Obstetric Hemorrhage - Dr. Fragneto

The lecture focuses on the most common and important issues in pregnancy and delivery, specifically discussing obstetric hemorrhage as a leading cause of maternal mortality. It highlights the significance of this topic for anesthesiologists worldwide.

Anesthesia-related deaths often involve obstetric hemorrhage. The main causes are antepartum and postpartum hemorrhage, with a focus on placenta previa, placental abruption, uterine rupture for antepartum; and uterine atony and abnormal presentations for postpartum.

Placenta previa has different types: total or complete placenta previa, and partial placenta previa.

Placenta previa complicates about one in 200 pregnancies, but the incidence is increased by about 12-fold for women who've had a previous previa in another pregnancy. There are other risk factors such as multiple pregnancies and previous placenta previa.

Placenta previa increases the risk for painless vaginal bleeding. There is an association between placenta previa and placental abruption, with about 10% of women having both conditions. The diagnosis is usually made using high-fidelity ultrasound equipment.

Diagnosis of Placenta Previa Placenta previa diagnosis is crucial for anesthetic management. Cesarean delivery is almost always required for complete or partial placenta previa, with rare attempts at vaginal delivery in marginal cases. Early anesthesia evaluation and preparation are essential due to the potential for significant hemorrhage during labor.

Anesthetic Management Regional anesthesia can be used for scheduled cesarean deliveries or when there's minimal bleeding and stable maternal/fetal conditions. General anesthesia may be necessary if there's significant hemorrhage leading to maternal instability or fetal compromise, requiring drugs like etomidate or ketamine to maintain hemodynamic stability.

Placental abruption presents with abdominal pain and vaginal bleeding in the majority of cases. However, about 15% of cases develop concealed bleeding due to a retro placental hematoma. This can lead to underestimated blood loss and inadequate resuscitation.

Placental abruption affects 1/2 to 1% of pregnancies in the US, leading to higher maternal morbidity and mortality compared to previa.

Placental abruption is the most common cause of DIC in pregnancy, affecting about 10% of all cases. Severe abruptions increase the risk for fetal distress, demise, and postpartum hemorrhage. Patients with severe abruption may develop acute renal insufficiency and have a higher risk for maternal mortality.

Risk factors for placental abruption include hypertension, preeclampsia, chronic hypertension, cocaine use, smoking, older age and multiple gestation. Trauma to the abdomen and thrombophilia are also risk factors.

Anesthetic Management of Mild to Moderate Placental Abruption For mild or moderate placental abruption, the delivery may not necessarily be via cesarean. However, it's important to have a plan in place for possible progression of separation and additional bleeding during vaginal delivery. Coagulation status assessment is mandatory before regional analgesia anesthesia.

Anesthetic Management of Severe Placental Abruption Severe placental abruption generally requires emergency cesarean delivery due to significant compromise in the baby or instability in the mother. Regional anesthesia may not be feasible if there are concerns about fetal distress, developing DIC, or maternal instability due to hemorrhage and hypovolemia.

In cases where a woman with an epidural experiences severe abruption requiring emergency delivery, using the existing epidural for cesarean delivery is acceptable if the mother is stable. If general anesthesia is needed, etomidate or ketamine are preferred induction agents due to their ability to maintain hemodynamic stability. Consideration should be given to uterine tone and placental perfusion when choosing these drugs.

Anesthesia Maintenance for Severe Abruption When maintaining general anesthesia for severe abruption, the choice between ketamine and etomidate depends on the mother's hemodynamic status. If tolerated by the mother, inhalational agents may help decrease uterine tone and placental perfusion compromise. Fluid resuscitation with crystalloid, colloid, and blood products is essential based on blood loss and coagulopathy severity.

Uterine Rupture: Catastrophic Situation Uterine rupture poses a potentially catastrophic situation with maternal mortality at about one in 500 cases. Fetal mortality associated with uterine rupture can be as high as six to eight percent. Signs of uterine rupture include abdominal pain, vaginal bleeding, unstable condition of the mother; however abnormal fetal heart rate (fetal bradycardia) is the most common sign (presenting in about 70% of cases).

Uterine rupture risk factors include prior cesarean delivery, myomectomy, abdominal trauma, inappropriate use of uterotonic drugs causing hypertonic uterus, and grand mal tippers with weak stretched-out uterus.

The risk of uterine rupture varies depending on factors such as the number of prior cesarean deliveries and the type of uterine incision. For a patient with one prior low transverse cesarean delivery, the risk is around 0.7-0.9%, while for those with two prior low transverse cesarean deliveries, it increases to about 2%. Women with a classical or vertical uterine incision have a much greater risk, closer to 10%. Labor induction significantly increases the risk by about three times compared to spontaneous labor.

Encouraging women to attempt VBAC after one prior cesarean delivery has not gained much traction due to concerns about neonatal outcomes. A large observational study found that attempting trial labor resulted in a higher rate of neonatal hypoxic encephalopathy, with the majority of cases associated with uterine rupture.

The risks associated with trial of labor after cesarean and uterine rupture may be unpredictable. Immediate availability of facilities and personnel for emergency cesarean delivery is optimal. In community practice, VBAC is often not attempted due to the lack of immediate resources.

Anesthetic Considerations for Uterine Rupture Uterine rupture during emergency cesarean delivery requires anesthetic considerations focused on blood loss, good ID access, and available blood. Patients may need repair of the uterus or hysterectomy if severe rupture occurs. Epidural anesthesia can be used for delivery but may require conversion to general anesthesia for complex surgery.

Postpartum Hemorrhage: Increasing Rates and Causes Postpartum hemorrhage complicates 5-10% of deliveries worldwide with increasing rates in the US. A study from 1995 to 2004 showed a 27% increase primarily due to uterine atony episodes, associated with about 20% maternal post-delivery deaths. Another study from 1999 to 2008 found that severe postpartum hemorrhage had doubled over a decade due to both atonic and non-atonic causes, including placenta accreta related to cesarean delivery.

Anesthesiologists are most concerned about severe postpartum hemorrhage due to the higher risk of morbidity and mortality. Risk factors include older maternal age, multiple gestation, preeclampsia, chorioamnionitis, instrumented vaginal deliveries (forceps or vacuum), and cesarean delivery. Patients with fibrinogen less than 200 are at significantly higher risk.

Postpartum hemorrhage can be caused by uterine atony, placenta accreta, abnormal presentations, vaginal or cervical lacerations, retain placenta and uterine inversion. Risk factors include age (young or old), cesarean delivery, antepartum hemorrhage especially placental abruption and over distended uterus due to multiple gestation or polyhydramnios.

The first-line treatment for uterine atony is oxytocin, which stimulates contractions. Methergine is a second-line option but can cause severe hypertension and other adverse effects. Another option is 15-methyl prostaglandin f2 alpha (Hemabate), which increases contraction strength but has side effects like bronchospasm and diarrhea.

When pharmacological treatment for uterine atony fails, invasive management may be necessary. This can include a DNC to remove placental pieces, intrauterine balloon tamponade (Bhakra balloon), c-section with b-lynch compression suture as an initial step before hysterectomy, arterial ligation to control bleeding without hysterectomy, and interventional radiology embolization as a last resort.

For anesthetic management during invasive techniques like hysterectomy, large-bore IV access and blood resuscitation are crucial due to major bleeding. Consider a central line if peripheral access is difficult. Ensure type and screen conversion to type and cross for available blood supply. Choice of anesthesia depends on maternal hemodynamic stability; regional anesthesia may be suitable unless the patient has experienced significant blood loss or is unstable.

Volatile anesthetics can interfere with obtaining adequate uterine tone during general anesthesia for cesarean delivery or postpartum hemorrhage. Studies show a dose-dependent decrease in the strength and duration of contractions induced by oxytocin, with complete inhibition at high levels of volatile agents. Pregnant myometrium is more sensitive to these effects than non-pregnant uterus. Desflurane causes less inhibition than sevoflurane in vitro studies.

Abnormal placentations include placenta accreta, increta, and percreta. Placenta accreta is adherent to the endometrium and causes significant bleeding when separated. Increta involves the placenta growing into the myometrium, making separation difficult or impossible. Percreta is the most serious type where the placenta penetrates through the uterus and may extend into other organs.

The incidence of placenta accreta has increased due to the rise in cesarean delivery rates. The risk is associated with previous cesarean deliveries, and having a placenta praevia significantly increases the risk.

In managing placenta accreta, preparation for massive rapid blood loss is crucial. Ultrasound has improved identification of placenta accreta in advance, reducing the risk of excessive bleeding during separation. Delivery via cesarean section followed by immediate hysterectomy is usually planned to minimize blood loss. Gravid hysterectomy involves greater blood loss than routine hysterectomy.

The choice between epidural anesthesia and general anesthesia for patients with significant accreta is controversial. Some prefer regional anesthesia to avoid the risks associated with general anesthesia, citing a retrospective study that reported no increase in maternal morbidity and less blood loss under regional compared to general. However, it's important to consider that this study may have excluded high-risk cases from the regional group. The speaker generally advocates for general anesthesia in these cases, especially when hysterectomy is planned or if there's a risk of massive blood loss due to sympathectomy caused by neuraxial block.

The management of obstetric hemorrhage is evolving to improve outcomes for patients. This includes the consideration of a massive transfusion protocol, intraoperative cell salvage, and an obstetric hemorrhage bundle. While some data suggest positive results with fibrinogen concentrate and tranexamic acid, there is not enough evidence to support routine use yet. Arterial embolization is also being used as a way to manage obstetric hemorrhage while preserving the uterus.

Massive Transfusion Protocol in Trauma Patients The military found that using lower RBC to FFP and RBC to platelet ratios during massive transfusion improved outcomes. Civilian trauma patient studies showed associations between specific blood cell ratios and decreased pulmonary failure, sepsis, multi-organ failure, and mortality. Simpler protocols with a one-to-one-to-one unit ratio have shown good outcomes.

Challenges of Massive Transfusion Protocol in Obstetric Hemorrhage Limited data on the use of massive transfusion protocol in obstetrics exists. Special challenges include obtaining blood availability due to different etiology of obstetric hemorrhage compared to trauma patients' hemorrhage. A specialized protocol for obstetric hemorrhage includes early inclusion of cryo due to low fibrinogen levels.

Intraoperative cell salvage has been a concern in OB patients due to potential contamination with amniotic fluid and fetal RBCs. However, over 400 cases have been reported without serious adverse maternal effects.

Cell salvage is recommended for patients at risk of obstetric hemorrhage who refuse blood products, such as Jehovah's Witnesses. Using a leukocyte reduction filter during blood washing reduces squamous cell contamination but does not decrease fetal red cell contamination.

The safety and technique of cell salvage in obstetric hemorrhage are now better established, with many recommending its consideration for severe hemorrhages. Some countries have reported routinely implementing it to minimize homologous blood transfusion, especially for patients at risk of hemorrhage due to placental abruption or other factors.

In the setting of amniotic fluid embolism, patients are at increased risk for significant postpartum hemorrhage. However, using cell salvage in these cases is not recommended due to safety concerns. There have been reports suggesting that giving cell salvage blood to patients with amniotic fluid embolism can lead to severe hypotension and hypoxemia.

Arterial embolization is an effective way to control obstetric hemorrhage, often used as an alternative to hysterectomy. It involves blocking the uterine or internal iliac artery and has shown success rates greater than 90%. Despite concerns about cutting off blood supply to the uterus, fertility has been maintained in some patients with collateral development. Logistical issues are a barrier to its use due to coordination among obstetricians, radiologists, and staff.

Improving logistical issues in high-risk patients, such as those with placenta percreta, by contacting the radiologist ahead of time and placing prophylactic femoral artery catheters to expedite access in case of bleeding. Some institutions have even performed cesarean delivery in the radiology suite for immediate access to equipment and embolization if major bleeding occurs.

Anesthesiologists face challenges in unfamiliar environments, such as those with radiology equipment. Despite the difficulties, their role is crucial in potentially saving lives during embolization procedures.

Obstetric hemorrhage is a leading cause of maternal mortality in the United States. To improve outcomes, a national obstetric hemorrhage bundle has been developed, involving various specialists and focusing on preparedness, access to supplies and medications, response team involvement, risk assessment for patients prenatally and during admission, accurate estimation of blood loss during delivery procedures such as c-sections.