Prolapsed Cord

Three varieties:¹

• Overt cord prolapse - if the presenting part of the fetus does not fit the pelvis snugly after membrane rupture, there is a risk that the umbilical cord can slip past and present at the cervix or descend into the vagina. This is known as overt cord prolapse. It represents an acute obstetric emergency as prolapse exposes the cord to intermittent compression compromising the fetal circulation. Depending on its duration and degree of compression, fetal hypoxia, brain damage and even death can occur. Exposure of umbilical cord to air causes irritation and cooling producing vasospasm of the cord vessels.
• Occult cord prolapse - where the umbilical cord lies alongside the presenting part.
• Funic presentation - where the cord can be felt to prolapse below the presenting part before membranes have ruptured. The cord may slip to one side of the head and disappear as the membranes rupture.

Incidence

Overall incidence approximately 3/1000 deliveries.²
Overt cord prolapse occurs in:

• 0.5% cephalic and frank breech presentations
• 5% complete breech
• 15% footling breech
• 20% transverse lie

Incidence of occult prolapse unknown but 50% of monitored labours show fetal heart rate changes suggesting umbilical cord compression, which is usually transitory and relieved by changing mother's position.

Risk factors³

• Multiparity
• Prematurity (less than 34 weeks gestation)
• Abnormal presentations - footling breech is particularly risky
• Cephalopelvic disproportion
• Pelvic tumours, placenta praevia, low lying placenta
• Polyhydramnios
• Macrosomia
• Multiple birth
• High fetal station
• Long umbilical cord
• Obstetric interventions including amniotomy (before presenting part is engaged), use of scalp electrode or intrauterine pressure catheter and attempted external cephalic version⁴

Signs

An ill-fitting or non-engaged presenting part should alert one to the possibility of cord prolapse.
Fetal monitoring - Whilst the fetus remains in good condition, variable fetal heart rate deceleration are seen during uterine contractions that promptly return to normal after contraction subsides. With prolonged and complete compression bradycardia occurs. With deteriorating fetal status activity diminishes and eventually stops. Any fetal bradycardia or decelerations that may indicate compression of a prolapsed cord should be confirmed/ruled out with a vaginal examination.
Diagnosis:

• Overt - cord can be seen protruding from the introitus or loops of cord can be palpated within the vaginal canal. If the cord is pulsating, the fetus is alive.
• Occult - rarely felt on pelvic examination and only indication may be fetal heart rate changes.
• Funic presentation - loops of cord are palpated through the membrane.

Loops of cord in front of the presenting of the presenting part can be visualized using colour Doppler studies. This is not routinely done but can be used to serially examine women at high risk.

Treat prolapsed cord as an emergency.

• Overt - if fetus viable, place mother in knee-chest position (patient facing the bed, chest level to bed, knees tucked under chest, pelvis and buttocks elevated) and apply upward pressure against presenting part to lift fetus away from prolapsed cord whilst proceeding to emergency caesarean section as soon as possible.
  If available give salbutamol 0.5mg IV slowly over 2 minutes to reduce contractions. Only proceed with vaginal delivery if delivery is imminent, the cervix is fully dilated and there are no contraindications. This can be expedited with episiotomy/vacuum extraction or forceps.
  Ensure resuscitation available for baby post-delivery.
  If the fetus has died, deliver in the manner that is safest for the woman.
• Occult (if suspected) - place mother in left lateral position. If fetal heart rate returns to normal, allow labour to continue with mother receiving O₂ and fetal heart rate continuously monitored. Otherwise rapid caesarean section.
• Funic presentation - A decision should be made between prompt elective caesarean section prior to membrane rupture or artificial rupture of membranes with full preparations for an emergency caesarian section in case the cord does become an overt prolapse on rupture.

Up to 20% perinatal mortality with all cases of overt prolapse with prematurity and congenital abnormality being the underlying factor in many cases^{4 8} .

Treat high-risk patients with constant fetal monitoring during delivery.
Do not artificially rupture membranes if presenting part is high.