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) Abnormalities of the cervix (1) In advanced primigravida, the cervical canal is tough and elastic, and the cervical dilatation is slow and easy to edema, resulting in prolonged labor. 2, scar formation after cervical electro-ironing, conical resection, partial amputation and shaping. The history of this kind of disease is clear. If the labor process is stalled, vaginal examination can identify the cause. (2) Reproductive organ tumors 1. Cervical cancer: There are increased leucorrhea and irregular bleeding during pregnancy. If not detected during pregnancy, there may be bleeding or slow dilatation of the cervix during labor; it is not difficult to identify if examined with a speculum. 2. Uterine fibroids: they often grow with the increase in the size of the uterus during pregnancy, and examination reveals a lump-like mass attached to the uterine body. If the tumor is located in the interstitial part of the uterus, it may cause deformation of the uterine cavity, some affect the fetal position, and some may cause miscarriage and premature delivery. If it is located in the lower part of the uterus or in the cervical region, it can obstruct the birth canal and affect the pelvic entry or descent of the fetus. If the tumor is only under the plasma membrane, it is usually harmful to the pregnancy. 3. Ovarian tumor: If it occupies part of the small pelvic cavity, it may cause obstruction of the birth canal. If the tumor is in the abdominal cavity, an extra-uterine mass can be found, but if there is no torsion or other complications, it is not felt. However, if the tumor rupture is induced in labor, the symptoms are similar to uterine rupture. 4.Vaginal wall cyst or tumor: Anal examination and vaginal examination can detect abnormalities and make a clear diagnosis. (iii) Abnormalities of the birth canal 1, longitudinal vaginal septum, transverse septum, double vagina, double uterus, etc., scarred vaginal stenosis due to burns, surgery, inflammation. 2, stump horned uterine pregnancy, more auxiliary examinations are required for a clear diagnosis, such as B-type ultrasonography or X-ray photography, etc. 3. Pregnancy in bicornuate uterus after Strassmann orthopedic surgery. (iv) Firm perineum, edema of vulva, venous aneurysm, etc.