Uterine atony | |
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Atonic uterus (held by surgeon) | |
Specialty | Obstetrics |
Symptoms | Uncontrolled postpartum bleeding, decreased heart rate, pain, soft non-contracted uterus |
Complications | postpartum hemorrhage, DIC, hypovolemic shock, renal failure, hepatic failure, and death |
Usual onset | third stage of labor |
Causes | trauma, complicated labor, medications, uterine distention, caesarean section |
Risk factors | Obesity, uterine distention, placental disorders, multiple gestation, prior PPH, coagulopathies |
Diagnostic method | Physical exam and observed blood loss |
Differential diagnosis | uterine inversion, obstetric laceration |
Prevention | Risk stratification and identification, active management of third stage of labor |
Treatment | Uterine massage, Oxytocin, uterotonics, tamponade or packing, surgical intervention |
Medication | Oxytocin (Pitocin), Carbetocin, Methergine, Hemabate or Carboprost, Misoprostol, Dinoprostone |
Prognosis | 2-3 times risk of recurrence |
Frequency | 80% of postpartum bleeding |
Uterine atony is the failure of the uterus to contract adequately following delivery. Contraction of the uterine muscles during labor compresses the blood vessels and slows flow, which helps prevent hemorrhage and facilitates coagulation. Therefore, a lack of uterine muscle contraction can lead to an acute hemorrhage, as the vasculature is not being sufficiently compressed. [1] Uterine atony is the most common cause of postpartum hemorrhage, which is an emergency and potential cause of fatality. Across the globe, postpartum hemorrhage is among the top five causes of maternal death. [2] Recognition of the warning signs of uterine atony in the setting of extensive postpartum bleeding should initiate interventions aimed at regaining stable uterine contraction.
There are many risk factors for uterine atony and several are due to the type of labor a mother experiences such as prolonged labor, labor lasting less than 3 hours, uterine inversion, the use of magnesium sulfate infusions, and extended use of oxytocin. Uterine distention caused by things like more than one fetus present, polyhydramnios, fetal macrosomia, uterine fibroids, chorioamnionitis can also lead to decreased uterine function and atony. Retained placental tissue or placental disorders, such as an adherent placenta, placenta previa, and abruption placentae increase the mother's risk of PPH. Body mass index (BMI) above 40 and coagulopathies are known risk factors. [1] [3] [2] [4]
Magnesium sulfate is used often in patients with preeclampsia and eclampsia, can inadvertently inhibit uterine contractions. In addition, preeclampsia can lead to blood disorders such as thrombocytopenia, platelet abnormalities, and disseminated intravascular coagulation. [5] Cesarean delivery, especially after prolonged labor, may cause the muscles of the uterus to become tired and stop contracting or contraction can be inhibited at the surgical site. [2]
Uterine atony occurs during 1 in 40 births in the United States and is responsible for at least 80% of cases of postpartum hemorrhage. [1] [6] [4]
The uterus is composed of an interconnected muscle fibers known as the myometrium. The blood vessels that provide the blood supply to the placenta pass through this muscle. [7] After labor it is the contraction of these muscles that physically squeeze the blood vessels so that hemostasis can occur after the delivery of the fetus and the placenta. [1] Local hemostatic factors like tissue factor type-1 plasminogen activator inhibitor and platelets and clotting factors aid in stopping the blood flow. [1] [7]
This physiological contraction does not occur if the myometrium becomes atonic. Oxytocin is released continuously during labor to stimulate uterine muscle contraction so that the fetus can be delivered and it is continued to be released after delivery to stop blood flow. [8] If the oxytocin receptors become desensitized and no longer respond to the hormone then the uterus does not contract. [8] The uterus can also be structurally damaged or distended to prevent contraction. Therefore, as placenta is delivered arteries are damaged and without the muscle contractions hemostasis cannot be reached. [1]
Blood loss is an expected part of labor and less than 500 mL is considered normal. [9] Generally, primary PPH is classified as being more than 500 mL of blood lost in the first 24 hours following delivery. [2] Those who have a caesarean section typically have more blood loss than a vaginal birth; so 1000 mL is commonly used to determine excessive blood loss. It is easy to underestimate maternal blood loss because the primary method of assessment is visual observation. [10] [11]
Identifying risk factors early in the pregnancy is essential in managing uterine atony and PPH. [12] This allows for planning and organizing the necessary resources including staff, medicines, assistive devices, and the proper blood products. The delivery plan should also be cognizant of the ability of the hospital or facility to provide an appropriate level of care if any complications occur. [1]
Most diagnoses of uterine atony are made during the physical exam directly upon completion of the delivery. Diffuse uterine atony is typically diagnosed by patient observation rather than blood loss. The uterus can be directly palpated or observed indirectly using a bimanual examination post-delivery. An atonic uterus can feel soft, "boggy" and/or enlarged. [2] Bleeding from the cervical os is also common. If the atony is localized to one area of the uterus, the upper, fundal region may still be squeezing while the lower uterine segment is non-functional. This can be difficult to see with a cursory abdominal examination and easily overlooked. Therefore, a comprehensive vaginal, abdominal, and rectal examination should be performed. The physical examination may include ultrasound imaging for rapid visualization of the uterus and other causes of bleeding. [1] Expulsion of gestational products such as the placenta and rapid identification of obstetric lacerations, helps exclude other causes of PPH. [1] Laboratory tests can be drawn if coagulopathies are suspected.
Before delivery all patients should be screened for risk factors and then assigned a postpartum hemorrhage risk stratification based on the American College of Obstetricians and Gynecologists recommendations. If the woman is at a medium risk, blood should be typed and screened. Those assessed to be high risk should be typed and cross-matched. [1] [13]
Medium Risk | High Risk |
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Prior uterine surgery | Placenta Previa |
Multiple gestation | Placenta accrete |
Grand multi-parity | Active bleeding |
Prior PPH | ≥ 2 medium risk factors |
Large fibroids | Platelets < 70,000 |
Macrosomia | Known coagulopathy |
BMI >40 | |
Anemia | |
Chorioamnionitis | |
Prolonged 2nd stage labor | |
Oxytocin longer than 24 hrs | |
Magnesium sulfate administration |
Active management of the third stage of labor is routinely implemented and is considered the standard for patient care. It can be utilized to reduce the risk of PPH. [14] [15] Active management of the third stage includes uterine massage and a IV low dose oxytocin. Whether it is given just before or after the delivery of the placenta is subject to provider preference. [1] It is suggested that using an uterotonic, such as oxytocin, prophylactically will help reduce blood loss and the need for a blood transfusion after delivery. [16]
A uterine massage is performed by placing a hand on the lower abdomen and using repetitive massaging or squeezing movements in attempt to stimulate the uterus. It is theorized, the massaging motion stimulates uterine contraction and may also trigger the release of local prostaglandins to help hemostasis. [17]
If uterine atony occurs even after all preventative measures have been taken, medical management should be implemented. Uterine fundal massage and compression should be maintained, while drugs are administered. [1] An intravenous catheter should also be started to administer fluids, medications, and blood products [18]
There are several different types of uterotonic drugs that may be given, and the each has its own advantages and disadvantages. [19] Moreover, the use of combination uterotonic therapy is a common practice and might be more effective at controlling bleeding than monotherapy. Some combinations might include oxytocin plus misoprostol, oxytocin plus ergometrine, and carbetocin. [20]
Medications used for PPH include the following: [1] [2]
After the medication is administered, the mother should be closely observed for to confirm the bleeding has stopped. If the bleeding has not stopped or physical exam does not show signs of restored uterine function within 30 minutes of medication administration, immediate invasive interventions are recommended. [27] [1]
Tamponade techniques include uterine packing (extending into the vagina) with gauze that also has a Foley catheter in place to allow for bladder drainage. It is inexpensive and readily available. [1] [16] Balloon tamponade is the suggested method of tamponade in guidelines for management of PPH. [28] A bakri balloon to tamponade (also with vaginal packing) can be used with Foley catheter insertion to facilitate bladder drainage. [1] [29] Vacuum-induced uterine tamponade is newer technique that uses low-level vacuum to evacuate blood from the uterine cavity and facilitate uterine contraction [30]
Surgical management techniques include:
PPH can cause a multitude of complications including: [2] [13]
In low‐income countries there are several other factors that play a role in PPH risk. Poor nutritional status, lack of healthcare access, and limited blood product supply are additional factors that increase morbidity and mortality. [34]
Postpartum anemia is common after an episode of uterine atony and postpartum hemorrhage. [1] Severe anemia due to PPH may require red cell transfusions, depending on the severity of anemia and the degree of symptomatology attributable to anemia. A common practice is to offer a transfusion to symptomatic women with a hemoglobin value less than 7 g/dL. In most cases of uterine atony-related postpartum hemorrhage, the amount of iron lost is not fully replaced by the transfused blood. Oral iron should thus be also considered. Parenteral iron therapy is an option as it accelerated recovery. Most women with mild to moderate anemia, however, resolve the anemia sufficiently rapidly with oral iron alone and do not need parenteral iron. [1] [2]
Women with a history of PPH have a 2 to 3 times higher risk of PPH in their following pregnancies. [35] [1] [36]
Placenta praevia is when the placenta attaches inside the uterus but in a position near or over the cervical opening. Symptoms include vaginal bleeding in the second half of pregnancy. The bleeding is bright red and tends not to be associated with pain. Complications may include placenta accreta, dangerously low blood pressure, or bleeding after delivery. Complications for the baby may include fetal growth restriction.
A hysterotomy is an incision made in the uterus. This surgical incision is used in several medical procedures, including during termination of pregnancy in the second trimester and delivering the fetus during caesarean section. It is also used to gain access and perform surgery on a fetus during pregnancy to correct birth defects, and it is an option to achieve resuscitation if cardiac arrest occurs during pregnancy and it is necessary to remove the fetus from the uterus.
Placental abruption is when the placenta separates early from the uterus, in other words separates before childbirth. It occurs most commonly around 25 weeks of pregnancy. Symptoms may include vaginal bleeding, lower abdominal pain, and dangerously low blood pressure. Complications for the mother can include disseminated intravascular coagulopathy and kidney failure. Complications for the baby can include fetal distress, low birthweight, preterm delivery, and stillbirth.
Bloody show or show is the passage of a small amount of blood or blood-tinged mucus through the vagina near the end of pregnancy. It is caused by thinning and dilation of the cervix, leading to detachment of the cervical mucus plug that seals the cervix during pregnancy and tearing of small cervical blood vessels, and is one of the signs that labor may be imminent. The bloody show may be expelled from the vagina in pieces or altogether and often appears as a jelly-like piece of mucus stained with blood. Although the bloody show may be alarming at first, it is not a concern of patient health after 37 weeks gestation.
Obstetrical bleeding is bleeding in pregnancy that occurs before, during, or after childbirth. Bleeding before childbirth is that which occurs after 24 weeks of pregnancy. Bleeding may be vaginal or less commonly into the abdominal cavity. Bleeding which occurs before 24 weeks is known as early pregnancy bleeding.
Uterine rupture is when the muscular wall of the uterus tears during pregnancy or childbirth. Symptoms, while classically including increased pain, vaginal bleeding, or a change in contractions, are not always present. Disability or death of the mother or baby may result.
Placenta accreta occurs when all or part of the placenta attaches abnormally to the myometrium. Three grades of abnormal placental attachment are defined according to the depth of attachment and invasion into the muscular layers of the uterus:
Postpartum bleeding or postpartum hemorrhage (PPH) is often defined as the loss of more than 500 ml or 1,000 ml of blood following childbirth. Some have added the requirement that there also be signs or symptoms of low blood volume for the condition to exist. Signs and symptoms may initially include: an increased heart rate, feeling faint upon standing, and an increased breathing rate. As more blood is lost, the patient may feel cold, blood pressure may drop, and they may become restless or unconscious. The condition can occur up to six weeks following delivery.
Carbetocin, sold under the brand names Pabal among others, is a medication used to prevent excessive bleeding after childbirth, particularly following Cesarean section. It appears to work as well as oxytocin. Due to it being less economical than other options, use is not recommended by NHS Scotland. It is given by injection into a vein or muscle.
A vaginal delivery is the birth of offspring in mammals through the vagina. It is the most common method of childbirth worldwide. It is considered the preferred method of delivery, with lower morbidity and mortality than caesarean sections (C-sections).
Uterine inversion is when the uterus turns inside out, usually following childbirth. Symptoms include postpartum bleeding, abdominal pain, a mass in the vagina, and low blood pressure. Rarely inversion may occur not in association with pregnancy.
A uterotonic, also known as an oxytocic or ecbolic, is a type of medication used to induce contraction or greater tonicity of the uterus. Uterotonics are used both to induce labor and to reduce postpartum hemorrhage.
Retained placenta is a condition in which all or part of the placenta or membranes remain in the uterus during the third stage of labour. Retained placenta can be broadly divided into:
Placental expulsion occurs when the placenta comes out of the birth canal after childbirth. The period from just after the baby is expelled until just after the placenta is expelled is called the third stage of labor.
The Bakri Balloon is a medical device invented and designed by Dr. Younes Bakri in 1999.
A resuscitative hysterotomy, also referred to as a perimortem Caesarean section (PMCS) or perimortem Caesarean delivery (PMCD), is a hysterotomy performed to resuscitate a woman in middle to late pregnancy who has entered cardiac arrest. Combined with a laparotomy, the procedure results in a Caesarean section that removes the fetus, thereby abolishing the aortocaval compression caused by the pregnant uterus. This improves the mother's chances of return of spontaneous circulation, and may potentially also deliver a viable neonate. The procedure may be performed by obstetricians, emergency physicians or surgeons depending on the situation.
Fundal massage, also called uterine massage, is a technique used to reduce bleeding and cramping of the uterus after childbirth or after an abortion. As the uterus returns to its nonpregnant size, its muscles contract strongly, which can cause pain. Fundal massage can be performed with one hand over the pubic bone, firmly massaging the uterine fundus, or with the addition of one hand in the vagina compressing the two uterine arteries. Routine use of fundal massage can prevent postpartum or post-abortion hemorrhage and can reduce pain; it may also reduce the need for uterotonics, medications that cause the uterus to contract. It is used to treat uterine atony, a condition where the uterus lacks muscle tone and is soft to the touch instead of firm.
Synthetic oxytocin, sold under the brand name Pitocin among others, is a medication made from the peptide oxytocin. As a medication, it is used to cause contraction of the uterus to start labor, increase the speed of labor, and to stop bleeding following delivery. For this purpose, it is given by injection either into a muscle or into a vein.
Emergency childbirth is the precipitous birth of an infant in an unexpected setting. In planned childbirth, mothers choose the location and obstetric team ahead of time. Options range from delivering at home, at a hospital, a medical facility or a birthing center. Sometimes, birth can occur on the way to these facilities, without a healthcare team. The rates of unplanned childbirth are low. If the birth is imminent, emergency measures may be needed. Emergency services can be contacted for help in some countries.
Uterine balloon tamponade (UBT) is a non-surgical method of treating refractory postpartum hemorrhage. Once postpartum hemorrhage has been identified and medical management given, UBT may be employed to tamponade uterine bleeding without the need to pursue operative intervention. Numerous studies have supported the efficacy of UBT as a means of managing refractory postpartum hemorrhage. The International Federation of Gynecology and Obstetrics (FIGO) and the World Health Organization (WHO) recommend UBT as second-line treatment for severe postpartum hemorrhage.