Obstetric Hemorrhage & Emergencies

Antepartum bleeding: previa, abruption, and vasa previa

First question: is it painful? Third-trimester bleeding is placenta previa until ultrasound proves otherwise when it is painless, and abruption when the uterus is painful and rigid. Stabilize with two large-bore IVs, type and crossmatch, fetal monitoring, and anti-D immunoglobulin if the mother is Rh-negative.

Never perform a digital vaginal exam until placenta previa is excluded—it can provoke catastrophic hemorrhage. Transvaginal ultrasound is safe.

Previa. A low-lying placenta seen in the second trimester often resolves as the lower segment develops, so it is rescanned in the third trimester. A persistent previa calls for pelvic rest and planned cesarean at about 36–37 weeks.

Abruption. Blood can collect behind the placenta (concealed hemorrhage), so vaginal bleeding may underestimate the loss. A normal ultrasound does not exclude abruption. Its dangers are DIC, maternal shock, and fetal demise.

Postpartum hemorrhage and the four T's

Definition. Postpartum hemorrhage (PPH) is cumulative blood loss ≥1000 mL, or bleeding with signs of hypovolemia, within 24 hours of birth, whatever the route of delivery.

Uterine atony is by far the most common cause: a soft, boggy, poorly contracted uterus with ongoing bleeding. Risk factors are overdistension (multiple gestation, polyhydramnios, macrosomia), prolonged or oxytocin-augmented labor, chorioamnionitis, and high parity. The first move is bimanual uterine massage.

Uterotonics—match the drug to the comorbidity.

• Oxytocin is first-line.
• Methylergonovine (an ergot alkaloid) causes vasoconstriction—avoid in hypertension and preeclampsia.
• Carboprost (PGF2α) causes bronchospasm—avoid in asthma.
• Misoprostol (PGE1) can be given rectally or sublingually.
• Tranexamic acid, an antifibrinolytic, reduces bleeding deaths when given within 3 hours of birth.

Resuscitate with blood products throughout, activating massive transfusion with balanced ratios of red cells, plasma, and platelets.

Placenta accreta spectrum

Abnormal invasion. Defective decidua lets villi attach directly to or invade the myometrium: accreta adheres to the myometrium, increta invades it, and percreta penetrates the serosa, reaching the bladder. The biggest risk is a prior cesarean plus a current placenta previa, and the risk climbs with each additional cesarean.

Diagnosis and planning. Ultrasound shows loss of the retroplacental clear zone, placental lacunae, and bladder-wall interruption; MRI helps assess depth. Plan a scheduled cesarean hysterectomy at 34 0/7 to 35 6/7 weeks at a center with blood bank support, leaving the placenta in place—massive hemorrhage is expected, and attempting to remove the placenta worsens it.

Delivery-room emergencies

Uterine rupture presents with sudden severe abdominal pain, loss of fetal station, fetal bradycardia (often the first sign), palpable fetal parts, and cessation of contractions—classically during a trial of labor after a prior uterine scar. Management is emergent laparotomy with delivery and repair or hysterectomy.

Umbilical cord prolapse. The cord slips ahead of the presenting part, causing compression and fetal bradycardia right after membrane rupture; the cord may be palpable and pulsating. Risk rises with malpresentation, an unengaged head, prematurity, and polyhydramnios.

Amniotic fluid embolism is a rare, catastrophic, anaphylactoid-like reaction during labor, delivery, or immediately postpartum: abrupt hypoxia, cardiovascular collapse, and DIC, sometimes with seizures. It is a clinical diagnosis of exclusion. Management is aggressive supportive care—airway, pressors, and blood products—with prompt delivery (perimortem cesarean if cardiac arrest occurs).

Obstetric DIC and Sheehan syndrome

Disseminated intravascular coagulation is triggered by abruption, amniotic fluid embolism, retained dead fetus, HELLP/severe preeclampsia, and sepsis. Labs show low platelets, low fibrinogen, high D-dimer, prolonged PT and PTT, and schistocytes. Fibrinogen normally rises in pregnancy, so a value in the "normal" nonpregnant range can already signal consumption. Treat the underlying cause (usually delivery) and replace with FFP, cryoprecipitate (fibrinogen), and platelets.

Sheehan syndrome. The pituitary enlarges in pregnancy and is vulnerable to ischemia, so severe PPH with hypotension can infarct it. The earliest clue is failure to lactate (low prolactin), followed by amenorrhea, fatigue, and other hormone deficiencies—secondary hypothyroidism and adrenal insufficiency. Treat with hormone replacement, giving glucocorticoids before thyroid hormone to avoid precipitating adrenal crisis.