Thrombosis and embolism

The MBRRACE‐UK 2014 report [7] shows that pulmonary embolism is still the major cause of death in the puerperium. The rate of death has remained unchanged for many years and approximately 50% of deaths occur post partum (Table 31.2). The authors suggest that it is unsurprising that there has been little impact on these figures because of the direct association with obesity. Some 49% of women who died of pulmonary embolism were either overweight or obese and this has become a major international issue. Data from the USA suggest that their maternal mortality rate is rising and one accepted factor is obesity. Over 60% of women falling pregnant in the USA are seriously overweight. Other factors are also contributing to the increased risk, including increased maternal age, changing ethnicity, and increasing medical complications of pregnancy.

All pregnant women should be assessed for venous thromboembolism (VTE) during pregnancy and this should be repeated either during or after birth to determine their suitability for thromboprophylaxis. If thromboprophylaxis is deemed appropriate, moderate‐risk women should receive this for 10 days and high‐risk women for 42 days.

Puerperal infection

Puerperal pyrexia, which is potentially fatal, may have several causes but is an important clinical sign that merits careful investigation. Infection may occur in several sites and each needs to be investigated in the presence of elevated temperature.

Urinary complications

Other than infection, urinary retention is the commonest complication following delivery, especially if there has been any trauma to the urethra and resulting oedema round the bladder neck. A painful episiotomy may make it very difficult for women to spontaneously micturate and retention of urine may occur. Following epidural anaesthesia, there may be temporary interruption of the normal sensory stimuli for bladder function and over‐distension of the bladder may occur. It is extremely important that in the immediate postnatal period urinary retention is avoided as over‐distension may lead to an atonic bladder, which is then unable to empty spontaneously. If the bladder is distended, it is usually palpable abdominally but if this is not the case or the clinician is uncertain of the abdominal findings, an ultrasound scan should be performed to determine the volume of urine retained in the bladder. The treatment of urinary retention is to leave an indwelling catheter on continuous drainage for 48 hours. The patient can be ambulant during this time. After the bladder has been continuously emptied, the catheter can be removed and then the volumes of urine passed can be monitored. If there is any suspicion that further retention is occurring, then a suprapubic catheter should be inserted so that the bladder can undergo a further period of continuous drainage and then intermittent clamping of the catheter can be instituted until normal bladder function returns.

Incontinence of faeces

It is now recognized that 35% of women undergoing their first vaginal delivery develop anal sphincter injury [11,12]. Approximately 10% will still have anal symptoms of urgency or incontinence at 3 months after birth. Again, in the 12‐year follow‐up study by Glazener et al. [10], there was no improvement in this anal incontinence rate over time and at 6 years the faecal incontinence rate actually increased to 13%. The aetiology of this type of anal sphincter trauma is complex in the same way that mechanisms which maintain continence are complex, but include instrumental delivery, prolonged second stage of labour, birthwieght over 4.0 kg, occipito‐posterior position and episiotomy. Instrumental delivery is a recognized cause of trauma and randomized trials suggest that the use of vacuum extraction is associated with less perineal trauma than forceps delivery [13,14]. The incidence figures confirm this: forceps delivery is associated with a 32% incidence of anal incontinence compared with a 16% incidence for vacuum extraction. The incidence of third‐ and fourth‐degree tears varies enormously from centre to centre, suggesting that the clinical ability to recognize this type of trauma may vary. In those women who have a recognized anal sphincter rupture, 37% continue to have anal incontinence despite primary sphincter repair [15]. A recent Cochrane review of the role of caesarean section in avoiding anal incontinence concluded that there is insufficient evidence to recommend this [16].

Secondary postpartum haemorrhage

Delayed postpartum bleeding occurs in 1–2% of patients. It occurs most frequently between 8 and 14 days after birth and in the majority of these cases it is due to sloughing of the placental site. However, if this bleeding is not self‐limiting, further investigation will be required. Ultrasound examination of the uterine cavity will usually determine whether there is a significant amount of retained products, although it can be difficult to distinguish between blood clot and retained placental tissue. Suction evacuation of the uterus is the treatment of choice and, if this is required, it is imperative that antibiotic cover is given. If curettage is not required immediately to arrest bleeding, it is best to start antibiotics at least 12 hours beforehand. This will reduce the risk of endometritis leading to uterine synechae. A combination of metronidazole and co‐amoxiclav can be used in those patients who have endometritis without retained products of conception. In those who do have retained products who require curettage, intravenous antibiotics in the form of metronidazole and a cephalosporin, clindamycin or gentamicin are the antibiotics of choice. Great care must be taken at the time of curettage as the infected uterus is soft and easy to perforate. Rarely, these measures do not result in cessation of bleeding, and in life‐threatening circumstances embolization of the uterine arteries may be effective in controlling the bleeding, as may the use of uterine tamponade using a Foley catheter balloon. If these techniques fail, then hysterectomy as a life‐saving procedure may be needed.

It is important to remember that choriocarcinoma may present in this manner and, if suspected, can be diagnosed by elevated levels of human chorionic gonadotrophin. Rarely, a patient with a coagulopathy may present with a secondary haemorrhage.

Puerperal psychological disorders

Mild pyschological disturbance and transient depression are extremely common in the few days after birth. This transient state of tearfulness, anxiety, irritation and restlessness has been variously described as the ‘blues’ and it may occur in up to 70% of women. It usually resolves by day 10 after delivery and is probably associated with disruptive sleep patterns and the adaptation and anxiety of having a newborn baby. The changes in steroid hormone levels that occur immediately following delivery are not correlated with this transient depressive state, and because it is transient no therapy is needed. Postpartum depression and psychosis are dealt with in Chapter 14.

Drugs during lactation

Drugs taken by a breastfeeding mother may pass to the child, and it is important to consider whether particular drugs will have any effect on the fetus. This is often a difficult problem and the reader is referred to Schaefer et al. [17] for more information.

Advantages of breastfeeding

Protection against infection

One of the most important secondary functions of breastfeeding is to protect the infant against infection. This is particularly important in developing countries, where it has been estimated that in each year there are 500 million cases of diarrhoea in infants and children and about 20 million of these are fatal. However, the extent to which breastfeeding protects against infection in infants in developed countries has been a matter of dispute. In a study from Dundee, Scotland, it was found that babies who had been breastfed for at least 3 months had greatly reduced incidences of vomiting and diarrhoea compared with babies who were either bottle‐fed from birth or completely weaned within a short time of delivery [19]. This study also found that the protection against gastrointestinal illness in breastfed babies persisted beyond the period of breastfeeding itself and, in the developed country setting at least, was not undermined by the early introduction of at least some supplements. There was a smaller protection against respiratory tract infections but not against other illnesses.

A number of mechanisms contribute to the anti‐infective properties of breast milk. Breast milk contains lactoferrin which binds iron, and because E. coli requires iron for growth, the multiplication of this organism is inhibited. Breastfeeding also encourages colonization of the gut by non‐pathogenic flora that competitively inhibit pathogenic strains. In addition, bactericidal enzymes such as lysozyme are present in breast milk that contribute to its protective effect.

However, the most specific anti‐infective mechanism is an immunological one. If a mother ingests a pathogen that she has previously encountered, the gut‐associated lymphoid tissue situated in the Peyer’s patches of the small intestine will respond by producing specific IgA, which is transferred to the breast milk via the thoracic duct (Fig. 31.1). This immunoglobulin, which is present in large amounts in breast milk, is not absorbed from the infant’s gastrointestinal tract but remains in the gut to attach to the specific offending pathogen against which it is directed. In this way the breastfed infant is given protection from the endemic infections in the environment against which the mother will already have immunity [20]. Breast milk also contains living cells, such as polymorphs, lymphocytes and plasma cells, and although their functions are not yet fully understood they may also be active against invading pathogens.

Trends in infant feeding in the UK

Because of the many advantages of breastfeeding, it is important that mothers are given accurate information and encouraged to breastfeed successfully whenever possible. Conversely, mothers who choose to bottle‐feed should be given proper instructions on best practice and be supported in their decision. In the UK, about 74% of mothers overall start to breastfeed but many discontinue after a short time. The prevalence of breastfeeding in the UK up to 2013 is shown in Table 31.6 and the figures have shown no significant change over the previous 10 years, although a small increase in breastfeeding at birth is noted. Factors associated with a higher breastfeeding prevalence include higher social class, primiparity, older age of mother and place of residence (mothers in the south of the UK have a higher prevalence). In attempting to improve these disappointingly low rates of successful breastfeeding, it is important that health professionals should understand the physiology of lactation.

Milk production

Two similar but independent mechanisms are involved in the establishment of successful lactation (lactogenesis): the first causes release of prolactin, which acts on the glandular cells of the breast to stimulate milk secretion (Fig. 31.3), and the second induces release of oxytocin, which acts on the myoepithelial cells of the breast to induce the milk ejection reflex (Fig. 31.4). Although these two mechanisms are similar, in that they can both be activated by suckling, they are mediated through two entirely different neuroendocrinological pathways. As can be seen in Figs 31.3 and 31.4, the key event in lactogenesis is suckling and the sensitivity of the breast accommodates itself to this important activity. During pregnancy the skin of the areola is relatively insensitive to tactile stimuli but becomes much more sensitive immediately after delivery. This is an ingenious physiological adaptation which ensures that there is an adequate stream of afferent neurological stimuli from the nipple to the hypothalamus to initiate and maintain the release of prolactin and oxytocin, both of which are required for successful lactation.

Milk ejection reflex

Successful breastfeeding depends as much on effective milk transfer from the breast to the baby as on adequate milk secretion. The milk ejection reflex is mediated by the release of oxytocin from the posterior pituitary gland (see Fig. 31.4). Oxytocin causes contraction of the sensitive myoepithelial cells that are situated around the milk‐secreting glands and also dilates the ducts by acting on the muscle cells that lie longitudinally in the duct walls. Contraction of these cells therefore has the dual effect of expelling milk from the glands and of encouraging free flow of milk along dilated ducts. This is recognized by the mother as milk ‘let‐down’ and she may be aware of milk being ejected from the opposite breast from which the baby is suckling. In contrast to prolactin, which is secreted only in response to suckling, oxytocin can be released in response to sensory inputs such as the mother seeing the baby or hearing its cry. Oxytocin has a very short half‐life in the circulation and is released from the posterior pituitary in a pulsatile manner. The highest levels of oxytocin may be released prior to suckling in response to the baby’s cry, while prolactin is released only after suckling commences. The milk ejection reflex is readily inhibited by emotional stress and this may explain why maternal anxiety frequently leads to failure of lactation. Successful breastfeeding depends on engendering confidence in the mother and ensuring correct fixing and suckling on the nipple.

Another factor is of potential physiological importance as an inhibitor of breast milk: if the milk is not effectively stripped from the breast at each feed, this will inhibit lactopoiesis and lead to a fall in milk production.

Volumes of breast milk

During the first 24 hours of the puerperium the human breast usually secretes small volumes of milk, but with regular suckling milk volumes steadily increase and, by the sixth day of the puerperium, an average volume of 500 mL will be taken by the baby. Once lactation is fully established, an average daily milk volume is about 800 mL. In well‐established lactation, it is possible to sustain a baby on breast milk alone for 4–6 months.