Uterine dehiscence is a rare but potentially severe obstetric complication for both mother and child. In most cases of uterine dehiscence, there is a previous history of caesarean section (1-3). However, studies show that any operation on the uterus raises the risk of later uterine (scar) dehiscence or even uterine rupture during pregnancy. The risk of uterine scar dehiscence following prior uterine incision is estimated to be 4-5% (4-6), the risk of uterine rupture 0.5-0.8% (7). In terms of risk of dehiscence, the location of the scar (upper versus lower uterine segment) and the thinning of the uterine wall < 3.5 mm (measured by ultrasound) are important risk factors (1, 5). Studies have demonstrated that there is a correlation between the thickness of the lower uterine segment at 37 weeks of gestation and the associated risk for uterine dehiscence or rupture during labor. Importantly, uterine dehiscence does not involve the fetal membranes or the uterine serosa.
Uterine dehiscence mostly occurs at the end of the second trimester. Diagnosis is often made by ultrasound and can be confirmed and further specified by magnetic resonance imaging (MRI) without any radiation exposure of the fetus.