Analgesia, Anaesthesia and Pregnancy. 4th Ed. Róisín Monteiro

Chapter 78. Major obstetric haemorrhage

Successive reports of the Confidential Enquiries into Maternal Deaths have highlighted major obstetric haemorrhage (MOH) as a significant direct cause of maternal mortality, accounting for about 10% of direct maternal deaths in recent years. In many cases, care is suboptimal; women at particular risk of haemorrhage are not identified beforehand, or else management is inadequate when bleeding does occur. A similar situation exists in other countries, especially developing ones, where haemorrhage is one of the leading causes of death, often related to a lack of resources.

Obstetric haemorrhage may be antepartum or postpartum. The most common causes of antepartum bleeding are placenta praevia and placental abruption. Postpartum haemorrhage is most commonly associated with uterine atony, trauma to the genital tract, ruptured uterus and caesarean section (see Chapter 79, Postpartum haemorrhage). There is no consensus on a definition of MOH; suggested criteria include:

• Blood loss > 1000 ml with ongoing loss or signs of clinical shock

• Blood loss > 1500 ml

• Loss of 50% of blood volume in 3 hours

• Transfusion > 4 units of packed red cells

• Decrease in haemoglobin of > 40 g/l

Problems and special considerations

The extent of bleeding may be underestimated because it is concealed, for example in the vagina or on bedclothes, between the legs (at caesarean section) or within the abdomen, or because it is mistaken for bloodstained amniotic fluid.

Pregnant women are generally healthy and tolerate blood loss well. The patient may therefore remain cardiovascularly stable even when there has been a significant decrease in her circulating blood volume. Consequently, the presence of hypotension, tachycardia and vasoconstriction in an obstetric patient represents severe hypovolaemia. A widely used classification of haemorrhagic shock is that of the American College of Surgeons (originally devised for trauma), which is shown in Table 78.1. It is important to consider the percentage of circulating volume lost rather than absolute loss, as the weight of pregnant women and their circulating volume (approximately 100 ml/kg) may vary substantially.

Apparently moderate bleeding in obstetric patients may rapidly progress to MOH.

Coagulopathy may be an underlying cause of haemorrhage, but severe haemorrhage may also result in impaired coagulation. Previously, coagulopathy as a result of haemorrhage was thought to be largely dilutional, and although this may occur, it is thought that coagulopathy develops also as a result of a rapid consumption of clotting factors, in particular fibrinogen, as occurs in trauma. In certain conditions (e.g. placental abruption), disseminated intravascular coagulation may also occur.

Table 78.1 Classification of haemorrhagic shock

Management options

The anaesthetist’s first priority is resuscitation of the patient, but the management of MOH must involve the whole delivery suite as a team, with strong leadership and communication a priority. An MOH protocol should be activated, thus allowing the emergency to be acknowledged, and informing all members of the team including laboratory staff and porters.

The diagnosis and treatment of the cause of bleeding should be carried out during the primary resuscitation. If intravenous access is problematic owing to peripheral vascular shutdown, intraosseous access may be used. The blood lost must be replaced urgently, and time should not be wasted placing monitoring lines. It is increasingly considered that blood products should be given early (and without blood filters, to avoid delay), as in trauma, and although baseline blood tests may be sent to the laboratory, resuscitation should not be delayed and/or based on the results of samples that have been sent 30-60 minutes previously. Equally, point-of-care tests of haemoglobin concentration (e.g. HemoCue) may give false reassurance, and anaesthetists should be guided by the acute clinical situation. Blood gas and lactate measurement may help monitor tissue perfusion and adequacy of resuscitation.

Many protocols for MOH have changed to follow those used in the armed forces, where red cells and clotting factors are given in a ratio of 1:1 or 2:1, which should be considered once product replacement reaches 50% of the estimated circulating volume. Plasma and platelets may be provided as part of an MOH ‘shock pack’, facilitating rapid replacement. Since there is evidence that fibrinogen levels fall rapidly early on in obstetric haemorrhage, it has been suggested that cryoprecipitate or fibrinogen concentrate be given early, bearing in mind that normal fibrinogen levels in the third trimester are raised (usually > 4 g/l); a level above 2 g/l should be maintained. All fluids given should be warmed, as hypothermia will exacerbate the situation.

Increasingly, thromboelastography- or thromboelastometry-guided protocols have been established, with specific blood products indicated according to the profiles obtained. Advantages that have been claimed include more targeted use of products, thus reducing costs and unnecessary transfusion with attendant risks, as well as earlier treatment, since initial results may be obtained from the point-of-care device within a few minutes.

If a surgical procedure is required (e.g. examination under anaesthesia, removal of retained placenta, caesarean section, hysterectomy, etc.), the presence of severe hypovolaemia combined with a possible coagulopathy usually precludes regional anaesthesia; general anaesthesia with careful administration of induction agents is usually preferable. Extubation should be delayed until resuscitation is adequate and bleeding has stopped. If an epidural catheter is already in situ, removal should be delayed until coagulation has been checked and any deficits corrected.

When major haemorrhage continues, aortic compression, uterine or internal iliac artery occlusion/ligation or hysterectomy (which may be life-saving) should be considered. Embolisation of the uterine arteries under radiological control has been used, but this requires special expertise.

Intraoperative cell salvage is well described now in obstetrics, and the risk of infusing amniotic fluid into the mother’s circulation is no longer considered a major concern. However, the benefit of using the intraoperative cell saver has been questioned in the emergency situation for obstetric haemorrhage; surveys in the UK have shown that the return of salvaged blood is often minimal and that its use is limited by the lack of availability of equipment and staff trained in its use. In addition, by the time it is set up much of the potentially salvageable blood may already have been lost.

Although the use of recombinant activated factor VII (rFVIIa; usual dose 75-100 mg/ kg) in intractable haemorrhage has been reported, it is no longer advocated routinely as there have been case reports of thromboembolic events and also of non-responders. If rFVIIa is given, any existing coagulopathy should be corrected first. Tranexamic acid (usual dose 1 g) has been shown to reduce deaths from postpartum haemorrhage and has the advantages of being relatively cheap and non-prothrombotic, and is now widely used early in MOH.

Major obstetric haemorrhage guidelines must be available on all delivery suites and should be rehearsed regularly by all the delivery suite staff. Guidelines are published and recommended in the Confidential Enquiries reports, although they may be adapted for local use. The guidelines should be brief, easily understood, with standard abbreviations and restricted to one A4 sheet so that they can be readily referred to in an emergency (Table 78.2).

It is good practice for a delivery suite to have all the equipment that may be needed for massive haemorrhage collected together for easy access, preferably on a mobile trolley that can be quickly wheeled to the patient’s bedside. This trolley should be checked and stocked on a daily basis. Multidisciplinary clinical review of all cases of haemorrhage greater than 1500 ml and an opportunity to debrief offered to the woman and her partner are recommended by the Royal College of Obstetricians and Gynaecologists.

Table 78.2 Example of a major obstetric haemorrhage (MOH) guideline

Key points

• Obstetric haemorrhage continues to be a major contributor to maternal mortality.

• Major haemorrhage guidelines should be in place in all delivery suites and should be regularly rehearsed.

Further reading

Allam J, Cox M, Yentis SM. Cell salvage in obstetrics. Int J Obstet Anesth 2008; 17: 37-45.

Bell SF, Rayment R, Collins PW, Collis RE. The use of fibrinogen concentrate to correct hypofibrinogenaemia rapidly during obstetric haemorrhage. Int J Obstet Anesth 2010; 19: 218-23.

Cotton BA, Au BK, Nunez TC, et al. Predefined massive transfusion protocols are associated with a reduction in organ failure and postinjury complications. J Trauma 2009; 66: 41-8.

Mallaiah S, Barclay P, Harrod I, Chevannes C, Bhalla A. Introduction of an algorithm for ROTEM-guided fibrinogen concentrate administration in major obstetric haemorrhage. Anaesthesia 2015; 70: 166-75.

Mercier FJ, Bonnet MP. Use of clotting factors and other prohemostatic drugs for obstetric hemorrhage. Curr Opin Anaesthesiol 2010; 23: 310-16.

Plaat F, Shonfeld A. Major obstetric haemorrhage. Contin Educ Anaesth Crit Care Pain 2015; 15: 190-3.

WOMAN Trial Collaborators. Effect of early tranexamic acid administration on mortality, hysterectomy, and other morbidities in women with post-partum haemorrhage (WOMAN): an international, randomised, double-blind, placebo-controlled trial. Lancet 2017; 389: 2105-16.