DOI: https://doi.org/10.53350/pjmhs2115102682 ORIGINAL ARTICLE 2682 P J M H S Vol. 15, No.10, OCT 2021 Diagnostic Accuracy of Lower Uterine Segment Scar Thickness ≤1.6mm in Prediction of Scar Dehiscence in patients with Previous One LSCS Who are Undergoing Repeat LSCS after Trial of Labour taking Intraoperative findings as Gold Standard FIZA ASIF, SOBIA ZAFAR, TEHMINA ZAFAR, TAYYABA MAJEED, ZAHID MAHMOOD* Department of Obstetrics & Gynaecology, Central Park Medical College, Lahore *Professor of Surgery, Lahore Medical & Dental College, Lahore Correspondence to Prof. Tayyaba Majeed, Email: dr.tayyaba@hotmail.com, Cell: 0300-4315535 ABSTRACT Background: Cesarean section uterine scar dehiscence (CSD) is a rare but notable complication of Lower segment cesarean section (LSCS) surgery. The cause for a uterine scar dehiscence is based on the etiology behind the uterine scar defect or any event that would predispose the cesarean scar to dehisce. Globally accepted option for assessing the CS scar is transvaginal ultrasonography of the non-pregnant uterus. Objective: To determine the diagnostic accuracy of lower uterine segment scar thickness≤1.6mm in the predict ion of scar dehiscence in patients with previous one LSCS who are undergoing repeat LSCS after trial of labour taking intraoperative findings as gold standard. Material and methods: This cross sectional study was conducted in Services Hospital, Lahore for 6 months. The Non probability consecutive sampling technique was used to include women with previous one LSCS at 36-38 weeks were asked to get their TVS done for scar thickness. Women with scar thickness≤1.6mm and scar thickness>1.6mm were identified. Their intraoperative findings of scar dehiscence were confirmed. All the data was entered and analyzed on SPSS version 20. Results: The mean age of patients was 29.87±6.07 years. The emergency LSCS was done in 599(49.1%) patients and elective LSCS was done in 621(50.9%) patients. The sensitivity, specificity & diagnostic accuracy of TVS was 98.31%, 99.05% & 98.69% respectively. Conclusion: According to our study results the TVS for uterine scar is a very useful and effective tool in the prediction of scar dehiscence in patients with previous one LSCS taking intraoperative findings as gold standard. Keywords: Transvaginal sonography, TVS, Uterine, Scar, dehiscence, LSCS, Intraoperative INTRODUCTION The number of women who have undergone cesarean sections (CS) increases by 1.5 million every year 1 . Thus, management of pregnant patients that have previously undergone CS has become routine in delivery rooms worldwide. The safety of vaginal birth after cesarean section (VBAC) has been evaluated in various clinical trials, although the possibility of uterine dehiscence and rupture exists in 0.3 to 3% of cases 1 . Several studies have reported the imminent risk of uterine dehiscence and rupture in women during trial of labor with prior history of lower segment cesarean section (LSCS). As the previous C-section is associated with greater risk of complication during trial of labor so the decision of mode of delivery in next pregnancy is left to the patient. 2 For the better access of risk of uterine dehiscence and rupture USG measurement of lower uterine segment scar thickness near term is being employed for the last few decades. During the second half of 20th century, a cesarean section implied that all subsequent pregnancies were very likely to be delivered in the same way. This policy was the result from the fear of catastrophic uterine scar rupture of classical cesarean section, which persisted even after its replacement with lower segment cesarean section (LSCS) without the same basis. Various prospective studies showed that there is an inverse relationship between scar thickness and risk of scar dehiscence. 3 Globally accepted option for assessing the CS scar is transvaginal ultrasonography of the non-pregnant uterus. When compared to the transabdominal approach, the proximity of the transvaginal probe to the pelvic organs enables obtaining high resolution images of the CS scar. Sonographically lower uterine segment consist of echogenic muscularis and mucosa of bladder wall, part of visceral and parietal peritoneum and relatively hypoechoic myometrium 4-6 . ----------------------------------------------------------------------------------------- Received on 13-05-2021 Accepted on 22-09-2021 LUS thickness may work as an excellent predictor of uterine scar defect in women undergoing VBAC. However, as present in ideal cut-off value cannot be recommended 4 . Uterine car thickness can be assess both by transabdominal or transvaginal scan but recent studies revealed that TVS is more reliable in this regard. The optimal cut off value for LUS scar by various studies is found to be 2 to 3.5mm. The positive predictive value for ultrasound measurement was found to be 60.7% while negative predictive value was 100% 7 while specificity is 88.6% and sensitivity is 77.8%. 4 Incidence of uterine scar dehiscence is 7.8%. 6 The optimal cut-off value varied from 1.6 to 3.5mm for full LUS thickness. The rationale of this study is to determine diagnostic accuracy of LUS scar thickness≤1.6mm in prediction of scar dehiscence after trial of labour as there are no local studies available and positive predictive value is proportional to magnitude of the disease in the population which is different in different areas. The objective of the study was to determine the diagnostic accuracy of lower uterine segment scar thickness≤1.6mm in the prediction of scar dehiscence in patients with previous one LSCS who are undergoing repeat LSCS after trial of labour taking intraoperative findings as gold standard. MATERIALS AND METHODS This cross sectional study was conducted in the Department of Gynae Unit, Services Hospital, Lahore for a period of six months from 26-1-2016 to 26-7-2016. Sample size of 1220 patients is calculated with 95% confidence level, 7% margin of error for sensitivity i.e. 77.8% and 5% margin of error for specificity i.e. 88.6% of LUS scar thicknesss≤1.6mm and percentage of scar dehiscence 7.8%. Sampling technique used was non probability consecutive sampling Inclusion Criteria: Pregnant women with singleton pregnancy at term 37-40wks assessed by LMP with previous history of one LSCS with vertex presentation assessed by scan undergoing trial of labor.