Every pregnant woman loses blood when giving birth. The average blood loss in a normal vaginal birth is between 200 to 400ml, with a range from 50 to 450ml.
The average blood loss in a Caesarean section is about 500ml. The majority of women (about 95 per cent) have blood loss within these numbers.
The amount of blood loss is usually estimated by the accoucheur, and is not measured because of practical difficulties. This estimate may be inaccurate. More accurate methods used to measure the amount of blood loss include blood collection drapes for vaginal deliveries and the weighing of swabs.
Post-partum haemorrhage (PPH) is a term for an estimated blood loss of more than 500ml from the birth canal following the delivery of an infant.
The term primary PPH refers to such blood loss within 24 hours of delivery. PPH can be minor (500 to 1,000ml) or major (more than 1,000ml). The latter can be moderate (1,000 to 2,000ml) or severe (more than 2,000ml). The blood loss can occur all at the same time or accumulate over a period of time.
The term secondary PPH refers to abnormal or excessive bleeding from the birth canal 24 hours after delivery until 12 weeks after the birth of the baby.
PPH is one of the major causes of maternal deaths in developed and developing countries.
Malaysia has had a confidential system of enquiry into maternal deaths (CEMD) since 1991. This is modelled on the triennial reports of England and Wales.
The first CEMD in 1991 reported that PPH was the cause of 61 (27.2 per cent) of the total of 224 maternal deaths. The CEMD for the period 2001 to 2005 reported that PPH was the cause of 17 (13.6 per cent) of the total of 125 maternal deaths. By comparison, there were only five deaths in England and Wales for the period 2006 to 2008.
The most common cause of PPH is a loss of contraction in the uterus (atony). Uterine contractions compress the blood vessels within it after the delivery of the placenta and promote coagulation, thereby minimising blood loss in most women.
Uterine atony forms about half of the causes of primary PPH. The other major cause is retained products of conception, which comprise about a third of cases. Vulvar or vaginal lacerations comprise the bulk of the rest.
The risk factors for primary PPH are related to pregnancy and/or delivery, and/or pre-existing maternal bleeding disorders.
The risk factors related to pregnancy include antepartum haemorrhage (APH) in the current pregnancy. Many an obstetric book states that it is the APH that maims and the PPH that kills.
The risk for a low-lying placenta (placenta praevia) is 12x (12 times more) and the risk for premature separation of the placenta from the uterus (abruptio placenta) is 13x compared to women who do not have these conditions.
Other risk factors (the relative risk is in brackets) include first delivery (3x), hypertension (4x), maternal anaemia (2x), obesity (2x), multiple pregnancy (5x), and previous PPH (3x).
The factors related to delivery include labour that exceeds 12 hours (2x), maternal fever in labour (2x), birthweight more than 4kg (2x), episiotomy (5x), operative vaginal delivery (2x), retained placenta (5x), unplanned Caesarean section (4x), and planned Caesarean section (2x).
Pre-existing maternal bleeding disorders include haemophilia carriers and von Willebrand's disease.
However, most cases of PPH have no identifiable risk factors.
The clinical features of primary PPH include continuous bleeding, which does not stop after the placenta has been delivered, and the signs and symptoms of shock.
Prolonged and/or excessive bleeding leads to disseminated intravascular coagulation, a condition in which the blood-clotting mechanisms are abnormal.
The Royal College of Obstetricians and Gynaecologists of the United Kingdom has summarised the treatment of PPH succinctly, ie communication, resuscitation, monitoring and investigation, and arresting the bleeding, all of which are carried out simultaneously.
The treatment of PPH requires teamwork by the whole obstetric team. If the PPH is between 500 and 1,000ml with no features of shock, the midwife in charge and the first-line obstetric and anaesthetic staff will be involved.
If the PPH is more than 1,000ml and there is continuing bleeding or there are features of shock, another experienced midwife, the obstetrician, anaesthetist and pathologist (or haematologist) will be involved. A member of the obstetric team will record events, fluids, drugs and vital signs of the patient.
Resuscitation involves assessing the airway and breathing, evaluating the state of the circulation, blood transfusion as soon as possible, rapid infusion of warmed intravenous fluids until blood is available, oxygen by mask, keeping the patient warm, and transfusion of blood components as indicated by the results of coagulation studies.
Clinical judgment is crucial in addressing the various aspects of resuscitation.
The investigations in PPH involve cross-matching blood, a full blood count, coagulation studies, and renal, as well as liver function tests. Intravenous line(s) will be established. The patient's blood pressure, pulse and respiration will be monitored continuously.
A catheter will be inserted into the bladder to monitor urine output. The various monitoring parameters and fluids given will be documented. Where appropriate, the patient may be nursed in a high dependency or intensive care unit.
Although the most common cause of primary PPH is uterine atony, an examination has to be done to exclude other or additional causes, ie retained products of conception (placenta, membranes, clots), vaginal or cervical lacerations or haematoma, ruptured uterus, broad ligament haematoma, uterine inversion, bleeding from outside the reproductive organs, and coagulation disorders.
Efforts to stop the bleeding can then be directed at its cause.
When uterine atony is the cause, the initial methods used to arrest the bleeding are medicines and mechanical methods. The medicines include intravenous oxytocin and/or prostaglandins, ie carboprost injected into the muscles and/or the uterus, or misoprostol inserted into the rectum.
The uterus may be rubbed up (bimanual uterine compression) to stimulate uterine contractions.
If the bleeding cannot be controlled by medicines and mechanical methods, surgery is indicated. The surgical methods used include balloon tamponade, haemostatic brace suturing, bilateral ligation of the uterine arteries, bilateral ligation of the internal iliac arteries, selective arterial embolisation, and hysterectomy.
Early surgical intervention is critical as delay is often the cause of mortality. In this respect, hysterectomy should be resorted to sooner rather than later, especially when the cause of the PPH is uterine rupture or abnormal adherence of the placenta to the uterine wall (placenta accreta).
Other or additional causes, ie retained products of conception (placenta, membranes, and clots), vaginal or cervical lacerations or haematoma, ruptured uterus, broad ligament haematoma, uterine inversion, bleeding from outside the reproductive organs, and coagulation disorders, have to be dealt with accordingly.
For example, retained products have to be removed, and uterine rupture has to be treated surgically by suturing the tear or doing a hysterectomy.
This usually presents as prolonged or excessive bleeding after discharge from the hospital.
There are two common causes - infection and retained products of conception.
Infection of the uterine cavity (endometritis) is not uncommon, and its risk factors include prolonged rupture of the membranes, prolonged labour, Caesarean section, and manual removal of the placenta.
The clinical features include fever, rapid pulse, tender abdomen and a raised uterus. A pelvic examination excludes lacerations, and even permits removal of blood clots. The investigations carried out include an ultrasound examination, full blood count, vaginal swab for culture, urine culture and blood culture.
Antibiotics are prescribed for the endometritis. If the suspected cause is retained products of conception, it is removed surgically under antibiotic cover.
Although considered a minor procedure, this has to be done by an experienced doctor as there is a high risk of perforating the uterus.
Surgery is also resorted to if there is excessive or continuing bleeding, irrespective of the ultrasound findings.
Prevention of PPH
There are several measures that prevent PPH. They include the active management of the third stage of labour; routine prophylactic oxytocics that reduce the risk of PPH by up to 60 per cent; ultrasound determination of the placental site in women who have had a previous Caesarean section; and availability of trained and effective staff, which includes midwives, obstetrician, anaesthetist and pathologist (or haematologist).