Umbilical cord prolapse is where the umbilical cord descends through the cervix, with (or before) the presenting part of the foetus. It affects 0.1 – 0.6% of births. Cord prolapse occurs in the presence of ruptured membranes, and is either occult or overt:
- Occult (incomplete) cord prolapse – the umbilical cord descends alongside the presenting part, but not beyond it.
- Overt (complete) cord prolapse – the umbilical cord descends past the presenting part and is lower than the presenting part in the pelvis.
- Cord presentation – the presence of the umbilical cord between the presenting part and the cervix. This can occur with or without intact membranes.
Although the incidence is relatively low, the mortality rate for such babies is high (91 per 1000). This is largely because cord prolapse occurs more frequently in preterm babies, who are often breech, and who may also have other congenital defects.
Umbilical cord prolapse is where the umbilical cord descends through the cervix, with (or before) the presenting part of the foetus. Subsequently, foetal hypoxia occurs via two main mechanisms:
- Occlusion – the presenting part of the foetus presses onto the umbilical cord, occluding blood flow to the foetus.
- Arterial vasospasm – the exposure of the umbilical cord to the cold atmosphere results in umbilical arterial vasospasm, reducing blood flow to the foetus.
The main risk factors for cord prolapse include:
- Breech presentation – in a footling breech, the cord can easily slip between and past the foetal feet and into the pelvis.
- Unstable lie – this is where the presentation of the foetus changes between transverse/oblique/breech and back.
- If >37 weeks gestation, consider inpatient admission until delivery due to risk of cord prolapse
- Artificial rupture of membranes – particularly when the presenting part of the foetus is high in the pelvis.
- Polyhydramnios – excessive amniotic fluid around the foetus
Firstly, call for help – umbilical cord prolapse is an obstetric emergency. It should be managed as follows:
- Avoid handling the cord to reduce vasospasm.
- Manually elevate the presenting part by lifting the presenting part off the cord by vaginal digital examination. Alternatively, if in the community, fill the maternal bladder with 500ml of normal saline (warmed if possible) via a urinary catheter and arrange immediate hospital transfer.
- Encourage into left lateral position with head down and pillow placed under left hip OR knee-chest position. This will relieve pressure off the cord from the presenting part.
- Consider tocolysis (e.g. terbutaline) – if delivery is not imminently available this will relax the uterus and stop contractions, relieving pressure off the cord. It may be sufficient to allow enough time for transfer to a location where delivery is feasible (e.g. an operating theatre for a Caesarean section). This is a particularly useful strategy if there are fetal heart rate abnormalities while preparing for a C-section.
- Delivery is usually via emergency Caesarean section
- Through the cervix and is alongside or below the presenting part of the foetus.
- It is an obstetric emergency, with a foetal mortality rate of 91 per 1000.
- The diagnosis should be suspected in any patient with a non-reassuring foetal heart trace and absent membranes.
- The first step is to call for help when the diagnosis is made.
- Manage by manually elevating the presenting part, and deliver via the quickest mode (usually Caesarean section).