Shoulder dystocia

　　Possible factors leading to shoulder dystocia:

　　① Macrosomic fetus;

　　② There is a possibility of shoulder dystocia when the fetal chest circumference is 1.3 cm larger than the biparietal diameter, the chest circumference is 1.6 cm larger than the head circumference, or the shoulder circumference is 4.8 cm larger than the head circumference according to B-type ultrasonography;

　　③ Macrosomic fetus combined with prolonged deceleration phase of the labor curve or second stage >1 hour, the rate of shoulder dystocia increases from 10% to 35%, so macrosomic fetus and prolonged second stage are considered as predictive signals for shoulder dystocia;

　　④ Difficult vaginal delivery with significant resistance, or when the biparietal diameter of the fetal head remains at the mid-pelvic plane after the cervix is fully dilated;

　　⑤ Macrosomic fetus in diabetic patients, as the trunk of the fetus grows faster than the head in pregnant women with diabetes.

　　In addition to its clinical manifestations, shoulder dystocia can also cause other diseases. Generally speaking, shoulder dystocia often occurs with neonatal brachial plexus injury or clavicle fracture, and if it lasts for more than a few minutes, it may lead to asphyxia and death due to umbilical cord compression.

　　Shoulder dystocia, also known as difficult delivery of the shoulder, refers to a situation where the fetus's head has been delivered outside the body during labor, but the anterior shoulder is stuck above the symphysis pubis, and cannot be delivered using conventional midwifery methods. According to Chinese reports, the incidence rate is 0.15%. After the fetal head of a macrosomic fetus is delivered, the anterior shoulder is trapped above the symphysis pubis, and the fetus cannot be delivered using conventional midwifery methods.

　　To ensure that the fetus does not move around in the birth canal, it is very important to control weight gain to an ideal level during pregnancy through reasonable diet and exercise (although a mother's weight gain is not always related to the size of the fetus; sometimes, a mother with excessive weight gain may mean the fetus is too large). Diabetic patients should be particularly cautious about controlling their physical condition to avoid giving birth to a super-large fetus.

　　1. General examination注意事项：General development, short stature, abnormal fetal position, nulliparous women with the fetal head not engaged in the pelvis before labor, and (or) with a hanging abdomen, all indicate that the pelvis may be narrow, and limping may indicate a tilted pelvis.

　　2. Pelvic measurement: sacral-pubis diameter

　　Diet should focus on small portions, variety, and richness, generally adopting a method of eating less but more frequently. It is important to control the amount of food intake, especially high-protein and high-fat foods, as excessive consumption of such foods without restriction can lead to excessive growth of the fetus, making delivery more difficult.

　　脂肪性食物里含胆固醇量较高，过多的胆固醇在血液里沉积，会使血液的黏稠度急剧升高，再加上妊娠毒素的作用，使血压也升高，严重的还会出现高血压脑病，如脑出血等。

　　饮食的调味宜清淡些，少吃过咸的食物，每天饮食中的盐量应控制在7克以下，不宜大量饮水。

　　孕妇应选体积小、营养价值高的食物，如动物性食品，避免吃体积大、营养价值低的食物，如土豆、红薯，以减轻胃部的涨满感。特别应摄入足量的钙，孕妇在吃含钙丰富食物的同时，应注意维生素的摄入。

　　孕妇要摄取足够的优质蛋白质和必需脂肪酸，但尿蛋白高的孕妇应限制蛋白质、水分和食盐的摄入，多吃植物性油。

　　注意均衡营养，平常的饮食生活要节制食盐的摄取，热量高的食物、甜食、米、面包等主食不要吃太多，要多吃含有优质蛋白质的蛋、牛奶、肉类以及大豆制品等，同时也要考虑食用含有其他营养成分的食物。

　　肩位难产时，医生要迅速试用各种方法娩出胎儿肩胛，让胎儿能经阴道娩出。如果经阴道分娩失败，很难把胎儿再推回阴道内，由剖宫产术结束分娩.

　　挽救肩位难产的胎儿有一系列的方法，包括进行外阴切开术, 女性外生殖器包括大、小阴唇，阴阜，阴蒂及阴道前庭。分娩时，阴道扩张以便娩出婴儿。在婴儿即将被娩出时，接产医师于产妇宫缩时在阴道口底部切开切口，这样可扩大阴道出口以利胎头娩出，防止阴道撕裂，当胎儿及胎盘娩出后缝合切口；旋转胎儿使其背部和肩部先出来，将母亲的膝盖上抬紧贴腹部；以中度力量压迫骨盆边缘；使用其他机动方法使胎儿肩部露出。如果其他方法失败，分开胎儿的锁骨。必要时，如果可能(很少会出现这种情况)，把胎儿的头部压回阴道，进行剖腹产。