Monday, March 22, 2021

Placental Abruption Case File

Posted By: Medical Group - 3/22/2021 Post Author : Medical Group Post Date : Monday, March 22, 2021 Post Time : 3/22/2021
Placental Abruption Case File
Lydia Conlay, MD, PhD, MBA, Julia Pollock, MD, Mary Ann Vann, MD, Sheela Pai, MD, Eugene C. Toy, MD

Case 36
A 34-year-old woman (G3P2), 34 weeks’ gestation, presents to the emergency room with a 1-day history of worsening abdominal tenderness and some dark red vaginal bleeding. She has a past medical history of smoking (15-pack-year), and sinusitis. Her prior pregnancies went to term with uneventful deliveries. She has no other significant past medical history. The patient last ate 2 hours ago. Her meal included a cheeseburger and fries with a caffeinated soda.

The patient’s physical examination is remarkable for some anxiety, and significant uterine tenderness. Vital signs show a blood pressure of 99/38 mm Hg and a heart rate of 109 beats/minute (bpm). The fetal heart rate varies between 165 and 175 bpm (normal 120-160 bpm). Laboratory findings reveal a hemoglobin concentration of 9.8 g/dL, a hematocrit of 27.1%, a platelet count of 102,000/μL, and a fibrinogen level of 154 mg/dL. An urgent sonogram was obtained, and showed an anterior placenta previa, and could not rule out placental abruption. The patient is scheduled for an urgent, emergency cesarean section.

➤ What are the anesthetic considerations for this patient?

➤ What is the anesthetic of choice for this procedure and why?

➤ What are the complications that accompany abruptio placenta?


ANSWERS TO CASE 36:
Placental Abruption

Summary: This is a 34-year-old woman, G3P2, at 34 weeks’ gestation, with clinical signs of placental abruption.

➤ Anesthetic considerations: This patient presents for emergent surgery in the face of under-resuscitated hypovolemic shock, fetal distress, and imminent coagulopathy. Considering the nature of presentation, she has probably not observed fasting guidelines for surgery and should be considered to have a full stomach.

➤ Anesthetic route of choice: Given the emergent nature of presentation, the possibility of coagulopathy, and likelihood of massive blood loss, a general anesthesia is indicated for this case.

➤ Complications of placental abruption: Include hemorrhage, undiagnosed hypovolemia, a coagulopathy from DIC or massive blood loss, and the risks posed by factors associated with placental abruption such as pregnancy induced hypertension and smoking.

ANALYSIS

Objectives
1. Understand pathophysiology of and major risk factors for abruption placenta.
2. Understand the risks and benefits of the different anesthetic approaches to the disorder.
3. Understand possible complications associated with placental abruption and urgent surgery.


Considerations
This patient presents with the diagnosis of placenta previa with possible imminent abruption. She has signs of hypovolemia, consumptive coagulopathy and fetal distress. This situation requires an emergent cesarean section to deliver the fetus, which is showing signs of distress. Given the signs of hypovolemia, the patient should receive immediate and aggressive fluid resuscitation. The availability of blood and blood products should be ensured, given the risk of massive blood loss. Because of the risk of DIC that accompanies placental abruption, as well as the dilutional coagulopathy that can accompany massive transfusion, general anesthesia with rapid-sequence induction and cricoid pressure is the anesthetic of choice.

Two large-bore peripheral intravenous access sites are secured and fluid resuscitation is initiated while ensuring that a sample of the patient’s blood is sent for typing and screening. A urethral catheter (Foley) is placed for assessment of adequacy of fluid resuscitation. The patient should be promptly transferred to the operating room where she is positioned supine with a left hip tilt. This enables uterine displacement from the aorta and vena cava and relieves aorto-caval compression and decreased venous return. Standard monitors (for noninvasive blood pressure measurement, pulse oximetry, and 5-lead ECG display) are applied and preoxygenation is begun.

The patient is requested to take a few vital capacity breaths of 100% oxygen over the next several minutes. A hypnotic, such as etomidate, and a short-acting muscle-relaxing agent are administered in succession while an assistant holds cricoid pressure. Once muscle relaxation is confirmed, direct laryngoscopy and endotracheal intubation are performed, an endotracheal tube is placed, and its position verified with bilateral chest auscultation and presence of end-tidal CO2. Cricoid pressure is then released, the endotracheal tube is secured, and surgery can proceed.

After delivery of the fetus, it is appropriate to administer narcotics, and an oxytocin infusion is begun to enable uterine contraction. The decision to transfuse blood and blood products is dictated by surgical blood loss, hemoglobin values, and evidence of hemodynamic instability. Depending on the site of the placental attachment, the patient may be prone to uterine atony and continued hemorrhage. Additional doses of oxytocin may be required, in addition to other contractile agents such as methylergonovine. In the rare case of refractory uterine atony and hemorrhage, a hysterectomy may be required.

As the case progresses, an arterial catheter placement may be considered to allow for quick assessment of hemoglobin and accurate hemodynamic monitoring. But in practicality, given the emergent nature of the case and the tasks that accompany transfusion, there is often simply no time for its insertion.


APPROACH TO
The Patient with Placental Abruption

An abruptio placenta is the separation of a normally implanted placenta from the deciduas basalis of the uterus prior to delivery of the fetus. It occurs at an incidence of 0.42%. The risk factors associated with placental abruption include drug, alcohol, and cigarette abuse by the mother, peripartum hypertension, and placenta previa. Prenatal care plays an important role in anticipating the presentation of placental abruption.

Hypovolemia is frequently underdiagnosed and undertreated at the time of presentation to the operating room. The extent of the patient’s bleeding is not necessarily evident, since some (or most) of it may remain trapped in the uterus. Once the fetus is delivered, the extent and severity of hypovolemia may well be unmasked. Active and aggressive resuscitation should be undertaken early in the course of the patient’s treatment, and prior to incision so that the degree of hypovolemia may be abated. Prolonged hypotension can precipitate end-organ dysfunction.

Along with being a risk factor for abruptio placentae, smoking causes other problems in the patient requiring general anesthesia. These include bronchospasm with endotracheal intubation, increased airway mucus production, and postoperative pulmonary complications.

Disseminated intravascular coagulation (DIC) is a risk in patients with placental abruption, and may be a source of ongoing bleeding. The longer the time between the onset of bleeding and diagnosis, the longer the generation of inflammatory mediators, and the worse the DIC. DIC is associated with a falling fibrinogen level and a rising d-dimer level. Hemostasis and various blood products are used to treat the coagulopathy. Blood and blood product transfusions are guided by the regular evaluation of coagulation status, although blood products carry a risk of complications including infection, transfusion reaction, hemolysis, and acute transfusion-related lung injury.

Fetal distress is often a marker for abruption reflecting placental blood loss and poor oxygen delivery to the fetus. This calls for immediate delivery of the fetus by surgical means.

Amniotic fluid embolism is also a potential complication of placental abruption. This is a major risk, since the open maternal vessels at the deciduas basalis can absorb amniotic fluid, which can subsequently embolize in the systemic circulation. Amniotic fluid embolus usually manifests with severe maternal hypotension and hypoxia. The treatment is largely supportive, and includes airway management, mechanical ventilation, and blood pressure control with vasoactive drugs. Nevertheless, this is often a disastrous complication.

Feto-maternal transfusion is another risk in placental abruption. Special consideration is given to Rhesus-negative parturients in this situation. Prophylactic administration of Rhogam should be considered in the setting of placental abruption.

The risk of worsening hypovolemia, consumptive coagulopathy, and fetal distress make delivery by c-section an emergency. Given the emergent surgery and coagulopathy, regional anesthesia is contraindicated. Furthermore, the sympathectomy caused by regional anesthesia can significantly exaggerate any preexisting hypotension, making its correction more difficult. Similarly, the worsening coagulopathy can lead to epidural bleeding and epidural hematoma formation, and thus neurological complications.

There is only one choice of anesthetic technique for this operation: general anesthetic with rapid-sequence induction (local anesthesia is also a distant possibility). As with all cases involving pregnancy, there is a higher incidence of difficult intubation. In addition, changes in maternal physiology cause delayed gastric emptying hence making pulmonary aspiration of gastric contents a very real possibility.


Comprehension Questions

36.1. A 32-year-old woman at 34 weeks’ gestation comes into the obstetrical unit for vaginal bleeding. The suspicion is placental abruption. Besides smoking and trauma, which of the following is the most significant risk factor for abruption?
A. Obesity
B. Preeclampsia
C. Prior cesarean
D. Diabetes mellitus

36.2. A 24-year-old G1P0 woman at 29 weeks’ gestation is noted to have bright red vaginal bleeding. Her uterus is firm and tender. The BP is 140/90 mm Hg and HR 100 bpm. No fetal heart tones are able to be obtained, and ultrasound identifies fetal bradycardia in the range of 70 bpm. Which of the following is the most important anesthetic consideration in the surgical management of this patient?
A. Hypertension
B. Disseminated intravascular coagulopathy
C. Hypervolemia
D. An indication for regional anesthesia


ANSWERS
36.1. B. Hypertension, maternal smoking, drug, cocaine use and alcohol abuse, and placenta previa are risk factors associated with placental abruption. Obesity, diabetes, or prior cesarean delivery are not risks factor for placental abruption.

36.2. B. DIC. A bleeding diathesis, the presence of hemodynamic instability including hypotension (not hypertension), and inadequate volume resuscitation (hypovolemia) complicate any anesthetic. General anesthesia is required for an emergent c-section. Even in small doses, general anesthetics cause vasodilatation, and thus exacerbate any preexisting hypovolemia and hypotension. Aggressive volume resuscitation should be begun preemptively in the case of suspected abruption since bleeding is expected when the fetus is delivered and the uterine tamponade is relieved.


Clinical Pearls
➤ An increased maternal age, multiparity, cigarette smoking, cocaine use during pregnancy, and hypertension are amongst the highest risk factors for placental abruption.
➤ Anesthetic management involves adequate, large-bore intravenous access, restoration of intravascular blood volume, and correction of coagulopathy as appropriate.
➤ General anesthesia with tracheal intubation is indicated in patients with placental abruption.

References

Ananth CV, Smulian JC, Srinivas N, et al. Placental abruption and perinatal mortality in the United States. Am J Epidemiol. 2001;153;332-337. 

Oyelese Y, Ananth CV, Yeo L, et al. Placental abruption. Obstet Gynecol. Oct 2006; 108:1005-1016. 

Sheiner E, Shoham-Vardi I, Hallak M, et al. Placental abruption in term pregnancy; clinical signs and obstetric risk factors. J Maternal-Fetal and Neonatal Med. Jan 2003;13:45-49.

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