Peripartum hemorrhage

Published on 07/02/2015 by admin

Filed under Anesthesiology

Last modified 22/04/2025

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Peripartum hemorrhage

K.A. Kelly McQueen, MD, MPH

Despite advances in obstetric care and improved diagnostic testing, peripartum hemorrhage remains a leading cause of maternal morbidity and death. Severe bleeding is most common in the third trimester of pregnancy and near the time of delivery.

Antepartum hemorrhage

Causes of antepartum hemorrhage

Severe antepartum hemorrhage is most commonly associated with placenta previa, abruptio placentae, and uterine rupture.

Placenta previa

Placenta previa is defined as abnormal implantation of the placenta on the lower uterine segment with partial to complete occlusion of the internal cervical os. It occurs in 1 in 200 to 1 in 250 deliveries and is associated with maternal mortality rate of up to 0.9%. The multiparous patient and the older patient are at increased risk for developing placenta previa, as are patients undergoing repeat cesarean section (C/S). The chance of recurrence in a subsequent pregnancy is approximately 5%.

Abruptio placentae

Abruptio placentae results from separation of a normally implanted placenta after 20 weeks of gestation and before birth. It occurs in 1 in 75 to 1 in 226 deliveries. Maternal mortality rate is 1.8% to 2.8%, and fetal mortality rate may be as high as 50%. Risk factors include hypertensive disorders, high parity, uterine abnormalities, trauma, intravenous drug use, and history of previous abruption. Bleeding may be apparent (external) or concealed (internal) and varies in severity from mild (<100 mL) to severe (>500 mL).

The type of delivery and the timing will depend on the severity of hemorrhage. With limited blood loss, vaginal delivery is often possible. If the mother or fetus is in distress, then rapid delivery by C/S is required. In mild or moderate abruptions with fetal death, maternal coagulation must be evaluated before regional anesthetic is administered because disseminated intravascular coagulation may occur within 8 h of fetal demise.

Uterine rupture

Uterine rupture is a rare but serious cause of hemorrhage occurring in 0.1% to 0.3% of pregnancies. Risk factors include previous uterine surgery, past history of uterine rupture, abnormal fetal presentation, operative vaginal delivery, use of uterotonic agents, and uterine distention. Maternal mortality rate approaches 5%, and fetal mortality rate is as high as 50%. Presenting signs and symptoms include atypical abdominal pain, shoulder pain, vaginal bleeding, uterine tenderness, hypotension, tachycardia, and shock.

Anesthetic management of antepartum hemorrhage

Anesthetic management includes ensuring the availability of blood and blood products and securing adequate venous access through placement of large-bore central cannulas, peripheral cannulas, or both. If an emergency C/S is required, general anesthesia is usually recommended because of maternal intravascular hypovolemia, coagulopathy, positioning problems during regional anesthetic administration, and surgical urgency.

When possible, before a C/S is undertaken, all efforts should be made to stabilize the mother while maintaining uterine perfusion pressure (uterine arterial pressure minus uterine venous pressure) and maximizing oxygenation. If time permits, maternal laboratory evaluation, including platelet concentration, prothrombin time, activated partial thromboplastin time, fibrinogen level, and hemoglobin concentration, should be ordered. If maternal hemodynamic status is stable and coagulation status is normal, then regional anesthesia can be used for the urgent C/S.

Postpartum hemorrhage

The vast majority of cases of severe postpartum hemorrhage occur within a few minutes after delivery. Postpartum hemorrhage is the most common hemorrhagic condition in obstetrics and is typically defined as a blood loss of 500 mL or more within 24 h of delivery. Postpartum hemorrhage can be massive and sudden and may require aggressive therapy. The three most common causes of postpartum hemorrhage are retained placenta and membranes, uterine atony, and genital tract disruption (Box 189-1).

Causes of postpartum hemorrhage

Placenta accreta

Placental accreta is an abnormally adherent placenta, which can lead to devastating acute blood loss. The incidence of this problem appears to be increasing as a result of the increasing numbers of repeat cesarean deliveries. Placenta accreta vera is present when the placenta is adherent to the myometrium without invasion into the uterine muscle. Placenta increta involves myometrial adherence with invasion into the muscle, and placenta percreta involves invasion into the uterine serosa and beyond—often involving other pelvic structures.

Retained placenta and membranes

The placenta and membranes are retained in about 1% of vaginal deliveries. Treatment usually includes manual exploration of the uterus, which may require treatment to provide uterine relaxation. Commonly used agents to facilitate exploration include intravenously administered nitroglycerin, sedation with ketamine or opioids, low doses of inhalation anesthetic agents, and induction of general anesthesia.

Uterine atony

Uterine atony of varying severity commonly occurs after vaginal delivery. Blood loss can be massive and sudden and is sometimes delayed for several hours. Risk factors include multiparity, multiple births, polyhydramnios, intrauterine manipulation, and retained placenta. Initial treatments include uterine massage and pharmacologic therapy (Table 189-1). Persistent uterine atony and maternal hemorrhage may necessitate massive blood transfusions and, in extreme cases, hysterectomy.

Table 189-1

Pharmacologic Treatment of Uterine Atony and Postpartum Hemorrhage

Medication	Dose	Side Effect(s)
Oxytocin (Pitocin)	10-40 units/L of IV fluid	Hypotension
Methylergonovine maleate (Methergine)*	0.2 mg IM	N/V
15-Methylprostaglandin F_2α (Hemabate)	250 μg IM or IV	Bronchospasm
Misoprostol (Cytotec)	600 μg PO or sublingual	Shivering, ↑ temperature, N/V, diarrhea

IM, Intramuscular(ly); IV, intravenous(ly); N/V, nausea and vomiting; PO, per os (by mouth).

^*Contraindicated in patients with preeclampsia.

Genital tract disruption

Genital tract disruption may result in severe postpartum hemorrhage. Lacerations may occur in the vagina, cervix, or body of the uterus. An episiotomy incision is another possible source of bleeding. Vigilance must be maintained after delivery, as blood loss may be delayed.

Treatment of postpartum hemorrhage

Treatment is similar to that for antepartum hemorrhage. Early diagnosis and aggressive treatment are important to decrease maternal morbidity and mortality risks. After the diagnosis is established, large-bore intravenous access should be secured as soon as possible. Preparations should be made for massive transfusion; adequate supplies of crystalloids, colloids, blood, and blood products should be available. Blood warmers should be used to prevent hypothermia. The use of invasive hemodynamic monitoring—including arterial catheterization and central venous pressure monitoring—should be considered (Box 189-2), as should the use of a rapid-infusion device.

Box 189-2 General Anesthesia for Emergency Cesarean Section for Maternal Hemorrhage

Administer nonparticulate oral antacid

Insert two large-bore IV catheters

Replace blood loss with crystalloids or colloids

Type and crossmatch 2 units of blood

Have access to a rapid-infusion blood-warming device

Maintain ongoing fluid resuscitation

Use a rapid-sequence induction while providing cricoid pressure

Induction agent

Etomidate, 0.3 mg/kg

Ketamine, 0.5-1 mg/kg

The treatment for uterine atony and retained products of conception (once extracted) include oxytocic and other vasoconstriction pharmacologic therapy. Oxytocic agents stimulate the smooth muscle of the uterus, thereby producing or augmenting uterine contractions. Oxytocin is a posterior pituitary hormone that stimulates uterine smooth muscle. The synthetic derivative of oxytocin, Pitocin, is the drug of choice to treat uterine atony because it has less antidiuretic and cardiovascular activity than does vasopressin. Pitocin is primarily given as an intravenous bolus, a continuous infusion, or both a bolus and an infusion titrated to effect; the use of Pitocin requires monitoring uterine contractions during labor and in the postoperative period. Pitocin generally affects the uterus by causing slow generalized contractions with periods of relaxation between contractions. The side effects of Pitocin include hypotension, especially when given as a bolus, and secondary tachycardia; these effects usually occur immediately after administration of the drug and are typically transient. Transient electrocardiographic changes, including T-wave flattening and inversion and a prolonged QT interval, may occur. When given in large doses or over extended periods, Pitocin may produce water intoxication and hyponatremia.

Methylergonovine maleate

A purified semisynthetic ergot alkaloid, methylergonovine maleate (Methergine) is typically given as a 0.2-mg intramuscular injection to augment uterine contractions if Pitocin does not produce the desired effect. Methergine is used exclusively in the postpartum period because it produces tonic contractions more quickly, as compared with Pitocin, that significantly limit blood flow. The major side effects include nausea, vomiting, and significant hypertension due to direct peripheral vasoconstriction. For this reason, intravenous administration of Methergine is controversial, and the drug must be carefully administered to parturients with essential hypertension or pregnancy-induced hypertension.

Prostaglandin F_2α

Severe uterine atony and postpartum hemorrhage may necessitate the use of prostaglandin F_2α (PGF_2α), a biochemical produced by the pregnant uterus that induces uterine contractions. PGF_2α can also cause bronchospasm. The 15-methyl analog of PGF_2α (Hemabate) acts similarly to PGF_2α but promotes stronger sustained uterine contractions, limiting blood flow to the uterus. 15-Methyl PGF_2α (250 μg) is administered intramuscularly or intramyometrially only after Pitocin and Methergine have been used and have failed to achieve the desired results because of the nausea, vomiting, and diarrhea associated with the use of 15-methyl PGF_2α.

For some patients with persistent postpartum hemorrhage whose bleeding fails to respond to pharmacologic interventions, angiographic uterine artery embolization may be an option. This procedure can be performed in the presence of coagulopathy and under local anesthesia. During angiography, the radiologist can identify the vessels responsible for bleeding and embolize these vessels effectively with Gelfoam, a technique that allows for return of flow over time, thereby preserving fecundity.

If pharmacologic and radiologic interventions fail, or if the cause of postpartum hemorrhage is only amenable to surgery (repair of genital tract disruption), a surgical approach may be necessary to control bleeding. Surgical approaches include bilateral hypogastric artery ligation, bilateral ovarian artery ligation, and uterine artery ligation. In rare cases, emergency hysterectomy is required to treat postpartum hemorrhage. Postpartum hysterectomy is the definitive treatment for postpartum hemorrhage.

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