Sonographic lower uterine segment thickness after prior cesarean section to predict uterine rupture: A systematic review and meta‐analysis

Abstract

Abbreviations: SROC, summary receiver-operating characteristics; TOLAC, trial of labor after cesarean section; VBAC, vaginal birth after cesarean section. AbstractIntroduction: Cesarean section rates are increasing with a decrease in the rate of trial of labor after cesarean section. The objective of this study was to systematically review the predictive characteristics of sonographic measurement of lower uterine segment thickness for uterine rupture during labor. Material and methods:The review was carried out in agreement with PRISMA and SEDATE guidelines. MEDLINE, EMBASE, ClinicalTrials.gov and Cochrane Library were searched from 1990 until November 2018. Quality of included studies was assessed using the QUADAS-2 tool. Data were extracted to construct 2 × 2 tables from each study comparing ultrasound measurement with uterine defect at time of delivery. The data were plotted as a summary receiver-operating characteristic (SROC) curve using the hierarchical SROC model. Results: Twenty-eight observational cohort studies met the selection criteria for inclusion. Sonographic lower uterine segment thickness was measured at a gestational age of 36-40 weeks in women with a previous cesarean section. The risk of bias and concerns regarding applicability were low among most studies. The sonographic measurement was correlated with either delivery outcome or lower uterine segment thickness at the time of repeat cesarean section. The cut-off value for lower uterine segment thickness ranged from 1.5 to 4.05 mm across all studies. An association between thin lower uterine segment measurement and uterine dehiscence and uterine rupture was shown in 27 and four studies, respectively. Nineteen studies were included in a meta-analysis with a subgroup analysis by ultrasound methodology. In the subgroup using the ultrasound methodology associated with uterine rupture, the cutoff value is more precise (2.0-3.65 mm) among these 12 studies. There were 18 cases (1.0%) of uterine rupture, 120 (6.6%) of uterine dehiscence and 1674 (92.4%) women with no uterine defect. The SROC curve showed a sensitivity of 0.88 (95% CI 0.83-0.92) and specificity of 0.77 (95% CI 0.70-0.83). The negative likelihood ratio was 0.11 (95% CI 0.08-0.16) and the diagnostic odds ratio was 34.0 (95% CI 18.2-63.5). Conclusions:Lower uterine segment thickness >3.65 mm, measured using a standardized ultrasound technique, is associated with a lower likelihood of uterine rupture. | 831SWIFT eT al.

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

“…These complications can occur sequentially or independent of one another. 34 A recent meta-analysis examining the uterine thickness after prior CS concluded that a lower uterine thickness of <2 mm suggests an increased risk of uterine rupture, 35 , 36 highlighting the importance of measuring the uterine thickness, especially within the lower uterus, after a previous CS. The literature also suggests that the size of a patient’s isthmocele can impact the risk of future complications; specifically, large diverticula (RMT of ≤2.2 mm) can increase the risk of scar dehiscence up to 42.9%.…”

Morphological description of uterine scar 1 year after cesarean section by 3D-SPACE 3.0T MR

“…At least two main shortcomings regarding ultrasound, for evalution of p-CS scar, should raise concern. First, it is heavily operator-dependent, second, the definition of LUS thickness on ultrasound is not standardized, inconformity was shown in many aspects, including between 2D thickness and 3D volume [16], or whether the bladder wall should be excluded [3,5].…”

“…Scar length was 0.66 ± 0.45 cm, width was 1.18 ± 0.53 cm and minimal scar thickness was 0.44 ± 0.22 cm. Scar volume was assumed as cuboid and calculated by multiplication of thickness, width and length, which was 0.35 ± 0.36 cm 3 .…”

“…In clinical practice, ultrasound was the most generally applied imaging modality for evaluation of post-CS uterine scar. Lower uterine segment (LUS) thickness was the commonly used parameter by ultrasound evaluation, studies have shown the relationship between increased risk of uterine rupture and thinner LUS thickness [1,3,4]. However, the measurement of LUS thickness is not standardized, and evaluation of ultrasound is operator-dependent, there is still no commonly accepted cutoff value of LUS thickness for uterine rupture risk prediction [5,6].…”

Modifiable predictors to maternal visceral adipose tissue during pregnancy: A clinical, demographic, and nutritional study

“…The same procedure showed accuracy among pregnant women with a reported prior spontaneous preterm birth history 3 . In addition, lower uterine segment's small thicknesses measured by ultrasound predict organ dehiscence or rupture during labor among prior cesarean section cases 4,5 …”