Obstetrical Emergencies

Placental Abruption

Definition

• Premature separation of the placenta from the uterine wall, which occurs in 0.4-1% of all pregnant patients¹
• Presentation: abdominal pain, signs of hemorrhagic shock without necessarily seeing the blood pass through the vagina, uterine hypotonia, fetal heart rate abnormalities. Primarily, a clinical diagnosis is made by an obstetrician.
• Risk Factors: chronic hypertension, pre-eclampsia, abdominal/uterine trauma, multiparity, pre-term premature rupture of membranes

Anesthetic Management

• Placental abruption is associated with coagulopathy, primarily disseminated intravascular coagulation (DIC). As a result, neuraxial anesthesia may be contraindicated in certain clinical situations.
• Treatment: establish access with two large-bore intravenous (IV) lines, begin blood product administration, add pressors as needed, and prepare for possible emergency cesarean delivery (CD) depending on fetal heart rate and maternal hemodynamic stability.
• Anticipate DIC and monitor with arterial blood gases and viscoelastic testing. Follow fibrinogen levels closely and have a low threshold to administer fibrinogen reconcentrate or cryoprecipitate.¹

Umbilical Cord Prolapse (UCP)

Definition and Pathophysiology

• UCP is an acute obstetric emergency defined by the umbilical cord descending through the cervix and lying below or alongside the fetal presenting part, typically after the rupture of membranes.
  • This compression causes severe and acute obstruction of blood flow, resulting in fetal hypoxia and acidosis.
  • The clinical manifestation is usually a profound and persistent fetal bradycardia or severe variable decelerations, which mandates immediate intervention to prevent fetal neurological injury or death.²

Anesthetic Management

• The definitive treatment for UCP is expedient delivery, most commonly via an emergent CD.
• Decompression maneuvers should be performed immediately by the obstetrician. These maneuvers are designed to relieve pressure on the cord while the patient is transferred to the operating room (OR).
• Key steps include manually applying continuous upward pressure on the fetal presenting part via the vagina, placing the mother in a steep Trendelenburg or knee-chest position, and considering temporary measures like rapid bladder filling (500–750 mL saline) or tocolysis (with terbutaline or nitroglycerin) to reduce uterine contractions.²
• The choice of anesthesia for CD must be made rapidly. General anesthesia (GA) with a rapid sequence induction (RSI) is the preferred technique when fetal distress is severe and persistent, or when there is no existing, functional neuraxial block.
• Regional anesthesia is acceptable if the fetal heart rate has stabilized or improved following decompression maneuvers, and/or if a functioning epidural catheter is already in place and can be rapidly extended for surgical anesthesia (e.g., using 2% lidocaine). Throughout the process, the patient’s position must be managed carefully to ensure decompression is maintained continuously until the moment of uterine incision.

Ectopic Pregnancy

Definition and Pathophysiology

• Ectopic pregnancy (EP) is defined as the implantation of a fertilized ovum outside of the endometrial cavity of the uterus, occurring in approximately 1–2% of all pregnancies.³
  • While the implantation can occur in the cervix, ovary, or abdominal cavity, over 95% are tubal pregnancies, most commonly implanting in the ampulla of the fallopian tube.
  • The inability of the fallopian tube to accommodate the growing embryo is central to the pathophysiology. As the trophoblast invades the surrounding tissue, it erodes local blood vessels, leading to tubal distension and eventually, tubal rupture. This rupture is a life-threatening surgical emergency that causes massive, rapid, and uncontrolled intra-abdominal hemorrhage, resulting in acute hypovolemic shock.
  • EP remains the leading cause of maternal mortality in the first trimester.
  • Risk factors often involve conditions that impede tubal migration, such as a history of pelvic inflammatory disease, previous tubal surgery, use of assisted reproductive technology, or a prior EP.

Anesthetic Management

• The anesthetic management of a patient with EP depends critically on the patient’s hemodynamic stability and whether the presentation is an unruptured or a ruptured ectopic pregnancy.³
• Ruptured Ectopic Pregnancy
  • Resuscitation: Establish two large-bore IVs (14G or 16G) immediately. Blood products (cross-matched or O-negative uncross-matched packed red blood cells) should be transfused early and aggressively, in conjunction with crystalloids and colloids. Goal-directed fluid therapy and continuous hemodynamic monitoring (arterial line may be necessary) are crucial.
  • Anesthesia: GA is usually mandatory due to the need for immediate surgery. An RSI should be considered for patients with a “full stomach.”
  • Anesthetic depth must be managed carefully, as unstable patients require significantly less agent, increasing the risk of awareness, a risk balanced against avoiding cardiovascular collapse. Pressor agents should be readily available.

Uterine Rupture

Definition and Pathophysiology

• Uterine rupture is a rare but catastrophic obstetric emergency defined as a full-thickness loss of integrity of the uterine wall and overlying visceral peritoneum.
• Most ruptures (over 90%) occur during labor in patients with a pre-existing uterine scar, most commonly from a prior CD, especially when undergoing a trial of labor after cesarean.⁴
• Other risk factors include high parity, induction or augmentation of labor (particularly with prostaglandins or excessive oxytocin), and prior uterine surgery like myomectomy.
• The pathophysiology is the mechanical tearing of the compromised uterine wall under the stress of powerful contractions. This event allows the fetus, placenta, or both to be partially or completely expelled into the maternal peritoneal cavity.
• The two critical, life-threatening consequences are acute fetal hypoxia (due to placental separation or collapse of uterine blood flow) and massive maternal hemorrhage (often concealed intra-abdominally), rapidly leading to hypovolemic shock.

Anesthetic Management

• Uterine rupture is a surgical emergency requiring immediate delivery and surgical hemostasis.
  • Resuscitation and Monitoring: The anesthesiologist’s role begins immediately with calling for help (massive transfusion protocol [MTP], OR staff, neonatal team) and rapid resuscitation. Two large-bore IVs (14G or 16G) must be secured. Aggressive volume replacement should be initiated immediately with warmed crystalloids, and blood products (uncross-matched O-negative or type-specific) should be requested and administered as soon as available. Comprehensive hemodynamic monitoring is mandatory, and an arterial line should be strongly considered for continuous blood pressure (BP) monitoring, especially in unstable patients.
  • GA with RSI is the technique of choice in the setting of hemodynamic instability with emergent delivery, due to the acute need for profound relaxation, the potential for massive blood loss, and the patient’s rapidly deteriorating hemodynamic status.
  • Neuraxial Considerations: If rupture is suspected but the patient is hemodynamically stable and an existing epidural is fully functional, it may be used to rapidly extend the block, though the high risk of rapid deterioration usually favors GA.
  • Postdelivery Management: The anesthesiologist must manage the massive transfusion and fluid shifts associated with surgical repair (or hysterectomy) and maintain stability while the surgeon achieves hemostasis. Uterotonics are administered only after delivery and may not be effective if the uterus is severely damaged, necessitating preparation for second-line agents and/or massive transfusion.⁴
• For more information, see the OA summary “Trial of Labor after Cesarean Section.” Link

Amniotic Fluid Embolism

Definition and Pathophysiology

• A rare but devastating clinical syndrome characterized by cardiovascular collapse, respiratory distress, and coagulopathy.
• Likely triggered by maternal immune response to fetal antigens, presenting with rapid, anaphylactoid symptoms
• Clinical presentation: hypotension, hypoxia, altered mental status, DIC, after ruling out pulmonary embolism, myocardial infarction, air embolism, and complications of neuraxial anesthesia.

Anesthetic Management

• Immediate cardiopulmonary resuscitation if arrest occurs
• Perimortem cesarean should be performed within 4 minutes of advanced cardiovascular life support, if there is no return of spontaneous circulation.
• Supportive care for cardiovascular collapse and pulmonary compromise
  • “A-OK” or atropine, ondansetron, ketorolac, has a pathophysiological basis for efficacy, but it has not yet been borne out in the literature.
  • Right ventricular dysfunction can be ameliorated with pulmonary vasodilators and inotropic support. Transthoracic or transesophageal echocardiography can help diagnose, rapidly if available.
    • Dobutamine vs. milrinone
    • Inhaled nitric oxide, inhaled and/or IV epoprostanol⁵
  • Management of the ensuing coagulopathy (early MTP activation with balanced transfusion and cryoprecipitate, aiming for fibrinogen levels greater than 150 mg/dL)
• For more information, see the OA summary “Amniotic Fluid Embolism.” Link

Postpartum Hemorrhage

Definition and Causes

• Blood loss of more than 1000 mL in either vaginal or CD
• The “4 Ts” or Tone (uterine atony), Trauma, Tissue (retained placenta), and Thrombin (coagulopathy).⁶

Possible Sequelae⁶

• Acute respiratory distress syndrome
• Hemorrhagic shock
• DIC
• Acute renal failure
• Sheehan syndrome

Anesthetic Management

• Rapid assessment and resuscitation
• Vascular access (at least two large-bore IVs) +/- invasive arterial monitoring
• Anesthetic technique for operative management (e.g., uterine massage, hysterectomy) → consider conversion to GA from neuraxial if in the OR.
• Pain management and monitoring

Pharmacologic and Fluid Management

• Uterotonic agents (oxytocin, carboprost, methylergonovine, misoprostol)
• MTP activation
• Use of viscoelastic tests (e.g., TEG, ROTEM) to guide hemostatic therapy.
• For more information see the OA summary “Postpartum Hemorrhage: Management.” Link

Severe Preeclampsia and Eclampsia

Definition and Etiology

• Preeclampsia is new-onset hypertension with proteinuria or end-organ dysfunction. Eclampsia is the occurrence of seizures in this setting.
• Abnormal placentation leading to systemic endothelial dysfunction, causing end-organ damage

Anesthetic Management

• BP control and fluid management.
  • IV labetalol, IV hydralazine, or oral nifedipine if the patient’s BP is greater than 160/110 mmHg.
• Seizure prophylaxis with magnesium sulfate (4g IV loading dose over 5 minutes followed by 1g/hour IV infusion stopped 24 hours after delivery)
  • Magnesium levels should be checked every 6 hours to evaluate for potential magnesium toxicity.
• Airway management during an eclamptic seizure.
  • nti-hypertensives or short-acting opioids should be considered to blunt the sympathetic response during laryngoscopy.
• Considerations for neuraxial vs. GA for delivery
  • Neuraxial anesthesia is associated with better outcomes than GA
  • Neuraxial anesthesia is contraindicated in patients with coagulopathies secondary to pre-eclampsia (thrombocytopenia, HELLP [Hemolysis, Elevated Liver enzymes and Low Platelets])
• For more information, see the OA summary “Hypertensive Disorders of Pregnancy.” Link

Placenta Accreta Spectrum

Definition

• An abnormal placental implantation requiring CD
  • Accreta: placenta firmly attaches to the uterine wall
  • Increta: placenta invades into the uterine wall
  • Percreta: placenta penetrates completely through the uterine wall

Risk Factors

• Prior CD, placenta previa, and previous uterine surgery
• It can be diagnosed with an ultrasound or magnetic resonance imaging.

Anesthetic Management

• Preoperative management: A multidisciplinary approach is essential.
  • Correction of anemia, preparation for MTP, and cell salvage technique should be considered.
  • Clinicians should determine if the plan is to go straight to hysterectomy after delivery or if the obstetricians will attempt to remove the placenta. There is typically more bleeding when the placenta is manipulated.
• Massive blood loss is common, requiring immediate preparation for massive transfusion.
• Anesthetic technique and management of potential hysterectomy.
  • A combined spinal epidural is associated with a lower rate of conversion to GA than a single-shot spinal.
  • GA may be preferred in hemodynamic instability, massive transfusion, and during urgent/emergent decisions to proceed to CD without an epidural catheter in place.
  • If starting with neuraxial anesthesia, it is imperative that everything needed to convert urgently to GA is set up. Usually, this conversation happens in the setting of a massive hemorrhage.
• Large IV access is required (i.e., rapid infusing catheter with a rapid infusion device attached to the patient. An arterial catheter for continuous BP monitoring and arterial blood gas analysis is imperative. A central line can also be considered, especially for more complicated cases (i.e., placenta percreta)
• A preoperative iliac artery embolization or aortic balloon placement should be considered to minimize blood loss.
• Preparation for a potential decision to proceed to complete hysterectomy.
• For more information, see the OA summary on “Placenta Accreta Spectrum.” Link

Summary