7.2 Dystocia Complications, Umbilical Cord Prolapse & Intraamniotic Infection

Neonatal & Maternal Complications of Shoulder Dystocia

Neonatal Injuries

• Brachial Plexus Palsies: Caused by downward lateral traction on the fetal head during attempted delivery, which stretches the cervical and thoracic nerve roots:
  • Erb-Duchenne Palsy (C5–C6 roots involved; most common, ~80%): Characterized by internal rotation and adduction of the shoulder, extension of the elbow, and flexion of the wrist ("waiter's tip" posture). The Moro reflex is absent on the affected side, but the palmar grasp reflex remains intact. Over 80% resolve spontaneously within 6 to 12 months.
  • Klumpke Palsy (C7–T1 roots involved): Affects intrinsic muscles of the hand and wrist flexors, resulting in a "claw hand" deformity. Palmar grasp is completely absent. If T1 sympathetic fibers are torn, it is accompanied by ipsilateral Horner syndrome (ptosis, miosis, anhidrosis).
• Skeletal Fractures: Clavicular fracture (crepitus, localized swelling, asymmetric Moro reflex) and humeral fracture.
• Perinatal Asphyxia & Hypoxic-Ischemic Encephalopathy (HIE): Severe systemic metabolic acidosis (arterial cord pH < 7.00, base deficit ≥ 12 mmol/L), neonatal seizures, and multiorgan dysfunction.

Maternal Complications

• Severe 3rd and 4th degree perineal lacerations and extensive vaginal/cervical trauma.
• Severe postpartum hemorrhage secondary to uterine atony and genital tract hematomas.
• Bladder rupture, urethral lacerations, and pubic symphysis separation (diastasis).

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Umbilical Cord Prolapse: Pathophysiology & Emergency Management

Umbilical cord prolapse occurs when a loop of the umbilical cord slips down ahead of or alongside the fetal presenting part, leading to mechanical compression of the umbilical vessels between the fetus and the maternal bony pelvis.

Classification

• Overt Cord Prolapse: The umbilical cord slips through the dilated cervical os ahead of the presenting part into the vagina or protrudes through the introitus. It is visible or palpated on digital examination following membrane rupture.
• Occult Cord Prolapse: The cord lies alongside the presenting part within the lower uterine segment or cervix, compressed against the pelvic wall. Membranes may be intact or ruptured. It is not palpated directly through the os.

Predisposing Risk Factors

• Unengaged Presenting Part: Performing amniotomy or spontaneous rupture of membranes when the vertex is at a high, negative station (–2 or –3).
• Fetal Malpresentation: Transverse lie (highest risk, up to 10%), footling breech (15% to 18%), complete breech (5%), while frank breech carries a lower risk (0.5%) because the buttocks seal the pelvis.
• Polyhydramnios: The sudden, high-velocity rush of large volumes of amniotic fluid sweeps the cord past the presenting part.
• Prematurity & Low Birth Weight (< 2,500 g): Small fetal size fails to fill the maternal pelvic inlet.
• Other Factors: Long umbilical cord (> 75 cm), multiparity, marginal or velamentous cord insertion, and multiple gestation (particularly the second twin).

Clinical Presentation

• Sudden, profound, prolonged fetal bradycardia (FHR dropping abruptly to 50–70 bpm) or recurrent, deep, atypical variable decelerations immediately following rupture of membranes.
• Digital palpation of a soft, pulsating, ropelike mass within the vagina or visualization of the cord at the vulva.

Emergency Management: The Decompression Sequence

                   [ Overt Cord Prolapse Recognized ]
                   (Pulsating mass in vagina + Bradycardia)
                                     │
         1. CALL FOR IMMEDIATE EMERGENCY ASSISTANCE / STAT C-SECTION
                                     │
         2. MANUAL DIGITAL ELEVATION OF PRESENTING PART
            (Insert gloved hand into vagina; push fetal head
             upward off the cord; KEEP HAND IN PLACE UNTIL DELIVERY)
                                     │
         3. MATERNAL REPOSITIONING (GRAVITY-ASSISTED)
            (Knee-Chest position, steep Trendelenburg, or
             exaggerated lateral Sims with hips elevated)
                                     │
         4. RETROGRADE BLADDER FILLING (Vago Maneuver)
            (Instill 500-750 mL sterile normal saline via Foley catheter
             into maternal bladder; clamp catheter; drain before incision)
                                     │
         5. UTERINE TOCOLYSIS
            (Terbutaline 0.25 mg SQ to arrest contractions
             and relieve intermittent compressive force)
                                     │
         6. PREVENT CORD VASOSPASM
            (Wrap protruding cord in warm, sterile saline-soaked gauze;
             DO NOT push cord back into vagina or manipulate excessively)
                                     │
         7. EXPEDITIOUS DELIVERY
            (Immediate stat cesarean delivery; or operative vaginal
             delivery if completely dilated and vertex at +3 station)

Key Principle of Manual Elevation: Once the clinician's hand is inserted to elevate the fetal head, that hand must not be removed during transfer to the surgical suite or patient positioning. The clinician remains on the stretcher or under the sterile surgical drapes maintaining upward cephalic displacement until the obstetrician makes the hysterotomy incision and extracts the fetal vertex.

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Intraamniotic Infection (Clinical Chorioamnionitis)

Intraamniotic infection (IAI), historically termed chorioamnionitis, is an acute polymicrobial bacterial infection of the amniotic fluid, fetal membranes, placenta, or umbilical cord resulting from ascending lower genital tract flora.

Diagnostic Criteria (ACOG / SMFM Standard)

Diagnosis requires documented maternal fever without another identifiable source, defined as:

• A single oral temperature of ≥ 39.0°C (102.2°F), OR
• An oral temperature of 38.0°C to 38.9°C (100.4°F to 102.0°F) measured on two occasions at least 30 minutes apart;

PLUS AT LEAST ONE of the following clinical features:

1. Fetal Tachycardia: Baseline FHR > 160 bpm persisting for ≥ 10 minutes (often the earliest physiological sign).
2. Maternal Leukocytosis: White blood cell (WBC) count > 15,000 cells/mm³ in the absence of antenatal corticosteroids.
3. Purulent Cervical Discharge: Grossly purulent or foul-smelling amniotic fluid or discharge draining from the cervical os.

Intrapartum Antimicrobial Therapy

Broad-spectrum intravenous antibiotics should be initiated immediately upon diagnosis to reduce maternal bacteremia, postpartum endometritis, and neonatal sepsis/pneumonia:

• Standard Vaginal Delivery Regimen:
  • Ampicillin: 2 g IV every 6 hours (provides coverage against Group B Streptococcus, Enterococcus, and Listeria), PLUS
  • Gentamicin: 5 mg/kg IV every 24 hours (or 1.5 mg/kg IV every 8 hours) (provides coverage against gram-negative enteric bacilli, including Escherichia coli).
• If Cesarean Delivery is Required:
  • Add anaerobic coverage to the Ampicillin + Gentamicin regimen: Clindamycin 900 mg IV every 8 hours OR Metronidazole 500 mg IV every 8 hours.
• Penicillin Allergy:
  • Mild allergy: Cefazolin 2 g IV every 8 hours PLUS Gentamicin.
  • Severe anaphylactic allergy: Clindamycin 900 mg IV every 8 hours OR Vancomycin 1 g IV every 12 hours PLUS Gentamicin.
• Antipyresis: Administer Acetaminophen 650 to 1,000 mg PO or IV to blunt maternal fever, reduce maternal metabolic demands, and reverse secondary fetal tachycardia and acidosis.