Umbilical cord prolapse is where the umbilical cord descends through the cervix, with (or before) the presenting part of the fetus. 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.
In this article, we shall look at the risk factors, clinical features and management of cord prolapse.
Umbilical cord prolapse is where the umbilical cord descends through the cervix, with (or before) the presenting part of the fetus. Subsequently, fetal hypoxia occurs via two main mechanisms:
- Occlusion – the presenting part of the fetus presses onto the umbilical cord, occluding blood flow to the fetus.
- Arterial vasospasm – the exposure of the umbilical cord to the cold atmosphere results in umbilical arterial vasospasm, reducing blood flow to the fetus.
The main risk factors for cord prolapse include:
- Breech presentation – in a footling breech, the cord can easily slip between and past the fetal feet and into the pelvis.
Unstable lie – this is where the presentation of the fetus 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 fetus is high in the pelvis.
- Polyhydramnios – excessive amniotic fluid around the fetus
Clinical Features and Differential Diagnosis
Cord prolapse should always be considered in the presence of a non-reassuring fetal heart rate pattern and absent membranes. It can be confirmed by external inspection or on digital vaginal examination. This is one of the reasons that vaginal assessment, after abdominal examination, encompasses a full assessment in the presence of a non-reassuring fetal heart rate pattern.
The fetal heart rate patterns can vary from subtle changes, such as decelerations with some of the contractions, to more obvious signs of fetal distress, such as a fetal bradycardia. The latter is strongly associated with cord prolapse; relating to the mechanism of occlusion of the cord by the presenting part.
An alternative diagnosis may be considered in the presence of bleeding per vagina or heavily blood-stained liquor with ruptured membranes. This would suggest placental abruption (the placenta starts to separate from the uterine wall) or vasa praevia (fetal vessels running in the fetal membranes adjacent to the internal os of the cervix).
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
- If fully dilated and vaginal delivery appears imminent, encourage pushing or consider instrumental delivery.
- If at threshold for viability (23 + 0 weeks – 24 + 6 weeks) and extreme prematurity, expectant management may be discussed due to significant maternal morbidity with caesarean at this gestation and poor fetal outcomes.
- Umbilical cord prolapse occurs when the cord descends through the cervix and is alongside or below the presenting part of the fetus.
- It is an obstetric emergency, with a fetal mortality rate of 91 per 1000.
- The diagnosis should be suspected in any patient with a non-reassuring fetal 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).