12 - Obstetric Hemorrhage

Placental abruption

Most common obstetric cause of antepartum hemorrhage

• Tone – uterine atony

• Tissue – retained placental tissue or blood clots

• Trauma – genital tract lacerations or hematomas

• Thrombin - coagulopathy

The "4 T's" of postpartum hemorrhage

Placenta previa

Abnormal implantation of placenta over internal cervical os

Complete previa

Placenta completely covers internal os

Partial previa

Placenta covers portion of internal os

Marginal previa

Edge of placenta reaches margin of os

Low-lying placenta

Implantation in lower uterine segment in proximity but not extending to internal os

Painless vaginal bleeding, with a sentinel bleed at >28 weeks AOG

Most typical sign of placenta previa

Placenta migration

Apparent movement of the placenta away from the internal os

Morbidly adherent placenta

Abnormal adherence of part or all of the placenta to the uterine wall

Nitabuch layer

The layer where the trophoblasts meet the decidua basalis

Placenta accreta

Villi are attached to the myometrium

Placenta increta

Villi actually invade the myometrium

Placenta percreta

Villi that penetrate through the myometrium and to or through the serosa

Total accreta

Abnormal adherence may involve all lobules

Partial accreta

Involves few to several cotyledons

Focal accreta

A single lobule is abnormally attached

Placenta previa, or prior CS delivery

Most significant risk factors in morbidy adherent placenta

Swiss cheese appearance of the myometrium

Ultrasound sign that refers to placental vascular lacunae or "lakes" which represent dilated vessels extending from the placenta through the myometrium

CS hysterectomy regardless of AOG

Management for morbidly adherent placenta with significant bleeding

CS hysterectomy at 34 to 35 6/7 weeks AOG, after giving corticosteroids

Management for morbidly adherent placenta that is asymptomatic

• After 1 CS: 3%

• After 2 CS: 11%

• After 3 CS: 40%

• After 4 CS: 61%

• After 5 CS: 67%

Rates of concurrent placenta accrete in patients who had prior CS deliveries

Vasa previa

· Occurs when a velamentous cord insertion causes the fetal vessels to pass over the internal os

· Also seen with velamentous and succenturiate placentas

Velamentous placenta

Occurs when blood vessels insert between the amnion and the chorion, away from the margin of the placenta, leaving the vessels largely unprotected and vulnerable to compression or injury

Succenturiate placenta

· An extra lobe of the placenta is implanted at some distance away from the rest of the placenta

· Fetal vessels may course between the two lobes, possibly over the cervix, leaving these blood vessels unprotected and at risk for rupture

Placental abruption (abruptio placentae)

Premature separation of implanted placenta from uterine wall, resulting in hemorrhage

Concealed hemorrhage

Bleeding confined in uterine cavity (20% of abruptions)

Revealed or external hemorrhage

Blood dissects toward cervix (80% abruptions)

History of previous abruption

Strongest risk factor for abruption (8- to 12-fold risk increase)

• 5.8 - 22% after one abruptio

• >50% after two abruptio

Risk of abruption in future pregnancy

Third trimester vaginal bleeding (78%)

Most common history finding in abruptio placenta

Couvelaire uterus

A term for a bluish purple myometrium as seen on surface of uterus in abruptio placenta

• 0.5-0.1% in prior low-transverse CS delivery

• 6-12% in prior classical CS delivery

Rates of uterine rupture for previous low-transverse and classical CS delivery

Nonreassuring fetal HR pattern

Most common sign of uterine rupture

Apt test

Laboratory test for determining the presence of fetal RBCs in maternal blood

34-36 weeks AOG

If patient is diagnosed with vasa previa, patients may opt for elective CS at what AOG?

• Cumulative blood loss > 1000 mL OR

• blood loss + signs and symptoms of hypovolemia

Blood volume loss required for a diagnosis of postpartum hemorrhage

Vaginal wall hematoma

Location of hematoma to be ruled out if patient has large drop in Hct after delivery without no visible bleeding site

Retroperitoneal hematoma

Location of hematoma to be ruled out if patient has large drop in Hct with low back pain

Uterine atony

Leading cause of postpartum hemorrhage

• IV oxytocin (20U in 1L crystalloid x 10 mL/min) OR

• IM oxytocin (10U)

Typically given prophylactically after delivery to prevent uterine atony

Methylergonovine

Second-line drug given for uterine atony

• Carboprost or Prostaglandin F2α

• Dinoprostone, a Prostaglandin E2 analog

• Misoprostol, a Prostaglandin E1 analog

Third-line drugs given for uterine atony

• Bimanual uterine compression

• Balloon tamponade (Bakri)

• Surgical procedures – uterine compression sutures (e.g., B-Lynch sutures), pelvic vessel ligation, embolization, or hysterectomy

Management options for bleeding unresponsive to uterotonic agents

Uterine inversion

Complete or partial turning-out of the uterus

Manual replacement

First step in management of uterine inversion

Laparotomy

Second-line management if unsuccessful manual replacement of inverted uterus

Huntington procedure

Laparotomy technique in resolving uterine inversion that uses atraumatic clamps used to apply upward traction to round ligaments

Haultain incision

Laparotomy technique in resolving uterine inversion that utilizes a sagittal cut to release constriction ring

Amniotic fluid embolism

Occurs due to embolization of meconium-laden amniotic fluid→AF and debris obstruct pulmonary artery flow

Abruptio placenta

Most common cause of disseminated intravascular coagulation

• Hypofibrinogenemia (<150 mg/dL)

• Thrombocytopenia

• Prolonged PT/PTT

Laboratory findings in DIC

Recombinant factor VIIa

Clotting factor that may be beneficial in severe cases of DIC

<25 volume percent

Rapid blood infusion should be done when hematocrit reaches...?

<50,000/uL

Platelet concentrate infusion should be given if platelet count is less than...?

Fresh frozen plasma in doses of 10-15 mL/kg or cryoprecipitate

Adjuncive therapy in a patient with prolonged PT/PTT with surgical bleeding

3-4%

Percent increase in Hct per unit of transfused compatible whole blood