Incidence Varies from 0.1% to 0.6% (1–6 per 1000) . Cord presentation occurs if the cord is below the presenting part but membranes are intact (Figure 10.3).
Definition Descent of the umbilical cord through the cervix, in the presence of ruptured membranes .
Figure 10.1 Overt cord prolapse.
Figure 10.2 Occult cord prolapse. Arrow on right points to loop of umbilical cord protruding lying alongside the fetal head that may be easily missed on vaginal examination and hence, it is called ‘occult’ cord prolapse. Arrow on left (centre) shows fetal head (presenting part) lying alongside the umbilical cord.
Figure 10.3 Cord presentation.
Perinatal hypoxia, resulting from prolonged compression and mechanical occlusion of the prolapsed cord (e.g. by the fetal head which is presenting) or by vasospasm due to the relatively cooler temperatures in the vagina and especially outside the vulval introitus, is the leading cause of perinatal death [3, 4].
Babies who survive may have cerebral palsy resulting from hypoxic ischaemic encephalopathy .
Cord prolapse occurring at home is associated with a higher risk of perinatal deaths .
Presenting part of the fetus not fitting into the maternal pelvic inlet (e.g. small preterm baby or twin; especially the second twin, transverse lie, malpresentation such as footling or flexed breech, and polyhydramnios).
Obstetric interventions such as amniotomy, stabilising induction, insertion of a supracervical balloon catheter for induction of labour, placement of internal monitoring devices, external cephalic version (ECV) and internal podalic version .
Key Diagnostic Signs
Routine abdominal real-time colour Doppler ultrasound scan examination has not been shown to be effective in antenatal diagnosis of cord presentation and predicting the possibility of cord prolapse .
Selective transvaginal scanning in women with high-risk factors such as a transverse lie, malpresentation (e.g. footling or flexed breech) or high presenting part of fetus, may be useful .
Women with persistent breech presentation or transverse, oblique or unstable lie should be offered admission to hospital at 38 weeks’ gestation. If this advice is declined, women should be advised immediate admission with any signs of labour or prelabour (prolonged) rupture of membranes (PROM) [2, 3].
During labour the presence of the cord should be looked for, at each vaginal examination.
Amniotomy is contraindicated if the cord is palpable below or by the side of the presenting part during vaginal examination. Upward pressure and dislodging the head from the pelvis should be avoided during amniotomy, and amniotomy should be avoided if the presenting part of the fetus is high and mobile [2, 3].
Women with unstable lies should be offered ripening of the cervix and stabilising induction of labour after 39 weeks’ gestation unless the cervix is favourable for induction by amniotomy and oxytocin infusion at that gestation. This involves external cephalic version (ECV) followed by an intravenous oxytocin infusion to stimulate uterine contractions that would stabilise the fetal head against the pelvic inlet, and then a careful controlled amniotomy after excluding a palpable cord. The same procedure could be adopted in cases of mild to moderate hydramnios. An assistant should steady the fetal head against the pelvic inlet during and after amniotomy. The amniotomy should be by minimal puncture and the fingers should be kept inside the vagina to carefully control the volume of liquor draining out. This will prevent the liquor gushing out and the fetal head floating away from the inlet, predisposing to cord prolapse.
Women with PROM should be offered a speculum examination irrespective of the period of gestation. A digital vaginal examination is best avoided if there is no cardiotocograph (CTG) abnormality or risk factors for cord prolapse .
A digital vaginal examination is indicated in the presence of PROM or preterm PROM (PPROM) with CTG abnormalities such as variable decelerations, prolonged decelerations and bradycardia and a suspicion of cord prolapse .
The cord may be visible outside the vulva or at the introitus or may be seen on speculum examination or felt on vaginal examination.
Additional help (obstetric colleagues, nurses and midwives) should be called for immediately, and the anaesthesiologist and neonatologist (and the feto-maternal specialist if the gestational period is 24–28 weeks) informed.
The aim is to prevent or minimise fetal hypoxia, resulting from mechanical compression or vasospasm of the prolapsed cord, until the delivery is achieved.
Establish whether the fetus is alive by palpating for cord pulsations or using the fetal (Pinard’s) stethoscope or hand-held Doppler fetal heart detector or CTG and ultrasound scan (USS), depending on the facilities available. If USS facilities are available, visualisation of the fetal heartbeat is a possibility even if the fetal heart sounds cannot be detected . If the fetus is dead, delivery is not urgent and the safest mode of delivery for the mother should be adopted. If the fetus is alive the measures described in the text that follows should be adopted.
Figure 10.4 Head low position.
Figure 10.5 Knee–chest position.
The fetal presenting part should be manually displaced away from the pelvic inlet to prevent the cord being compressed between the pelvic wall and the presenting part of the fetus. This could be achieved digitally through the vagina (especially if the cord prolapse occurs during vaginal examination or amniotomy) and maintained abdominally by an assistant thereafter (Figures 10.6 and 10.7).
Figure 10.6 Displacement of the presenting part away from the pelvic inlet.
Figure 10.7 Maintaining displacement of the presenting part away from the pelvic inlet.
The cord should be gently cradled in the hand and replaced within the vagina (Figure 10.8), and a gauze towel, vaginal pack or tampon soaked in warm saline should be inserted into the vagina below the cord, if it tends to come out of the introitus.
Figure 10.8 Replacement of cord within the vagina.
Using a Foley catheter and an IV infusion set the bladder should be filled with 500–750 mL of normal saline, until it is visibly distended above the pubic symphysis, and then the catheter should be clamped (Figure 10.9). The full bladder will relieve the pressure on the cord by moving the presenting part away and may also inhibit uterine contractions.