Placental separation involves the sudden exposure of a vascular bed receiving up to 20% of the maternal cardiac output. Prevention of potentially massive haemorrhage requires contraction of uterine and arteriolar muscle, activation of circulating and endothelial clotting factors and platelet aggregation and deposition.
Postpartum haemorrhage (PPH) occurs in ~2% of deliveries and is defined as a blood loss of over 500 ml after delivery of the placenta. A PPH occurring within 24 hours of childbirth is termed primary PPH and is divided into minor (500-1000 ml) and major (> 1000 ml), the latter further subdivided into moderate (1001-2000 ml) and severe (> 2000 ml). (Note that lower cut-offs are appropriate in women < 60 kg.)
A secondary PPH occurs within the next 12 weeks and is usually due to retained products of conception and/or infection.
Postpartum haemorrhage can be one of the most frightening obstetric emergencies and may be associated with maternal mortality.
Problems and special considerations
There are a number of different causes of PPH (Table 79.1). These have been summarised into four descriptive groups as an aide-memoire: tone, trauma, tissue and thrombin (‘the four Ts’). Although initial management is the same (i.e. resuscitation), subsequent management depends on the cause, which may be difficult to ascertain in the face of continuing haemorrhage.
After a normal delivery, attention is often focused on the baby, and thus PPH may be unnoticed initially. This is compounded by the ability of normal pregnant women to compensate until hypovolaemia is severe (see Chapter 78, Major obstetric haemorrhage).
There may be few medical and midwifery staff in close attendance if PPH occurs without warning, especially following a spontaneous vaginal delivery in a delivery room. The severity of blood loss may be underestimated in such circumstances, and there may be a delay in resuscitation unless staff are well versed in the emergency management of such cases.
Management options
The first priority of the anaesthetist arriving at a PPH is resuscitation, followed by urgent assessment of the cause of bleeding. Initial management is as for major obstetric haemorrhage (MOH; see Chapter 78), including activation of an MOH protocol and early evaluation of coagulation using point-of-care devices if available.
Table 79.1 Causes of postpartum haemorrhage
|
Obstetric |
Uterine atony • Large placental site, e.g. multiple pregnancy • Long or precipitous labour • Prolonged oxytocic infusion • Grand multiparity • Chorioamnionitis • Drugs, e.g. volatile anaesthetic agents, tocolytic drugs • Inverted or ruptured uterus Retained intrauterine products (placenta or membranes) Trauma to the cervix, birth canal or perineum |
|
Non-obstetric |
Coagulopathy • Primary, e.g. von Willebrand’s disease • Secondary, e.g. disseminated intravascular coagulation, HELLP syndrome, post-massive transfusion coagulopathy, drugs |
The extent of haemorrhage is often underestimated. Any woman who has an unexplained tachycardia or a hypotensive episode in the postpartum period should be treated as having had a major blood loss until proven otherwise. If PPH does not occur immediately after delivery, the use of a modified early obstetric warning score (MEOWS) may help identify changing physiology and trigger an early response to haemorrhage (see Chapter 156, Modified early obstetric warning scores).
The most common cause of PPH is uterine atony. It is routine practice to administer oxytocics at the delivery of the anterior shoulder of the baby (see Chapter 64, Oxytocic and tocolytic drugs). This hastens placental separation and encourages uterine contraction in the third stage of labour. If the uterus fails to contract and bleeding continues, further oxytocic drugs may be given (Table 79.2), aided by manual rubbsng of the uterus to stimulate contraction. If the uterus continues to relax, the possibility of retained products of conception should be considered, which necessitates exploration of the uterus. A retained placenta may involve the whole or part of the placenta, and manual removal of the placenta is indicated.
Genital tract trauma should be sought, and this may require anaesthesia. Ideally, primary resuscitation of the patient, together with confirmation of preparation of blood for transfusion, should be established before anaesthesia is administered. It is often necessary to proceed to anaesthesia before the blood is available; general anaesthesia may be preferable in the haemodynamically unstable patient.
If there is continued uterine bleeding, the abdomen needs to be opened. Hysterectomy may sometimes be avoided by packing the uterus or using an intrauterine balloon, compression (B-Lynch) sutures, and ligation or embolisation of the uterine or internal iliac arteries or use of intravascular balloon catheters (depending on expertise and the proximity of the radiology department). Recent evidence suggests the incidence of peripartum hysterectomy in the UK is 4-5 per 10,000 births (ranging from 1 in 30,000 for a first vaginal delivery, to 1 in
Table 79.2 Prevention and drug treatment of uterine atony causing postpartum haemorrhage (PPH)
|
Routine prophylaxis |
Oxytocin 10 U intramuscularly at delivery of the anterior shoulder |
|
PPH occurs |
Oxytocin 5-10 U given slowly, intravenously, or an infusion containing 40 U oxytocin + 500 ml saline at a rate depending on the clinical response but usually over a 4-hour period |
|
PPH persists |
Ergometrine 250-500 μg intramuscularly, repeated after an hour |
|
PPH unresponsive to the above |
Carboprost (PGF2a) 250 µg given by deep intramuscular injection, repeated at intervals of > 15 minutes, up to a total dose of 2 mg (8 doses). Direct injection into the myometrium is not recommended |
|
Various a |
Misoprostol 200-1000 µg depending on the route. Oral, sublingual, vaginal, rectal, and intrauterine administration have been described |
a Use of misoprostol may vary according to local protocols, but it has been used to prevent as wellas treat PPH.
N.B. Consider retained placenta, genital tract trauma and other causes of haemorrhage.
See Chapter 78, Major obstetric haemorrhage, for general management of haemorrhage.
220 for a third caesarean section, to 1 in 32 for placenta praevia). Tranexamic acid (1 g) has been shown to reduce the incidence of death from PPH, especially if given early.
Key points
• Any postpartum haemorrhage must be seen as a potential major obstetric haemorrhage and should be treated early and aggressively.
• Senior help should be sought at an early stage.
• Full resuscitation should not be regarded as being complete until the cause of the bleeding has been identified and treated.
Further reading
Kayem G, Kurinczuk JJ, Alfirevic Z, et al. Specific second-line therapies for postpartum haemorrhage: a national cohort study. BJOG 2011; 118: 856-64.
Knight M; UKOSS. Peripartum hysterectomy in the UK: management and outcomes of the associated haemorrhage. BJOG 2007; 114: 1380-7.
Liabsuetrakul T, Choobun T, Peeyananjarassri K, et al. Treatment for primary postpartum haemorrhage. Cochrane Database Syst Rev 2007; (1): CD003249.
Mavrides E, Allard S, Chandraharan E, et al.; Royal College of Obstetricians and Gynaecologists.
Prevention and management of postpartum haemorrhage. Green-top Guideline 52. BJOG 2016; 124: e106-49.
Royal College of Obstetricians and Gynaecologists. The role of emergency and elective interventional radiology in postpartum haemorrhage. Good Practice 6. London: RCOG, 2007. www.rcog.org.uk/globalassets/documents/guidelines/goodpractice6roleemergency2007.pdf (accessed December 2018).
Weeks A. The prevention and treatment of postpartum haemorrhage: what do we know, and where do we go to next? BJOG 2015; 122: 202-10.