Objective: To assess the prevalence and investigate possible risk factors of cesarean scar niche after one cesarean delivery using three-dimensional ultrasonography.
Methods: A descriptive cross-sectional study conducted on 250 non pregnant women attended to outpatient clinic in Mansoura university hospital. Patients with only one cesarean delivery done from 6 to 12 months prior to time of examination were evaluated by three-dimensional trans-vaginal ultrasonography to detect possible cesarean scar niche. The main outcome measure was the presence of cesarean scar niche. Women with cesarean scar niche were compared with those with intact scar (control group). Maternal demographic variables, obstetric and peri-operative variables were analyzed in both groups to detect possible risk factors of cesarean scar niche.
Results: Cesarean scar niche was found in 77.2% of study group, with 58.4% of all study group having large defect. The most common shape of cesarean scar niche was triangular (71.6%). The following variables were more detected in cesarean scar defect group than in control group; advanced maternal BMI (as mean BMI in cesarean scar defect group was 27.15 ± 4.17 versus 25.28 ± 2.90 in control group; P value 0.001), presence of active labor (45,6% of women in cesarean scar defect group had active labor versus only 17.5% in the control group; P value ≤ 0.001), peripartum fever (34.2% of cesarean scar defect group had peripartum fever versus only 17.5% in the control group; P value 0.016), and uterine retroversion (uterus was retro flexed in 26.4% in the cesarean scar defect group versus only 12.3% in the control group; P value 0.016). Gestational age at time of delivery and fetal weight were not found to affect the risk of cesarean scar niche formation.
Conclusion: Based on ultrasound examination, increased maternal BMI, presence of active labor, peripartum fever, and uterine retroversion were found to be associated with increased risk of cesarean scar niche. Reduced distance between cesarean section scar or niche and cervical internal os was associated with large defects.