Abnormal labor and delivery

Umbilical cord complications

Vasa Previa

Umbilical Cord Prolapse

• Pathophysiology/Risk Factors
  • Umbilical cord descends below the fetal presenting part after membrane rupture.
  • RFs: Breech presentation, transverse lie, polyhydramnios, prematurity, long cord.
• Clinical Features
  • History:
    • Sudden onset of fetal heart rate (FHR) abnormalities immediately following spontaneous rupture of membranes (SROM) or AROM.
  • Physical Exam:
    • Overt Prolapse: Direct visualization or palpation of a soft, pulsatile cord loop inside the vagina or protruding from the introitus.
    • Occult Prolapse: Cord compressed alongside the presenting part without herniating through the cervix (cord not directly palpable; identified by FHR patterns).
  • Fetal Heart Rate (FHR) Tracing:
    • Abrupt, severe prolonged decelerations or recurrent, deep variable decelerations due to mechanical cord compression and vasospasm.
• Management
  • Immediate Management (Relieve Compression):
    1. Manual elevation: Insert gloved hand into vagina and push presenting part upward; keep hand in place continuously until delivery.
    2. Maternal repositioning: Knee-chest or steep Trendelenburg position (uses gravity to shift fetus). c
    3. Tocolysis: Administer terbutaline 0.25 mg SQ to arrest uterine contractions and reduce pressure.
    4. Cord care: Do NOT push cord back inside (triggers vasospasm); cover exposed cord with warm, moist saline dressings.
  • Definitive Delivery:
    • Emergent C-section: Standard of care for nearly all viable cases.
    • Operative vaginal delivery (Forceps/Vacuum): Only if cervix is fully dilated (10 cm), head is low/engaged, and delivery is instantaneous.

Velamentous Cord Insertion

• Pathophysiology
  • Umbilical cord inserts into the chorioamniotic membranes rather than the placental mass.
  • Fetal vessels travel between amnion and chorion without protection of Wharton jelly before reaching the placenta.
• Complications
  • ↑ Risk of Vasa Previa.
  • Vessel rupture causing fetal hemorrhage.
  • Intrauterine Growth Restriction (IUGR).

Single Umbilical Artery (2-Vessel Cord)

• Anatomy
  • Normal: 2 Arteries (deoxygenated blood), 1 Vein (oxygenated blood).
  • Pathology: Aplasia or atrophy of one umbilical artery.
• Associations
  • Can be an isolated finding in normal pregnancies.
  • ↑ Risk of congenital anomalies, specifically Renal (do fetal renal ultrasound) and Cardiac.
  • Associated with Aneuploidy (Trisomy 13, 18).

Nuchal Cord & True Knots

• Nuchal Cord
  • Cord wrapped around fetal neck (very common).
  • Fetal Heart Rate Tracing: Variable decelerations (abrupt drop and return) due to cord compression.
  • Management: Usually benign; monitor. Reduce cord at delivery if tight.
• True Knots
  • Rare; cord ties into a knot.
  • RFs: Monoamniotic twins (cords entangle), polyhydramnios, long cord.
  • Complication: Fetal asphyxia if knot tightens.

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Abnormal stages of labor

• Etiology (3 Ps): Power (<200 MVUs), Passenger (OP position, macrosomia), Passage (CPD).
• First Stage Abnormalities (0–10 cm dilation):
  • Prolonged Latent Phase (<6 cm): >20 hr (nulliparous) or >14 hr (multiparous).
    • Mgmt: Rest, hydration, or sedation (NO C-section).
  • Active Phase Protraction (≥6 cm): Progressing <1–2 cm/2 hr.
    • Mgmt: Place IUPC $\to$ Oxytocin + AROM if contractions <200 MVUs.
  • Active Phase Arrest (≥6 cm + ROM): No progress for ≥4 hr (adequate contractions, >200 MVUs) OR ≥6 hr (inadequate contractions w/ oxytocin). c
    • Mgmt: Cesarean delivery.
• Second Stage Abnormalities (10 cm to fetal delivery):
  • Arrest/Protraction of Descent: Pushing >3 hr in nulliparous (>4 hr w/ epidural) or >2 hr in multiparous (>3 hr w/ epidural).
    • Cause: Most commonly occiput posterior (OP) position.
    • Mgmt
      • Evaluate fetal station, orientation, and maternal contractions.
      • If contractions inadequate $\to$ Oxytocin titration.
      • If head is engaged (station ≥ +2) and maternal/fetal distress or arrest occurs $\to$ Operative vaginal delivery (vacuum or forceps). c
      • If head is unengaged (station < +2) or operative delivery fails/contraindicated $\to$ Cesarean delivery.
• Third Stage Abnormalities (Fetal delivery to placenta):
  • Retained Placenta: Unextracted placenta after >30 min.
  • Mgmt: Uterine massage + oxytocin $\to$ Manual extraction $\to$ Emergency hysterectomy if placenta accreta present.

Mechanical obstruction of labor

• Etiology & Risk Factors:
  • Passage: Contracted pelvis, uterine fibroids.
  • Passenger: Macrosomia (EFW >4500g / >4000g in DM), malpresentation (brow, mentoposterior face, transverse lie), malposition (persistent occiput posterior [POP])
  • Risks: Nulliparity, maternal obesity, post-term pregnancy, maternal DM.
• Clinical Features:
  • Active phase arrest: No cervical change in ≥4 hrs w/ adequate contractions or ≥6 hrs w/ inadequate contractions.
  • Bandl ring: Pathological retraction ring (visible abdominal groove) indicating impending uterine rupture.
  • Fetal head physical findings: Severe head molding, extensive caput succedaneum, station non-progression.
  • Cervical edema, maternal exhaustion, distended bladder, hematuria.
• Diagnosis:
  • Partogram: Arrest of cervical dilation/descent.
  • IUPC: Adequate contractions (≥200 MVUs) w/ failure to progress confirms CPD.
  • Transabdominal US: Confirm malpresentation, EFW, fetal structural anomalies.
• Management:
  • Immediate: Stop oxytocin immediately (prevents uterine rupture); IVF, Foley catheter, intrauterine resuscitation.
  • Definitive: Emergency C-section (treatment of choice for true CPD, arrest, or uncorrectable malpresentation).
  • Operative Vaginal Delivery (Forceps/Vacuum): Strictly allowed only if 10 cm dilated, engaged head (station ≥+2), vertex presentation.
• Complications:
  • Maternal: Uterine rupture, PPH (atony/laceration), vesicovaginal/rectovaginal fistulae (from prolonged ischemic necrosis), chorioamnionitis.
  • Fetal: HIE / fetal asphyxia, birth trauma (brachial plexus injury, skull fracture, cephalohematoma), IUFD.

Shoulder dystocia

• Definition & Pathophysiology: Impaction of anterior fetal shoulder behind maternal pubic symphysis after head delivery.
• High-Yield Risk Factors:
  • Maternal GDM/DM (most significant preventable RF; alters fetal fat distribution).
  • Fetal macrosomia (EFW > 4000 g in DM, > 4500 g in non-DM).
  • Prior shoulder dystocia (highest risk of recurrence: 10-15%).
  • Maternal obesity, post-term pregnancy, prolonged 2nd stage, operative vaginal delivery. c
• Clinical Presentation:
  • Turtle sign: Fetal head retracts tightly against perineum.
  • Failure of restitution (head does not rotate externally).
• Diagnosis: Clinical intrapartum diagnosis upon failure of gentle downward traction to deliver anterior shoulder.
• Management Hierarchy:
  • Immediate Protocol: Call for help, stop pt from pushing, NEVER perform fundal pressure (causes uterine rupture & severe impaction).
  • 1st-Line Maneuvers:
    • McRoberts maneuver: Maternal hip hyperflexion/abduction towards abdomen (flattens sacrum).
    • Suprapubic pressure: Downward + lateral pressure above pubic symphysis (dislodges shoulder).
  • 2nd-Line Maneuvers:
    • Delivery of posterior arm: Reach in, sweep posterior arm across fetal chest.
    • Internal rotation: Rubin II or Wood’s screw maneuvers.
    • Gaskin maneuver: Roll pt to all-fours.
    • Episiotomy (improves hand access only, does not un-impact bone).
  • 3rd-Line / Rescue:
    • Zavanelli maneuver: Flex head & push back into vagina $\to$ STAT Emergency C-section.
    • Intentional clavicular fracture.
• Complications:
  • Maternal: PPH (atony/lacerations), 3rd/4th-degree perineal tears, uterine rupture.
  • Fetal:
    • Erb-Duchenne palsy (C5-C6: “waiter’s tip”, Moro absent, grasp intact).
    • Klumpke palsy (C8-T1: “claw hand” $\pm$ Horner syndrome).
    • Clavicle / Humerus fracture (crepitus, asymmetric Moro).
    • Perinatal asphyxia / HIE.

Induction of labor

Elective Delivery

• Elective Delivery: Planned initiation of labor (induction of labor [IOL]) or elective cesarean delivery (CD) in the absence of maternal or fetal medical indications.
• Timing & Eligibility ($\text{GA}\ge 39\text{w }0\text{d}$)
  • Elective delivery (IOL or CD) is strictly contraindicated prior to $39\text{w }0\text{d}$ to prevent iatrogenic neonatal morbidity (RDS, TTN, NICU admission). c
  • ARRIVE Trial: Elective IOL at $39\text{w }0\text{d}–39\text{w }4\text{d}$ in low-risk nulliparous pts reduces CD rates and gestational HTN without increasing neonatal risks.
  • Criteria to Confirm GA > 39w: Requires US $<20\text{w}$, FHT $\ge 30\text{w}$ by Doppler, or (+) pregnancy test $\ge 36\text{w}$ prior.