Umbilical cord prolapse is a serious obstetric complication defined by the descent of the umbilical cord through the cervix and into the vagina before the baby’s presenting part. It is considered an acute obstetric emergency because the cord is vulnerable to compression by the fetus, especially during uterine contractions. This pressure can rapidly reduce or stop the blood flow through the cord’s vessels, which carry oxygen and nutrients to the fetus. The resulting oxygen deprivation, known as fetal hypoxia, poses an immediate threat of permanent neurological damage or death to the baby.
Mechanism and Classification
Cord prolapse occurs when the space between the fetal presenting part and the cervix allows the cord to slip down, usually after the rupture of the amniotic membranes. The condition is categorized into two main types. Overt, or complete, cord prolapse is the most clinically evident form, characterized by the umbilical cord being visible outside the cervix or protruding from the vagina. This type occurs only after the membranes have broken and the cord has fully descended past the fetal presenting part.
Occult, or hidden, cord prolapse is a less obvious situation where the umbilical cord is positioned alongside the presenting part, trapped between the fetus and the uterine wall. In this scenario, the cord is not visible or palpable during a vaginal examination, but it is still subject to compression with each contraction. The primary danger in both types is that the physical squeezing of the cord’s vessels occludes fetal circulation, leading to a profound reduction in oxygen supply. Exposure of the cord to the cooler vaginal environment can also trigger a vasospasm, where the blood vessels constrict, further compromising blood flow and causing rapid fetal distress.
Factors Contributing to Prolapse
Cord prolapse is closely linked to conditions that prevent the fetal presenting part, typically the head, from fitting snugly into the maternal pelvis, leaving an open channel for the cord to descend. Primary risk factors include fetal malpresentation, such as a transverse lie (sideways) or a breech presentation (buttocks or feet first). These abnormal positions fail to seal the pelvic inlet, allowing the cord to bypass the baby. Prematurity or low birth weight also increases the risk because a smaller fetus may not fully engage in the pelvis, leaving excess space.
An abnormally high volume of amniotic fluid, called polyhydramnios, is another contributing factor because the sudden gush of fluid upon membrane rupture can carry the cord along with it. Multiple gestations, such as twins or triplets, are associated with a higher incidence of prolapse, often affecting the second twin after the first is delivered. Iatrogenic factors, which relate to medical intervention, also play a role. The most notable is the artificial rupture of the membranes when the fetal presenting part is still high and unengaged, as the sudden release of fluid can force the cord down.
Recognizing the Critical Signs
For medical staff monitoring a laboring patient, the most frequent and serious indicator of umbilical cord prolapse is a sudden, severe, and sustained deceleration in the fetal heart rate. This pattern, often characterized by fetal bradycardia (heart rate dropping below the normal range), signals acute distress resulting from cord compression and lack of oxygen. This change in the fetal heart rate tracing is often the first and only sign of occult prolapse, necessitating immediate investigation.
For a patient outside of a monitored hospital setting, the primary physical sign of an overt prolapse occurs immediately following the rupture of the membranes. This is often described as a sudden gush of warm fluid, after which the patient may feel a soft, pulsating structure in the vagina or at the vulva. Any report of feeling something in the birth canal after the water breaks should trigger an immediate emergency response. A healthcare professional confirms the diagnosis by seeing or feeling the cord during a rapid vaginal examination.
Immediate Emergency Response
Once umbilical cord prolapse is confirmed, intervention must be swift, focusing on relieving pressure and achieving the fastest possible delivery. The single most important first-aid step is to manually elevate the fetal presenting part, using fingers to push the head or buttocks upward and off the compressed cord. This manual displacement must be maintained continuously, even during transport, until an emergency delivery can occur. The hand remains inside the vagina to keep the pressure off the cord.
Changing the mother’s position uses gravity to help shift the fetus away from the pelvic inlet, alleviating cord compression. The knee-chest position, where the mother is on her hands and knees with her chest low and her buttocks raised, is highly effective. Alternatively, the Trendelenburg position, where the mother lies on her back with her head lower than her feet, achieves a similar effect. In a hospital setting, the urinary bladder may be temporarily filled with sterile fluid via a catheter; this distended bladder acts as a cushion to lift the presenting part off the cord.
The ultimate treatment is the immediate delivery of the baby, which is overwhelmingly accomplished via an emergency Cesarean section. If immediate delivery is not feasible, medications called tocolytics may be administered to temporarily stop uterine contractions, reducing pressure while surgery preparations are made. If the prolapse occurs outside of a hospital, the person should immediately call emergency services and assume the knee-chest position. Critically, avoid attempting to push the cord back inside the vagina, as this manipulation can cause vessel spasm and worsen the fetal condition.