Atony
The most common cause of bleeding immediately postpartum is uterine atony. Atony occurs in 1 in 20-40 deliveries and is responsible for about 70-80% of postpartum hemorrhage. The patient will present with steady bleeding and possible large clots visible from the cervix after the placenta has been delivered. No visible signs of trauma should indicate that this is atony and aggressive fundal massage should ensue with medication management of hemorrhage. Risk factors for uterine atony are anything that overdistends the uterus such as multifetal gestation, polyhydramnios, fetal macrosomia as well as labor induction, prolonged labor, chorioamnionitis, retained products, abnormal placentation and the use of tocolytics or halogenated anesthetics.
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Trauma
Lacerations and abrasions that cause bleeding in the postpartum period can occur in these main areas that experience birthing trauma: the perineum, vulva, vagina, cervix, and periurethral area. The exact incidence of genital tract lacerations is unknown but they are very common and vary in degrees. Vaginal lacerations occur in about 85% of vaginal births and are more likely to occur in nulliparous patients. Urethral tears are very rare, occuring in about 0.03-0.05% of birthing women. It is the second leading cause of postpartum hemorrhage. Women will present with mild to severe bleeding and on physical exam there will be an identifiable laceration or abrasion as the source. If the source of bleeding can not be identified, make sure that you are able to obtain good visualization of the cervix, using a retractor if needed, to rule out cervical laceration. Cervical lacerations are more common after a fast transition from the first stage of labor into the second stage (more common in multiparous women) or if there is an instrumented delivery with vacuum or forceps. Other risk factors include fetal malpresentation, fetal macrosomia, episiotomy, prior cerclage, Dührssen incision, or shoulder dystocia.
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Hematoma
Hematomas (vulvar or vaginal) occur in about 1:300- 1:1,500 deliveries. These normally bleed into the skin or surrounding tissue to form a purple/blue bruise or mass that may protrude into the vulva or vagina. Hematomas are painful and tender to touch so the patient may present with discomfort and state it is worse with pressure or tight clothing etc. Hematomas rarely bleed externally but they can expand and cause pressure necrosis or rupture spontaneously in which case external bleeding will be visible. Retroperitoneal hematomas also exist however they are a source of internal bleeding and can result in a surgical emergency.
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Retained placenta
Retained products of conception including amniotic membranes and placental tissue occur in about 1% of deliveries. Retention of these products prevents the uterus from contracting down appropriately after delivery and results in persistent painless bleeding with the passage of clots and possible tissue products. Uterine bleeding refractory to massage and medication management should raise suspicion for retained products and ultrasound should be used to make the diagnosis. Risk factors for retained placenta are midtrimester delivery, chorioamnionitis, and accessory placental lobes.
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Endometritis
Endometritis following delivery occurs in about 1% of vaginal deliveries, 3% of cesareans performed prior to labor, and 5-10% of unscheduled cesareans after labor has begun. They can present with a variety of symptoms including fever, abdominal or pelvic pain, uterine tenderness, vaginal discharge, +/- vaginal bleeding, leukocytosis. Sometimes the only indication is a low-grade fever. Risk factors for endometritis includes prolonged rupture of membranes, prolonged labor, frequent digital cervical exams, chorioamnionitis, internal monitors, cesarean, manual removal of placenta, PPH, colonization with GBS, BV and diabetes.
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Uterine Inversion
Uterine inversion occurs in about 3 per 10,000 deliveries and is an emergent situation that has moderate to severe brisk bleeding depending on the amount of inversion. If there is brisk vaginal bleeding, a visible mass felt at or below the cervix, a fundus that is not palpable on fundal massage, and maternal hemodynamic instability then complete uterine inversion should be suspected and immediate action taken to resolve it. There are less severe inversions where the fundus is folded in but not completely prolapsed that still require intervention and correcting. Risk factors for uterine inversion include fetal macrosomia, rapid or prolonged labor/delivery, congenital uterine malformations, fibroids, short umbilical cord, use of uterine relaxing agents, nulliparity, retained placenta, or PAS.
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Normal lochia
It is normal for women to bleed postpartum for up to 6 weeks. The amount of bleeding and the size of the clots will tell you whether or not the bleeding is pathologic. Many women will have slow small amounts of bleeding after birth and this can be normal for 3-4 days. There will be bleeding and reddish-brown blood as the uterus and vagina expel old blood. Eventually they will transition to lochia serosa which is a light pink and mucopurulent discharge. This occurs on average 22-27 days however many women may still say they are “bleeding” at 6 weeks and it is because they are having a lightish pink discharge.
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Coagulopathy (acquired vs congenital)
Coagulopathies cause bleeding complications in about 12 in 10,000 delivery-related hospitalizations. Consumptive coagulopathies present as bleeding, hypotension out of proportion to the amount of bleeding, hemolytic anemia, and end organ damage that can appear as ARDS, AKI, elevated AST/ALTs, etc. Associated abnormal labs are thrombocytopenia, hemolysis on smear, decreased fibrinogen, elevated fibrin and D-dimer, prolonged PT and PTT. Common obstetric complications that are associated with coagulopathy are placental abruption, PPH, preeclampsia/HELLP/eclampsia syndromes, AFLP, AFE, pregnancy related sepsis, and retained IUFD.