Saline infusion sonohysterography in nonpregnant women with previous cesarean delivery : The niche in the scar

Objective. To apply an existing diagnostic imaging test (saline infusion sonohysterography) to characterize the filling defect of a previous cervical cesarean delivery scar in the nonpregnant uterus. Methods. Forty-four patients with histories of cesarean delivery who underwent saline infusion sonohysterography for a variety of gynecologic indications were included. During the procedure, the area below the bladder recess was examined using transvaginal sonography. A filling defect or niche was defined as a triangular anechoic structure at the presumed site of a previous cesarean delivery scar. The depth of the niche was measured. Uterine size, the presence of fibroids and polyps, and the number of previous cesarean deliveries were noted. Results. All patients had a niche indenting the anterior uterine-cervical wall. The mean ± SD depth of the niche was 6.17 ± 3.6 mm. There was no correlation between the number of cesarean deliveries and the depth of the niche. Thirty-six percent of our patients had fibroids, and 18% had endometrial polyps. Conclusion. Saline infusion sonohysterography was able to detect filling defects in women who previously had cesarean deliveries. We hope that by focusing our attention on the transvaginal sonographic appearance of the detectable uterine scar (niche) with or without the use of saline infusion sonohysterography in the nonpregnant uterus, it will train our eyes to look for the scar in the pregnant uterus. In addition, our study patients had a high prevalence of abnormal uterine bleeding. The role of the cesarean delivery scar in women with unscheduled bleeding needs to be further evaluated.