"Pocket sign" on hysterosalpingography: an adjunctive imaging finding suggestive of caesarean isthmocele

Caesarean scar defects, known as isthmocele, are increasingly recognized in women with secondary infertility, yet hysterosalpingographic (HSG) criteria remain poorly defined. We describe a reproducible HSG feature, the "pocket sign," observed in seven women with prior caesarean delivery. This finding appears as contrast pooling in the anterior lower uterine segment near the internal cervical os. In all cases, it correlated with transvaginal ultrasound and hysteroscopic findings. Although non-specific and not diagnostic, the pocket sign may serve as an adjunctive indicator prompting further evaluation. Given anatomical variability and intrinsic limitations of HSG, multimodal imaging remains essential.