Cord Prolapse







‘Yet sometimes the navel string falls down and comes before it; for which cause the child is in much danger of death … As soon as ’tis perceived, you must immediately endeavor to put it back, to prevent the cooling of it, behind the child’s head, lest it be bruised … But sometimes, not withstanding all these cautions, and the putting back of it, it will yet come forth every pain; then without further delay, the chirurgeon must bring the child forth by the feet, which he must search for, tho the infant comes with the head; for there is but this only means to save the child’s life.’


Francois Mauriceau


The Diseases of Women with Child, and in Child-Bed. London: John Darby, 1663, p255

Prolapse of the umbilical cord is the classic obstetric emergency. It occurs when the membranes are ruptured and part of the cord lies below the presenting part of the fetus. Cord presentation is the same situation with intact membranes – a much rarer diagnosis. Over the past century the incidence of cord prolapse has decreased from about 1 in 150 to 1 in 500 deliveries; probably due to most malpresentations being delivered by caesarean section and more active management of the preterm fetus. Similarly, in well-equipped hospitals, the perinatal mortality has fallen over the past 50 years from 50–60% to 2–15%.


The risk to the fetus is the loss of umbilical blood flow to and from the placenta with consequent hypoxia due to physical compression of the blood vessels in the cord, or spasm of the blood vessels due to the colder temperature if the cord prolapses outside the vagina.


Predisposing Factors


The following conditions may interfere with the close application of the fetal presenting part to the lower uterine segment and cervix and therefore predispose to cord prolapse.


Fetal





  • Malpresentations such as complete and footling breech, transverse and oblique lie.



  • Prematurity: the premature fetus is more likely to lie in malpresentation and, in addition, the small size of the presenting part may facilitate prolapse of the cord.



  • Fetal anomaly: the abnormal fetus is more likely to lie in an abnormal position and may have an irregular presenting part (e.g. anencephaly).



  • Multiple pregnancy has a higher association with prematurity and malpresentations.



Maternal





  • High parity, associated with lax uterine musculature and a high presenting part.



  • Contracted pelvis.



  • Pelvic tumours, such as a cervical fibroid.



Placental





  • Minor degree of placenta praevia. The lower edge of the placenta elevates the fetal presenting part and the insertion of the umbilical cord is nearer the cervix and more prone to prolapse.



Amniotic Fluid





  • Polyhydramnios is more often associated with malpresentation or a high presenting part. In addition, the cascade of a large volume of amniotic fluid when the membranes rupture increases the likelihood of washing down the cord.



  • Prelabour rupture of the membranes.



  • Amniotomy to induce or augment labour is often given as a risk factor, but provided it is appropriately carried out is no more likely to lead to cord prolapse than spontaneous rupture of the membranes. Furthermore, should cord prolapse occur it is better that it is detected and managed as soon as possible.



Cord





  • Long umbilical cord.



Obstetric Manipulation





  • Manual or forceps rotation of the fetal head.



  • Version.



  • Amnioinfusion.



Many of the above factors are interrelated, with the main culprits being prematurity, mal­presentations and multiple pregnancy.




Diagnosis


On rare occasions, cord prolapse may be obvious with the dramatic appearance of a loop of umbilical cord at the introitus, usually shortly after spontaneous rupture of the membranes. The most common method of diagnosis is by vaginal examination and this should be carried out in all women with predisposing factors to cord prolapse. Thus, all women with breech presentations should have a vaginal examination immediately after spontaneous rupture of the membranes. Similarly, when fetal heart rate abnormalities are noted, particularly the cord compression pattern of variable or prolonged decelerations, a vaginal examination should be undertaken to exclude cord prolapse. Failure to perform vaginal examination in the presence of an abnormal fetal heart rate pattern is the commonest cause of delay in diagnosis and worsening of perinatal outcome. A loop or loops of cord may be obvious on vaginal examination but, on occasions, the presentation can be quite subtle with a loop just beside and barely below the presenting part ( Fig 18-1 ).




FIGURE 18-1


(a) Occult cord prolapse. (b) Prolapsed cord.


With the increased availability of ultrasound on labour wards, the diagnosis of cord presentation can be made in cases with predisposing factors before rupture of the membranes. However, cord presentation on antenatal ultrasound examination reverted to the normal position during labour in about half the cases in one study. Occasionally, loops of cord can be felt through the intact membranes below the presenting part.

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Jul 21, 2019 | Posted by in OBSTETRICS | Comments Off on Cord Prolapse
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