Department of Reproductive Imaging Reproductive BioMedicine Research Center, Royan Institute for Reproductive BioMedicine, ACECR, Tehran, Iran



Isthmocele, also is called “Niche”, “Pouch”, or” Uterine scar defect” develops when the cesarean
section incision dose not heal completely.
In     general,    most    isthmoceles    are asymptomatic being found incidentally on ultrasound examination. Symptoms including AUB, postmenstrual spotting, dysmenorrhea, pelvic pain, and infertility have now been associated with isthmocele. Obstetric complications of isthmocele were described in the literature, such as placenta accrete, placenta previa, scar dehiscence, uterine rupture and C.S-EP. The association between isthmocele and secondary infertility has been reported.
Various imaging methods including TVS, SHG, MRI, can be used to diagnosis isthmocele. TVS is the initial most usual method. The standard diagnosis procedure for identification of isthmocele is transvaginal sonography (TVS), however, sonohysterography has been proven to be an at least equally apt alternative method. The defect has been described on TVS as an anechoic triangle defect in the myometrium with the base communicating to the uterine cavity.
Some authors have classified the findings according to the size of the defect, a large defect is described as a myometrial reduction of >50% of the wall of the thickness. A large defect may also be classified as residual myometrium (RM)
< 2.2 mm by TVS and < 2.5 mm by SHG.