Oxytocin Versus Misoprostol Plus Oxytocin in the Prevention of Postpartum Hemorrhage at a Semi-Urban Hospital in sub-Saharan Africa: A Retrospective Cohort Study

1.1. Background of the Study

Postpartum hemorrhage (PPH) is a life-threatening obstetric emergency that occurs after cesarean section (CS) or normal vaginal delivery (NVD). It is defined as a blood loss of ≥ 500mls after a vaginal delivery or 1000mls after a cesarean delivery.1 Worldwide, evidence abounds that PPH is the leading cause of maternal mortality, claiming 480,000 global maternal deaths between 2003 to 2009, of which 41.6% of these PPH-related maternal deaths occurred in sub-Saharan Africa (SSA).2–7 Similarly, in Cameroon, an SSA country, many interventions still need to be done to decrease the contemporary maternal mortality ratio (MMR) from 789 per 100, 000 live births to the targeted global MMR of less than 70 per 100,000 live births by the year 2030.8 The way forward partly entails curbing the burden of PPH which has been reported as the primary cause of maternal deaths in many hospital-based audit reports,8,9 as well as tackling a composite of factors which further contribute to a high MMR in this country such as inadequate antenatal care coverage,8 late hospital presentation of parturients with obstetrical complications, the relatively high cost of health care poverty and the absence of a national health insurance policy.9 Efforts to curb PPH-related maternal mortality have focused on several medical treatments, mechanical or non-pharmacological measures, uterus preserving surgeries surgery or hysterectomy.10

Medical management with uterotonic drugs remains an important integral part of the first-line management of PPH,10 particularly as the main etiology of PPH in Cameroon and most SSA countries is uterine atony.11,12 The most commonly used uterotonic agents in hospital-based settings in Cameroon are oxytocin, methyl-ergometrine, misoprostol and carboprost tromethamine.4 Sulprostone, a potent uterotonic drug is inexistent or scarcely available in Cameroon.4 The usual protocol used to treat PPH due to uterine atony using uterotonics in this country entails the successive administration of an oxytocin infusion, a single dose of methylergometrine, and then carboprost tromethamine are used in 15-to-20-minute intervals. They are administered parenterally and therefore require skillful health personnel for their administration to parturients. Also, ergometrine requires refrigeration and oxytocin may be inactivated if exposed to high temperatures. Misoprostol, a prostaglandin E₁ analog, is an inexpensive readily available drug and can be absorbed by the following routes of administration: vaginally, rectally, or sublingually.13,14 Gastrointestinal symptoms (nausea, vomiting, and diarrhea), shivering and fever are the most common adverse effects of misoprostol, which often are mild and self-limited.15,16 The off-label use of misoprostol has entered into clinical practice for this indication because of its strong uterotonic properties, and its advantages over other synthetic prostaglandin analogs due to the advantage that it does not necessarily requires skilled personnel for its administration. Furthermore, its aforementioned numerous routes of administration, its stability at ambient temperatures, the long half-life, wide availability, and low cost are some additional advantages of misoprostol use.17,18 A 600 mcg dose of oral misoprostol is safe and effective in preventing PPH.19,20 It is worth mentioning that the oxytocin is most potent uterotonics at this writing and WHO recommends its only use as first-line uterotonic to prevent PPH.10 However, due to the aforementioned benefits of misoprostol, the use of misoprostol to prevent PPH has received considerable attention in Cameroon (with an alarming MMR of 789 per 100, 000 live births),8 where unpublished guidelines by the Cameroon Society of Obstetricians and Gynecologists (CSOG) recommend the concomitant use of oxytocin and misoprostol since 2014 for a more potent synergistic uterotonic effect geared at the prevention of PPH. However, misoprostol was not widely available in Cameroon until September 2015. Prior to this date very few stokes of it where available only in urban parts of Cameroon. The widespread distributions and/or sales of misoprostol to semi-urban and rural areas of Cameroon began in November 2015. Against this background, we sought to evaluate the effectiveness of oxytocin versus oxytocin plus misoprostol in the prevention of PPH in a semi-urban Cameroonian hospital by comparing the era when oxytocin was used alone to the era when the combined oxytocin-misoprostol protocol was used.

1.2. Objectives of the Study

The study objective was to assess the effectiveness of oxytocin compared to oxytocin and misoprostol alone in the prevention of PPH amongst women delivering at the semi-urban sub-Saharan African Hospital. We hypothesized that misoprostol plus oxytocin will be more efficacious in preventing PPH compared to oxytocin alone.

2.1. Study Design and Setting

This study was a retrospective cohort study. The study setting was the Bamenda Regional Hospital (BRH), Cameroon. The BRH is a state-owned university teaching hospital located in a semi-urban region of the Northwest Region of Cameroon. The BRH is a secondary level health facility in the referral system of Cameroon. It thus serves as a referral hospital for nearby primary health centers in the Northwest Region of Cameroon. The BRH is made up of with the following departments: Pediatrics, Surgery, Obstetrics/Gynecology, Radiology, Nephrology/Hemodialysis, Anesthesiology/Operating room, Intensive Care Unit, Emergency Unit and Internal Medicine department. The study precisely took place in the Obstetrics/Gynecology Unit of the hospital. This unit is further divided into three outpatient consultation rooms which serve for both gynecological consult and antenatal care visits; a family planning unit; an admission ward with a capacity of 33 beds; a labor ward that is sub-divided into six delivery rooms. The Obstetrics/Gynecology Unit is run by three Obstetricians-Gynecologists, two general practitioners and 16 midwives. Averagely, there is one Obstetricians-Gynecologist, one general practitioner and five midwifes per 12 hourly working shifts.

2.2. Study Population and Study Procedure

Through a chart review, were enrolled the obstetric records of all consecutive women with a minimum gestational age of 28 weeks who delivered at the BRH. The files of these parturients were divided into two groups. One group (group A) comprised of all women who gave birth between January 2015 to April 2015, before the implementation of misoprostol use for PPH prevention. This group was routinely administered oxytocin 10 IU intravenously within a minute after vaginal delivery or administration of 10 UI intravenously within a minute after cesarean delivery followed by continuous infusion of 30 IU of oxytocin in Dextrose 5% solution over the next 24 hours of delivery as medical treatment to prevent PPH. The other group (group B) comprised of the obstetric records of all women delivering at the BRH between January 2016 to April 2016 after the implementation of misoprostol in BRH for the PPH prevention. This group was administered 800 mcg of misoprostol sublingually or intra-rectally after within a minute following vaginal/cesarean delivery plus oxytocin 10 IU intravenously within a minute after vaginal delivery or administration of 10 IU intravenously within a minute after caesarean delivery followed by continuous infusion of 30 IU of oxytocin in Dextrose 5% solution over the next 24 hours of delivery as medical treatment to prevent PPH. During the aforementioned chart review, we identified all names women who delivered in the labor room of BRH by consulting the admission registry. Then we proceeded to the archives of the Obstetrics/Gynecology Unit where the files of all these women were retrieved. For women who delivered by cesarean delivery we consulted the operating room register to get details of the operations.

2.3. Study Variables

Overall, through the chart review process we studied the following variables (i) Socio-demographic data: maternal age, level of education, occupation, religion, marital status, urban/rural residence, gestational age, birth weight of the newborn, and gender of the neonate. (ii) Clinical characteristics: maternal comorbidities, parity, gravidity. (iii) Details of delivery: induction of labor, vaginal/cesarean delivery, type/amount/route of uterotonic drugs administered, singleton/multiple pregnancies, spinal/general anesthesia for cesarean section delivery, the occurrence of PPH, etiology of PPH, non-medical and surgical management of PPH, maternal or neonatal death.

2.4. Definition of Terms

PPH was defined as an estimated blood loss greater than 500 ml within 24 hours after vaginal delivery and greater than 1000 ml following cesarean section.1 Medical management of PPH was defined as the parenteral administration of oxytocin, methyl-ergometrine, and/or misoprostol. Non-medical management of PPH entailed uterine massage, bimanual uterine compression followed by subsequent compression of the abdominal aorta, and/or repair of any vaginal or cervical lacerations and manual uterine revision where appropriate.10 Uterus preserving surgery was defined as any surgical intervention consisting of ligation of pelvic arteries or application of uterine compression sutures to achieve hemostasis while concomitantly conserving the uterus e.g. Bilateral hypogastric artery ligation, Uterine artery ligation, B-lynch uterine compression suture, Tsirulnikov triples ligation and Hysterorraphy. Tsirulnikov Triple ligation entailed bilateral ligation of the round ligaments, utero-ovarian ligaments and uterine arteries.10 B-lynch uterine compression suture consisted of making a lower segment transverse hysterotomy or removing the sutures of a recent cesarean section to apply lateral uterine brace sutures to envelop and compress the bleeding uterus to achieve hemostasis.21 Hysterectomy was defined as a surgical procedure geared at achieving hemostasis through resection of the uterus e.g. subtotal abdominal hysterectomy or total abdominal hysterectomy. Total abdominal hysterectomy consisted of complete resection of the uterus and cervix, while the cervical stump was left in-situ in subtotal abdominal hysterectomy.

2.5. Statistical Analysis

After obtaining data from the patients’ files, questionnaires that were not properly filled were sorted out. Questionnaires were then attributed serial numbers that could help match them to the database if there was a need for cross-verification and then the data were then entered into an electronic data entry form by the primary investigator. Data were entered and analyzed using the Statistical Package for Social Sciences (SPSS) Standard version, Release 20.0 (IBM Inc. 2012). Distribution of sociodemographic and clinical characteristics was compared between the misoprostol plus oxytocin group and the oxytocin only group using the Chi-square test. We calculated the relative risk (RR) and their corresponding 95% confidence intervals (95% CI) to measure associations. The original alpha-value was set at 0.05. To reduce the chance of obtaining false-positive results from the multiple analyses performed on the same dependent variable, the Bonferroni adjusted p-value was calculated by dividing the alpha-value by the number of comparisons. The subsequent alpha values calculated were 0.0029, 0.0039 and 0.0056 as seen below in Table 1, 2 and 3 respectively. Hence, any comparison was statistically significant if it was inferior to the Bonferroni adjusted p-value. Variables with too much missing data precluding meaningful analyses were excluded. The study was approved by the Institutional Review Board of the School of Health and Human Sciences, Saint Monica University Higher Institute, Buea, Cameroon and the Ethics committee of the BRH.

3.1. Sociodemographic Characteristics of Parturients

During the two study periods, 2056 women delivered at the BRH. Of these 2056 obstetric records, 278 were excluded because the women’s gestational ages were below 28 weeks. Hence, 1778 files corresponding to 86.5% of the initial records retrieved were retained for this study. The files were repartitioned as follows: 857 in the oxytocin only group and 879 in the oxytocin plus misoprostol group. The overall mean age of 26.3 ±5.2 years (range: 14 – 48 years) with the most frequent age group being between 18-35 years (93.1%). Both groups were comparable (no statistical difference) in terms of their mean ages, age categories, places of residence (urban versus rural), parity, gravidity, gestational ages, occupations, frequency of preterm deliveries and multiple gestations. On the other hand, being married, being a Christian, being referred to the BRH by another health facility, being HIV-positive, having a history of abortion, and being pregnant of a macrosomic fetus were predictors of being administered oxytocin plus misoprostol, not attenuated by Bonferonni correction (Table 1).

3.2. Peripartal Factors

Amongst the women included in this study (n=1778), 48 had PPH, giving an overall prevalence rate of PPH of 2.7%. Table 2 summarizes the proportion of women with PPH and those without PPH in the two treatment groups. The risk of PPH in the oxytocin only group was about 1.5 times higher than in the oxytocin plus misoprostol group (3.4% vs 2.2%). The amount of blood lost was significantly higher in the oxytocin group compared with the oxytocin plus misoprostol group (1100 ± 150 vs 800 ± 100 ml; p< 0.0001). Unlike cesarean delivery, vaginal delivery conveyed protection against the only use of oxytocin (RR: 0.78; < 0.0001).

3.3. Factors Associated with Postpartum Hemorrhage

In this study, 33 (68.6%) of patients with PPH required a doubled dose of 600 micrograms of misoprostol for PPH management while 15 (31.4%) of patients with PPH received adjuvant intravenous oxytocin. About 66.7% of patients with PPH had surgery for better management despite receiving medical management with oxytocin and/or misoprostol. The active management of the third stage of labor without misoprostol was the only risk factor for PPH (RR: 1.04; 95 % CI: 1.02-1.05; p: 0.0008) which was not attenuated by Bonferroni correction (Table 3).

4.1. Limitations

With an extensive literature search, to the best of our knowledge, this study is one of the first comparative studies on oxytocin alone versus oxytocin plus misoprostol in the prevention of PPH in Cameroon. Its strength lies in its large sample size (N = 1778) and cohort design over two different eras to assess this comparison. Its main limitation is its retrospective design because the obstetric records studied were not filled to carry out a study later on. However, we noticed the records were well filled with little missing data.

4.2. Recommendations for Further Studies

We recommend the conduct of similar studies with a prospective cohort design on a larger scale of participants at multicenter levels to yield better quality evidence which can be generalizable in Cameroon. Although WHO guidelines recommend the use of oxytocin only as the first-line uterotonic in the prevention of PPH.10 Perhaps multinational studies evaluating the effectiveness of oxytocin plus misoprostol compared to oxytocin only as the first-line uterotonic in the prevention of PPH, may show a superiority of oxytocin plus misoprostol in this regards which may call for a revision of WHO guidelines.10