Anesthesiology

Retained Placenta, Management

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What the Anesthesiologist Should Know before the Operative Procedure

Obstetric hemorrhage is a leading cause of maternal mortality worldwide. The definition of obstetric hemorrhage has recently been redefined as cumulative blood loss of > 1,000 mL or blood loss accompanied by signs/symptoms of hypovolemia within 24 hours of delivery. Retained placenta is one of the three leading causes of postpartum hemorrhage (PPH) and represents 20%-30% of cases, the other two being uterine atony and cervical or vaginal lacerations. All three together account for 95% of PPH cases. Retained placenta occurs in 3% of vaginal deliveries and the risk of postpartum haemorrhage is increased if retained for longer than 30 minutes.

Often, retained placenta is associated with uterine atony. Retained placenta is sometimes anticipated as in abnormal placental implantation; however, most the time it is unanticipated. It only becomes recognized after the placenta or placental fragments fail to separate from the uterus. For the uterus to contract appropriately, it must be emptied of all its contents. There are three types of retained placenta. Placenta adherens occurs when the myometrium fails to contract behind the placenta but is easily separated manually. Trapped placenta happens when the placenta is detached but is behind a closed cervix. Placenta accreta occurs when the placenta abnormally invades into the myometrium. Risk factors for retained placenta include prior history of retained placenta, previous injury or surgery (caesarean section) to the uterus, preterm delivery, induced labor, multiparity, advanced maternal age, uterine malformation, infection, and preeclampsia.

Uterine exploration and removal under anesthesia is the definitive treatment of retained placenta. Uterine exploration can be done either manually or with currettage under ultrasound guidance. These patients are typically young and healthy and rarely have associated coexisting morbidities. Lack of recognition can lead to a crisis event which could have potentially been avoided. The amount of blood loss is often underestimated. Be aware that the amount of blood loss can be slow and continuous but ultimately be life threatening.

The progression of hemorrhage can be interrupted prior to severe morbidity and mortality using a standardized approach, comprehensive, and multidisciplinary protocols.

The National Partnership for Maternal Safety which represents all major women’s healthcare professional organizations developed an obstetric hemorrhage safety bundle. The goal is to have the safety bundle adopted by every birthing center in the United States to improve outcomes. These are evidence-based recommendations for practice that aids implementation and consistency of practice. Low-resource hospitals that are unable to accomplish all the recommendations should consider sending higher risk patients to another hospital.

The obstetric hemorrhage bundle has been organized into four action domains: Readiness, Recognition and Prevention, Response, and Reporting and Systems Learning. The Readiness domain includes five focus areas that should be addressed to prevent delays and to prepare for optimal treatment of the patient. First, a hemorrhage cart with necessary supplies can be developed. The cart should contain medications, if it can be locked, as well as cognitive aids and equipment for placing sutures and tamponade balloons. Immediate access to hemorrhage treating medications and hemorrhage treatment kits could even be developed with pharmacy to make access to meds easier and faster.

A response team should be established to help the primary physician and nurse and typically include clinicians from anesthesiology, gynecologic surgery, operating room, interventional radiology, and blood bank. Protocols for the emergency release of blood products and massive transfusion should be implemented. Emergency release products can be universally compatible (O- blood) and given immediately without waiting for type and crossmatch of blood products. These products are delivered in combination packs of packed red blood cells, fresh frozen plasma, and if needed apheresis platelets. Once the management plan is finalized, education about the protocol will need to be implemented.

The Recognition and Prevention domain addresses three areas: assessment of hemorrhage risk, measurement of cumulative blood loss, and active management of third stage labor. The hemorrhage risk assessment should be done at multiple time points during delivery, starting antepartum and continuing into postpartum. If someone is deemed high risk early on, the institution can ensure there is blood available at time of delivery or transfer the patient if needed. Imprecise evaluation of actual blood loss is the leading cause of a delayed treatment response.

Direct measurement of blood loss by canisters or drapes during delivery can improve the accuracy of the estimation. Weighing blood soaked items and clots can also help with the blood loss estimations. The most important prevention method of obstetric hemorrhage is active management of the third stage of labor. Prophylactic use of oxytocin remains the most effective medicine with the fewest side effects. Every facility should have a protocol for oxytocin use in the postpartum period.

The Response domain entails having a detailed management plan for responding to hemorrhagic emergencies like a Code Blue response for cardiopulmonary arrest. The plan should include careful examination to ensure less common causes, like retained placenta, are not missed and the accurate diagnosis is determined. Early recognition of abnormal vital signs and trends, defining the response team members and communication plan for activating the response is crucial.

Lastly, identifying the necessary treatment medications and equipment should be done. Since this is a highly traumatic event for families and the staff treating them, support teams should be available to update family members. The maternity team should also be allowed to debrief after incident, with counselling available if needed.

The Reporting domain focuses on improvement in the system. Briefings and huddles should become routine for communication and to define team members’ roles during an obstetric hemorrhage. Multidisciplinary review of the incident in a more formal setting is important. The Joint Commission recommends multidisciplinary reviews for all severe obstetric hemorrhage cases (any requiring ICU admission or more than four units of packed red blood cells transfused). Monitoring the process and outcome measures is also needed.

What is the risk of delay in order to obtain additional preoperative information?

The urgency of the surgery depends on the degree of blood loss, presence or absence and amount of continuing blood loss, and hemodynamic status of the patient. The amount of bleeding may be rapid or insidious. The risk in delaying surgery is further hemodynamic compromise. The degree of blood loss is often underestimated. All hemorrhage should be considered severe until proved otherwise.

Emergent: Significant amount of blood loss and ongoing hemorrhage with unstable hemodynamics.

Urgent: Moderate amount of blood loss but not actively bleeding and with stable hemodynamics.

Elective: This surgery is not elective as the placenta must be removed to prevent further bleeding and infection.

2. Preoperative evaluation

Typical issues should be addressed: medications and allergies, past medical and surgical history, anesthetic complications, airway and physical exam, and laboratory evaluation if time permits. Coordinate multidisciplinary management between obstetricians, anesthesiologists, blood bank, laboratory, etc. Coordinated teamwork is essential to optimize outcome.

The need for fluid resuscitation should be anticipated based on the degree of blood loss (although the amount is frequently underestimated), ongoing blood loss, urine output, vital signs, and laboratory values. Review ongoing fluid resuscitation and pharmacologic interventions. Additional large-bore IV access, invasive monitoring, and request for blood products should be considered and initiated. Recent studies in trauma patients have shown that early and aggressive transfusion of coagulation factors (FFP: PRBC in ratio of 1:1) may improve outcome. Also, consider an apheresis platelet transfusion if 6-8 units of packed red blood cells has been transfused.Fibrinogen is also rapidly consumed during obstetric haemorrhage and will need to be monitored and replaced with cryoprecipitate as needed.

Medically unstable conditions warranting further evaluation include none.

Delaying surgery may be indicated if the patient is so hemodynamically unstable that resuscitation is required before initiation of surgery.

b. Cardiovascular system

Acute/unstable conditions: Rarely an issue in parturients.

c. Pulmonary

Pulmonary disease: Rarely an issue in parturients.

d. Renal-GI:

Due to the changes of pregnancy, even NPO patients should be considered to have a full stomach and to be at risk of pulmonary aspiration. Pregnant patients are considered at risk until 6 weeks' postpartum. Pulmonary aspiration prophylaxis with nonparticulate antacids, H2 blockers, and medications promoting gastric motility should be given. Rapid sequence intubation with cricoid pressure should be performed if general anesthesia is needed.

e. Neurologic:

Acute issues: Rarely an issue

Chronic disease: Rarely an issue.

f. Endocrine:

Rarely an issue.

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (e.g., musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

Not applicable

4. What are the patient's medications and how should they be managed in the perioperative period?

Parturients are usually on no medications except a multivitamin with iron, which does not need to be continued.

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

This may include medications specific to diseases associated with surgery. These patients are typically on an oxytocin infusion, which can be associated with hypotension if given at a rapid rate. Once the placenta is removed, oxytocin should be given to augment uterine tone. Retained placenta is often associated with uterine atony. Start with 20 units/L of isotonic fluids. If uterine tone is not improving, additional oxytocin can be added to the infusion (up to a total of 80 units/L). If the uterus still does not contract adequately, ergot alkaloids (methylergonovine 0.2 mg IM q 2-4 hours) or prostaglandin analogs (carboprost 0.25 mg IM q 15-90 minutes, max 8 doses) can be given. Methylergonovine should be avoided in hypertensive patients. Carboprost should be avoided in asthmatic patients.

i. What should be recommended with regard to continuation of medications taken chronically?

Parturients are rarely on any drugs chronically.

j. How To modify care for patients with known allergies -

Avoid allergy triggering agents. Substitute another class of drug if needed.

k. Latex allergy- If the patient has a sensitivity to latex (e.g., rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products

Avoid latex-containing items such as latex gloves, tourniquets, Foley catheters, etc.

l. Does the patient have any antibiotic allergies - Common antibiotic allergies and alternative antibiotics

There are no data to support the use of prophylactic antibiotics in the management of retained placenta to prevent endometritis; however, the obstetrician may order cefazolin 1-2 grams as surgical prophylaxis.

m. Does the patient have a history of allergy to anesthesia?

Malignant hyperthermia

Documented: Avoid all trigger agents such as succinylcholine and inhalational agents:

  • Proposed general anesthetic plan: TIVA with propofol and nondepolarizing muscle relaxants

  • Ensure MH cart available:

  • Family history or risk factors for MH: proceed with TIVA with propofol and nondepolarizing muscle relaxants

Local anesthetics/muscle relaxants

Use a different class of local anesthetics or muscle relaxant.

5. What laboratory tests should be obtained and has everything been reviewed?

If your clinical judgment indicates the need for blood transfusion, do not delay the transfusion while awaiting laboratory results.

Hemoglobin or hematocrit levels, acid-base status, coagulation panel, lactic acid, ionized calcium, and platelets provide useful information during an ongoing resuscitation. Frequent blood samples may be required, so consider arterial access.

Hemoglobin levels: Decrease with blood loss associated with retained placenta, although the extent depends on the amount of blood loss and whether ongoing blood loss is occurring. These patients are typically young and healthy and will tolerate a lower hemoglobin than those patients with coexisting cardiac or pulmonary disease. They also have an increased plasma volume of about 1500 mL as a result of normal physiologic changes of pregnancy. The need for transfusion will depend on the extent of blood loss, ongoing blood loss, hemodynamic instability, need for vasopressors, and presence of inadequate end organ perfusion as noted by acidosis.

Electrolytes: A decrease in ionized calcium and increase in potassium may be seen depending on the degree of blood loss and transfusion of PRBCs.

Coagulation panel: Should be obtained if significant blood loss has occurred as dilutional coagulopathy can result from massive blood loss or transfusion

Imaging: Not needed

Other tests: Acid-base status and lactate level as the patient may become acidotic with significant blood loss. Dilutional thrombocytopenia will occur with ongoing blood loss and fluid resuscitation.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

The surgery can be performed under MAC, regional (spinal, epidural, CSE), or general anesthesia depending on the degree of blood loss, ongoing hemorrhage, and hemodynamic stability. The patient is in the lithotomy position. Ensure appropriate lower extremity positioning and padding to avoid nerve or pressure point injures. Avoid over flexion of knees or hips, which compress major vessels at these joints. Avoid over flexion the hips to avoid stretching of lateral femoral cutaneous nerves. Avoid compression of the popliteal space or the upper dorsal thigh with the leg holders.

Regional anesthesia (epidural, spinal, or combined-spinal epidural)

These techniques can be performed in a patient who is hemodynamically stable and not actively bleeding. This can be accomplished with activation of an already existing epidural or a new regional technique.

Neuraxial

Benefits: Avoids a possible difficult intubation and pulmonary aspiration.

Drawbacks: Contraindicated in hemodynamically unstable patients as the sympathectomy can worsen hypotension. If massive blood loss subsequently occurs, the patient may become obtunded from cerebral ischemia and not have a controlled airway. Induction of general anesthesia and intubation may be more difficult with unstable hemodynamics. Potential for uterine perforation exists during curettage, which then requires exploratory laparotomy and need for general anesthesia.

Must not have any evidence of coagulopathy.

Issues: The surgeons may need uterine relaxation with nitroglycerin or other tocolytics. Nitroglycerin provides rapid onset (30-40 sec) and short duration (1-2 min) of smooth muscle relaxation. It can be administered sublingually as a spray or pill (400 mcg) or intravenously (50-500 mcg). It has few clinical side effects other than headache at these doses. The obstetrician needs to be prepared to start the procedure and have his or her hand at the cervical introitus to palpate when the uterus relaxes as the duration of relaxation is very short.

General Anesthesia

Will be necessary in hemodynamically unstable patient or with patients who have persistent active bleeding or coagulopathy.

Benefits: The patient has a controlled airway, and volatile anesthetics provide uterine relaxation, which may be needed for exploration of the uterus. The volatile anesthetics depress uterine contraction equally in a dose-dependent manner. Uterine contractions are decreased by 50% at 1.5 minimum alveolar concentration. If other surgical procedures such as a laparotomy are needed, the patient already has a controlled airway.

Drawbacks: Potential risk of failed intubation or pulmonary aspiration during induction and extubation. If the patient is hemodynamically unstable, she may not tolerate the concentrations of volatile anesthetics needed for uterine relaxation.

Other issues: If the patient has an unrecognized placenta accreta, further surgical interventions may be needed such as exploratory laparotomy, uterine arterial embolization, or hysterectomy.

Airway concerns: Parturients are more likely to be difficult intubations, especially during fluid resuscitation when airway edema can occur.

Monitored Anesthesia Care

This procedure is too uncomfortable to be done with minimal sedation, but MAC can be accomplished if the patient is hemodynamically stable and is not actively bleeding using IV sedation (for example, midazolam with ketamine 0.5 mg/kg increments) and a paracervical block.

Benefits: Avoids possible difficult intubation and pulmonary aspiration.

Drawbacks: Patient may become over-sedated with a loss of airway reflexes and potential for pulmonary aspiration, remembering that she should be considered a full stomach.

Other issues: Uterine relaxation may be needed, but this can be provided with nitroglycerin rather than volatile anesthetics.

6. What is the author's preferred method of anesthesia technique and why?

Assess the situation early and do not wait to provide active resuscitation until hypotension develops. The anesthesia provider needs to provide sufficient analgesia to allow for manual exploration and removal of the placenta by the obstetrician. If the patient is hemodynamically unstable or blood loss is ongoing, be prepared to move the patient from an LDR room to the operating room where positioning and lighting will be better and the anesthesia provider has access to equipment and medications.

If the patient is hemodynamically stable without further ongoing blood loss, regional anesthesia is my preferred technique as it results in a comfortable cooperative patient and avoids the potential of a failed intubation. If needed, intravenous sedation can be provided with midazolam or fentanyl. A T10 level should be adequate for comfort for uterine exploration.

If the patient is hemodynamically unstable and has continuing blood loss, general anesthesia is my preferred anesthesia technique. The potential for difficult intubation due to airway edema increases with the fluid shifts associated with resuscitation and transfusion. By having a controlled airway from the start, the potential for a failed intubation later during the case is minimized. It allows us to focus on aggressive transfusion and hemodynamic management of the patient from the start. Invasive monitoring is placed once the patient is asleep. Perform a RSI using ketamine or etomidate and succinylcholine. Once intubation is confirmed, anesthesia is maintained with volatile anesthetics and narcotics as tolerated by the patient.

What prophylactic antibiotics should be administered?

Based on the current evidence, there are no data to support the use of prophylactic antibiotics in the management of retained placenta; however, cefazolin 1-2 grams is usually ordered by the obstetrician.

What do I need to know about the surgical technique to optimize my anesthetic care?

A vaginal approach is used, so the patient is in lithotomy position.

What can I do intraoperatively to assist the surgeon and optimize patient care?

Uterine relaxation may be requested to assist in removal of the placenta. This can be achieved with nitroglycerin or volatile anesthetics. Nitroglycerin can be given sublingually or intravenously (400 mcg SL or 50- 500 mcg IV). Volatile anesthetics require general anesthesia with a secure airway. If the patient is hemodynamically compromised, she may not tolerate the amount of volatile anesthetics required to produce uterine relaxation. Once the placenta and any placental fragments are removed, uterine tone should be enhanced by giving oxytocin, and decreasing concentrations of volatile anesthetics.

What are the most common intraoperative complications and how can they be avoided/treated?

Prioritize them by urgency. Perforation of the uterus may occur, leading to an exploratory laparotomy. The obstetricians will minimize the risk by using manual removal or curretage under ultrasound guidance. Avoid sharp curretage. Coagulopathy should be treated by transfusion of blood products. Excessive traction on the umbilical cord can lead to uterine inversion if the placenta is adherent. This can lead to massive blood loss and a shock state in the mother due to hypovolemia and vagal stimulation from traction on uterosacral ligaments.

Complications

Cardiac: Depending on the severity and amount of blood loss, myocardial ischemia or injury can occur.

Pulmonary: Airway edema can occur secondary to aggressive volume resuscitation, and a period of postoperative ventilation should be considered. All parturients are at risk of thromboembolic complications such as pulmonary embolism, so lower extremity sequential devices should be used.

Neurologic: Not applicable.

a. Neurologic

Unique to procedure: not applicable.

b. If the patient is intubated, are there any special criteria for extubation?

The patient should be extubated based on standard extubation criteria with the patient awake, alert, and responsive. Have a low threshold for postoperative ventilation until her hemodynamics have stabilized and the risk of airway edema has receded.

c. Postoperative management

What analgesic modalities can I implement?

Depending on the stability of the patient, intravenous or oral narcotics, IV ketorolac, or PO ibuprofen can be used. Since there is no incision after curettage, postoperative pain us usually easily controllable.

What level bed acuity is appropriate?

Bed acuity will depend on the degree of resuscitation needed, hemodynamic stability, and the intraoperative course and can range from a routine L&D postpartum bed to ICU status for postoperative ventilation.

What are common postoperative complications, and ways to prevent and treat them?

Continued bleeding and hemodynamic instability may require interventional radiology techniques or hysterectomy. Thromboembolic complications should be prevented with lower extremity compression devices, anticoagulation, and eventually aggressive mobilization.

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