22.4 Hemorrhagic Complications of Pregnancy: Placenta Previa, Abruption, Vasa Previa, Placenta Accreta Spectrum, Uterine Rupture, Third-Stage Management and Postpartum Hemorrhage

Why this area matters

TOS area C asks you to:

• identify abnormal placentation and other conditions that increase the risk of obstetric hemorrhage;
• differentiate bleeding from different causes and explain the risks to mother and fetus;
• select diagnostic tools;
• provide appropriate treatment.

Hemorrhage, especially postpartum hemorrhage, is a leading cause of maternal death in the Philippines and worldwide. Most deaths happen within hours of birth and are preventable with active management of the third stage, early recognition and a prepared team. The DOH emphasizes facility-based delivery and emergency obstetric and newborn care (BEmONC and CEmONC) networks so that hemorrhage can be treated and referred quickly.

Antepartum Hemorrhage (Vaginal Bleeding $> 20\text{ Weeks}$)

Antepartum hemorrhage refers to genital tract bleeding occurring from 20 weeks of gestation until delivery. The three major causes are placenta previa, abruptio placentae, and vasa previa.

Placenta Previa

Implantation of the placenta overlying or adjacent to the internal cervical os.

• Classification (current ultrasound terminology):
  • Placenta Previa: Placental tissue covers the internal os, partly or completely. The older terms "complete", "partial" and "marginal" previa are no longer recommended.
  • Low-lying Placenta: The placental edge lies within 2 cm of the internal os but does not cover it.
  • A placental edge 2 cm or more from the os is normal. Most low placentas found in the second trimester "migrate" away from the os as the lower segment forms, so the finding is rechecked at about 32 weeks.
• Clinical Manifestation: Sudden, episodic, painless, bright red vaginal bleeding in the late second or third trimester. The uterus is soft, nontender, and relaxed. Fetal heart tones are typically reassuring unless severe maternal hypovolemia occurs.
• The Absolute Cardinal Rule: DIGITAL VAGINAL EXAMINATION IS STRICTLY CONTRAINDICATED in any woman presenting with third-trimester vaginal bleeding until placenta previa has been definitively ruled out by ultrasonography. Digital examination can shear the placental attachment and provoke massive exsanguinating hemorrhage.
• Diagnosis and Management: Confirmed via transabdominal ultrasound followed by transvaginal ultrasound (which is safe when the probe is angled toward the anterior fornix). Stable preterm patients are managed expectantly with pelvic rest, corticosteroids for lung maturity (between 24 and 34 weeks), and hemodynamic monitoring. Delivery is via scheduled Cesarean delivery at 36 0/7 to 37 6/7 weeks.

Abruptio Placentae (Placental Abruption)

Premature separation of a normally implanted placenta from the uterine decidua basalis prior to delivery.

• Etiology and Risk Factors: Maternal chronic hypertension, preeclampsia, sudden uterine decompression (rapid rupture of membranes in polyhydramnios, delivery of first twin), blunt abdominal trauma, cocaine use, tobacco smoking, and prior abruption.
• Clinical Manifestation: Sudden onset of severe, continuous abdominal or back pain accompanied by painful, dark red vaginal bleeding. On physical examination, the uterus is hypertonic, tender, and firm ("woody" or "board-like" uterus) with high resting tone and frequent low-amplitude contractions. In 20% of cases, bleeding is entirely concealed (retroplacental hemorrhage), causing maternal hypovolemic shock out of proportion to visible vaginal blood loss.
• Pathology and Complications: Massive decidual hemorrhage releases placental tissue thromboplastin into the maternal circulation, triggering Consumptive Coagulopathy / Disseminated Intravascular Coagulation (DIC) with severe hypofibrinogenemia ($< 150\text{ mg/dL}$). Blood dissects through the myometrium beneath the uterine serosa, producing a purplish, ecchymotic, atonic uterus known as a Couvelaire uterus.
• Management: Large-bore IV access (two 16-gauge lines), crystalloid resuscitation, blood component therapy (packed red blood cells, fresh frozen plasma, cryoprecipitate, platelets), and continuous fetal monitoring. Immediate Cesarean delivery is indicated for fetal distress or maternal hemodynamic instability.

Vasa Previa

Fetal blood vessels from the umbilical cord or placenta traverse the internal cervical os unsupported by Wharton's jelly or placental tissue (associated with velamentous cord insertion or a succenturiate placental lobe).

• Clinical Manifestation: Sudden, painless vaginal bleeding occurring immediately upon rupture of membranes (spontaneous or artificial), followed rapidly by profound fetal bradycardia, sinusoidal FHR pattern, and fetal death. The bleeding is entirely fetal; because total fetal blood volume at term is only about 250 to 300 mL, the loss of 50 to 100 mL is rapidly fatal to the fetus while maternal vitals remain completely stable.
• Diagnosis: Color Doppler transvaginal ultrasound antepartum. Post-bleeding differentiation of fetal from maternal blood is achieved via the Apt test or Kleihauer-Betke test (in the Apt test, fetal hemoglobin resists alkali denaturation with 1% NaOH and remains pink, whereas adult hemoglobin denatures into yellowish-brown alkaline hematin).
• Management: Immediate emergency Cesarean delivery.

Placenta accreta spectrum and uterine rupture

• Placenta accreta spectrum (accreta, increta, percreta):
  • abnormal invasion through a defective decidua basalis;
  • risk rises steeply with placenta previa plus previous cesarean deliveries, and also follows myomectomy, curettage and Asherman syndrome;
  • ultrasound shows loss of the clear zone, placental lacunae and bladder-wall interruption, and MRI helps;
  • planned cesarean hysterectomy at about 34 to 35 weeks, with the placenta left in place, at a center with blood bank and surgical support;
  • attempts to remove an accreta manually cause torrential bleeding.
• Uterine rupture:
  • most often in labor after a previous cesarean or other uterine surgery, or in obstructed labor and with oxytocin or prostaglandin misuse;
  • the earliest and most common sign is fetal heart rate abnormality (prolonged deceleration or bradycardia);
  • other signs are sudden abdominal pain, loss of station of the presenting part, cessation of contractions, vaginal bleeding and maternal shock;
  • management is immediate laparotomy, delivery and repair or hysterectomy.
• Disseminated intravascular coagulation complicates abruption, amniotic fluid embolism, sepsis, fetal death in utero and massive hemorrhage. Treat the cause and replace fibrinogen (cryoprecipitate), plasma and platelets.

Active Management of the Third Stage of Labor (AMTSL)

AMTSL is an evidence-based clinical package that significantly reduces postpartum hemorrhage due to uterine atony. It consists of three synchronized interventions:

1. Prophylactic Uterotonic Administration: Administer Oxytocin 10 IU intramuscularly (IM) or as an intravenous infusion within 1 minute following delivery of the infant (after palpating the abdomen to rule out an undiagnosed second twin).
2. Controlled Cord Traction (CCT): Using the Brandt-Andrews maneuver, the operator applies gentle traction to the clamped umbilical cord while simultaneously exerting upward countertraction on the lower uterine segment above the pubic symphysis to prevent uterine inversion once signs of placental separation are noted:
   • Sudden gush of blood from the vagina.
   • Lengthening of the umbilical cord protruding from the introitus.
   • The uterine fundus becomes globular, firm, and rises toward the umbilicus.
3. Uterine Fundal Massage and Tone Checks: Immediately after placental delivery, massage the uterine fundus through the abdominal wall until it is firm, and check uterine tone regularly in the first 2 hours postpartum so that atony is detected early. WHO no longer recommends sustained massage for women who received prophylactic oxytocin, but regular assessment of uterine tone is recommended for all women.

Prevention of PPH:

• Oxytocin 10 IU IM or IV is the recommended uterotonic for all births. Heat-stable carbetocin or misoprostol are alternatives where oxytocin cannot be stored cold.
• Correct anemia in pregnancy.
• Identify high-risk women (previous PPH, multiple pregnancy, polyhydramnios, macrosomia, grand multiparity, prolonged or induced labor, chorioamnionitis) so they deliver in a facility able to manage hemorrhage.

Postpartum Hemorrhage (PPH) & The "4 Ts"

Postpartum hemorrhage is traditionally defined as blood loss of 500 mL or more after vaginal delivery or 1,000 mL or more after cesarean delivery (WHO uses 500 mL for any birth). ACOG defines it as cumulative blood loss of 1,000 mL or more, or any blood loss with signs or symptoms of hypovolemia, within 24 hours of birth. Primary PPH occurs within 24 hours, and secondary PPH between 24 hours and 12 weeks.

The "4 Ts" Etiologic Framework

1. Tone (Uterine Atony): Accounts for 70% to 80% of all PPH cases. Failure of the myometrium to contract down and compress spiraling intramyometrial blood vessels ("living ligatures"). Clinically palpated as a soft, flaccid, boggy uterus enlarged above the umbilicus. Risk factors: uterine overdistension (polyhydramnios, multiple gestation, macrosomia), prolonged labor, chorioamnionitis, multiparity, high-dose oxytocin desensitization, halogenated anesthetics.
2. Trauma (Lacerations, Hematomas, Uterine Rupture, Uterine Inversion): Accounts for ~20% of cases. Suspected when there is persistent bright red vaginal bleeding despite a firmly contracted, rock-hard uterus. Inversion occurs when the uterine fundus collapses through the cervix into the vagina, often precipitated by excessive umbilical cord traction on an unseparated placenta; management requires immediate manual replacement (Johnson maneuver) before uterotonic administration.
3. Tissue (Retained Placenta / Cotyledons / Morbid Adherence): Retained placental fragments prevent uniform myometrial contraction. Spectrum of morbidly adherent placenta:
   • Placenta Accreta: Chorionic villi attach directly to the myometrium without intervening decidua basalis.
   • Placenta Increta: Chorionic villi invade deeply into the myometrium.
   • Placenta Percreta: Chorionic villi penetrate through the entire myometrium and uterine serosa, frequently invading adjacent structures (urinary bladder).
4. Thrombin (Coagulopathies): Congenital (von Willebrand disease) or acquired coagulopathies (DIC from placental abruption, amniotic fluid embolism, massive transfusion hemodilution).

Systematic Stepwise Management Algorithm for Uterine Atony

1. Initial Physical Measures: Simultaneous fundal massage and bimanual uterine compression (one gloved hand in the anterior vaginal fornix pressing against the anterior uterine wall while the abdominal hand compresses the posterior wall). Place a Foley catheter to decompress the bladder (a distended bladder displaces the uterus and inhibits contraction). Establish two large-bore IV lines (16-gauge), send blood for type and crossmatch, CBC, and coagulation studies, and administer high-flow oxygen.
2. Medical Pharmacotherapy:
   • Oxytocin: First-line agent. 10 to 40 IU in 1,000 mL normal saline IV infusion (or 10 IU IM). Acts on uterine G-protein-coupled receptors to stimulate rhythmic contractions. Rapid undiluted IV bolus is contraindicated due to peripheral vasodilation and hypotension.
   • Methylergonovine Maleate (Methergine): 0.2 mg IM (never IV due to severe hypertensive crisis). Ergot alkaloid inducing sustained, tetanic uterine contraction. STRICTLY CONTRAINDICATED in hypertension, preeclampsia, and cardiovascular disease.
   • Carboprost Tromethamine (15-methyl $\text{PGF}_{2\alpha}$ / Hemabate): 0.25 mg IM or intramyometrial; may repeat every 15 to 90 minutes (maximum 8 doses / 2.0 mg). Potent prostaglandin analog causing myometrial contraction. STRICTLY CONTRAINDICATED in patients with BRONCHIAL ASTHMA (induces intense bronchoconstriction). Common side effects: profuse diarrhea, vomiting, and pyrexia.
   • Misoprostol (Cytotec / $\text{PGE}_1$): 800 to 1,000 $\mu\text{g}$ administered rectally or sublingually. Heat-stable; valuable in low-resource environments.
   • Tranexamic Acid (TXA): 1.0 g IV over 10 minutes administered within 3 hours of birth; reduces bleeding mortality without increasing thromboembolic risk.
3. Uterine Tamponade and Surgical Interventions:
   • Intrauterine Balloon Tamponade: Placement of a Bakri balloon filled with 300 to 500 mL warm sterile saline (creates hydrostatic pressure overcoming capillary/venous pressure).
   • Uterine Compression Sutures: Placement of B-Lynch or Hayman compression sutures at laparotomy.
   • Vascular Ligation: Bilateral uterine artery ligation (O'Leary stitches) and internal iliac (hypogastric) artery ligation.
   • Peripartum Hysterectomy: The definitive, life-saving surgical procedure when conservative measures fail to arrest hemorrhage.

Early detection and the first-response bundle:

• Visual estimation underestimates blood loss. WHO now recommends objective measurement, for example with a calibrated under-buttocks drape.
• As soon as PPH is detected, give a bundle together:
  • uterine massage;
  • oxytocic drugs;
  • tranexamic acid 1 g IV within 3 hours of birth (repeated once if bleeding continues after 30 minutes);
  • IV crystalloids;
  • examination of the genital tract and placenta;
  • escalation to the next level of care if bleeding continues.
• A shock index (heart rate divided by systolic BP) of 1 or more signals significant blood loss in an obstetric patient.
• Secondary PPH (24 hours to 12 weeks) is usually caused by retained products, endometritis or subinvolution. It is treated with uterotonics, antibiotics and evacuation if tissue remains.