ABRUPTIO PLACENTAE

ABRUPTIO PLACENTAE - Cathryn B. Heath, MD
BASICS
DESCRIPTION
Premature separation of otherwise normally implanted placenta
• Grades
- Grade 1: Minimal or no bleeding; detected as retroplacental clot after delivery of viable fetus. Mild uterine irritability (40% of cases)
- Grade 2: Viable fetus with bleeding and tender, irritable uterus. Mild to moderate bleeding; fibrinogen level decreased (45% of cases)
- Grade 3: Type A with dead fetus and no coagulopathy; type B with dead fetus and coagulopathy (A and B total 15% of all cases of abruptio placenta)
• Increased pelvic blood flow of pregnancy may enhance blood loss.
• Amniotic fluid embolism is rare but may present with disseminated intravascular coagulation and severe respiratory distress.
• If placenta is in anterior position, there is increased risk of fetal-maternal transfusion with trauma.
• System(s) Affected: Cardiovascular; Reproductive
• Synonym(s): Placental abruption; Premature separation of the placenta
GENERAL PREVENTION
Eliminate risk factors when possible.
EPIDEMIOLOGY
• Predominant age: Childbearing ages
• Predominant sex: Female only
Incidence
• 0.5-1.2% of all deliveries
• 15% if 1 prior episode
• 25% if 2 or more prior episodes
• 80% of cases occur prior to onset of delivery
RISK FACTORS
• Prior abruption (increases risk 10-fold)
• Blunt trauma
• Maternal smoking
• Severe small-for-gestational-age birth
• Hypertension: Pregnancy-induced and chronic
• Uterine anomalies
• Advanced maternal age
• Increased risk if hypertensive and parity >three
• Preterm rupture of membranes, especially if bleeding occurs during observation interval (1)[B]
• Vaginal bleeding before spontaneous rupture of membranes
• Factor V Leiden and other thrombophilic disorders
• Multiple gestation pregnancies (2)[B]
ETIOLOGY
• Cocaine use and abuse
• Trauma of variable amounts, especially blunt abdominal trauma in which external signs of trauma may be incongruent with fetal injury (motor vehicle collision or domestic violence)
• Sudden decompression of overdistended uterus, as in hydramnios or twin gestation
ASSOCIATED CONDITIONS
• Preeclampsia and other forms of hypertension in pregnancy
• Hypertension
• Postpartum hemorrhage
• Maternal and fetal organ damage from hypoperfusion


DIAGNOSIS
SIGNS AND SYMPTOMS
• Classic triad of vaginal bleeding, abdominal pain, and contractions
• 2nd- or 3rd-trimester vaginal bleeding of >1 pad or tampon per hour
• Back pain
• Abdominal pain
• Uterine tenderness, hypertonia, or high-frequency contractions
• Blood loss may be concealed
- Clinical signs of shock may occur with little vaginal bleeding.
• Because blood volumes increase in pregnancy, volume lost may exceed 30% before signs of shock or hypovolemia occur.
- Vital signs may be preserved even with significant loss.
• Fetal distress or demise
• Idiopathic preterm labor with or without fetal distress
TESTS
• Kleihauer-Betke for fetal-maternal transfusion
• Bedside clot test, with red-top tube of maternal blood with poor or nonclotting blood after 7-10 minutes indicating coagulopathy
• Apt test for fetal blood origin
- Mix vaginal blood with small amount of tap water to cause hemolysis, centrifuge several minutes, mix pink hemoglobin-containing supernatant with 1 mL 1% sodium hydroxide (NaOH) for each 5 mL of supernatant; read color after 2 minutes, with fetal hemoglobin staying pink and adult turning yellow-brown
• Wright stain of vaginal blood
- Observe for nucleated red blood cells (RBCs), usually of fetal origin
• Lecithin/sphingomyelin ratio if delay of delivery is an option and length of pregnancy is preterm
Lab
• Blood type, Rh, Coombs
• CBC with platelet count
• Prothrombin time
• Partial thromboplastin time
• Fibrinogen levels
• Cross-match at least 4 U packed RBCs
• Drugs that may alter lab results
- Those that affect clotting parameters
- RHoD immune globulin administered 12 weeks prior may affect antibody test
• Disorders that may alter lab results
- Fibrinogen levels climb to 350-550 mg/dL (3.5-5.5 g/L) in 3rd trimester and must fall to 100-150 mg/dL (1.0-1.5 g/L) before partial thromboplastin time will rise.
- Fibrin split or degradation products are elevated in pregnancy and are not very helpful in assessing disseminated intravascular coagulation.
Imaging
Although ultrasound may show sonolucent retroplacental clot, rounded placental margin, or thickened placenta, it is often not definitive, especially with posterior placement or mild abruption. However, ultrasound of the uterus, placenta and fetus may diagnose abruption placenta in 50% of cases. Large (>60 mL) are associated with a >50% fetal mortality.
Diagnostic Procedures/Surgery
External uterine monitoring often shows elevated baseline pressure and frequent low-amplitude contractions.
Pathological Findings
• Normocytic normochromic anemia with acute bleeding
• Elevated prothrombin time and partial thromboplastin time, fibrinogen levels below 100-150 mg/dL (1.0-1.5 g/L), platelets 20,000-50,000/uL if disseminated intravascular coagulation active
• Positive Kleihauer-Betke reaction if fetal-maternal transfusion has occurred
• Positive antibody if RhoD isosensitization has occurred
DIFFERENTIAL DIAGNOSIS
• Uterine rupture
• Placenta previa
• Vasa previa
• Marked bloody show
• Cervical and vaginal causes (e.g., chlamydia or gonorrhea with bloody, friable cervix)
• Masses
• Other painful conditions (e.g., appendicitis, pyelonephritis)
• Labor
TREATMENT
GENERAL MEASURES
• History and physical exam with medical history, allergies, prior ultrasounds this gestation, and time of last meal
• In general, severe abruption best managed by delivery of fetus
• Grade 1: Usual labor protocol
• Grade 2: Rapid delivery, most often by cesarean delivery
• Grade 3: Vaginal delivery preferable if mother stable
• In trauma, monitor in the inpatient setting for at least 6 hours for evidence of fetal insult, abruption, fetal-maternal transfusion. If contractions or preterm labor occur, patient should be monitored for at least 24 hours. Risk factors for contractions with trauma include
- Gestational age >35 weeks
- Assaults
- Pedestrian/vehicular collisions
- Ejections from vehicle or lack of restraints (3)[B]
• Early aggressive restoration of maternal physiology to protect fetus and maternal organs from hypoperfusion/disseminated intravascular coagulation
• Stabilize vitals
• Maintain urine output >60 mL/h
• Bedrest with external fetal and labor monitoring, if fetus is viable
• Large-bore, 16- to 18-gauge IV crystalloid infusion
- Central line placement only after coagulation status has been assessed
• Transfusions of whole blood and packed RBCs as necessary to maintain hematocrit >30%
• Fresh frozen plasma and platelet transfusions for coagulopathy, with cryoprecipitate and fibrinogen given if indicated
• Follow hemoglobin/hematocrit and coagulation status every 1-2 hours
• Place intrauterine pressure catheter, because fetal risk climbs with elevated pressure
• Role of amniotomy to prevent amniotic fluid embolism is debatable but will speed delivery
• Positioning on left side may enhance venous return and cardiac output
• Oxygen for all patients
Diet
NPO until status defined and possibility of cesarean delivery ruled out
Activity
Bed rest until status defined
SPECIAL THERAPY
IV Fluids
Saline or Ringer's lactate
MEDICATION (DRUGS)
• May use oxytocin (Pitocin) augmentation to speed delivery
• Tocolytics such as terbutaline may be used in mild noncompromising preterm abruption.
• RhoD immune globulin IM for RhoD-negative mother if undelivered or indicated after delivery
• 300 ug RhoD immune globulin/15 mL fetal blood transfused, if Kleihauer-Betke test returns positive, administered IM
• Contraindications
- Tocolytics should be withheld in preterm labor until abruption ruled out and fetal status defined
• Precautions
- Suffusion of blood into myometrium with weakening may increase risk of uterine rupture with oxytocin (Pitocin) augmentation
- Cryoprecipitate and fibrinogen may represent greater transfusion infection transmission risk
SURGERY
May need cesarean delivery after maternal stabilization if fetus is viable and the situation urgent
FOLLOW-UP
DISPOSITION
Hospitalize until stable
Discharge Criteria
If trauma without compromise after observation or small abruption and preterm, may observe outpatient, encouraging reduction of risk factors
PROGNOSIS
• 0.5-1% fetal mortality and 30-50% perinatal mortality
• With trauma and abruption, 1% maternal and 30-70% fetal mortality
• Labor typically more rapid, but hypotonus from blood suffusion may occur
COMPLICATIONS
• Infection transfusion risks: Hepatitis, cytomegalovirus, human immunodeficiency virus, and others
• Sensitization from blood product transfusion
PATIENT MONITORING
• If not delivered, monitor for intrauterine growth retardation
• See regularly and assess for preterm labor
REFERENCES
1. Ananth CV, Oyelese Y, et al. Preterm premature rupture of membranes, intrauterine infection, and oligohydramnios: risk factors for placental abruption. Obst  Gynecol. 2004;104(1): 71-77.
2. Salihu HM, Bekan B, et al. Perinatal mortality associated with abruptio placenta in singletons and multiples. Am J Obstet Gynecol 2005;193(1):198-203.
3. Curet MJ, Schermer CR, et al. Predictors of outcome in trauma during pregnancy : identification of patients who can be monitored for less than 6 hours. J Trauma. 2000;49(1):18-24.