Postpartum hemorrhage

　　1. Etiology

　　There are four main causes of postpartum hemorrhage, with uterine inertia accounting for about 50% of postpartum hemorrhage; laceration of the soft birth canal accounts for about 20%; placental retention or retention accounts for 5% to 10%; and postpartum hemorrhage caused by coagulation dysfunction is rare.

　　1. Uterine Inertia

　　After the fetus is delivered, the placenta detaches and is expelled from the uterine wall, causing bleeding due to the opening of blood sinuses in the uterine wall of the mother. In normal circumstances, due to the reduction in uterine cavity volume after childbirth and the strengthening of muscle fiber contraction, the blood vessels interwoven between the muscle fibers in the uterine wall are compressed to stop bleeding. At the same time, the blood sinuses close, and bleeding stops. At the same time, due to the hypercoagulable state of the maternal blood, a large number of platelets adhere to the endothelial collagen fibers on the damaged blood vessels after the placenta is stripped, forming thrombi. Fibrin deposition on platelet thrombi forms larger blood clots, effectively blocking the uterine blood vessels, so that bleeding does not occur when the muscle fibers relax after contraction. If the uterine contraction is insufficient after the fetus is delivered, causing the uterus not to contract and contract normally, and if the placenta has not been stripped or the blood sinuses have not been opened, bleeding will not occur. However, if the placenta has been partially stripped or stripped out, insufficient uterine contraction cannot effectively close the blood sinuses of the uterine wall where the placenta is attached, leading to excessive bleeding, which is one of the main causes of postpartum hemorrhage.

　　(1) General factors: such as the weak constitution of the mother, acute and chronic diseases, prolonged labor, dystocia, mental tension, excessive use of sedatives or deep anesthesia, etc.

　　(2) Local factors: ① Overdistension of the uterine muscle wall, excessive stretching of muscle fibers, affecting the contraction of muscle fibers. Such as polyhydramnios, multiple pregnancy, macrosomia, large placenta, α-thalassemia, fetal hydrops syndrome, etc. ② Multiparous women, repeated pregnancy and delivery, uterine muscle fibers are damaged, connective tissue is relatively increased, and there is degenerative change. ③ Uterine maldevelopment or surgical scar. ④ Factors affecting uterine contraction caused by placental factors. Such as placenta previa, early placental detachment, necrotic hemorrhage of decidua,渗血 of the uterine muscle layer, placental posterior hematoma, etc. ⑤ Overdistension of the bladder and rectum can affect uterine contractions.

　　2. Birth canal tear

　　The birth canal is rich in blood vessels and充血 during pregnancy, and if there is a tear in the birth canal during delivery, the amount of blood loss can be very large, especially when the laceration involves the upper vagina, cervix, and uterus, it is often difficult to stop bleeding. The reasons for the birth canal tear include the following aspects:

　　(1) Quick labor: during quick labor, due to excessive strength of uterine contractions or excessive effort by the mother, as the perineum has not been fully expanded, the delivery of the fetus can cause severe lacerations of the soft birth canal.

　　(2) Large fetus: insufficient estimation of fetal size before birth, failure to perform a perineal incision or an insufficiently large incision, can cause lacerations of the soft birth canal.

　　(3) Obstetric surgery: such as forceps delivery, manual version of the fetal head, destruction of the fetus, internal version, or shoulder dystocia, all of which can cause lacerations of the perineum, vagina, cervix, or even the lower uterine segment, leading to postpartum hemorrhage. A certain district in Shanghai once statistically analyzed the causes of postpartum hemorrhage, among which 37.9% were due to improper operation of obstetric vaginal surgery, which is related to the lack of skill in the operation technique of young obstetricians.

　　(4) Poor elasticity and extensibility of the perineum itself: such as congenital maldevelopment of the perineum, vulvovaginal inflammation, leukoplakia, etc.

　　(5) Formation of hematoma: If the injury involves blood vessels, while the mucosa and skin of the birth canal remain intact, or if the stitching of the wound is not completely sealed to stop bleeding, or if the laceration of the cervix and vaginal fornix extends upwards to tear the vascular ligament, forming a hematoma, there may not be much external bleeding at this time, but the bleeding within the hematoma can be significant, leading to shock.

　　3. Placental factors

　　Postpartum hemorrhage caused by placental factors includes incomplete placental detachment, retention after placental detachment, placental impaction, placental adhesion, placental implantation, and retention of placenta and/or amniotic membrane.

　　Partial detachment of the placenta and retention after detachment can be caused by insufficient uterine contractions. Placental impaction occasionally occurs after the use of oxytocin or ergometrine, which can cause spasmodic contraction near the internal os of the cervix, forming a narrow ring that embeds the placenta that has already been detached in the uterine cavity, hindering uterine contractions and causing bleeding. This narrow ring can also occur during rough massage of the uterus. Overdistension of the bladder can also obstruct the expulsion of the placenta and increase bleeding. When the placenta is completely or partially adherent to the uterine wall and cannot be stripped off by itself, it is called placental adhesion. Partial adhesion is prone to cause bleeding. Multiple induced abortions are likely to cause damage to the endometrium and the occurrence of endometritis. Endometritis can also be caused by infection from other causes, and endometritis can cause placental adhesion.

　　Placental implantation refers to the implantation of placental villi into the uterine muscle layer due to reasons such as poor development of the endometrium. It is relatively rare in clinical practice. It can be divided into complete and partial types according to the area of placental implantation.

　　Placental retention is more common and can be caused by premature traction of the umbilical cord or premature and excessive massage of the uterus. Placental retention may include partial placental lobes or accessory placenta retention adhering to the uterine wall, affecting uterine contraction and causing bleeding. Placental retention may also include partial retention of the amniotic membrane.

　　4. Coagulation dysfunction

　　It is a rare cause of postpartum hemorrhage. For example, blood diseases (thrombocytopenia, leukemia, decreased factors VII and VIII, aplastic anemia, etc.) often exist before pregnancy and are contraindications for pregnancy. Severe hepatitis, prolonged retention of intrauterine dead fetus, placental abruption, severe pregnancy-induced hypertension, and amniotic fluid embolism can all affect coagulation or lead to disseminated intravascular coagulation, causing coagulation disorders, uncoagulable postpartum bleeding, and difficult止血.

　　Second, Pathogenesis

　　Acute massive bleeding over a short period of time mainly causes a sharp decrease in blood volume, leading to insufficient cardiovascular filling and causing collapse, irreversible shock, or death. The compensatory mechanism in the early stage of acute hemorrhage is through the adjustment of cardiovascular dynamics and the stimulatory effect of adrenaline, which increases heart rate, cardiac output, and the redistribution of blood volume. Vessels in the skin, muscles, and spleen constrict, and vessels in organs with high tolerance to hypoxia such as the kidneys and gastrointestinal tract also constrict, thereby ensuring the blood supply to important organ tissues and sensitive organs to hypoxia such as the heart, lungs, liver, and brain. At this time, since red blood cells and plasma are lost in proportion, the determination of hemoglobin and hematocrit may still be within the normal range, and anemia does not occur. The main clinical manifestation is insufficient blood volume. This is the first stage of acute hemorrhage and generally lasts for 2 to 3 days.

　　After this, the recovery of blood volume mainly relies on the expansion of plasma volume, that is, mainly relies on water, electrolytes, and albumin being mobilized from outside the blood vessels into the plasma. The blood becomes diluted, viscosity decreases, blood flow accelerates, which is beneficial for the organ tissues to absorb more oxygen. On the other hand, due to the dilution of blood, the concentration of hemoglobin and the hematocrit of blood cells continuously decline, leading to anemia. When a large amount of bleeding reaches about 20% of the total blood volume in the body, it takes 20 to 60 hours to restore the total blood volume to normal. After 2 to 3 days of bleeding, when the blood volume returns to normal or nearly normal, the main problem is the excessive loss of red blood cells, leading to acute hemorrhagic anemia. This is the second stage of acute hemorrhage. If the total amount of blood loss in the patient is still relatively large, but the speed is not fast, and the compensatory mechanism of plasma volume expansion is sufficient, the manifestation of hemorrhagic shock may not be obvious, and acute hemorrhagic anemia may be the main manifestation. Healthy young adult patients can tolerate a loss of 50% to 60% of red blood cell volume, while patients with coronary heart disease may exhibit symptoms of organ hypoxia when the red blood cell volume loss is less than 30%.

　　Acute blood loss can stimulate the kidneys to produce erythropoietin, which increases the concentration of plasma erythropoietin 6 hours after acute blood loss and is negatively correlated with hemoglobin concentration. Erythropoietin not only promotes the proliferation of erythroid progenitor cells and the maturation of erythrocytes in the bone marrow, but also promotes the release of immature reticulocytes into the circulation from the bone marrow. Since these are immature erythrocytes, they contain more ribonucleic acid and ribosomal particles, and therefore appear as polychromatophilic large erythrocytes in Wright-stained blood smears. These cells can be seen 6 to 12 hours after acute blood loss, and after several days, the bone marrow production increases, and polychromatophilic erythrocytes can significantly increase. The proliferation of erythrocytes in the bone marrow begins on the second day after acute hemorrhage, but the maturation of erythrocytes requires 2 to 5 days. After 5 days of acute hemorrhage, the proliferation of erythrocytes reaches a peak, reversing the granulocyte-to-erythrocyte ratio. The rate of erythropoiesis reaches its maximum after 10 days of acute hemorrhage. When the loss of red blood cell volume reaches 10% to 20%, the bone marrow proliferation can exceed 2 to 3 times that of a normal healthy person. If the hematocrit is below 30%, it indicates that the loss of red blood cell volume is about 25%, and the level of erythropoietin in the plasma is even higher. At this time, if iron supply is sufficient, the bone marrow proliferation can be 5 times greater than that of a normal healthy person. If iron storage is insufficient, it is impossible to reach this level. Therefore, the ability of the bone marrow to compensate for acute blood loss anemia depends on whether the bone marrow hematopoietic function is intact, the erythropoietin response, and whether the iron supply is sufficient. If there are pre-existing bone marrow diseases, kidney diseases that reduce erythropoietin production, or accompanying diseases such as inflammation or tumors that interfere with the action of erythropoietin; or if the iron storage is not sufficient, it will affect the ability of the bone marrow to compensate for the increased proliferation. The content of 2,3-diphosphoglycerate (2,3-DPG) in the newly formed erythrocytes increases, which reduces the affinity of hemoglobin for oxygen, thus increasing the release of oxygen in the tissues and alleviating the hypoxic state.

　　1, The complications of postpartum hemorrhage are hemorrhagic shock, heart failure, and electrolyte disturbance leading to death.

　　2, Postpartum hemorrhage caused by genital tract infection can lead to anemia and reduced resistance in the mother, and the increased opportunity for uterine cavity manipulation increases the risk of postpartum infection. Therefore, it is advisable to use broad-spectrum antibiotics for the prevention and treatment of genital tract infections.

　　3, Severe postpartum hemorrhage in Sheehan syndrome can lead to ischemic necrosis of the anterior pituitary, resulting in disrupted endocrine function. The patient lacks prolactin, leading to no milk secretion, and lacks thyroxine, causing cold intolerance, weight gain, decreased basal metabolic rate, and increased glucose tolerance test.

　　The main clinical manifestations of postpartum hemorrhage are excessive vaginal bleeding, with blood loss exceeding 500ml within 24 hours after delivery, followed by hemorrhagic shock and a tendency to develop infection. Depending on the cause, the clinical manifestations may also vary, ranging from sudden massive bleeding, causing the mother to quickly fall into a shock state, with chills, dizziness, nausea, vomiting, yawning, shortness of breath, restlessness, and anxiety. Examination may reveal pale complexion, cold sweat, cold limbs, decreased blood pressure, and rapid pulse; it may also manifest as persistent slight or moderate bleeding; sometimes, the uterus may become relaxed after delivery, with uterine bleeding retained in the uterine cavity and vagina, the fundus of the uterus is soft and unclear to the touch. If the uterus is massaged and pressed downward, a large amount of blood and clots may be seen.

　　Nursing:

　　1. Take positive and effective emergency measures, and medical staff must cooperate closely and command unification. While determining the cause, they should save every second to carry out rescue efforts.

　　2. Assist the mother to adopt a supine position with slightly elevated lower limbs, provide oxygen inhalation, pay attention to warmth, closely monitor blood pressure, pulse, respiration, and consciousness changes. Observe the color of the skin, mucous membranes, lips, and nails, the temperature of the limbs, and urine volume, and discover early signs of shock in a timely manner. Pay close attention to the involution of the uterus.

　　3. Establish a good venous access (you can take two-way peripheral venous indwelling infusion, and catheterize the internal jugular vein when necessary), accelerate the speed of infusion and blood transfusion, and maintain sufficient blood volume.

　　4. Place a catheter, keep the catheter unobstructed, and pay attention to urine volume and color. Make various records, especially changes in vital signs and intake and output.

　　5. Accurately collect various specimens according to medical advice and deliver them for testing in a timely manner.

　　6. Provide different hemostatic measures according to the different causes of postpartum hemorrhage.

　　7. Actively prevent and treat infections, maintain a clean environment, ventilate the room for 30 minutes, twice a day, and regularly disinfect. Keep the bed sheets clean and dry, frequently change the sanitary pads, and clean the perineum twice a day with 10% virucide iodine swabs to maintain cleanliness, and use effective antibiotics.

　　8. Provide psychological support. After the postpartum hemorrhage is saved, although the life is saved, due to the large amount of blood loss, serious secondary pituitary anterior lobe necrosis may occur, with decreased function and various hormone levels. This condition is known as Sheehan syndrome. The mother may face problems such as poor physical strength, lack of endurance, and difficulties in self-care. Encourage the mother to express her feelings, provide timely psychological comfort and assistance to the mother and her family, and guide them on how to strengthen nutrition, effectively correct anemia, gradually increase activity, and promote early recovery. Provide good discharge instructions, remind them to continue to observe the uterine involution and lochia after discharge, and make it clear to them the time, purpose, and significance of postpartum follow-up visits so that they can receive the examination on time to verify their physical and mental recovery, solve breastfeeding issues, adjust the postpartum guidance plan, and help them recover better.

　　1. Blood count

　　(1) Erythrocytes: The changes in erythrocytes after acute hemorrhage vary with time. In the early stage of hemorrhage, erythrocytes flow out of the blood vessels along with plasma in proportion. Although the blood volume decreases sharply, the concentration of erythrocytes and hemoglobin per unit volume does not decrease; even due to the reflex contraction of blood vessels, the redistribution of blood, and the concentrated blood in the organs entering the circulating blood, the hematocrit and hemoglobin concentration can be slightly increased. Therefore, in the initial few hours of acute hemorrhage, measuring the hemoglobin content and hematocrit cannot be used to estimate the amount of blood loss. At this time, blood loss should be estimated based on symptoms and signs. Two to three days after acute hemorrhage, the recovery of blood volume is achieved through the expansion of plasma volume. Patients who rest in a supine position mainly rely on mobilizing body fluids and electrolytes from outside the blood vessels into the blood vessels in the first 24 hours. For active patients, the expansion of plasma volume is very slow, mainly relying on mobilizing extracellular albumin into the blood vessels. Due to dilution of the blood, the hematocrit and hemoglobin concentration gradually decrease. This change is most significant 2 to 3 days after hemorrhage. Anemia is normocytic and normochromic. The number of reticulocytes in peripheral blood begins to increase 3 to 5 days after acute hemorrhage, and the degree of increase is proportional to the amount of blood loss. It reaches its peak between 6 to 11 days, generally reaching 5% to 10%, and will not exceed 14%. The early increase in reticulocytes reflects the effect of erythropoietin, which causes premature release of reticulocytes from the bone marrow into peripheral blood. The late increase reflects the compensatory hyperplasia of the bone marrow, with newly formed erythrocytes released into the blood. Initially, the erythrocyte morphology is mostly normal. However, when reticulocytes increase, polychromatophilic erythrocytes and an increase in large erythrocytes can be seen, which also causes a transient increase in MCV. If examined at this time, it may be misdiagnosed as hemolytic anemia. However, except for blood loss occurring in the body cavity or tissue spaces, serum bilirubin does not increase in acute hemorrhagic anemia. In severe hemorrhage causing shock or tissue hypoxia, a small number of nucleated red blood cells may appear in the peripheral blood smear. The peripheral blood erythropoiesis image described above usually disappears within 10 to 15 days. Otherwise, it suggests that bleeding is still ongoing.

　　(2) Leukocytes: Within 2 to 5 hours after acute hemorrhage, leukocytes rapidly increase, reaching up to (10 to 20) × 10^9/L, with the highest level reaching 35 × 10^9/L. The mechanism of leukocyte increase is partly due to the action of adrenaline, which causes granulocytes to move from the marginal pool to the circulation pool, and simultaneously released into the blood from the reserve pool in the bone marrow. Classification count shows that the increased leukocytes are mainly neutrophils, and nuclear left shift phenomenon can be seen. In severe hemorrhage, neutrophil late blast and even neutrophil intermediate blast cells may appear. The leukocyte count usually returns to normal within 3 to 5 days. Persistent leukocytosis often indicates that bleeding has not stopped or there are other complications present.

　　(3) Platelets: During or shortly after bleeding, platelet count, coagulation time, and plasma fibrinogen may temporarily decrease. They can return to normal within 15 minutes after bleeding stops. After that, platelet count increases rapidly, and platelet count can reach 500×109/L within 1-2 hours, even up to 1000×109/L. If severe shock occurs, disseminated intravascular coagulation may occur. Platelet count usually returns to normal within 3-5 days after bleeding stops.

　　2. Bone marrow image

　　After the second day of acute blood loss, the bone marrow can show hyperplasia. By the fifth day, the proliferation of erythrocytes reaches a peak, and the ratio of granulocytes to erythrocytes can be 1:1 or reversed. The morphology of erythrocytes is normal, with intermediate erythrocytes being the majority. After 10-14 days of bleeding cessation, the hyperplasia of erythrocytes basically disappears, and the extracellular iron in the bone marrow is mostly disappeared, and the number of sideroblasts is significantly reduced or disappeared. The above-mentioned insufficient iron storage manifestations often occur in the late stage of acute hemorrhagic anemia.

　　3. Other

　　If acute blood loss is due to internal bleeding, blood enters the body cavity, cysts, and tissue spaces. Due to the destruction of red blood cells, free bilirubin levels may increase, serum lactate dehydrogenase levels may increase, and hemoglobin levels may decrease. In addition, an increase in reticulocytes may occur, resembling hemolytic anemia. Acute gastrointestinal bleeding can cause blood urea nitrogen levels to rise, which may be due to reduced renal blood flow or due to the digestion and absorption of a large amount of blood proteins in the digestive tract.

　　According to the condition and clinical manifestations, choose to do electrocardiogram and ultrasonic examination.

　　1. What is good to eat

　　Diet should be light, easy to digest, and nutritious. Alkaline foods such as tofu, kelp, dairy products, and various vegetables and fruits can be eaten more commonly.

　　2. What not to eat

　　Avoid fatty, acidic, cold, spicy, and刺激性 food, quit smoking and drinking

　　Preventive measures for postpartum hemorrhage can greatly reduce its incidence. Preventive measures should be implemented throughout the following stages:

　　1. Do a good job of pre-pregnancy and prenatal health care, start prenatal examination and monitoring from the early pregnancy, and terminate pregnancy for those who are not suitable for pregnancy in time during early pregnancy.

　　2. Prepare for early treatment for pregnant women with a high risk of postpartum hemorrhage, including those with: (1) multiple pregnancies, multiple deliveries, and multiple uterine cavity surgeries; (2) primiparas with advanced age or primigravidas with early pregnancy; (3) history of myomectomy; (4) incomplete or malformed reproductive organs; (5) pregnancy-induced hypertension; (6) complications with diabetes, blood diseases, etc.; (7) prolonged labor with uterine contraction weakness; (8) instrumental deliveries such as vacuum extraction and forceps, especially when using uterotonics; (9) stillbirths, etc.

　　3. Closely observe the condition of the mother during the first stage of labor, pay attention to the supplementation of water and nutrition, avoid overfatigue of the mother, and inject Demerol intramuscularly if necessary to give the mother a chance to rest.

　　4. Pay attention to the management of the second stage of labor, guide the mother to use abdominal pressure appropriately and correctly. For those who may develop postpartum hemorrhage, a doctor with a high level of professional skills should be on standby. For those with indications, a mediolateral episiotomy or midline episiotomy should be performed in a timely and moderate manner. The operation of delivery techniques should be standardized, and the fetal head, shoulders, and fetal head should be guided out smoothly. For those with uterine contraction weakness, 10U oxytocin should be intramuscularly injected after the fetal shoulders are delivered, followed by intravenous infusion of oxytocin to enhance uterine contraction and reduce bleeding.

　　5. Properly handle the third stage of labor, accurately collect and measure the amount of postpartum hemorrhage. After the signs of placental detachment appear, gently press the lower segment of the uterus and gently pull the umbilical cord to help the placenta and amnion be completely expelled, and carefully check whether the placenta and amnion are intact. Check for lacerations or hematoma in the soft birth canal. Check the uterine contraction status and massage the uterus to promote uterine contraction.

　　6. After the placenta is delivered, the mother should continue to stay in the delivery room for 2 hours for observation, as approximately 80% of postpartum hemorrhage occurs within 2 hours after delivery. Therefore, close monitoring of general condition, vital signs, vaginal bleeding, and uterine contraction should be emphasized. However, the bleeding situation after 12 hours should not be ignored either. Important precautions should be communicated to the mother, and medical staff should regularly patrol and handle problems in a timely manner.

　　7. For those with significant blood loss but without signs of shock, it is advisable to replenish blood volume in a timely manner, which is much better than replenishing the same amount of blood after shock occurs.

　　8. Early breastfeeding can stimulate uterine contraction and reduce the amount of vaginal bleeding.

　　Application of the postpartum hemorrhage scoring table: The postpartum hemorrhage scoring table is formulated according to factors that may cause postpartum hemorrhage, such as the presence of pregnancy-induced hypertension, the number of times of induced abortion and curettage, fetal size, platelet count, and history of antepartum hemorrhage. Appropriate preventive measures can be taken according to the score, which can significantly reduce the incidence of postpartum hemorrhage.

　　The total score of the scoring table is 29 points. Women with a score of ≥5 are prone to postpartum hemorrhage and should be vigilant and take timely preventive measures to reduce blood loss. For hospitals with poor medical conditions and blood transfusion conditions, pregnant women with a high score for postpartum hemorrhage should be transferred to a hospital in a timely manner.