actual placenta accreta.

Conclusion: We developed a nomogram predicting the risk of placenta accreta in scarred uterus patients in China. Validation using both the training set and the validation set demonstrated good discrimination and calibration, suggesting good clinical utility.

Isthmocele: an overview of diagnosis and treatment

An isthmocele, a cesarean scar defect or uterine niche, is any indentation representing myometrial discontinuity or a triangular anechoic defect in the anterior uterine wall, with the base communicating to the uterine cavity, at the site of a previous cesarean section scar. It can be classified as a small or large defect, depending on the wall thickness of the myometrial deficiency. Although usually asymptomatic, its primary symptom is abnormal or postmenstrual bleeding, and chronic pelvic pain may also occur. Infertility, placenta accrete or praevia, scar dehiscence, uterine rupture, and cesarean scar ectopic pregnancy may also appear as complications of this condition. The risk factors of isthmocele proven to date include retroflexed uterus and multiple cesarean sections. Nevertheless, factors such as a lower position of cesarean section, incomplete closure of the hysterotomy, early adhesions of the uterine wall and a genetic predisposition may also contribute to the development of a niche. As there are no definitive criteria for diagnosing an isthmocele, several imaging methods can be used to assess the integrity of the uterine wall and thus diagnose an isthmocele. However, transvaginal ultrasound and saline infusion sonohysterography emerge as specific, sensitive and cost-effective methods to diagnose isthmocele. The treatment includes clinical or surgical management, depending on the size of the defect, the presence of symptoms, the presence of secondary infertility and plans of childbearing. Surgical management includes minimally invasive approaches with sparing techniques such as hysteroscopic, laparoscopic or transvaginal procedures according to the defect size.

Hysterotomy level at Cesarean section and occurrence of large scar defects: a randomized single-blind trial

OBJECTIVE

To study the association between the level of Cesarean hysterotomy and the presence of large uterine scar defects 6-9 months after delivery.

METHODS

This was a two-center, randomized, single-blind trial of a surgical procedure with masked assessment of the principal outcome under study. Women without a history of Cesarean section (CS) who underwent emergency CS at cervical dilatation ≥ 5 cm were randomized to high or low incision. Hysterotomy was performed 2 cm above and 2 cm below the plica vesicouterina in the high and low incision groups, respectively. Women were examined using saline contrast sonohysterography to assess the appearance of the hysterotomy scar 6-9 months after delivery. The main outcome was presence of a large scar defect, defined as the remaining myometrial thickness over the defect being ≤ 2.5 mm. Secondary outcomes were perinatal outcome, operative complications within 8 weeks after delivery and long-term outcome in a subsequent pregnancy.

RESULTS

Of 122 patients enrolled in the trial, 114 were assessed by ultrasound examination, of whom 55 were randomized to high and 59 to low CS incision. Large scar defects were seen in four (7%) women in the high-incision group and in 24 (41%) in the low-incision group (P < 0.001; odds ratio, 8.7 (95% CI, 2.8-27.4)). There were no differences in operative complications and perinatal outcomes between the two groups. The median follow-up time was 4 years and 7 months, during which 56 (49%) women had a subsequent pregnancy. No significant differences were observed in the rate of complications in subsequent pregnancy and delivery between women who had low and those who had high incision at the index CS.

CONCLUSION

Low Cesarean hysterotomy level in women in advanced labor is associated with higher incidence of large scar defects detected by transvaginal ultrasound examination 6-9 months after delivery. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Technique of sonographic assessment of lower uterine segment in women with previous cesarean delivery: a prospective, pre/intraoperative comparative ultrasound study

OBJECTIVE

The purpose of this study was: (A) to establish the effects of different ultrasound measurement methods (linear versus curved array) and measuring conditions [impact of pressure by fetal head/pelvis on the lower uterine segment (LUS)] during LUS-muscular-thickness measurement, (B) to introduce the intraoperative ultrasound measurement of LUS-muscular thickness (reference measurement method), and (C) to evaluate the correlation between different combinations of LUS-muscular-thickness measurement ultrasound techniques at birth planning and preoperative versus intraoperative measurements.

METHODS

A prospective clinical observational study of women with the previous cesarean delivery was conducted. LUS-muscular thickness was measured: first at birth planning and second preoperatively using linear and curved probes (transabdominal) and an endocavitar probe (transvaginal), examined with and without pressure by fetal head/pelvis on LUS during measurement and third intraoperatively during repeat cesarean. Bland-Altman plots, paired t tests, Pearson's correlation coefficient, and scatter plots were used.

RESULTS

Thirty-three women were included in the study (ultrasound measurements: n = 601). There was no systematic difference between LUS-muscular-thickness measurements with linear versus curved array (mean difference = 0.06 mm; p = 0.24; n_m = 133) but between measurements with pressure by the fetus versus without (mean difference = - 0.37 mm; p < 0.001; n_m = 243). The highest correlation coefficients were detected for the preoperative (at the day of cesarean section), transabdominal-vaginal approach combined ultrasound measurements versus the intraoperative ultrasound measurements of LUS-muscular thickness-as long as the measurements were made without pressure from the fetal head/pelvis on the LUS [0.86, p < 0.001, n = 24, 95% CI (0.70, 0.94)].

CONCLUSIONS

The systematic application of predetermined measuring conditions, standardized setup criteria improves the performance of LUS thickness measurement by ultrasound near term. CLINICALTRIALS.

GOV IDENTIFIER

NCT02827604.

Rupture of a myomectomy site in the third trimester of pregnancy after myomectomy, septoplasty and cesarean section: A case report

Uterine rupture during pregnancy is a rare but dangerous complication. A history of cesarean section is known to be a risk factor, but other types of uterine surgery can also increase the risk. We report a case of rupture of a myomectomy site in the third trimester of pregnancy without uterine contractions in a woman who had previously undergone myomectomy, septoplasty and cesarean section. The 39-year-old woman (gravida 2, para 2) presented at 29 weeks' gestation with uterine contractions. She was successfully treated with tocolytics. At 32 weeks of pregnancy, in the absence of contractions, the patient complained of severe abdominal pain and she became hypotensive. Emergency laparotomy and cesarean section were performed, resulting in the delivery of a live infant. The myomectomy site was found to have ruptured but the cesarean and septoplasty scars were intact. This case suggests that myomectomy scars are at greater risk of rupture during pregnancy than those resulting from cesarean section and septoplasty.

•

Previous cesarean, septoplasty and myomectomy are risk factors for uterine rupture.

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The characteristics of uterine rupture depend on the types of surgery the woman has previously undergone.

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After myomectomy, uterine rupture can occur during pregnancy without contractions.

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Myomectomy may be a bigger risk factor for uterine rupture than cesarean section.

Ultrasound elastography of the lower uterine segment in women with a previous cesarean section: Comparison of in-/ex-vivo elastography versus tensile-stress-strain-rupture analysis

OBJECTIVES

The purpose of this study was to assess, if the biomechanical properties of the lower uterine segment (LUS) in women with a previous cesarean section (CS) can be determined by ultrasound (US) elastography. The first aim was to establish an ex-vivo LUS tensile-stress-strain-rupture(break point) analysis with the possibility of simultaneously using US elastography. The second aim was to investigate the relationship between measurement results of LUS stiffness using US elastography in-/ex-vivo with results of tensile-stress-strain-rupture analysis, and to compare different US elastography LUS-stiffness-measurement methods ex-vivo.

STUDY DESIGN

An explorative experimental, in-/ex-vivo US study of women with previous CS was conducted. LUS elasticity was measured by point Shear Wave Elastography (pSWE) and bidimensional Shear-Wave-Elastography (2D-SWE) first in-vivo during preoperative examination within 24 h before repeat CS (including resection of the thinnest part of the LUS = uterine scar area during CS), second within 1 h after operation during the ex-vivo experiment, followed by tensile-stress-strain-rupture analysis. Pearson's correlation coefficient and scatter plots, Bland-Altman plots and paired T-tests, were used.

RESULTS

Thirty three women were included in the study; elastography measurements n = 1412. The feasibility of ex-vivo assessment of LUS by quantitative US elastography using pSWE and 2D-SWE to detect stiffness of LUS was demonstrated. The strongest correlation with tensile-stress-strain analysis was found in the US elastography examination carried out with 2D-SWE (0.78, p < 0.001, 95%CI [0.48, 0.92]). The laboratory experiment illustrated that, the break point - as a surrogate marker for the risk of rupture of the LUS after CS - is linearly dependent on the thickness of the LUS in the scar area (Coefficient of correlation: 0.79, p < 0.001, 95%CI [0.55, 0.91]). Two extremely stiff LUS-specimens (outlier or extreme values) rupture even at less stroke/strain than would be expected by their thickness.

CONCLUSION

This study confirms that US elastography can help in determining viscoelastic properties of the LUS in women with a previous CS. The data from our small series are promising. However whether individual extreme values of high stiffness and consecutive restricted biomechanical resilience can explain the phenomenon of rupture during TOLAC in cases of LUS with adequate thickness remains a question which prospective trials have to analyze before US elastography can be introduced into clinical practice.

Single versus double-layer uterine closure at cesarean: impact on lower uterine segment thickness at next pregnancy

BACKGROUND

Uterine rupture is a potential life-threatening complication during a trial of labor after cesarean delivery. Single-layer closure of the uterus at cesarean delivery has been associated with an increased risk of uterine rupture compared with double-layer closure. Lower uterine segment thickness measurement by ultrasound has been used to evaluate the quality of the uterine scar after cesarean delivery and is associated with the risk of uterine rupture.

OBJECTIVE

To estimate the impact of previous uterine closure on lower uterine segment thickness.

STUDY DESIGN

Women with a previous single low-transverse cesarean delivery were recruited at 34-38 weeks' gestation. Transabdominal and transvaginal ultrasound evaluation of the lower uterine segment thickness was performed by a sonographer blinded to clinical data. Previous operative reports were reviewed to obtain the type of previous uterine closure. Third-trimester lower uterine segment thickness at the next pregnancy was compared according to the number of layers sutured and according to the type of thread for uterine closure, using weighted mean differences and multivariate logistic regression analyses.

RESULTS

Of 1613 women recruited, with operative reports available, 495 (31%) had a single-layer and 1118 (69%) had a double-layer closure. The mean third-trimester lower uterine segment thickness was 3.3 ± 1.3 mm and the proportion with lower uterine segment thickness <2.0 mm was 10.5%. Double-layer closure of the uterus was associated with a thicker lower uterine segment than single-layer closure (weighted mean difference: 0.11 mm; 95% confidence interval [CI], 0.02 to 0.21 mm). In multivariate logistic regression analyses, a double-layer closure also was associated with a reduced risk of lower uterine segment thickness <2.0 mm (odd ratio [OR], 0.68; 95% CI, 0.51 to 0.90). Compared with synthetic thread, the use of catgut for uterine closure had no significant impact on third-trimester lower uterine segment thickness (WMD: -0.10 mm; 95% CI, -0.22 to 0.02 mm) or on the risk of lower uterine segment thickness <2.0 mm (OR, 0.95; 95% CI, 0.67 to 1.33). Finally, double-layer closure was associated with a reduced risk of uterine scar defect (RR, 0.32; 95% CI, 0.17 to 0.61) at birth.

CONCLUSION

Compared with single-layer closure, a double-layer closure of the uterus at previous cesarean delivery is associated with a thicker third-trimester lower uterine segment and a reduced risk of lower uterine segment thickness <2.0 mm in the next pregnancy. The type of thread for uterine closure has no significant impact on lower uterine segment thickness.

Assessment of Cesarean hysterotomy scar before pregnancy and at 11-14 weeks of gestation: a prospective cohort study

OBJECTIVE

To compare the appearance and measurement of Cesarean hysterotomy scar before pregnancy and at 11-14 weeks in a subsequent pregnancy.

METHODS

This was a prospective cohort study of women aged 18-35 years who had one previous Cesarean delivery (CD) at ≥ 37 weeks. Women were examined with saline contrast sonohysterography 6-9 months after CD. A scar defect was defined as large if scar thickness was ≤ 2.5 mm. Women were followed up and those who became pregnant were examined by transvaginal ultrasound at 11-14 weeks. Scar thickness was measured and scars were classified subjectively as a scar with or without a large defect. A receiver-operating characteristics curve was constructed to determine the best cut-off value for scar thickness to define a large scar defect at the 11-14-week scan.

RESULTS

A total of 111 women with a previous CD were scanned in the non-pregnant state and at 11-14 weeks in a subsequent pregnancy. The best cut-off value for scar thickness to define a large scar defect at 11-14 weeks was 2.85 mm, which had 90% sensitivity (18/20), 97% specificity (88/91) and 95% accuracy (106/111). In the non-pregnant state, large scar defects were found in 18 (16%) women and all were confirmed at the 11-14-week scan. In addition, a large defect was found in three women at 11-14 weeks that was not identified in the non-pregnant state.

CONCLUSION

The appearance of the Cesarean hysterotomy scar was similar in the non-pregnant state and at 11-14 weeks in a subsequent pregnancy. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.