The soft birth canal includes the lower uterine segment, cervix, vagina and vulva. Lesions in the soft birth canal itself can cause obstructed labor, and lesions in and around other parts of the genital tract can also affect the soft birth canal and make labor difficult, but the former is more common. The obstructed labor due to soft birth canal abnormalities is much less common than that due to bony birth canal abnormalities, so it is easy to be overlooked, resulting in missed diagnosis. Therefore, vaginal examination should be performed routinely in early pregnancy to find out whether there are any abnormalities in the genital tract and pelvis. Since abnormalities of the soft birth canal can also cause obstructed labor, it is of clinical significance to perform a vaginal examination in early pregnancy to understand the condition of the vulva, vagina and cervix, as well as any other abnormalities of the pelvis. 1. Cervical opening The degree of dilatation, thickness and softness of the cervical opening (based on the peak of contraction), the presence and extent of edema in the cervix, and whether there is a gap between the cervix and the fetal head at the peak of contraction. These are very helpful to determine the type, nature and degree of obstructed labor. 2. Check the fetal orientation The direction of the sagittal suture and the position of the anterior and posterior fontanelles are the most important. Special attention should be paid to the possibility of misidentification of fontanelle and posterior fontanelle and the sagittal suture not being clearly felt when the fetal head is severely edematous and when the skull overlap is obvious. In the second stage of labor, the vaginal examination before the surgical assisted delivery is often used to find out the direction of the auricle to help determine whether the fetal orientation is accurate. This is very important for the diagnosis of obstructed labor (including the determination of whether the fetal previa can pass through the bony birth canal) and the decision of the treatment method (vaginal assisted labor or cesarean delivery), and no obvious error is allowed. Sometimes it is necessary to check with the other hand on the abdomen (on the pubic symphysis) whether the fetal head has passed through the pelvic inlet, especially in cases of severe fetal head deformation, sometimes the lowest point of the fetal head is even exposed. However, the biparietal diameter is still stuck above the pelvic inlet.