The third stage of labor begins immediately after the birth of the baby and ends with the delivery of the placenta and fetal membranes. Although typically the shortest stage of labor, it is a critical period because of the risk of postpartum hemorrhage (PPH), a leading cause of maternal mortality worldwide. Effective management of the third stage is therefore paramount.

Physiology of the Third Stage:

• Placental Separation: After the baby is born, the uterus continues to contract and retract. This reduction in uterine size causes the inelastic placenta to begin shearing away from the uterine wall at the decidua basalis layer. Signs of placental separation include:

  • A sudden gush of dark blood from the vagina.

  • Lengthening of the visible portion of the umbilical cord.

  • The uterus becomes firmer, globular (rounded), and rises in the abdomen.

  • The mother may feel a mild contraction or urge to push.

• Placental Expulsion: Once separated, the placenta descends into the lower uterine segment or vagina, from where it is expelled by maternal effort (bearing down) or by controlled cord traction performed by the healthcare provider.

Duration:

• Typically lasts 5-15 minutes.

• Considered prolonged if it exceeds 30 minutes with active management, or 60 minutes with expectant management (though definitions can vary slightly). A prolonged third stage increases the risk of PPH.

Key Goals of Management:

• Prevent postpartum hemorrhage (PPH).

• Ensure complete expulsion of the placenta and membranes.

• Minimize maternal blood loss.

• Promote uterine contraction and tone.

• Prevent uterine inversion.

Approaches to Management:

There are two main approaches to managing the third stage of labor:

Active Management of the Third Stage of Labor (AMTSL):

• Definition: A package of interventions designed to facilitate placental delivery, reduce the risk of PPH, and decrease the duration of the third stage.

• Recommended by WHO and other major health organizations as the standard of care, especially in settings with moderate to high risk of PPH.

• Components of AMTSL:

  • Administration of a Uterotonic Drug:

    • Timing: Given within one minute of the baby’s birth (ideally after ruling out the presence of another baby).

    • Preferred Drug: Oxytocin (10 IU intramuscularly or intravenously) is the first-line uterotonic due to its effectiveness and favorable side-effect profile.

    • Alternatives: If oxytocin is unavailable or contraindicated, other uterotonics like ergometrine/methylergometrine, carbetocin, or misoprostol may be used, depending on local guidelines and availability. (Note: Ergometrine can cause hypertension and should be used with caution in women with hypertensive disorders).

  • Controlled Cord Traction (CCT):

    • Procedure: Gentle, sustained downward traction on the umbilical cord while applying counter-traction (suprapubic pressure) upwards on the uterine body with the other hand to prevent uterine inversion.

    • Timing: Performed only when the uterus is well-contracted and there are signs of placental separation.

    • Caution: Excessive or premature traction can cause cord avulsion (cord snaps) or uterine inversion. If the placenta does not descend with gentle CCT, wait for the next contraction and signs of separation before trying again.

  • Uterine Massage After Placental Delivery:

    • Procedure: Gently massaging the uterine fundus through the maternal abdomen after the placenta is delivered to stimulate uterine contraction and maintain tone.

    • Timing: Performed immediately after placental delivery and then periodically as needed until the uterus remains firm.

• Benefits of AMTSL: Significantly reduces the incidence of PPH (by about 60-70%), reduces the need for blood transfusion, and shortens the third stage of labor.

Expectant Management (Physiological or Conservative Management):

• Definition: A hands-off approach where placental separation and expulsion occur spontaneously without routine uterotonic administration or CCT.

• Procedure:

  • No routine uterotonic drugs are given.

  • The cord is clamped and cut (timing can vary).

  • The provider waits for signs of placental separation.

  • Once separation occurs, the mother is encouraged to bear down to expel the placenta. Gravity (e.g., upright position) and nipple stimulation (e.g., by breastfeeding) may be encouraged to promote natural oxytocin release and uterine contraction.

  • CCT is not routinely used.

• Indications: May be considered in very low-risk women who have a strong preference for minimal intervention, in settings where AMTSL components are unavailable, or by some practitioners who favor a more physiological approach. However, it is associated with a higher risk of PPH and a longer third stage compared to AMTSL.

• Transition to Active Management: If bleeding becomes excessive or the third stage is prolonged with expectant management, a switch to active management interventions is necessary.

Assessment and Monitoring During the Third Stage:

• Maternal Vital Signs: Monitor blood pressure and pulse regularly.

• Vaginal Bleeding: Continuously assess the amount of blood loss. Quantifying blood loss (e.g., by weighing pads/drapes or using calibrated collection devices) is more accurate than visual estimation.

• Uterine Tone: Palpate the uterine fundus to assess its firmness and contractility. A boggy (soft, poorly contracted) uterus is a sign of uterine atony, a major cause of PPH.

• Signs of Placental Separation: As described above.

Examination of the Placenta and Membranes:

• Once the placenta is delivered, it must be carefully examined to ensure completeness.

• Maternal Surface (Dirty Duncan): Check for missing cotyledons (lobes). If any part is missing, it may indicate retained placental fragments, which can cause delayed PPH or infection.

• Fetal Surface (Shiny Schultze): Examine the membranes (amnion and chorion) to ensure they are intact and complete. Check for evidence of succenturiate (accessory) lobes.

• Umbilical Cord: Note the number of vessels (normally two arteries and one vein – “AVA”). Abnormalities can be associated with fetal anomalies. Note the insertion site (central, marginal, velamentous).

• Any abnormalities or suspected retained products should prompt further investigation and management (e.g., manual exploration of the uterus, though this is an invasive procedure reserved for specific indications).

Immediate Post-Third Stage Care (Often considered part of the “fourth stage” or immediate postpartum period but initiated during/after third stage management):

• Continued Uterine Massage: As needed to maintain uterine tone.

• Perineal Repair: If an episiotomy was performed or lacerations occurred, they are assessed and repaired after placental delivery.

• Comfort Measures: Ensure the mother is comfortable, warm, and clean.

• Initiation of Breastfeeding: Encourage early skin-to-skin contact and breastfeeding, which stimulates natural oxytocin release and helps the uterus contract.

• Monitoring for PPH: Vigilant monitoring for excessive bleeding continues into the fourth stage of labor (the first 1-4 hours postpartum).

Potential Complications of the Third Stage and Their Management:

Postpartum Hemorrhage (PPH):

• Definition: Traditionally defined as blood loss >500 mL after vaginal birth or >1000 mL after Cesarean birth. Clinically, any bleeding that causes hemodynamic instability is significant.

• Causes (The “4 Ts”):

  • Tone (Uterine Atony): Most common cause (70-80%). The uterus fails to contract adequately after placental delivery. Management: Uterine massage, uterotonic drugs (oxytocin, ergometrine, misoprostol, carboprost), bimanual compression, intrauterine balloon tamponade, surgical interventions (e.g., B-Lynch suture, hysterectomy).

  • Trauma (Lacerations): Tears of the cervix, vagina, perineum, or uterus. Management: Identify and repair lacerations.

  • Tissue (Retained Placenta/Products): Retained placental fragments or membranes prevent the uterus from contracting effectively. Management: Manual removal of retained products, D&C.

  • Thrombin (Coagulopathy): Pre-existing or acquired clotting disorders. Management: Treat underlying cause, blood product transfusion.

• Immediate response to PPH (“Call for help, assess, massage, drugs, fluids, find cause, stop bleeding”).

Retained Placenta:

• Definition: Placenta not delivered within 30 minutes (with AMTSL) or 60 minutes (with expectant management).

• Management:

  • Ensure bladder is empty.

  • Attempt controlled cord traction again if appropriate.

  • Administer additional uterotonics.

  • If these measures fail, manual removal of the placenta (MRP) under appropriate anesthesia and aseptic conditions is required. This involves inserting a hand into the uterus to detach and remove the placenta. Prophylactic antibiotics are usually given.

Uterine Inversion:

• Definition: A rare but life-threatening emergency where the uterine fundus collapses and turns inside out, protruding through the cervix into or outside the vagina.

• Causes: Most commonly due to mismanagement of the third stage (e.g., excessive cord traction on a non-contracted uterus or fundal pressure when the uterus is relaxed).

• Signs: Sudden profound shock, severe pain, hemorrhage, visible or palpable inverted uterus.

• Management: Immediate manual replacement of the uterus (Johnson maneuver) often requiring tocolytics to relax the uterus, followed by uterotonics to contract it once replaced. Surgical intervention may be necessary. Aggressive management of shock and hemorrhage.