Umbilical cord prolapse happens when the umbilical cord

Umbilical cord

In placental mammals, the umbilical cord is the connecting cord from the developing embryo or fetus to the placenta...

 precedes the fetus' exit from the uterus

Uterus

The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...

. It is an obstetric

Obstetrics

Obstetrics is the medical specialty dealing with the care of all women's reproductive tracts and their children during pregnancy , childbirth and the postnatal period...

 emergency during pregnancy

Pregnancy

Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...

 or labor that imminently endangers the life of the fetus. Cord prolapse is rare. Statistics on cord prolapse vary, but the range is between 0.14% and 0.62% of all births in most studies.

Cord prolapse is often concurrent with the rupture of the amniotic sac. After this happens the fetus moves downward into the pelvis and puts pressure on the cord. As a result, oxygen and blood supplies to the fetus are diminished or cut-off and the baby must be delivered quickly.

Treatment and mortality rate

Some practitioners will attempt to reduce pressure on the cord and deliver vaginally right away. Frequently the attempt to resolve the prolapsed cord and deliver the baby vaginally fails, and an emergency caesarean section

Caesarean section

A Caesarean section, is a surgical procedure in which one or more incisions are made through a mother's abdomen and uterus to deliver one or more babies, or, rarely, to remove a dead fetus...

 must be performed immediately. While the patient is being prepared for a caesarean, the woman is placed in the Trendelenburg position

Trendelenburg position

In the Trendelenburg position the body is laid flat on the back with the feet higher than the head by 15-30 degrees, in contrast to the reverse Trendelenburg position, where the body is tilted in the opposite direction. This is a standard position used in abdominal and gynecological surgery...

 or the knee-elbow position, and an attendant reaches into the vagina

Vagina

The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...

 and pushes the presenting part out of the pelvic inlet and back into the pelvis to remove the pressure from the umbilical cord. If attempts to deliver the baby prompty fail, the fetus' oxygen and blood supply are occluded and brain damage or death will occur.

The mortality rate

Mortality rate

Mortality rate is a measure of the number of deaths in a population, scaled to the size of that population, per unit time...

 for the fetus is given as 11–17%. This applies to hospital births or very quick transfers in a first world environment. One series is reported where there was no mortality in 24 cases with the novel intervention of infusing 500ml of fluid by catheter into the woman's bladder, in order to displace the presenting part of the fetus upward, and to reduce compression on the prolapsed cord ; however a recent trial comparing manual support alone (n=29) versus manual support plus bladder-filling (n=15) showed no added benefit in terms of neonatal outcome.

Risk factors

Potential predisposing risk factors include:

• Premature
  Premature birth
  In humans preterm birth refers to the birth of a baby of less than 37 weeks gestational age. The cause for preterm birth is in many situations elusive and unknown; many factors appear to be associated with the development of preterm birth, making the reduction of preterm birth a challenging...
  
   rupture of the amniotic sac
  Amniotic sac
  The amniotic sac is the sac in which the fetus develops in amniotes. It is a tough but thin transparent pair of membranes, which hold a developing embryo until shortly before birth. The inner membrane, the amnion, contains the amniotic fluid and the fetus. The outer membrane, the Chorion,...
  
  
• polyhydramnios
  Polyhydramnios
  Polyhydramnios is a medical condition describing an excess of amniotic fluid in the amniotic sac. It is seen in 0.2 to 1.6% of pregnancies,,...
  
   (having a large volume of amniotic fluid
  Amniotic fluid
  Amniotic fluid or liquor amnii is the nourishing and protecting liquid contained by the amniotic sac of a pregnant woman.- Development of amniotic fluid :...
  
  ). The cord may be forced out with the more forceful gush of waters.
• long umbilical cord
• fetal malpresentation
• multiparity
• multiple gestation