Abstract
This is the most common cause of maternal collapse in the immediate postnatal period, and in the most recent MBRRACE report, the number of maternal deaths as a result of this has risen from 13 to 21 in the last triennium [1]. Postpartum haemorrhage (PPH) occurs following approximately 1%–5% of deliveries. Primary PPH is defined as more than 500 mL of blood lost from the genital tract with 24 hours of delivery and is categorised as minor (500–1000 mL) and major (>1000 mL). A loss of more than 2000 mL of blood is often classed as massive postpartum haemorrhage and is often audited [2]. The causes of primary PPH can be remembered as ‘the 4 T’s’ – tone, trauma, tissue and thrombin. Secondary PPH occurs after 24 hours of delivery and is attributable mostly to retained products of conception (placental fragments) and endometritis.
Key Facts
Maternal collapse is an acute event involving the cardiorespiratory system and/or brain, resulting in a reduced or absent consciousness level (and potentially death), in the immediate period following delivery and up to 6 weeks after delivery.
Maternal collapse occurs in 0.14–6 of 1000 births, making it crucial that health care professionals are sufficiently trained in prompt resuscitation, investigations and management, to avoid potentially devastating consequences.
The causes of postpartum collapse can be conveniently grouped into immediate (within 24 hours of delivery) and late (24 hours to 6 weeks postnatal), as the underlying causes are potentially different.
75% of maternal deaths in 2013–2015 occurred in the postpartum period according to the UK Enquiries into Maternal Deaths and Morbidity report.
Cardiac causes remain the leading cause of maternal death, while thromboembolism is the leading direct cause of death.
There has been a 99% increase in deaths due to haemorrhage in 2013–2015, mostly secondary to an increase in abnormal placentation.
Causes of Immediate Postpartum Collapse
Haemorrhage
This is the most common cause of maternal collapse in the immediate postnatal period, and in the most recent MBRRACE report, the number of maternal deaths as a result of this has risen from 13 to 21 in the last triennium [1]. Postpartum haemorrhage (PPH) occurs following approximately 1%–5% of deliveries. Primary PPH is defined as more than 500 mL of blood lost from the genital tract with 24 hours of delivery and is categorised as minor (500–1000 mL) and major (>1000 mL). A loss of more than 2000 mL of blood is often classed as massive postpartum haemorrhage and is often audited [2]. The causes of primary PPH can be remembered as ‘the 4 T’s’ – tone, trauma, tissue and thrombin. Secondary PPH occurs after 24 hours of delivery and is attributable mostly to retained products of conception (placental fragments) and endometritis.
Tone
Atony, or a loss of tone due to a lack of uterine contractility, is the most common cause of PPH. It is important to assess the woman for antenatal and intrapartum risk factors (Table 19.1) in order to make adequate preparations for prompt management.
Table 19.1 Risk factors for uterine atony
| Antepartum |
| High BMI/obesity |
| Past history of PPH |
| Multiple pregnancy |
| Polyhydramnios |
| Macrosomia |
| Uterine fibroids |
| Induction of labour |
| Antepartum haemorrhage |
| Intrapartum |
| Induction or augmentation of labour |
| Failure to progress in labour |
| Prolonged labour |
| Operative/instrumental delivery |
| Chorio-amnionitis |
| Use of general anaesthetic |
| Postpartum |
| Inappropriate third stage management |
| Retained placenta/manual removal |
Trauma
Vaginal, perineal and cervical trauma are commonly seen following vaginal deliveries and are particularly associated with instrumental deliveries. Haematomas, from a ruptured vessel during the course of delivery, or from unsecured haemostasis following perineal suturing, can form postpartum. This can be an immediate or late complication post-delivery.
Uterine rupture typically presents intrapartum but can occasionally also present in the immediate postpartum period. Collapse in a patient with a scarred uterus following delivery, with or without associated bleeding and/or abdominal pain, should raise suspicion. Therefore, it is important to remember that visual estimation of blood loss does not always correlate with the actual volume lost and is often underestimated. Therefore, it is vital to assess the patient clinically. Due to the physiological changes of pregnancy, heart rate and blood pressure may not begin to show alterations unless the blood loss has exceeded 1000 mL [2].
Tissue
Retained placental tissue can prevent uterine contractility and cause continued bleeding. In a primary PPH, it is essential to check that both the placenta and its membranes are complete.
The increase in caesarean section rates has led to an increase in the prevalence of abnormally invasive placenta (placenta accreta spectrum). This can cause massive bleeding during planned caesarean sections, or if a woman laboured with an undiagnosed placenta accreta. Preparations to minimise bleeding should be made prior to such planned caesarean sections, such as availability of a skilled surgeon and anaesthesiologist, interventional radiology input, availability of blood products, and consent for hysterectomy [3]. In women with previous caesarean section and a low-lying anterior placenta, an assessment with ultrasound (and MRI if necessary) should be arranged at 32–36 weeks to exclude placenta accreta spectrum [3].
Thrombin
Patients with inherited bleeding disorders or those who are on anticoagulants will be at an increased risk of PPH. Antenatal plans should be made with regards to the timing of their anticoagulation around the time of delivery, and availability made for blood products in those with bleeding disorders, with input from the haematologist if required.
Preeclampsia may cause a reduced platelet count and coagulopathy that can predispose the mother to PPH. Disseminated intravascular coagulation (DIC) can also occur in women who have suffered a placental abruption, or those with severe sepsis or a massive haemorrhage. It is therefore important to gain an accurate and up-to-date clotting profile at the time of diagnosing these conditions in order to promptly identify DIC and liaise with the blood bank to prepare for necessary blood products.
Other Causes
Intra-abdominal bleeds can occur, more often following a caesarean section, but can also rarely take form in liver or splenic rupture, particularly associated with severe preeclampsia. Broad ligament haematomas have been reported following instrumental vaginal deliveries. The bleeding is concealed and the symptoms can be non-specific, making diagnosis difficult. Clinical signs of shock, along with abdominal pain, uterine deviation, and a fall in haemoglobin, should raise the suspicion of an intra-abdominal bleed. Imaging such as CT or ultrasound can aid diagnosis but should not delay treatment if the patient’s condition is critical.
Eclampsia
Most cases of eclamptic seizures postpartum occur within the first 24 hours but can occur up to 6 weeks postpartum. The diagnosis of a collapse due to eclampsia is usually obvious, particularly on the background of preeclampsia; however, the onset of this can occur suddenly and unexpectedly. Care should be taken to risk-assess each patient for disease severity and their need for anticonvulsants, which should be commenced without delay (if indicated) to prevent disease progression. Epilepsy should also be considered in patients who experience fits postnatally, especially in the absence of hypertension and proteinuria [4].
Amniotic Fluid Embolism
Amniotic fluid embolism is a rare but catastrophic emergency and occurs in 2 of 100,000 maternities. Survival have increased to as high as 80% [4]; however, it is still a significant cause of maternal death, responsible for 8 deaths in the past triennium according to the UK Enquiries into Maternal Deaths and Morbidity report [1]. Postpartum collapse is typically seen within 30 minutes of delivery, but can occur as late as 48 hours after [4, 5]. Clinical signs include hypotension, hypoxia and respiratory distress, and in severe instances, seizures and cardiac arrest. Pulmonary hypertension develops as a result of pulmonary vasospasm, which can result in left ventricular failure, and is also often associated with DIC, predisposing these women to a PPH. Unfortunately, no identifying cause has been found, which deems it unpreventable [5], but early recognition and diagnosis can ensure prompt treatment and a better prognosis.
Uterine Inversion
The incidence of uterine inversion have been described to be 1 of 3737 deliveries [6], and can be seen during or immediately following the third stage of labour. The most common cause is premature cord traction or fundal pressure, but can also be associated with morbidly adherent placentas, uterine atony and connective tissue disorders [6]. This can be characterised by pain associated with or immediately following the delivery of the placenta, neurogenic shock due to stretching of the pelvic nerves and ligaments and PPH will often take place immediately following the event in 94% of cases [6]. Shock out of proportion to blood lost, inability to feel the uterine fundus trans-abdominally and a bulge into the vagina during examination should trigger recognition of a uterine inversion.
Non-obstetric Causes
Drug Toxicity
Drug overdose and toxicity, as well as recreational drug use, should always be considered in cases of maternal collapse. Drugs commonly used in labour that can lead to collapse are magnesium sulphate, lidocaine (if accidentally injected IV), and high regional block, all of which can cause maternal collapse. Symptoms can range from altered consciousness to convulsions and cardiac arrest [4]. Magnesium toxicity is more likely to occur in cases of renal impairment. High regional blocks can lead to sudden respiratory collapse and loss of consciousness and are easily recognisable following a spinal or epidural top-up.
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