Persistent occiput posterior and lateral positions

　　1. Abnormal pelvis often occurs in male pelvis or anthropoid pelvis. The characteristics of these two types of pelvises are that the anterior part of the pelvic inlet is narrow, not suitable for the fetal head's occiput to engage, and the posterior part is wide, making the fetal head easy to engage in a posterior or transverse position. This type of pelvis often has a narrow middle pelvis, which affects the fetal head's forward rotation in the middle pelvis and becomes a persistent posterior or transverse position.

　　2. If the fetal head engages in a posterior position with poor flexion, the fetal spine is close to the mother's spine, which is not conducive to the flexion of the fetal head. The anterior fontanel becomes the lowest part of the fetal head during descent, and the lowest point often turns to the front of the pelvis. When the anterior fontanel turns to the front or side, the fetal head's occiput turns to the back or side, forming a persistent posterior or transverse position.

　　3. Other causes of inadequate uterine contractions affect the flexion and internal rotation of the fetal head, which are easy to cause persistent posterior or transverse positions of the fetal head. Some scholars report that the incidence of posterior position is high when the placenta is anterior.

　　The fetal head often engages in a transverse position, even if it engages in a posterior position, during the delivery process, strong uterine contractions can usually make the fetal head's occiput rotate forward by 90° to 135°, turning into an anterior position and delivering naturally. If it cannot be turned into an anterior position, there are the following two types of delivery mechanisms:

　　(1) In the case of left (right) posterior position, the fetal head's occiput rotates backward by 45° when reaching the middle pelvis, making the sagittal suture consistent with the anteroposterior diameter of the pelvis, and the fetal occiput faces the sacrum to form a normal posterior position. There are two types of delivery methods: ① Good flexion of the fetal head: when the fetal head continues to descend and the anterior fontanel reaches below the pubic arch, the fetal head flexes with the anterior fontanel as the fulcrum, allowing the top and occiput to be delivered from the anterior perineal margin. Subsequently, the fetal head extends upwards, and the forehead, nose, mouth, and chin are successively delivered below the symphysis pubis. This is the most common method of vaginal delivery assistance for posterior position. ② Poor flexion of the fetal head: when the root of the nose appears below the inferior margin of the symphysis pubis, the root of the nose is used as the fulcrum, the fetal head is first flexed, and the anterior fontanel and the top and occiput are delivered from the anterior perineal margin. Then the fetal head extends upwards, and the nose, mouth, and chin are successively delivered below the symphysis pubis. Due to the larger occipitoparietal circumference rotation, the delivery of the fetus is more difficult, and often requires surgical assistance.

　　(2) In the case of partial transverse position, if a part of the fetal head does not rotate internally during the descent process, or the fetal head in posterior position only rotates forward by 45° to become a persistent transverse position, although a persistent transverse position can be delivered vaginally, most cases require manual rotation of the fetal head or use of vacuum extraction to turn the fetal head to anterior position for delivery.

　　What diseases can be concurrent with persistent posterior or transverse positions of the fetal head:

　　1. In late engagement and poor flexion of the fetal head during labor, due to the difficulty of the fetal presenting part in posterior position to adhere closely to the cervix and lower uterine segment, it often leads to inadequate uterine contractions and slow cervical dilation. Because the occipital bone continuously stays at the posterior part of the pelvis, compressing the rectum, the woman feels rectal prolapse and defecation. This leads to the early use of abdominal pressure before the cervix is fully dilated, which is easy to cause edema of the anterior cervix and fatigue in the mother, affecting the progress of labor.

　　2. The impact on the mother is that abnormal fetal position leads to secondary uterine contraction weakness, prolonging the labor. It often requires instrumental delivery, which is easy to cause damage to the soft birth canal, increasing the chance of postpartum hemorrhage and infection. If the fetal head compresses the soft birth canal for a long time, it can cause ischemia, necrosis, and shedding, forming a fistula in the reproductive tract.

　　3. The impact on the fetus due to the prolongation of the second stage of labor and the increase in the opportunity for instrumental delivery often causes fetal distress and neonatal asphyxia, increasing the perinatal mortality rate.

　　The fetal vertex engagement is late and the flexion is poor during labor. Since the presenting part of the occipito-posterior position is not easy to adhere tightly to the cervix and lower segment of the uterus, it often leads to inadequate uterine contraction and slow cervical dilation. Because the occipital bone is continuously located behind the pelvis, compressing the rectum, the parturient feels anal prolapse and defecation. This leads to the use of abdominal pressure too early before the cervix is fully dilated, which is easy to cause edema of the anterior cervix and fatigue of the parturient, affecting the progress of labor. Persistent occipito-posterior position often leads to a prolonged second stage of labor. If the fetal hair is seen at the vaginal orifice, but the fetal head does not continue to descend smoothly during multiple uterine contractions, it should be considered that it may be persistent occipito-posterior position.

　　1. Pregnant women should not sit or lie for a long time, and should increase gentle activities such as walking, massaging the abdomen, and turning the waist.

　　2. Abnormal fetal position has occurred in many pregnant women during pregnancy, but the vast majority of people can correct it themselves at the end of pregnancy. Expectant mothers do not need to worry about this.

　　3. Avoid cold and gas-forming foods, such as watermelons, sweet potatoes, legumes, milk, etc.

　　4. Keep the bowels open, it is best to have a bowel movement every day.

　　What needs to be reminded to all expectant mothers is that if the above therapy can help you correct the abnormal fetal position, it is very good, but if it cannot be corrected, there is no need to be anxious. You need to be hospitalized for delivery 1-2 weeks before the expected delivery date, and the doctor will decide the mode of delivery according to the specific condition of the pregnant woman.

　　1. Abdominal examination

　　The fetal buttocks can be felt at the fundus of the uterus, the fetal back is biased towards the posterior or lateral side of the mother's body, and the fetal limbs can be felt distinctly on the opposite side. If the fetal head has engaged, sometimes the fetal chin can be palpated above the pubic symphysis on the side of the fetal limbs. The fetal heart sound is the most distinct on the lateral side of the umbilicus. In the posterior position, due to the straightening of the fetal back, the anterior chest is close to the mother's abdominal wall, and the fetal chest on the side of the fetal limbs can also be heard.

　　2. Anal examination or vaginal examination

　　When the cervix is partially dilated or fully open during rectal examination, if it is in the posterior position, there is a feeling of emptiness in the posterior pelvic area. It is found that the fetal vertex suture is located on the oblique diameter of the pelvis, the anterior fontanelle is in the right anterior part of the pelvis, and the posterior fontanelle (occipital) is in the left posterior part of the pelvis, which is the left occipito-posterior position, and vice versa is the right occipito-posterior position. If the fetal vertex suture is located on the transverse diameter of the pelvis, and the posterior fontanelle is on the left side of the pelvis, it is the left occipito-transverse position, and vice versa is the right occipito-transverse position. If fetal head edema occurs, craniocerebral overlap, and the fontanelle is not palpable, a vaginal examination is needed to determine the fetal position by the position and direction of the fetal ear and ear helix. If the ear helix faces the posterior part of the pelvis, it can be diagnosed as the posterior position; if it faces the lateral part of the pelvis, it is the transverse position.

　　3. B-ultrasound examination

　　According to the position of the fetal head, face, and occiput, the fetal head position can be accurately identified to clarify the diagnosis.

　　Avoid cold and flatulent foods, such as watermelons, sweet potatoes, legumes, dairy products, etc. The patient's diet should be light and easy to digest, eat more vegetables and fruits, and rationally match the diet, ensuring adequate nutrition. In addition, patients should also avoid spicy, greasy, and cold foods..

　　1. During the first stage of labor, closely observe the progress of labor, pay attention to the descent of the fetal head, the extent of cervical dilation, the strength of uterine contractions, and whether the fetal heart rate changes. It should be estimated that the labor process will be long, and adequate nutrition and rest for the mother should be ensured. The mother should lie on the opposite side of the fetal back to facilitate the rotation of the fetal head forward. If the uterine contractions are poor, oxytocin should be administered intravenously as soon as possible. Before the cervix is fully dilated, the mother should not breathe or exert force too early to avoid causing edema of the anterior cervix and hindering the progress of labor. If there is no obvious progress in labor, the fetal head is high or there are signs of fetal distress, cesarean section should be considered to end labor.

　　2. If the second stage of labor progresses slowly, and the primipara has been nearly 2 hours and the multipara has been nearly 1 hour, a vaginal examination should be performed. When the biparietal diameter of the fetal head reaches the level of the ischial spines or lower, the fetal head can be manually rotated forward so that the sagittal suture is consistent with the anteroposterior diameter of the pelvic outlet, or natural delivery, or vaginal assistance (low forceps delivery or vacuum extraction). If it is difficult to turn to the anterior position, it can also be rotated backward to the posterior position, and then assisted by forceps. If the fetus is delivered in the posterior position, a larger perineal lateral incision is required to avoid perineal laceration. If the fetal head is high and there is a suspicion of cephalopelvic disproportion, cesarean section should be considered, and mid-forceps should not be used.

　　3. Due to the prolonged labor, the second stage of labor is prone to postpartum uterine atony, so uterine contraction agents should be administered immediately after the placenta is delivered to prevent postpartum hemorrhage. In cases of lacerations of the soft birth canal, timely repair should be performed. Newborns should be closely monitored. Patients who undergo cesarean section or have lacerations of the soft birth canal should be given antibiotics to prevent infection.