Prolapsed Cord

There are 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 the umbilical cord to air causes irritation and cooling, resulting in 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

The overall incidence of overt prolapsed cord is between 1 and 6/1000 deliveries.²

Overt cord prolapse occurs in more than 1% breech deliveries:

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

Transverse lie is associated with a risk of cord prolapse as high as 20%.
The incidence of occult prolapse is unknown but 50% of monitored labours show fetal heart rate changes suggesting umbilical cord compression. This is usually transitory and relieved by changing mother's position.

Risk factors^2,3,4

• Multiparity
• Prematurity
• Low birth weight (<2.5 kg)
• Abnormal presentations (breech, oblique, transverse, unstable lie)
• Fetal congenital abnormality
• Cephalopelvic disproportion
• Pelvic tumours
• Low lying placenta or other abnormal placentation
• Polyhydramnios
• Macrosomia
• Multiple births (2nd twin at particular risk)
• 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 or internal podalic version⁵

Signs

• Abdominal examination: an ill-fitting or non-engaged presenting part should alert one to the possibility of cord prolapse.
• Vaginal examination (VE) - examine for the cord at every VE during labour and specifically after rupture of membranes if risk factors:
  • With an overt prolapse, the 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 prolapses are rarely felt on pelvic examination and only indication may be fetal heart rate changes.
  • With a funic presentation, loops of cord are palpated through the membrane.

Whilst it is generally important to avoid digital examination of women in preterm labour, suspicion of cord prolapse is an important exception and speculum and/or digital exam should be swiftly undertaken in these circumstances.²

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.

Have a high index of suspicion for cord prolapse, particularly if fetal monitoring changes occur soon after rupture of membranes, whether spontaneous or with amniotomy.

Routine antenatal ultrasound is not adequately sensitive to detect cord presentation. Most suspected cord presentations do not develop into a cord prolapse at delivery.
Loops of cord in front of the presenting of the presenting part can be visualised using colour Doppler studies. This is not routinely done but can be used to serially examine women at high risk.

Treat a prolapsed cord as an acute obstetric emergency.

• With an overt prolapse:
  • If the fetus is viable, place mother in the knee-chest position (patient facing the bed, chest level to bed, knees tucked under chest, pelvis and buttocks elevated) or head-down tilt in the left lateral and apply upward pressure against presenting part to lift the fetus away from the prolapsed cord. This can be done manually (gloved hand/2 fingers pushing upwards against the presenting part or once the presenting part is above the pelvic brim, using continuous suprapubic pressure in an upwards direction) or by filling the urinary bladder.
  • Manual replacement of the prolapsed cord above the presenting part is not currently recommended. Avoid handling cord outside the vagina as this induces vasospasm.
  • Proceed to emergency caesarean section as soon as possible.
  • If available, give terbutaline 0.25 mg subcut to reduce contractions when there are persistent fetal heart rate trace abnormalities despite attempts to prevent cord compression manually and there may be delays in achieving delivery.
  • 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 is available for baby post-delivery.
  • If the fetus has died, deliver in the manner that is safest for the woman.
• If an occult prolapse is suspected:
  • Place the mother in left lateral position.
  • If the fetal heart rate returns to normal, allow labour to continue with mother receiving O₂ and fetal heart rate continuously monitored.
  • If fetal heart rate remains abnormal, expedite a rapid caesarean section.
• With funic presentation, a decision needs to be made between prompt elective caesarean section prior to membrane rupture or artificial rupture of membranes with full preparations for an emergency caesarean section in case the cord does become an overt prolapse on rupture.

In the community, cord prolapse is associated with a tenfold increase in perinatal mortality rate, compared to that occurring in hospital.

Perinatal mortality rate associated with cord prolapse of 91/1000. Prematurity and congenital abnormality are underlying factors in many cases.^5,9 Even congenitally normal, full-term babies can die as a consequence of cord prolapse - home birth and delay in transfer to hospital have been identified as particular risks in these cases.²The most common serious morbidities associated with cord prolapse relate to asphyxia: hypoxic brain injury and cerebral palsy. There are few long-term studies looking at long-term sequelae of cord prolapse.

• Consider admission of all pregnant women with transverse, oblique or unstable lie from 37+6 weeks of gestation. Cord prolapses occurring in hospital have better outcomes than those occurring within the community. Advise these women that they will require rapid assessment if they start labour or have a spontaneous rupture of membranes and should seek help as soon as possible.
• Similarly, admit women with premature rupture of membranes and a non-cephalic presentation.
• Avoid artificial rupture of membranes (AROM) where possible. If an AROM is performed with a mobile presenting part, ensure arrangements have been put in place for an immediate emergency section should a cord prolapse occur.
• Whenever a VE or other obstetric procedure is performed following rupture of membranes with a high presenting part, avoid any upward pressure on the presenting part.
• Treat high-risk patients with constant fetal monitoring during delivery.