Điều này có thể được sau Previa và đứt nhau thai hoặc khi sản phẩm được giữ lại trong tử cung ngăn ngừa co rút đủ để ngăn chặn chảy máu hoặc co thắt tử cung không hiệu quả. Điều kiện hơn nữa phù hợp với mô tả của suy thai và xác định C / S được mô tả dưới đây. Dây (rốn) sa liên quan đến việc di chuyển xuống dây trước khi có các biểu hiện thai nhi. | Obstetric anaesthesia 123 than 500 ml from the genital tract after the birth of the child. It may be immediate or if it occurs between 24 hours and 6 weeks is classified as primary and beyond this period is termed secondary haemorrhage. This can be following placenta previa and abruption or when products are retained in the uterus preventing sufficient retraction to stem bleeding or ineffective uterine contraction. Further conditions which fit into the description of foetal distress and determine C S are described below. Prolapsed umbilical cord involves the downward displacement of the cord before the foetus presents. With vasa previa a foetal blood vessel lies over the os and is in danger of rupture and shoulder dystocia is failure of the foetal shoulders to traverse the pelvis after delivery of the head. This is more likely to progress to episiotomy and application of external pelvic pressure with the mother in the lithotomy or left lateral position than open surgery. All of the above conditions can threaten the viability of the foetus and lead to C S. In fact anything that interferes with foetal oxygenation will cause foetal distress Chamberlain 1995 . Approximately 30 of breech births also result in emergency C S Dobson 2004 . Even though obstetric anaesthesia is specialised and to some extent standardised in procedure it does not conform or adhere to a universal model or algorithm but in general will involve the avoidance of drugs and agents that cross the placental barrier depress foetal vital signs cause myocardial or respiratory depression and initiate untimely uterine contractions. Preoperative preparation whether elective or emergency would have involved establishing an IV line and measures to control and neutralise gastric acid with oral antacids given as close to theatre time as possible. Fasting would only be an issue in the case of an elective procedure. Premedication is not standard or indeed desirable especially narcotics and drugs used for .
