Types of abnormal soft birth canal:
1. Abnormal Perineum
1. Perineal Edema
Varicose veins, varicose ulcers, and stenosis of the perineum are causes of dystocia.
2. Perineal Tumor
It can lead to dystocia, and the abscess of the perineum should be incised and drained during vaginal delivery.
3. Perineal Scar
After major surgeries of the perineum and after perineal laceration, scars are more likely to tear during childbirth, making vaginal delivery difficult.
2. Abnormal Vagina
1. Congenital Vaginal Stenosis
Although it can be softened after pregnancy, it can cause lacerations due to poor extensibility during childbirth.
2. Vaginal Surgery Scar
For example, after repair of uterine prolapse, the formation of severe inflammatory scars, cervical laceration, it may soften during pregnancy and expand during childbirth, but it can cause deep scars and bleeding. Early diagnosis is recommended, and elective cesarean section is preferred.
3. Vaginal Tumor
Generally, vaginal cysts are discovered during childbirth, which can be punctured. Other conditions such as cancer, sarcoma, fibroma, etc., with limited extension and increased fragility and tend to bleed and become infected, should opt for elective cesarean section when full term.
4. Vaginal Septum
A complete septum extends from the uterus to the cervix to the vagina, often accompanied by double uterus and double cervix malformations, complete septum. Generally, during the descent of the fetal head, half of the vagina can be fully expanded to pass through. An incomplete septum is divided into upper and lower parts, which can obstruct the descent of the fetal head. Sometimes it may naturally rupture, but if it is thick, it should be cut off, and the remaining septum should be removed after the fetus is delivered, and the residual ends should be sutured with catgut.
5. Vaginal Septum
The vaginal septum is often located in the upper and middle segments of the vagina. During labor, digital examination may misdiagnose it as the cervical os, but one can feel that the cervical os is above the level of the septum. During vaginal examination, the external os of the cervix can be found above the small hole of the septum. If the os is fully dilated, the fetal head has descended to the pelvic floor, and the septum can be expanded with fingers or an X-shaped incision made. After the fetus is delivered, the edges are sutured. In difficult cases, cesarean section is recommended.
3. Cervical Lesion
1. Cervical Lesion
Infection after cervical laceration can cause the cervix to split irregularly on the left and right sides, forming scars, hard nodules, and narrowing of the cervical os. The labor process may be prolonged during childbirth, and forceps-assisted delivery can cause deep lacerations and bleeding. Elective cesarean section is still recommended.
2. Cervical canal stenosis
Due to serious damage or infection of the cervix tissue caused by difficult labor, generally the cervix softens after pregnancy, and if the cervix cannot dilate or dilate slowly during labor, cesarean section should be performed.
3. Cervix orifice adhesion
During the process of labor, the cervical canal has disappeared but the cervix orifice does not dilate, the cervix orifice wraps the fetal head and descends. There is a thin layer of cervical tissue between the presenting part and the vagina. If the descent of the fetal head has reached 2cm below the spina, it can be pierced by hand, and the cervix orifice will dilate quickly. It can also cut the cervix 1-2cm at the 10 o'clock, 2 o'clock, and 6 o'clock of the uterus orifice edge, and then assist with forceps, but there is a risk of cervical laceration.
4. Obstruction of cervix orifice dilation
The uterine contraction is normal, the progress of labor is smooth, the fetal head has connected, the internal orifice of the uterus is dilated, the cervix has disappeared, and only the external orifice is opened to the tip of the finger, the orifice is thin like a paper wrapping the fetal head without dilation. It occurs in primiparas during the process of labor, presenting as incomplete dilation of the cervix orifice. Multiparous women can cause uterine rupture, which is divided into primary and secondary two types.
(1) Primary uterine cervix abnormalities: congenital defects, the cervix and the orifice are small without pregnancy, and the obstruction of labor is caused by the lack of expansion of the tissueology during labor.
(2) Secondary uterine orifice abnormalities: tissueological abnormalities of the uterine orifice, such as multiple deliveries, multiple histories of induced abortions, scar tissue at the edge of the uterine orifice, hardening of the uterine vagina, past cervical incision surgery, or radium therapy of the cervix and vagina, as well as cervical cancer, etc., most are multiparous. If not treated, it can cause uterine rupture, and occasionally partial necrosis of the cervix can occur, presenting as annular shedding and bleeding.
Abnormalities in the cervical canal mentioned above, if there is a history of suspicion before labor, can be examined vaginally, detected early, and treated early.
5. Cervical edema
It is generally common in flat pelvis, narrow pelvis, edema of the lower part of the cervix caused by compression between the pelvic wall and the fetal head, which is caused by the compression of the fetal head, blood flow obstruction, and the obstruction of cervix dilation. Long-term compression leads to the停滞 of labor. If it is mild edema, puncture can remove tension, which can dilate the cervix and deliver smoothly. In severe cases, selective cesarean section should be performed.
6. Variation of the uterine orifice
At the beginning of labor, the presenting part enters the anterior wall of the cervix, the posterior wall of the cervix is not well dilated, pushing the cervix orifice towards the sacral direction, changing its position upwards and backwards, called OS Saccalis. The external orifice of the uterus reaches the sacral promontory, generally the fingers cannot be felt during anal examination, causing obstruction of cervix dilation and dystocia. However, during the process of labor, the cervix orifice above and behind often moves to the center to be consistent with the pelvic axis, and there are those who can dilate and deliver. If the cervix orifice cannot turn to the center, the dilation of the cervix is obstructed, the labor is prolonged, leading to dystocia, affecting the health of both the mother and the baby.
7. Adhesion of the cervix and amniotic membrane
Due to inflammation, the lower part of the cervix is adhered to the amniotic membrane, causing the progress of labor to slow down. If a vaginal examination is performed, the hand can be inserted into the deep part of the cervical orifice to剥离, making it separate from the lower segment of the uterus and the cervix wall, forming the amniotic sac, and the progress of labor will be rapid.
8. Cervical fibroids
It is relatively rare to have cervical fibroids during pregnancy, accounting for about 0.5%, most of which are uterine fibroids during pregnancy, cervical fibroids. When labor occurs, the contraction of the uterine body is obstructed by the upward traction of the cervix, causing dystocia.
When subserosal fibroids are impacted in the Douglas pouch, there is significant labor obstruction. Vaginal examination is used for diagnosis, and cesarean section is recommended.
9. Cervical cancer tumor
Generally, women aged 20 to 30 have cervical cancer during delivery, the cervix lacks extensibility and elasticity, the cervix dilates with difficulty, the tissue is fragile, causing lacerations, bleeding, necrosis, infection, and other risks. Early examination and timely diagnosis can perform selective cesarean section. For patients with cervical cancer, cesarean section is first performed, and after the fetus is delivered, if conditions permit, a radical hysterectomy can be performed, otherwise, postoperative radiotherapy is performed.
10. Cervical rigidity
(1) Cervical rigidity: It is divided into upper cervical rigidity, referring to abnormal cervical canal or incomplete muscularization of the cervical canal, and lower cervical rigidity, referring to fibrous rigidity of the cervical connective tissue, which makes the cervix immature. Both affect the softening, disappearance, flattening, and dilation of the cervix and the entry of the fetal head into the pelvis, causing dystocia.
(2) The connective tissue of the cervical canal becomes hard and abnormal, making the cervix immature. If in labor, incomplete maturity of the cervix, the cervix opens to the tip of the finger, causing prolongation of labor, leading to fetal asphyxia, labor arrest, and cesarean section is required.
4. Abnormal uterus
1. Uterine prolapse
Complete prolapse of the uterus, after 4 months of pregnancy, it gradually rises into the abdominal cavity and no longer prolapses. During delivery, there is no resistance at the pelvic floor, and delivery is quick. However, when the corpus uteri is in the abdominal cavity, the cervical canal is long and prolapses outside the vagina, due to the proliferation and hypertrophy of connective tissue, it affects the dilation of the cervix, often causes premature rupture of membranes, prolonged labor, uterine cavity infection, cervical laceration, sudden rupture of membranes, downward effort, cervical edema, affecting the dilation of the cervix and causing dystocia.
2. Uterine torsion
The cervix of the pregnant uterus is divided into upper and lower parts. The upper part twists, which can cause fetal death in severe cases. During vaginal examination, it is difficult for the finger to enter the internal os of the cervix, which can be diagnosed. It is better to end labor early and confirm the diagnosis by bimanual or three-hand examination.
3. High anteversion of the uterus and postoperative fixation of the anterior abdominal wall
The pregnant uterus is in an anteverted position, the fundus height descends, presenting as a hanging abdomen. The cervix is pulled upwards. At the beginning of labor, it is difficult for the fetal head to enter the pelvis, and it is prone to premature rupture of membranes. Strong uterine contractions make the cervix thin and pulled upwards, the cervix dilates slowly, the fetal head is tightly pressed against the posterior wall of the cervix, which can cause posterior wall rupture. Pregnancy after uterine and abdominal wall fixation also becomes a hanging abdomen, the cervix dilates with difficulty, the fetal head compresses the posterior wall of the cervix, overextends, and there is a risk of posterior wall rupture. Those with a history of this condition or a hanging abdomen should be vigilant, make early estimates, and selective cesarean section can be performed.
4. Uterine malformation
(1) Disunited double uterus, double cervix, and bicornuate uterus: Disunited double uterus or double cervix, bicornuate uterus similar to unicinate uterus, with poor development, rarely achieving term pregnancy. Generally, cervical dilation is obstructed, there is malpresentation of the pelvis and head, easy prolongation of labor. Once detected, selective cesarean section should be performed. Uterine malformations are classified into 19 types (Figure 1), and fetal positions in malformed uterine pregnancy are classified into 8 types.
(2) Bicornuate uterus with a single cervix: The two uterine horns are short, resembling a uterus with a mid-septum, and there is a high incidence of breech presentation and multiple complications. Cesarean section is recommended.
(3) Septate uterus or incomplete septate uterus: It is mostly infertility, and there are more abortions and preterm births after pregnancy. Due to the presence of a uterine septum, the amnion enlarges and causes obstruction, resulting in transverse or breech position. There are difficulties in placental detachment after delivery, and there is more postpartum hemorrhage. It is easy to be missed, and it is often discovered by X-ray examination.
(4) Bicornuate uterus: The fundus of the uterus bulges into the uterine cavity, and transverse position is most common after pregnancy.
(5) Unilateral uterus: This is one side of the Mullerian duct development, one side is underdeveloped. After pregnancy, the fetus is often in breech position, and it is generally not possible to reach full term. There are more abortions and preterm births. The uterine muscle development is poor. Once labor starts, the uterine contractions are weak, the labor is prolonged, and there are more maternal and fetal complications. The uterus is prone to rupture during delivery. Unilateral uterus pregnancy is slightly better than accessory horn uterus pregnancy, where 50% of accessory horn uterus pregnancies result in uterine rupture. It should be examined during pregnancy, and early diagnosis and treatment should be made.
5. Uterine hypoplasia
Uterine hypoplasia is always combined with poor ovarian function, so infertility is common. Even if pregnancy occurs, there are more abortions and preterm births. At full term, the dilatation of the cervix is obstructed, the uterine contractions are weak, the labor is prolonged, and cesarean section is often performed to save the fetus.
6. Uterine contraction ring
During the process of delivery, local muscle spasm occurs at the lower segment of the uterus or the internal os of the uterus, that is, the labor is long, the mother is tired and dehydrated, and the uterine muscle function occurs in an uncoordinated contraction, with the internal os as the common occurrence part. A part of the spasm narrows, tightly wrapping the neck and waist of the fetus, and a part of the abdomen can be felt as a depression. Abnormal elevated narrowed ring-like objects can be felt in the uterine cavity. Narrowing can occur near the internal os during the opening phase. Due to compression, the cervix becomes relaxed, edematous, and contracted, making it difficult for the fetal head to descend, prolonging the labor, and compressing the bladder and rectum. If a narrowed ring appears after delivery, it can cause placental impaction. The narrowed part of the uterus needs to be relaxed before the fetus or placenta can be delivered. Cesarean section should be performed to save the fetus if necessary.
5. Myoma of the uterus combined with pregnancy
The myoma of the uterus increases in size with the increase of gestational weeks. The myoma of the uterus may undergo red degeneration during pregnancy and puerperium, with local pain and tenderness, accompanied by low fever and increased white blood cells. If infection occurs, antibiotic treatment is required.
Submucosal myomas combined with pregnancy are prone to abortion and preterm birth, affecting placental function. When the pregnancy reaches full term, due to the prolapse of submucosal myomas to the outside of the vagina, infection may occur. Once diagnosed, selective cesarean section can be performed when the fetus is mature.
After the intermuscular myoma is in labor, it can cause uterine contraction weakness and prolong the labor. Myomas growing in the cervix, the lower segment of the uterus, or subserosal myomas embedded in the pelvic cavity can all cause difficulties in delivery. Myomas located on the posterior wall of the uterus have a greater impact. Early selective cesarean section should be performed after diagnosis. The uterus that has undergone myomectomy may have scar rupture during the delivery process, which should not be ignored.
Generally, when a myoma is combined with pregnancy, the mode of delivery should be judged according to the position of the fetal head and the myoma. If the myoma is above the pelvic cavity and the fetal head has entered the pelvis, and if the uterine contractions are good and the labor progresses normally, a natural delivery can be performed. If the myoma is located below the presenting part and the fetal head is floating, there will be certain difficulties in vaginal delivery, and cesarean section should be performed. During cesarean section, myomectomy is generally not performed.
Six, pelvic tumors
1. Ovarian cyst
Ovarian cysts during pregnancy, most often occur in the third month of pregnancy and during the postpartum period due to torsion of the pedicle. If the ovarian cyst blocks the birth canal, it can lead to rupture of the ovarian cyst or obstruction of labor, occasionally causing uterine rupture. Therefore, after diagnosis, elective surgery should be performed, such as removal of the ovarian cyst at 4 months of pregnancy or during a period of time after delivery. If the ovarian cyst is incarcerated in the pelvis during labor, cesarean section must be performed.
2. Pelvic mass
Clinically, it is relatively rare, but there may be severe bladder distension, or vaginal bladder prolapse, vaginal rectal prolapse, and prolapsed kidneys that block the pelvis, hindering the progress of labor. Cesarean section can be performed.