Wednesday, April 18, 2012

Postpartum Hemorrhage


Severe postpartum hemorrhage (blood loss of more than 1000mls) occurs in approximately 2% of spontaneous vaginal births, and many hemorrhages are predictable 1,2. Accurate measurement of blood loss in most births is seldom possible, but average blood loss for vaginal birth is approximately 500 mls, and 1000 mls for cesarean birth 1.

Primary PPH is defined as excessive blood loss (1000ml or more) from the genital tract up until 24 hours following birth. Secondary PPH is defined as excessive blood loss from the genital tract after 24 hours following birth, until six weeks post birth 4.

In industrialized countries, PPH usually ranks in the top 3 causes of maternal mortality, along with embolism and hypertension. Mortality from PPH in industrialized countries is approximately 12 per 100,000 live births 3.

Major cause:

Uterine atony
The major cause of postpartum hemorrhage is uterine atony. This is defined as a loss of tone in uterine muscle. Normally, contraction of the uterine muscle compresses the vessels and reduces flow after baby and the placenta have been born. This increases coagulation and prevents bleeding. Thus, lack of uterine contraction can cause hemorrhage. Clinically, 75-80% of postpartum hemorrhages are due to uterine atony 5,6. Possible causes for uterine atony include:

Overdistended uterus , causes include:
  • multiple gestation 4.5 fold increase 2
  • large fetus (over 4000 grams) 3.5 fold increase 2
  • excess amniotic fluid 7
Fatigued uterus, causes include:
  • prolonged third stage of labor 7.5 fold increase  8
  • prolonged labor
  • rapid labor
  • induction of labor 2 fold increase 8
  • infection/chorioamniotitis (bacterial infection of the amniotic membranes)
  • use of uterine tocolytics—drugs used to stop labor or pre-term labor 7
Obstructed uterus, causes include:
  • retained placenta tissue 20 fold increase 2, 18
  • placenta accrete (deeply attached placenta unable to detach)
  • full/swollen bladder 7

Other causes:

Trauma
  • genital tears and lacerations 2 fold increase 8
  • need for perineal sutures 66% increase 2
  • episiotomy 70% - 5 fold increase 7
  • instrumental delivery 2 fold increase 7
  • prelabor cesarean 3 fold increase 8
  • emergency cesarean 6 fold increase
  • emergency cesarean after induction and previous cesarean 7.8 fold increase 8
  • uterine rupture 4
  • uterine inversion (placenta pulls the uterus lining with it as it exits) 4
Other risk factors
  • analgesia or anesthesia
  • hyperthermia
  • severe anemia (worsens effect of hemorrhage) 10
  • pre-eclampsia (hypertension and protein in urine) 5 fold increase 7
  • first pregnancy 13% increase 8
  • more than 5 pregnancies
  • mother over 35 years old 10
  • vaginal birth after previous cesarean 2 fold increase 8
  • previous uterine surgery 17
  • previous postpartum hemorrgage 3.5 fold increase 7
  • uterine fibroids 17
  • hereditary blood clotting abnormalities 4
  • endometriosis 11

Prevention of postpartum hemorrhage:

Active Management of 3rd stage of birth
Active management of the third stage of birth involves administering uterotonics (substances that induce the uterus to contract) and cord traction to help expel the placenta quickly and contract the uterus, thereby reducing risk of hemorrhage 12. Research shows that in high risk women a 66% reduction in risk of primary hemorrhage (blood loss of 1000ml within the first 24 hrs after birth) is seen using active management. In low risk women however there is no difference. Active management results in significant increases in maternal diastolic blood pressure, vomiting after birth, after-pains, use of analgesia, headaches, dissatisfaction with the 3rd stage of labor, more women returning to hospital with bleeding, and a decrease in the baby's birthweight due to the lower blood volume from early cord clamping 13.

The controlled cord traction involved in active management requires the immediate clamping of the umbilical cord, which increases the risk of infant anemia 14,15. Cord traction also carries the risk of breaking the cord, or causing hemorrhage if not performed strictly according to protocol. Research shows cord traction is not needed in the prevention of hemorrhage and can safely be left out of the active management procedure, leaving medical attendants to instead focus on administration of uterotonics, while leaving the cord intact so the newborn can transfuse the placental blood 16. Mothers should discuss with their care givers their desire to exclude cord traction from active management, should it be needed during birth.

In New Zealand active management is not routine midwifery practice, but is recommended to be implemented upon signs of hemorrhage.

Other preventive measures: 12

Before birth
  • Detect and treat underlying causes/risk factors (anemia, pre-eclampsia, hereditary blood clotting disorders, infection)
  • Distribute uterotonic Misoprostol to high risk pregnant women during the third trimester of pregnancy in case they give birth without a skilled birth attendant
During birth
  • Limit intervention unless absolutely necessary (induction, augmentation, episiotomy, forceps, vacuum or cesarean)
  • Do not encourage pushing before the cervix is fully dilated
  • Do not use fundal pressure to assist the birth of the baby or the placenta
  • Do not massage the uterus prior to delivery of the placenta
  • Do not perform cord traction unless absolutely necessary
  • If using cord traction a uterotonic drug must be administered first, and countertraction must be used to support the uterus
After birth
  • Inspect genitals for lacerations
  • Inspect the placenta and membranes for completeness
  • Evaluate if the uterus is well contracted
  • Massage the uterus, and check for vaginal bleeding and uterine hardness every 15 minutes for the first two hours after birth
  • Teach the mother to massage her own uterus to keep it firm
  • Encourage the mother to keep her bladder empty during the immediate postpartum period

Sources:

1.Postpartum Hemorrhage
http://emedicine.medscape.com/article/275038-overview

2.Risk factors for postpartum hemorrhage in vaginal deliveries in a Latin-American population.
http://www.ncbi.nlm.nih.gov/pubmed/19461428

3.Obstetric Hemorrhage
http://www.obfocus.com/high-risk/bleeding/hemorrhagepa.htm

4.Management of Postpartum Haemorrhage
http://www.medsafe.govt.nz/profs/puarticles/mpph.htm

5.Active versus expectant management in the third stage of labour.
http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD000007/abstract

6.Uterine atony
http://en.wikipedia.org/wiki/Uterine_atony

7.Postpartum Hemorrhage in Emergency Medicine
http://emedicine.medscape.com/article/796785-overview

8.Preventing Postpartum Hemorrhage: Managing the Third Stage of Labor
http://www.aafp.org/afp/2006/0315/p1025.html

9.Effects of onset of labor and mode of delivery on severe postpartum hemorrhage
http://www.sciencedirect.com/science/article/pii/S0002937809006279

10.Post-partum haemorrhage--a risk factor analysis.
http://www.ncbi.nlm.nih.gov/pubmed/20395927

11.Prevalence and risk factors for obstetric haemorrhage in 6730 singleton births after assisted reproductive technology in Victoria Australia
http://humrep.oxfordjournals.org/content/early/2009/11/07/humrep.dep376.full

12.Postpartum hemorrhage
http://www.pphprevention.org/pph.php

13.Active versus expectant management for women in the third stage of labour.
http://www.ncbi.nlm.nih.gov/pubmed/22071837.1

14.Effect of timing of umbilical cord clamping of term infants on maternal and neonatal outcomes
http://apps.who.int/rhl/pregnancy_childbirth/childbirth/3rd_stage/cd004074_abalose_com/en/index.html

15.Late vs Early Clamping of the Umbilical Cord in Full-term Neonates
http://jama.ama-assn.org/content/297/11/1241.short

16.Active management of the third stage of labour with and without controlled cord traction: a randomised, controlled, non-inferiority trial
http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)60206-2/abstract

17.The midwife confronts postpartum hemorrhage
http://www.sapienspublishing.com/pph_pdf/PPH-Chap-43.pdf

18.Postpartum haemorrhage in nulliparous women: incidence and risk factors in low and high risk women. A Dutch population-based cohort study on standard (> or = 500 ml) and severe (> or = 1000 ml) postpartum haemorrhage.
http://www.ncbi.nlm.nih.gov/pubmed/15262350

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