Overt cord prolapse: Kevin Somerville
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While rare, umbilical cord prolapse can be a life-threatening emergency for the fetus. It's estimated to occur in 0.14% to
0.62% of pregnancies, with perinatal mortality ranging between 36 and 345 per 1,000.1 Fortunately the overall perinatal mortality has decreased from 375 per 1,000 in 1948 to as low as 36 per 1,000, probably
because of improvements in neonatal intensive care and immediate delivery by cesarean section once cord prolapse is diagnosed.2
Occult cord prolapse: Kevin Somerville
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As you probably know, prolapse can occur as the cord passes alongside or past the fetal head, causing the umbilical vessels
to compress. Two types of umbilical cord prolapse have been described.3 Overt prolapse, the more common of the two, involves protrusion of the umbilical cord past the fetal presenting part through
the cervical os and into or past the vagina in the setting of ruptured membranes. Occult prolapse, on the other hand, occurs
when the cord descends alongside but not past the fetal presenting part; it's not always palpable on digital examination.
Occult prolapse can occur even when fetal membranes remain intact. The diagnosis of occult prolapse should be considered when
membranes are intact and there's a sudden deceleration in fetal heart rate.
Who's at risk?
Fetal factors that predispose to umbilical cord prolapse are largely related to conditions that result in a poor fit between
the fetal presenting part and the maternal bony pelvis, which allow the cord to prolapse past the fetal presenting part. These
conditions include fetal malpresentation, low birthweight, multiparity, multiple gestation, prematurity, polyhydramnios, and
funic presentation.
Figure 1. This umbilical cord prolapse occurred during a breech birth, with the cord presenting above the cervix.
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Several studies have shown that abnormal fetal presentations including breech, transverse, and oblique lies can all increase
the threat of umbilical cord prolapse.1,4,5 In one study, 36.5% of all cases of umbilical cord prolapse occurred during a breech presentation (Figure 1).1 Similarly, prolapse is twice as likely to occur when birthweight is less than 2,500 g.1,4Multiparous patients are 60% more likely to experience umbilical cord prolapse.5 The presenting fetal part is less likely to be engaged at the onset of labor in a multiparous patient and if the membranes
do rupture, it can allow the umbilical cord to pass beyond the unengaged presenting part. Multiple gestations delivering vaginally
are also at risk but that risk is greater for the second twin because of a greater likelihood of malpresentation for the second
twin.1,6,7 Murphy and associates showed that delivery at less than 37 weeks is independent of birth weight as a risk factor for umbilical
cord prolapse.7 Polyhydramnios is yet another independent risk factor for cord prolapse, as it is frequently associated with unstable lie.8 Subsequent membrane rupture, whether spontaneous or artificial, can result in a fluid gush that inadvertently forces the cord
to pass beyond the presenting part.
Which obstetrical interventions pose a danger?
Obstetrical interventions that involve manipulation or elevation of the presenting fetal part can predispose to cord prolapse
by allowing the cord to pass alongside the presenting part and result in either overt or occult prolapse. Interventions that
increase the likelihood of cord prolapse include artificial rupture of membranes, internal scalp electrode application, intrauterine
pressure catheter placement, forceps or vacuum application, manual rotation of the fetal head, amnioinfusion, and external
cephalic version.3,9 Keep in mind, however, that some of the evidence to "indict" these obstetric interventions has been challenged.
In a study conducted by Roberts and associates, for instance, induction of labor, cervical ripening, amnioinfusion, and amniotomy
did not increase the risk of umbilical cord prolapse; but there was a link with higher fetal station at the time of umbilical
cord prolapse.10 There was no difference in the incidence of umbilical cord prolapse among those patients who underwent amniotomy compared
to spontaneous membrane rupture.
How do patients present, and how do you manage them?
You are most likely to see a patient with cord prolapse present with a sudden onset of persistent variable decelerations or
prolonged bradycardia.1 On vaginal examination a cord will be felt if the prolapse is overt but may not be readily identified if the prolapse is
occult, particularly if the patient's membranes are intact. Less commonly, an overt prolapse can occur without changes in
fetal tracing and a pulsatile cord will be palpated on routine exam to assess labor progress.3 The average cervical dilation at which prolapse has been reported to occur is 5.7 2.9 cm with similar averages reported
in other studies and an average station of 1.6 1.8.9,10 However, the reported range is broad and prolapse can occur in patients who are minimally or fully dilated.
Once umbilical cord prolapse is diagnosed, standard obstetrical practice requires immediate delivery to prevent fetal demise
or compromise. Proceeding with immediate C/S is recommended, particularly in the first stage or early second stage of labor.
While preparations are being made to proceed with emergency C/S, be sure to keep pressure off of the cord. If not relieved,
persistent cord compression can cause fetal hypoxia and eventually asphyxia.
Funic decompression, the most common method used to alleviate the cord compression, involves elevation of the presenting fetal
part off of the cord. The technique requires you to maintain a hand in the vagina after diagnosis of cord prolapse and to
elevate the presenting fetal part off of the cord until the fetus is delivered abdominally. Patient positioning at the time
of diagnosis can also help. Placing the patient into steep Trendelenburg or knee-chest position will help to elevate the presenting
part and alleviate compression.
Funic reduction is another maneuver that has been described as an initial step in the management of cord prolapse. This maneuver
involves elevating the fetal head vaginally and then digitally elevating the cord above the widest part of the fetal head
in an attempt to position it in the nuchal area. Suprapubic pressure is simultaneously applied to help elevate the vertex
and decrease the likelihood of converting to a transverse or oblique lie. Once considered a suitable first step in the management
of cord prolapse, funic reduction has been abandoned in favor of emergent C/S because reduction has been linked with intrapartum
asphyxia and demise.11
However, this association was observed prior to the advent of continuous fetal monitoring. In the presence of continuous fetal
monitoring, this technique may permit vaginal delivery and avoid emergent C/S in selected patients. In a published series
of eight patients with umbilical cord prolapse, funic reduction was attempted and successful in five patients without anesthesia
who all went on to deliver vaginally with a mean funic reduction-to-delivery time of 14 to 512 minutes. There was no perinatal
morbidity or mortality reported in this small series.11 Funic reduction in patients who are undergoing continuous fetal monitoring is a viable alternative, especially when vaginal
delivery is considered imminent or if C/S is delayed.
Filling the urinary bladder is yet another technique to alleviate cord compression. This method involves filling the bladder
with 500 to 700 mL of normal saline immediately after cord prolapse is discovered. The distended bladder lifts the presenting
part off of the cord, relieving the compression and potentially eliminating the need for prolonged vaginal digital decompression.
In a series of 51 cases of acute cord prolapse, combining ritodrine with bladder filling resulted in no cases of perinatal
mortality and the majority of newborns had Apgar scores of 7 or higher at 5 minutes with a mean interval of 35 minutes from
diagnosis to delivery.12 Tocolytic use in this series was not associated with postdelivery uterine atony or hemorrhage. Bladder filling can be a viable
option, particularly when immediate C/S is not feasible.
What's the prognosis?
Most patients with umbilical cord prolapse can expect good neo-natal outcomes if you intervene promptly.12,13,14 As you might expect, the amount of time between cord prolapse and delivery plays a major role in neonatal outcome and perinatal
mortality. In studies that have assessed perinatal outcome during cord prolapse, when prolapse occurred outside the hospital setting there was a higher perinatal mortality rate. In a series of 71 cases of cord prolapse, for example, seven
cases occurred outside the hospital and of those seven, three died.5
Several other studies have evaluated the diagnosis to delivery time and its effect on fetal outcome. In one retrospective
analysis of umbilical cord prolapse, Murphy and associates found that delivering the infant within 30 minutes of diagnosis
caused little detrimental effects on the 1 and 5 minute Apgar score.7 But the same study also found evidence of acidemia occurring with earlier delivery times and that did not correlate with
Apgar scores.
When Prabulos and associates evaluated fetal outcome and delivery time in 65 cases of umbilical cord prolapse, they found
five cases of neonatal asphyxia, all of which had shorter than average diagnosis-to-delivery times. These observations suggest
that it's not simply the delivery interval that affects fetal outcome; the degree of cord compression may also be a factor.13 Although prompt delivery remains paramount, it is important to ensure adequate intrauterine resuscitation with changing maternal
position, cord decompression by funic decompression or bladder distention, and tocolysis where appropriate, while preparing
for immediate C/S delivery.
There are rare circumstances reported in the literature where prolonged cord prolapse has been managed expectantly. Poetker
and colleagues reported a case of prolonged cord prolapse that was diagnosed at 23 2/7 weeks and managed expectantly in the
setting of extreme prematurity.15 The fetus survived and was neurologically intact on the eighth month of follow up.
There are little data on the long-term outcomes of these children. Of the series of 132 cases of cord prolapse that looked
at morbidity and mortality, one of the children identified as acidotic at birth was reported to have had a long-term handicap.7
Preventing a disaster
Table 1: Risk factors for umbilical cord prolapse
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Identifying patients at risk for cord prolapse and avoiding unnecessary obstetric interventions in these at- risk patients
may prevent some cases of cord prolapse (Table 1). Certain obstetrical interventions are necessary. Amniotomy should generally
be performed only when the fetal vertex is well applied to the cervix. In cases where amniotomy is necessary and the fetal
vertex is not well applied, controlled amniotomy with either a fetal scalp electrode or small-gauge needle can be used.
When placing a scalp electrode or intrauterine pressure catheter, obtaining a fetal scalp sample, manually rotating the fetal
vertex, or applying forceps or vacuum, be careful to avoid dislodging the fetal vertex. Preterm patients with premature rupture
of membranes and malpresentation are at particular risk and should be carefully monitored for umbilical cord prolapse, especially
in the setting of malpresentation and cervical dilation.
Using ultrasound to detect the problem
Ultrasound examination is not routinely done to assess cord location. However, it has been used as an adjunct to diagnose
cases where cord presentation is suspected.16 When cord presentation is identified as an incidental finding, follow-up scans have been recommended to determine the mode
of delivery. In one study, three of 13 patients initially identified as having cord presentation on ultrasound had persistent
sonographic evidence of cord presentation on follow-up scans and were delivered by C/S.17 The role of routine U/S for the evaluation of cord presentation is controversial.
Although the overall incidence and associated perinatal mortality has declined, umbilical cord prolapse remains a life-threatening
emergency for the fetus. Emergent C/S remains the standard mode of delivery. Knowledge of risk factors and proper preparation
may help prevent some cases of prolapse.
REFERENCES
1. Koonings PP, Paul RH, Campbell K. Umbilical cord prolapse. A contemporary look. J Reprod Med. 1990;35:690-692.
2. Panter KR, Hannah ME. Umbilical cord prolapse; so far so good? Lancet. 1996;347:74.
3. Bush M, Eddleman K. Umbilical cord prolapse. UpToDate. 2004;version 13.1.
4. Yla-Outinen A, Heinonen PK, Tuimala R. Predisposing and risk factors of umbilical cord prolapse. Acta Obstet Gynecol Scand. 1985;64:567-570.
5. Uygur D, Kis S, Tuncer R, et al. Risk factors and infant outcomes associated with umbilical cord prolapse: Int J Gynaecol Obstet. 2002;78:127-130.
6. Qureshi NS, Taylor DJ, Tomlinson AJ. Umbilical cord prolapse. Int J Gynaecol Obstet. 2004;86:29-30.
7. Murphy DJ, MacKenzie IZ. The mortality and morbidity associated with umbilical cord prolapse. Br J Obstet Gynaecol. 1995;102:826-830.
8. Kahana B, Sheiner E, Levy A, et al. Umbilical cord prolapse and perinatal outcomes. Int J Gynaecol Obstet. 2004;84;127-132.
9. Usta IM, Mercer BM, Sibai BM. Current obstetrical practice and umbilical cord prolapse. Am J Perinat. 1999;16:479-484.
10. Roberts WE, Martin RW, Roach HH, et al. Are obstetric interventions such as cervical ripening, induction of labor, amnioinfusion,
or amniotomy associated with umbilical cord prolapse? Am J Obstet Gynecol. 1997;176:1181-1183; discussion 1183-1185.
11. Barrett JM. Funic reduction for the management of umbilical cord prolapse. Am J Obstet Gynecol. 1991;165:654-657.
12. Katz Z, Shoham Z, Lancet M, et al. Management of labor with umbilical cord prolapse: a 5-year study. Obstet Gynecol. 1988;72:278-281.
13. Prabulos AM, Philipson EH. Umbilical cord prolapse. Is the time from diagnosis to delivery critical? J Reprod Med. 1998;43:129-132.
14. Qureshi NS, Taylor DJ, Tomlinson AJ. Umbilical cord prolapse. Int J Gynaecol Obstet. 2004;86:29-30.
15. Poetker DM, Rijhsinghani A. Fetal survival after umbilical cord prolapse for more than three days. A case report. J Reprod Med. 2001;46:776-778.
16. Lange IR, Manning FA, Morrison I, et al. Cord prolapse: is antenatal diagnosis possible? Am J Obstet Gynecol. 1985;151:1083-1085.
17. Ezra Y, Strasberg SR, Farine D. Does cord presentation on ultrasound predict cord prolapse? Gynecol Obstet Invest. 2003;56:6-9.
Article at a glance
- Umbilical cord prolapse results in large part because there's a poor fit between the fetal presenting part and the maternal
bony pelvis. Risk factors include fetal malpresentation, low birthweight, multiparity, multiple gestation, prematurity, polyhydramnios,
and funic presentation.
- Obstetrical interventions that involve manipulation or elevation of the presenting fetal part can predispose to cord prolapse.
These include artificial rupture of membranes, internal scalp electrode application, intrauterine pressure catheter placement,
forceps or vacuum application, manual rotation of the fetal head, amnioinfusion, and external cephalic version.
- Once prolapse is diagnosed, immediate cesarean section is recommended, particularly in the first stage or early second stage
of labor. While preparations are being made to proceed with emergency C/S, funic decompression, funic reduction, and bladder
filling may help alleviate cord compression.
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