Definition The definition of retained placenta is arbitrary and is based on the length of time that elapses between the birth of the baby and the expected delivery of the placenta. The most widely accepted definition is the retention of the placenta in utero for more than 30 minutes. The management is influenced by whether or not significant bleeding is occurring. This bleeding may be visible or manifest only by the increasing size of the uterus. In the absence of any evidence of placental detachment, consider the diagnosis of complete placenta accreta or a variant. This condition may be present with bleeding if a portion of the placenta detaches. Types: (1) detached (placenta has separated completely and is retained inside); (2) partially detached (placenta has partially separated and is retained inside); (3) non-detached (placenta has not separated at all) (Figure 20.1).
About 25% of maternal deaths in African and Asian countries are due to haemorrhage during pregnancy, delivery or the postpartum period. Of these, almost 30% are caused by PPH. About 15%–20% of these PPH maternal deaths are due to retained placenta. In less developed countries, it affects about 0.1% of deliveries and has a 10% case fatality rate. In developed countries, it is more common (about 3% of vaginal deliveries) but is very rarely associated with mortality. A systematic review of observational studies show that the median rate of retained placenta at 30 minutes was higher in developed countries (2.67% vs. 1.46%, p < 0.02), as was the median manual removal rate (2.24% vs. 0.45%, p < 0.001). In addition to this, there appears to have been a rise in rate of manual removal in the United Kingdom from a mean of 0.66% in the 1920s to 2.34% in the 1980s (p < 0.0001) . The retained placenta is the second major indication for blood transfusion in the third stage of labour.
Appropriate management of the third stage of labour can help to reduce retained placenta and it is a potentially preventable cause of PPH. The incidence of retained placenta varies according to the management practices of the third stage of labour .
Maternal: postpartum haemorrhage, shock, sepsis, perforation, retained products, uterine inversion, trauma, rhesus-isoimmunisation, anaesthetic complications, severe maternal morbidity and maternal deaths
Medico-legal: clinical negligence claims due to delay in removing the placenta or inappropriate management
Uterine abnormality, uterine scars
Constriction ring or reforming cervix
Inappropriate active management of third stage of labour
Age above 35 years
Following induction of labour
Past history of retained placenta
Key Diagnostic Signs
Many interventions are in practice for the management of retained placenta. The choice of intervention will depend on the clinical scenario, the available facilities and the skill and experience of the doctor. If the patient is stable and presents no evidence of active bleeding there is no necessity to rush and proceed to every available intervention at once. An expectant management for a period of an hour (arbitrary time period) will be useful. Meanwhile the bladder will be emptied and the patient has to be observed carefully for bleeding and signs of separation of placenta. In trapped placenta ultrasound can be performed to confirm separation and use controlled cord traction with or without a short-acting tocolytic such as glyceryl trinitrate. Sometimes when it is trapped in the cervical canal and in the vagina it can be removed easily during vaginal examination with or without anaesthesia.
The role of systemic oxytocics in the management of retained placentas is controversial. Oxytocics given prophylactically at the time of delivery increase the number of placental deliveries at 20 and 40 minutes but have no effect on the number of placentas that eventually need manual removal . As an alternative to all of the foregoing, intra-umbilical vein oxytocin injection can be tried. Use of tocolytics, either alone or in combination with uterotonics, may be of value in minimising the need for manual removal of the placenta in the theatre under anaesthesia. The following drugs can be useful during the procedure: nitric oxide donors, β-adrenergic stimulants, calcium channel blockers, halogenated anaesthetics and magnesium sulphate. One randomised controlled trial (involving 24 women) compared the use of nitroglycerin tablets versus placebo after the treatment with oxytocin had failed. There was a statistically significant reduction in the need for manual removal of placenta [risk ratio (RR) 0.04, 95% confidence interval (CI) 0.00–0.66]. There was also a statistically significant reduction in mean blood loss during the third stage of labour [mean difference (MD) 262.50 mL, 95% CI 364.95–160.05]. Sublingual nitroglycerin caused some haemodynamic changes, as it lowers the systolic blood pressure and diastolic blood pressure by a mean of 6 and 5 mm Hg respectively. The pulse rate increased by a mean of two beats per minute . Although sublingual nitroglycerin appears to be an effective and safe drug that can be used to manage retained placenta, its routine use cannot be recommended because of the small study sample size.
If there is significant bleeding, it should be managed as a primary postpartum haemorrhage and manual removal of the placenta should be done without delay. The time allowed to lapse before manual removal varies, but many authorities suggest a delay of 30–60 minutes in the absence of haemorrhage. This is because there is no increase in haemorrhage until at least 30 minutes postpartum, and because of the finding that between 30 and 60 minutes a further 40% of placentas will spontaneously deliver with an average blood loss of only 300 mL.
We have classified the interventions into ‘first line’ (SP) and ‘second line’. The latter should be used when the first-line interventions fail and are associated with increased maternal morbidity. Therefore, an experienced medical officer’s presence is recommended during the performance of second-line interventions.
Use of Intra-umbilical Vein Oxytocin Injection
Much interest has been aroused by the notion that oxytocin may be delivered directly to the retro-placental myometrium by injecting it into the placental bed via the umbilical vein. This allows the treatment to be directed specifically at the area with the contractile failure. If there is no active bleeding, consider intra-umbilical uterotonic agents before resorting to a more invasive procedure such as manual removal.
Shout for help (experienced medical officer, anaesthetist and alert the blood bank) as soon as possible. Stop unnecessary handling of the uterus. Do not pull on the cord: it can avulse.
Scribe – Assign someone to alert the blood bank and to monitor the patient.
Procedure – The Pipingas technique has been shown to be effective in delivering drugs to the placental bed . A size 10 nasogastric tube is passed along the umbilical vein until resistance is felt, under aseptic conditions, then retracted about 5 cm, and prostaglandin F2a (20 mg diluted in 20 mL of normal saline) or oxytocin (30 IU diluted in 20 mL of normal saline) is injected through the catheter . There is some evidence that the umbilical vein injection of normal saline with uterotonic drugs such as oxytocin to induce uterine contractions seems to have promising results . There is no significant difference between umbilical vein injection of normal saline alone and expectant management in the incidence of manual removal of placenta (RR: 0.97; 95% CI: 0.83–1.14). Umbilical vein injection of saline solution plus oxytocin compared with expectant management showed a reduction in manual removal, although this was not statistically significant (RR: 0.86; 95% CI: 0.72–1.01). Saline solution with oxytocin compared with saline solution alone showed a significant reduction in manual removal of the placenta (RR: 0.79; 95% CI: 0.69–0.91) (number needed to treat: 8; 95% CI: 5–20). No discernible difference was detected in the length of the third stage of labour, blood loss, haemorrhage, haemoglobin, blood transfusion, curettage, infection, hospital stay, fever or abdominal pain.