Dystocia due to abnormal labor power

　　The contraction function of the uterus depends on the synchronization degree of uterine myogenic, neurogenic, and hormone regulatory systems. Any abnormal function of any of the three can directly lead to abnormal labor power.

　　1. General causes of abnormal uterine contractions

　　(1) Maternal emotional tension: Poor tolerance to pain, irritability, or even clamor, which can interfere with the normal function of the central nervous system and affect uterine contractions.

　　(2) Endocrine disorders: Insufficient estrogen, oxytocin, prostaglandins, and acetylcholine in the mother's body, or a slow decline in孕激素 levels, as well as reduced sensitivity of the uterus to acetylcholine, can all affect the uterine muscle excitation threshold and affect uterine contraction.

　　(3) Overuse or improper use of sedatives and other drugs can suppress uterine contraction and cause uterine contraction weakness.

　　(4) Women with acute or chronic diseases, or weakness and fatigue, or diseases leading to acidosis, water and electrolyte disorders, can lead to uterine contraction weakness.

　　2. Local uterine factors

　　(1) Overdistension of the uterine wall, causing excessive elongation of the uterine muscle fibers and weakening of contraction ability, such as twins or multiple births, polyhydramnios, macrosomia, etc.

　　(2) Uterine maldevelopment, uterine malformation, or uterine fibroids can all affect uterine contraction.

　　(3) Multiparous women, those with a history of uterine infection, etc., can cause fibrosis of the uterine muscle wall, affecting uterine contraction ability.

　　3. Malpresentation and fetal position abnormality

　　The presenting part cannot adhere closely to the lower segment of the uterus and the cervix, and cannot stimulate the uterine vaginal nerve plexus to cause strong reflexive uterine contraction, leading to secondary uterine contraction weakness. This is usually seen in cases of malpresentation, floating presenting part, breech presentation, transverse lie, placenta previa, etc. (Long-term distension of the bladder can also lead to uterine contraction weakness).

　　Abnormal uterine contraction is clinically divided into two types: uterine contraction weakness and uterine contraction strength. Each type is further divided into coordinated uterine contraction and uncoordinated uterine contraction.

　　What diseases can be complicated with dystocia?

　　Fetal meconium aspiration syndrome. The amniotic fluid ingested by the fetus contains some shed cells, fetal hair, fetal fat, and other impurities. As the fetus approaches full term, these impurities accumulate in the intestines to form a thick, dark brown-green substance called (meconium). Babies usually pass meconium after birth. If the fetus experiences oxygen deficiency or distress in the uterus, it stimulates the vagus nerve, causing the anal sphincter to relax, and meconium is excreted prematurely, polluting the amniotic fluid. Fetal meconium appears earlier in high-risk pregnancies such as post-term pregnancy, intrauterine growth restriction, oligohydramnios, and prolonged labor. However, prenatal ultrasound cannot distinguish whether meconium is present in the amniotic fluid, and it is only discovered when the water breaks. Continuous fetal heart rate monitoring can ensure the health of the fetus during the subsequent labor process. During delivery, a pediatrician should be summoned to assist. Once the fetal head is delivered, immediately suction the foreign matter from the mouth and nose. After the body is delivered, it should also be suctioned clean as soon as possible. Do not hurry to stimulate the baby to cry loudly. However, the fetus has obvious breathing movements in the uterus, and some meconium has already been present in the trachea, so it is inevitable that it may be inhaled into the lungs, causing respiratory distress. After birth, active monitoring and treatment by a pediatrician are required, and the prognosis is almost always good.

　　The shoulder dystocia before labor (shoulder dystocia) is a relatively hot topic. The normal delivery process is that the body slides out after the fetal head is delivered. Once it is found that the fetus's shoulders are stuck in the outlet of the birth canal, the perineal incision is immediately widened, the mother's legs are raised, the uterus is pushed strongly, and the fetus's shoulders are rotated back and forth. If it still cannot be delivered, it is necessary to break the fetal clavicle.

　　Uterine contraction weakness is mainly manifested by uterine contraction weakness, short duration, and irregular intervals. At the strongest contraction of the uterus, the abdomen does not become hard or bulge. Clinical examination shows that the cervix cannot dilate as scheduled, and the fetus cannot gradually descend, leading to an extended labor.

　　How to prevent dystocia due to abnormal uterine contraction

　　Prenatal education for pregnant women should be conducted to alleviate their mental concerns and eliminate their fear of pregnancy, making them understand that pregnancy and childbirth are physiological processes, to prevent uterine contraction weakness caused by nervous tension, encourage pregnant women to eat more during labor, supplement nutrition via intravenous injection when necessary, avoid excessive use of sedatives, and pay attention to check for any misalignment between the pelvis and the fetus, which are effective measures to prevent uterine contraction weakness.

　　To prevent the occurrence of a localized constricted ring, unnecessary stimulation should be reduced. After its occurrence, stop all stimulation, such as prohibiting intravaginal operations, stopping the use of oxytocin, etc. If there are no signs of fetal distress, pethidine or morphine can be administered. When the uterine contractions return to normal, vaginal assistance or waiting for natural delivery can be performed. If the above treatments do not relieve the uterine spastic ring constriction, the cervix is not fully dilated, the presenting part of the fetus is high, or there are signs of fetal distress, an immediate cesarean section should be performed. If the fetus is dead in the uterus and the cervix is fully dilated, ether anesthesia can be performed for vaginal delivery.

　　General examinations should pay attention to general development, such as short stature, abnormal fetal position, the fetal head not entering the pelvis before labor in primiparas, and (or) a pendulous abdomen, which may indicate a narrow pelvis. In cases of limping, the pelvis may be oblique. Measure the sacral-ischial diameter of the pelvis

　　During the first stage of labor, due to the long duration, the mother's sleep, rest, and diet will be affected by the pain. To ensure that she has enough energy to complete the delivery, the mother should try to eat. The food should be mainly semi-liquid or soft foods, such as egg noodles, cakes, bread, congee, etc.

　　As the second stage of labor approaches, due to frequent uterine contractions, the pain intensifies, and consumption increases. At this time, the mother should try to consume some liquid foods such as fruit juice, lotus root starch, and brown sugar water during the intercontraction phase to replenish energy and assist in the delivery of the fetus. The food during labor should be chosen to be easily digested and absorbed, such as high-sugar or starch-rich foods, to quickly replenish energy. It is not advisable to eat greasy, high-protein foods that take too long to digest.

　　Prenatal education for pregnant women should be conducted to alleviate their mental concerns and eliminate their fear of pregnancy, making them understand that pregnancy and childbirth are physiological processes and to prevent uterine contraction weakness caused by nervous tension. Encourage pregnant women to eat more during labor, and supplement nutrition via intravenous injection when necessary. Avoid excessive use of sedatives. Pay attention to check for any misalignment between the pelvis and the fetus, which are effective measures to prevent uterine contraction weakness.

　　To prevent the occurrence of localized constrictive rings, unnecessary stimulation should be reduced. After occurrence, all stimulations should be stopped, such as prohibiting intravaginal operations, stopping the use of oxytocin, etc. If there are no signs of fetal distress, pethidine or morphine can be given. When the uterine contractions return to normal, vaginal assistance or waiting for natural delivery can be performed. If the above treatment does not relieve the uterine spasmotic constrictive ring, the cervix is not fully dilated, the presenting part is high, or there are signs of fetal distress, cesarean section should be performed immediately. If the fetus is dead in the uterus, and the cervix is fully dilated, ether anesthesia can be administered, and vaginal delivery can be performed.

　　It should first be determined whether there is cephalopelvic disproportion and obvious malpresentation, birth canal abnormalities, and exclude factors such as birth canal obstruction, maternal exhaustion, and fetal distress, and then treatment such as strengthening uterine contractions should be given according to the situation.

　　1. Coordinated (hypotonic) uterine contraction weakness

　　(1) Regardless of primary or secondary (coordinated) uterine contraction weakness, the cause should be sought first, whether there is cephalopelvic disproportion and malpresentation, and the situation of cervical dilation and presenting part descent should be understood.

　　(2) The first stage of labor

　　① General treatment: Eliminate tension through various methods.

　　② Strengthening uterine contraction

　　A. Artificial rupture of membranes: If the cervix is dilated above 3cm and there is no cephalopelvic disproportion, artificial rupture of membranes can be performed to make the fetal head directly adhere to the lower segment of the uterus and the cervix, causing a reflexive strengthening of uterine contractions.

　　B. Oxytocin intravenous infusion: It is suitable for coordinated (hypotonic) uterine contraction weakness.

　　C. Application of prostaglandins: Dinoprostone (prostaglandin E2) and F2a both have a promoting effect on uterine contractions.

　　(3) The second stage of labor

　　① If there is no cephalopelvic disproportion but uterine contraction weakness, oxytocin intravenous infusion should also be given to strengthen uterine contractions and promote the normal progression of labor.

　　② According to different situations, episiotomy, forceps delivery, or vacuum extraction of the fetal head can be used to assist delivery.

　　③ If the fetal head has not engaged, cesarean section should be used to end delivery, and it should not be delayed.

　　④ If there are signs of fetal distress during the second stage of labor, and the biparietal diameter of the fetal head has passed the interischial diameter, the midforceps should be used to assist delivery immediately; if the biparietal diameter has not reached the ischial spines or the presenting part is above +2, an emergency cesarean section is more beneficial to both the baby and the mother than a midforceps operation.

　　(4) The third stage of labor: It is especially important to prevent postpartum hemorrhage, including the use of oxytocin and prostaglandins to strengthen uterine contraction, artificial placental extraction when necessary, and manual compression and massage of the uterus with both hands, etc. For a long labor process and a long rupture of membranes, antibiotics should be administered to prevent infection.

　　2. Incoordination (hypertonic) uterine contraction weakness:The principle of treatment is to regulate uterine contractions and restore the polarity of uterine contractions.

　　(1) The use of pethidine 100mg intramuscular injection, or diazepam 10mg intramuscular or intravenous injection, to block the incoordination and ineffective uterine contractions is the main treatment. The mother can get sufficient rest, and after waking up, she can usually recover to coordinated uterine contractions, and the labor process is often very smooth.

　　(2) If the above treatment does not correct the incoordination of uterine contractions, or there are signs of fetal distress, or there is cephalopelvic disproportion, cesarean section should be performed.

　　(3) If the incoordination of uterine contractions has been controlled after treatment, but the uterine contractions are still weak, the method of strengthening uterine contractions during the coordination of uterine contractions can be adopted. It must be noted

　　①It is strictly forbidden to use oxytocin before the uterine contractions return to coordination;

　　②After the use of sedatives such as pethidine and diazepam, although the incoordination of uterine contractions has been controlled, the uterine contraction force is still poor, the incidence of dystocia and fetal distress is very high, and it must be fully emphasized, strictly monitored, and the delivery should be ended correctly and in time.

　　3. Strong Uterine Contractions with Coordination

　　(1) Women with a history of emergency delivery should not travel far in the 1-2 weeks before the expected date of delivery, and those who have the conditions should be admitted to the hospital early to wait for delivery. It is not advisable to enema during labor, and preparations for delivery and neonatal resuscitation should be made in advance.

　　(2) Do not let the mother push down during the delivery of the fetus. If an emergency delivery is too late to disinfect, disinfect the umbilical cord after cutting it. Newborns who fall to the ground should be given vitamin K intramuscularly to prevent intracranial hemorrhage, and 1500U of refined tetanus antitoxin should be injected as soon as possible.

　　(3) After delivery, carefully examine the condition of the soft birth canal laceration and suture it.

　　(4) If it is an unsterile delivery, antibiotics should be given to prevent infection.

　　4. Incoordination of Strong Uterine Contractions

　　(1) Uterine Rigidity

　　①Administer uterine contraction inhibitors: 20ml of 25% magnesium sulfate added to infusion is slowly injected or infused intravenously. Or give nitrous oxide (laughing gas) by nasal inhalation to inhibit uterine contractions and alleviate the pain of uterine contractions.

　　②If the cause of obstruction is due to it, it should be immediately changed to cesarean section. If the uterine rigidity does not relieve after inhibiting uterine contractions, or there is fetal distress, an emergency cesarean section should also be performed.

　　(2) Uterine Spasm Ring

　　①Carefully find the cause of the spasm ring and correct it in time.

　　②Stop all stimulation to the uterus (such as prohibiting vaginal operations, stopping oxytocin, etc.).

　　③Sedatives, such as 100mg pethidine intramuscular injection, or 10mg diazepam intramuscular or intravenous injection, to eliminate the uterine spasm ring. When uterine contractions return to normal, natural delivery or assisted delivery can be performed.

　　④If the uterine spasm ring cannot be eliminated after the above treatment, the cervix is not fully dilated, the presenting part of the fetus is high, or there is fetal distress, an emergency cesarean section should be performed immediately.

　　⑤If the fetus dies in the uterus and the cervix is fully dilated, it can be delivered vaginally under anesthesia. The principle is to avoid maternal tissue delivery injury as much as possible.