Cord prolapse, amniotic fluid embolism and collapse

• Cord prolapse is an obstetric emergency in which the umbilical cord slips past the fetal presenting part after the waters break, so the presenting part compresses it and cuts off oxygen supply to the baby.
• The first actions are to call for help, relieve pressure on the cord by lifting the presenting part (knee-chest position, then manual elevation or bladder filling), and deliver the baby, usually by category 1 caesarean.
• Amniotic fluid embolism is a rare collapse during or just after birth, presenting with sudden hypoxia, hypotension and often seizures, followed by disseminated intravascular coagulation in survivors; diagnosis is clinical and management is supportive.
• Maternal collapse is an acute fall in consciousness, with or without cardiac arrest, at any time from early pregnancy to six weeks after birth; it is assessed with the ABCDE approach and the 4 Hs, 4 Ts, eclampsia and intracranial haemorrhage.
• In pregnancy, resuscitation is modified by relieving aortocaval compression (manual left uterine displacement), and if there is no return of spontaneous circulation by four minutes at over twenty weeks, peri-mortem caesarean should be performed, ideally within five minutes.

By the end of this page you should be able to:

1. Recognise cord prolapse, distinguish overt from occult prolapse, and state its incidence and risk factors.
2. Outline the steps of initial and definitive management of cord prolapse, including funic decompression and decision to birth.
3. Describe the presentation, diagnostic criteria and differential diagnosis of amniotic fluid embolism.
4. Apply the supportive management of amniotic fluid embolism, including oxygenation, haemodynamic support and correction of coagulopathy.
5. Approach maternal collapse systematically, naming the reversible causes in pregnancy and the pregnancy-specific modifications to resuscitation.
6. Explain when and how to perform a peri-mortem caesarean and the expected maternal and fetal considerations.

Cord prolapse has been defined as the descent of the umbilical cord through the cervix alongside (occult) or past the presenting part (overt) in the presence of ruptured membranes. Cord presentation is the presence of the umbilical cord between the fetal presenting part and the cervix, with or without membrane rupture. ^[1] In overt prolapse the cord is visible or palpable in the vagina as a pulsatile mass; in occult prolapse only fetal heart rate abnormalities may be seen, and the cord is neither visible nor palpable. ^[5] In practical terms the immediate management of the two is the same. ^[5]

The overall incidence of cord prolapse ranges from 0.1% to 0.6%, and in the case of breech presentation is slightly higher than 1%. Male fetuses appear predisposed. ^[1] One large series found a perinatal mortality rate of 91 per 1000. ^[1] Most adverse outcomes in hospital are linked to prematurity and congenital malformation, but birth asphyxia is also a cause, and cord prolapse occurring outside hospital carries a greatly increased risk of death. ^[1][5]

The asphyxia is thought to come from cord compression and umbilical arterial vasospasm, which prevents venous and arterial flow to and from the fetus. ^[1] Premature and low birth weight infants carry about twice the mortality of term infants, largely because of the underlying condition and the preterm delivery required rather than the prolapse itself. ^[5]

Risk factors fall into two groups: general and procedure related. A simplified set is given below. ^[5]

Fetal bradycardia or recurrent variable decelerations soon after membrane rupture should prompt immediate vaginal or speculum examination to exclude cord prolapse. Antenatal ultrasound for cord presentation is a poor predictor and is not recommended as a screen. ^[5]

In overt prolapse the cord is felt in the vagina as a pulsating structure or seen protruding. In occult prolapse only fetal heart rate abnormalities appear. ^[5] Once prolapse is suspected, funic decompression must begin immediately, before any test result.

The steps, in order, are: ^[5][4]

1. Call for help: pull the emergency buzzer, make a 2222 call and declare an obstetric and neonatal emergency.
2. Tell the woman what has happened and that the baby must be delivered now.
3. Put her in the knee-chest position; if mobility is limited, use left lateral with a pillow under the hip and a head-down tilt.
4. Replace the cord gently into the vagina if it is visible at the introitus, with minimal handling, to keep it warm. Do not handle it excessively and do not try to push it above the presenting part.
5. Insert a gloved hand or two fingers into the vagina and lift the presenting part off the cord; keep the hand in place.
6. If a catheter is already in place, fill the bladder with 500 mL of 0.9% sodium chloride through an intravenous giving set and clamp the catheter. This often removes the need for continuous manual elevation.
7. Turn off oxytocin if running; consider tocolysis with terbutaline 250 micrograms when contractions are causing compression.
8. Give high-flow oxygen and obtain intravenous access, full blood count and group and save.

The knee-chest position is the most effective elevation method, followed by bladder filling to 500 mL. Trendelenburg, left lateral with a pillow, or bladder filling with less than 300 mL have only modest effects. ^[5]

Definitive management is expedient delivery, usually by caesarean. ^[4][5] The decision pathway depends on cervical findings. ^[5]

A practitioner competent in neonatal resuscitation must attend every birth after cord prolapse. If the fetus is dead or the pregnancy is pre-viable, a vaginal or medical approach is chosen instead of emergency surgery. ^[4][5]

Women should be advised, when possible, to adopt the knee-chest face-down position while awaiting ambulance transfer. A community midwife supports if nearby but must not delay transfer. The cord is replaced into the vagina if possible; otherwise it is covered with a moist pad, without overhandling. Bladder filling may be used during transfer. Transfer is in the left lateral position with a pillow under the hip. ^[4][5]

Fetal mortality is now under 10%, a fall from older estimates of 32 to 47%, attributed to the availability of caesarean birth and advances in neonatal resuscitation. About two thirds of survivors of cord prolapse are not associated with long-term morbidity; surviving infants can, however, suffer neonatal encephalopathy or cerebral palsy from asphyxia. ^[1][5]

Amniotic fluid embolism is a rare, catastrophic obstetric emergency in which amniotic fluid and fetal debris enter the maternal circulation, provoking an abrupt immune and inflammatory response. It is better described as an anaphylactoid syndrome of pregnancy than a true mechanical embolism, because the harm is driven by vasoconstriction and mediator release rather than by simple obstruction. ^[6]

The UK incidence reported in the 2019 to 2021 MBRRACE report is 0.39 per 100,000 maternities. ^[4] An international literature range of 2 to 8 per 100,000 deliveries and 2.2 to 7.7 per 100,000 in the United States have been quoted in reviews. ^[6] Amniotic fluid embolism is most often the second leading cause of peripartum maternal death in the United States and a leading cause of peripartum cardiac arrest. ^[6]

Risk is increased with multiple pregnancy, polyhydramnios, placenta praevia, placental abruption, induction of labour, older maternal age and caesarean delivery. Placenta accreta spectrum carries the strongest association in some reports, with a roughly ten-fold increased risk. ^[4][6]

The condition usually presents intrapartum or within about 30 minutes of delivery. ^[4] The classic picture is sudden hypoxia, sudden hypotension and then profuse bleeding from disseminated intravascular coagulation. ^[6] Respiratory distress, agitation or a feeling of impending doom often precede collapse; seizures, dysrhythmia and cardiac arrest may follow. About 53% of cases present at or just before delivery, the remainder on average 19 minutes afterwards. ^[6]

The pain of entry of amniotic and fetal material triggers intense pulmonary vasoconstriction and bronchoconstriction, then right heart failure and septal bowing into the left ventricle, with a fall in cardiac output. Inflammatory mediators activate coagulation and fibrinolysis, producing a fibrinolytic form of disseminated intravascular coagulation in roughly 80% of patients. ^[6]

Amniotic fluid embolism is fundamentally a clinical diagnosis: no reliable definitive test exists. The characteristic pattern is abrupt hypotension or cardiopulmonary collapse, evidence of disseminated intravascular coagulation, absence of fever, and onset during labour or within 30 minutes of delivery. ^[6] Detection of fetal squamous cells in the maternal pulmonary circulation is no longer accepted as proof of the diagnosis. ^[6]

The differential diagnosis includes pulmonary embolism, peripartum cardiomyopathy, septic shock, anaphylaxis, eclampsia, myocardial infarction, local anaesthetic toxicity, air embolism, uterine rupture, abruption and major obstetric haemorrhage. Pulmonary embolism can look similar but lacks the profound coagulopathy; echocardiography supports distinction, showing right ventricular dilation and septal bowing in amniotic fluid embolism. ^[6]

Diagnostic criteria proposed by the Society for Maternal-Fetal Medicine and the Amniotic Fluid Embolism Foundation (2016) require: sudden cardiopulmonary collapse or hypotension with hypoxia; severe haemorrhage or disseminated intravascular coagulation by the International Society on Thrombosis and Haemostasis criteria modified for pregnancy; onset during labour or delivery of the placenta or within 30 minutes; and absence of fever or other explanation. ^[6]

There is no proven specific therapy; management is supportive. Early recognition, high quality resuscitation and anticipation of coagulopathy are the mainstays. ^[4][6]

The following are the priorities. ^[4][6]

• Call for help early and involve obstetrics, anaesthesia, critical care, haematology and maternal-fetal medicine.
• Give high-flow oxygen at 15 L per minute through a tight-fitting reservoir mask and proceed to intubation if there is collapse or respiratory distress. Avoid excessive ventilation.
• Begin immediate cardiopulmonary resuscitation if there is arrest, with standard basic and advanced life support protocols, including manual left uterine displacement above 20 weeks.
• Start delivery preparation at the same time, and deliver if there is no return of spontaneous circulation after about four minutes at a viable gestation; delivery should be achieved as soon as possible.
• Give vasopressors and inotropes as haemodynamic status requires; avoid excessive intravenous fluid.
• Send blood for full blood count, clotting, fibrinogen, cross-match (6 units), urea and electrolytes, arterial blood gas and lactate; blood cultures if sepsis is possible. Point-of-care viscoelastic testing is useful.
• Correct coagulopathy aggressively with fresh frozen plasma, cryoprecipitate and platelets, guided by results; massive transfusion protocols should be activated early.
• Managing major haemorrhage may require uterotonic drugs, intrauterine balloon tamponade and, if bleeding cannot be controlled, surgery.
• Echocardiography helps guide care.
• After resuscitation, care is multidisciplinary, usually on an intensive care unit.

Norepinephrine is commonly used as the vasopressor of choice in practice reviews, with dobutamine or milrinone for right ventricular support, although local protocols vary. Recombinant activated factor VII is reserved for cases in which bleeding cannot be controlled by massive component replacement. ^[4][6] Extracorporeal membrane oxygenation has been used successfully in isolated cases. ^[6]

Historical maternal mortality was reported as high as 61%, but more recent data suggest it is closer to 10%. About half of those affected die within the first hour and two thirds within 5 hours. The neonatal mortality rate is about 30%, and survivors may have hypoxic-ischaemic encephalopathy, cerebral palsy or cognitive impairment. ^[6]

Maternal collapse is an acute event involving the cardiorespiratory systems or central nervous system, resulting in a reduced or absent conscious level, with or without cardiac arrest and death, at any stage in pregnancy up to six weeks after birth. ^[4] Cardiac arrest itself is much rarer, at around 1 in 36,000 maternities, with a case fatality rate of about 42%. ^[4]

The 4 Hs and 4 Ts of generic resuscitation are used, with the addition of eclampsia and intracranial haemorrhage in pregnancy, and the pregnancy-specific causes of the thrombosis T. ^[2][4]

Early recognition is essential. ^[4] An obstetric modified early warning score, together with clinical judgement, should be used for all women undergoing observation, so that deterioration is detected before collapse. ^[2][4] All staff must be skilled in initial resuscitation and prompt involvement of senior obstetric, anaesthetic, haematology and intensive care staff improves outcomes. ^[4]

Resuscitation follows the Resuscitation Council UK 2021 and 2025 guidance, with standard advanced life support, modified for pregnancy. ^[2][3][4]

• Consider pregnancy in any collapsed woman of childbearing age.
• Relieve aortocaval compression: from 20 weeks gestation onwards, or when the uterus is palpable at or above the umbilicus, place the woman flat and apply manual left uterine displacement; this is preferred over a lateral tilt during cardiac arrest because chest compressions are more effective flat. ^[3][4]
• Use standard cardiopulmonary resuscitation ratios and hand position; apply early manual uterine displacement throughout.
• Apply defibrillation pads and defibrillate if indicated: shock is safe in pregnancy and standard energies are used.
• Intubation may be more difficult; airway pressures may be higher; use a smaller endotracheal tube if needed; capnography is essential and, if no expired carbon dioxide is seen, suspect oesophageal intubation.
• Access intravenous lines above the diaphragm; use intraosseous access if venous access fails. Give adrenaline 1 mg every 3 to 5 minutes in non-shockable rhythms, and consider amiodarone after the third shock.
• Give 100% oxygen throughout.
• Consider a 500 mL crystalloid bolus, tranexamic acid if haemorrhage is suspected, and magnesium for eclampsia; atropine may be used where vagal tone is likely.
• Systematically look for the 4 Hs, 4 Ts and the obstetric causes (the 4 Ps: pre-eclampsia and eclampsia, puerperal sepsis, placental and uterine complications, and peripartum cardiomyopathy). ^[3]
• Address causes even if chest compressions are briefly interrupted.

In parallel with resuscitation, obtain: blood glucose; arterial or venous blood gas with lactate; full blood count; urea and electrolytes; clotting studies and fibrinogen; group and save or cross-match 4 to 6 units depending on cause; blood cultures; and a 12-lead electrocardiogram and chest radiograph after stabilisation. ^[4]

Peri-mortem caesarean, also called resuscitative hysterotomy, should be seen as a resuscitative procedure performed primarily in the interests of maternal survival. ^[4][3]

The indication, timing and setting are these. ^[4][3]

• It is considered from 20 weeks of gestation (or when the uterus is at or above the umbilicus). At a pre-viable gestation the procedure may still improve maternal outcome; below 20 weeks uterine evacuation does not usually confer maternal benefit.
• If there is no response to correctly performed cardiopulmonary resuscitation within four minutes of collapse, or resuscitation is continued beyond that, peri-mortem caesarean should be undertaken to assist maternal resuscitation. It should ideally be achieved within five minutes of collapse. ^[4]
• It must be performed where the woman lies, at the site of the arrest, by a skilled team, without waiting to move to theatre; transfer is appropriate only if it can be completed within one to two minutes.
• A midline vertical or suprapubic transverse incision may be used, whichever gives the fastest access. Scalpel and cord clamps should be available on every resuscitation trolley in areas where collapse may occur.
• Remove all devices and document times; after return of spontaneous circulation or at delivery, manage bleeding, uterine atony and coagulopathy.

Delivery can relieve aortocaval compression and may improve the chance of return of spontaneous circulation, even if the fetus is not viable. ^[6]

After return of spontaneous circulation, care is multidisciplinary: correction of the cause, intensive care, uterotonic and haemostatic support, tranexamic acid and, if needed, massive transfusion, uterine tamponade or hysterectomy. Careful documentation, a critical incident report, and debriefing for the woman, her family and staff are recommended. ^[3][4] Deaths must be reported to the national confidential enquiry. ^[4]

Related topics include: postpartum haemorrhage and massive transfusion; hypertensive disorders of pregnancy and eclampsia; venous thromboembolism in pregnancy; peripartum cardiomyopathy; obstetric anaesthesia complications; newborn resuscitation; sepsis in pregnancy.

• Cord prolapse occurs in 0.1% to 0.6% of deliveries and up to 1% of breech deliveries; one large series found perinatal mortality of 91 per 1000.
• It is an obstetric emergency: call for help, relieve cord compression, deliver urgently; do not try to push the cord above the presenting part.
• Knee-chest position is the most effective way to relieve compression; bladder filling with 500 mL of saline is the next best and avoids continuous manual elevation.
• Category 1 caesarean is indicated with fetal compromise and cervical dilatation under 10 cm; consider tocolysis with terbutaline 250 micrograms.
• Amniotic fluid embolism occurs in about 0.39 per 100,000 maternities in the UK; it is a clinical diagnosis with no definitive test.
• Its triad is abrupt hypoxia, hypotension and coagulopathy, usually within 30 minutes of delivery.
• Management is supportive: oxygen, resuscitation, early delivery, haemodynamic support with vasopressors, and aggressive correction of coagulopathy.
• Maternal collapse is defined as reduced consciousness in pregnancy or up to six weeks postpartum, from a wide range of causes.
• Use the modified early warning score to identify deterioration early.
• In resuscitation, relieve aortocaval compression by manual left uterine displacement, not left tilt alone, and use standard shocks and drugs.
• If there is no return of spontaneous circulation by four minutes at over 20 weeks, perform peri-mortem caesarean on site, ideally achieving delivery by five minutes.
• Resuscitative hysterotomy is done for maternal benefit; poor fetal viability at very early gestations does not remove the indication.