Hemorrhaging: Postpartum hemorrhage- The Causes and Risk Factors

Hemorrhaging is also known as bleeding or abnormal bleeding as a result of blood loss due to internal.external leaking from blood vessels or through the skin.
Postpartum hemorrhage
Postpartum hemorrhage (PPH) is a loss of blood greater than 500 ml, following vaginal delivery, or 1000 ml,  following cesarean section.The mortility rate is of 1000 women per 100,000 live births as a result of Postpartum hemorrhage (PPH). In the evaluation of all  randomly assigned participants,active bleeding was controlled within 20 min with study treatment alone for 440 (90%) women given misoprostol and 468 (96%) given oxytocin (relative risk [RR] 0·94, 95% CI 0·91—0·98; crude difference 5·3%, 95% CI 2·6—8·6). Additional blood loss of 300 mL or greater after treatment occurred for 147 (30%) of women receiving misoprostol and 83 (17%) receiving oxytocin (RR 1·78, 95% CI 1·40—2·26). Shivering (229 [47%] vs 82 [17%]; RR 2·80, 95% CI 2·25—3·49) and fever (217 [44%] vs 27 [6%]; 8·07, 5·52—11·8) were significantly more common with misoprostol than with oxytocin. No women had hysterectomies or died(1).

G.1. Causes and Risk factors
1. Causes
Causes of Postpartum hemorrhage (PPH) are of result of uterine atony, trauma, retained placenta, and coagulopathy(4Ts)
a. Uterine atony
Uterine atony is a loss of functions of compression of the vessels to reduce blood flow after child birth. According to the study of Department of Obstetrics and Gynecology, Duke University School of Medicine, omen with severe PPH had a mean oxytocin area under the curve of 10,054 mU compared to 3762 mU in controls (P < .001). After controlling for race, body mass index, admission hematocrit, induction status, magnesium therapy, and chorioamnionitis using logistic regression, oxytocin area under the curve continued to predict severe PPH(2).

b. Trauma
Trauma due to a body wound or shock as a sudden physical injure such as car accidence are associated to the to the cause of Postpartum hemorrhage (PPH.Uncontrolled bleeding continues to be a major cause of mortality in trauma, cardiac surgery, postpartum hemorrhage and liver failure, according
 to the study of Use of Activated Recombinant Factor VII in Severe Bleeding - Evidence for Efficacy and Safety in Trauma, Postpartum Hemorrhage, Cardiac Surgery, and Gastrointestinal Bleeding(3).

c. Tissues
Blood clots or retained tissues after birth, including retained placenta accounts for 10% of PPH. The primary tissue-based etiology of PPH is retained placenta. In the study of intravenous sulprostone infusion in the treatment of retained placenta, showed that the placenta was successfully expelled in 39.7% of cases, whereas 60.3% of women underwent manual removal of placenta. Blood loss was significantly lower in women with successful placental expulsion than in women who had manual removal of the placenta (582 ± 431 ml vs. 1275 ± 721 ml, p < 0.0001). Sulprostone infusion did not cause adverse effects or significant postpartum morbidity(4).

d. Coagulopathy 
Coagulopathy is defined as a condition of  coagulation abnormalities in which blood clots fail to form. According to the study by the Duke University Medical Center, Durham, systemic bleeding at the time of postpartum hemorrhage (PPH) is usually the result of coagulopathy that has developed acutely as a result of massive hemorrhage after uterotonics and sutures have failed(5).

e. Etc.

2. Risk factors
a. In vaginal delivery
According to the study of University of Uruguay, Montevideo, Uruguay, moderate and severe postpartum hemorrhage occurred in 10.8% and 1.9% of deliveries, respectively. The risk factors more strongly associated and the incidence of moderate postpartum hemorrhage in women with each of these factors were: retained placenta (33.3%) (adjusted odds ratio [OR] 6.02, 95% confidence interval [CI] 3.50-10.36), multiple pregnancy (20.9%) (adjusted OR 4.67, CI 2.41-9.05), macrosomia (18.6%) (adjusted OR 2.36, CI 1.93-2.88), episiotomy (16.2%) (adjusted OR 1.70, CI 1.15-2.50), and need for perineal suture (15.0%) (adjusted OR 1.66, CI 1.11-2.49). Active management of the third stage of labor, multiparity, and low birth weight were found to be protective factors. Severe postpartum hemorrhage was associated with retained placenta (17.1%) (adjusted OR 16.04, CI 7.15-35.99), multiple pregnancy (4.7%) (adjusted OR 4.34, CI 1.46-12.87), macrosomia (4.9%) (adjusted OR 3.48, CI 2.27-5.36), induced labor (3.5%) (adjusted OR 2.00, CI 1.30-3.09), and need for perineal suture (2.5%) (adjusted OR 2.50, CI 1.87-3.36)(6).

b. In caesarean section
caesarean section is associated to increased risk of  recurrent massive uterine bleeding, according to the report of a 37 yr old patient suffered severe atonic bleeding requiring different operating procedures (Clipping of the uterine arteries) in combination with an uterotonic and haemostaseological medication as well as massive transfusion of blood components and recombinant factor VIIa. After a period of 17 days without any bleeding the patient presented to the emergency room with recurrent massive uterine bleeding(7).
 
c. Racial and ethnic disparities
Hispanic ethnicity and Asian/Pacific Islander race were associated with a statistically significant increased odds of atonic PPH in comparison with Caucasians, despite adjustment for potential mediators (adjusted odds ratio [OR] for Hispanics: 1.21, 99% confidence interval [1.18, 1.25]; for Asians/Pacific Islanders: 1.31 [1.25, 1.38], with Caucasians as reference)(8).

d. Others risk factors
According to the study of Risk Factors for Postpartum Hemorrhage: Can We Explain the Recent Temporal Increase?, major independent risk factors for PPH included primiparity, prior Caesarean section, placenta previa or low-lying placenta, marginal umbilical cord insertion in the placenta, transverse lie, labour induction and augmentation, uterine or cervical trauma at delivery, gestational age < 32 weeks, and birth weight ≥ 4500 g. An overall increase in rate of PPH over the study period (OR 1.029; 95% CI 1.024 to 1.034 per year) disappeared (OR 0.995; 95% CI 0.988 to 1.001 per year) after inclusion of maternal age, parity, prior Caesarean section, labour induction and augmentation, placenta previa or low-lying placenta, and abnormal placenta, with most of the reduction attributable to rises in previous Caesarean section and labour augmentation(9). Also according to  the length of the third stage of labor and the risk of postpartum hemorrhage, Obstet Gynecol.  2005;105:290–3 and Stones  RW, Paterson  CM, Saunders  NJ.  Risk factors for major obstetric haemorrhage.  Eur J Obstet Gynecol Reprod Biol.  1993;48:15–8., risk factors for postpartum hemorrhage also include a prolonged third stage of labor, multiple delivery, episiotomy, fetal macrosomia, and history of postpartum hemorrhage.

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Sources
(1) http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2809%2961924-3/abstract
(2) http://www.ncbi.nlm.nih.gov/pubmed/21047614
(3) http://www.ncbi.nlm.nih.gov/pubmed/22670132
(4) http://www.ncbi.nlm.nih.gov/pubmed/22862433
(5) http://www.ncbi.nlm.nih.gov/pubmed/22430921
(6) http://www.ncbi.nlm.nih.gov/pubmed/19461428
(7) http://www.ncbi.nlm.nih.gov/pubmed/22628026
(8) http://www.ncbi.nlm.nih.gov/pubmed/22886840