Abakaliki is the capital of Ebonyi State, a mainland south-eastern state of Nigeria. Urban Abakaliki consists of two local government areas, namely Abakaliki and Ebonyi, out of 13 local government areas in Ebonyi State. The Federal Teaching Hospital (FETHA) is a tertiary hospital located in Abakaliki metropolis. The hospital is the merger between the former Ebonyi State University Teaching Hospital and the Federal Medical Centre, Abakaliki. The hospital gets referrals from within Ebonyi State and the neighbouring states of Enugu, Abia, Imo, Cross River and Benue.

This was a double blind randomized control study of pain management of uncomplicated caesarean section cases between April 1 and December 31, 2015. Initially, computer generated random numbers were collated and each number was sealed in a brown envelope. Each number was coded with a particular drug: either placebo (3 milliliters of sterile water for injection) or diclofenac and each participant chose a number that corresponded with the one in the envelope. All the participants received pentazocine (Penzor manufactured by Elyzium pharmaceutical Limited, India) 30 mg 4 hourly for 24 hours. In addition each participant received injection of either placebo (3 milliliters of sterile water for injection) 12 hourly for 24 hours or diclofenac (Olfen-75 manufactured by Merkel, Blaubeuren-Weiler Germany) 75 mg 12 hourly for 24 hours. All the drugs were administered by intramuscular route and each patient was treated along the line of packed analgesic as stated.

The sample size for the study (N) was calculated using the formula [21]:

N= (U+V)² {P₁ (1-P₁) +P₂ (1-P₂)}/(P₁-P₂)² where U was power at 90%, V was confidence interval at 95% and it was 1.96; P₁ was expected patient satisfaction using combined pentazocine and diclofenac analgesics and a previous study showed a 90% satisfaction [22]. P₂ was expected patient satisfaction using pentazocine only analgesic and the same study showed a 70% satisfaction [22]. Adding a 10% attrition rate, the sample size for each of the groups was 67.

Inclusion criteria involved consenting low risk parturients who had either elective or emergency caesarean section, under spinal anaesthesia, who were fully conscious at FETHA, Abakaliki, Ebonyi, Nigeria. However, the exclusion criteria comprised the parturients who had caesarean section under general anaesthesia, had stillbirth or history of allergy to pentazocine or diclofenac. Also, excluded were the parturients with history of severe obstetric haemorrhage, delirium, preexisting opioid dependency, sickle cell haemoglobinopathy, peptic ulcer disease, psychiatric illness, illiteracy and those that declined consent to participate in the study despite adequate counselling. The consent to participate in the study was obtained from the eligible participants before the caesarean section.

The agents for the study were administered within one hour after the surgery, according to the group each of the parturients belongs. The primary outcome measure was postoperative pain control, while the secondary outcome measures comprised patient satisfaction and maternal and neonatal adverse outcomes. Pain control was assessed using a VAS [23]. Each participant was taught on how to use the VAS at enrolment prior to the surgery. Score of 1-4 was classified as mild pain, 5 to 8 as moderate pain and above 8 as severe pain. Trained research assistants and the investigators undertook the assessment at the 1^st, 2^nd, 6^th, 12^th, 18^th and 24^th hour after the surgery. The side effects of the drugs, such as drowsiness, nausea and vomiting (in the mothers) and excessive sleeping (in the newborns), were also noted. Additional dose of pentazocine was used as break through analgesic at patient’s request or when the VAS was > 6.

The information obtained was entered into a predesigned data sheet. The social class of the participants was calculated using the classification by Olusanya O and his co-authors [24]. The data was analysed with Statistical package for Social Sciences (IBM SPSS Inc, Chicago, IL, USA) version 20.0. Categorical variables were analysed using the Pearson chi square test while the continuous variables were analysed using the student’s t-test. The level of significance was set at < 0.05. The ethical clearance for this study was obtained from the Ethics Committee of FETHA. This manuscript adheres to the applicable equator guidelines.

A total of 146 parturients who had uncomplicated caesarean section participated in the study. However, it was only 140 (95.9%) of them who made the inclusion criteria that were analysed and 70 of them were in each group. Six of the parturients opted out in the course of the study. [Table/Fig-1] contains the socio-demographic characteristics of the participants. There was no statistical significant difference between the 2 groups of participants on the variables. The distribution of the type of surgery among the participants is contained in [Table/Fig-2]. There was no statistical significant difference between the participants who received the PP and those who received PD on the types of surgery performed on them. [Table/Fig-3] contains the mean parity, age, gestational age at delivery, estimated blood loss and duration of surgery among the participants. Also there was no statistical significant difference between the two groups of participants on these variables.

[Table/Fig-4] shows the mean pain scores and duration of activities of the participants. The use of PD for 24 hour post caesarean section analgesia achieved better pain relief than the use of PP (p-value ≤0.002). When compared with PP, the use of PD for 24 hour post caesarean section analgesia showed faster onset of postoperative ambulation, bowel sound auscultation and onset of oral feeding (p-value=0.001). However, there was no statistical significant difference between the 2 groups of patients on the passage of flatus and duration of hospital stay (p-value ≥0.05). The maternal and newborn side effects of the drugs among the participants are contained in [Table/Fig-5]. There were significant side effects associated with PP when compared with PD on post caesarean section analgesia (p-value=0.009). [Table/Fig-6] contains the comparison of level of satisfaction among the participants. There was no statistical significant difference on the level of satisfaction between the participants on PP and those on PD (p-value ≥0.05). [Table/Fig-7] contains the comparison of the cost of post caesarean section analgesia. The combined use of pentazocine and diclofenac was significantly more expensive than pentazocine alone for post caesarean section analgesia (p-value=0.0001).

This study has shown that though, the combined use of pentazocine and diclofenac for 24 hour post caesarean section analgesia was more expensive, it achieved better pain relief and faster onset of postoperative ambulation, bowel sound auscultation and oral feeding than the use of pentazocine alone (p-value ≤0.002). There were significant maternal side effects associated with the use of only pentazocine for post caesarean section analgesia (p-value=0.009). There was no difference on the level of satisfaction between the participants on pentazocine only and those on combined pentazocine and diclofenac (p-value ≥0.05).

The combined use of pentazocine and diclofenac for 24 hour post caesarean section analgesia achieving better pain relief than the use of only pentazocine in this study is similar to the previous findings in Osogbo and Ife, southwest Nigeria, Kano, northern Nigeria, Iran and Switzerland [25-29]. Despite the differences either in the drug dosages or types of analgesics used in these studies, their findings showed that multimodal post caesarean section analgesia achieve a better pain relief than unimodal analgesia. The improved analgesia obtained with the combination of the pentazocine and diclofenac could be explained by the effect of combined action of two different analgesics that interrupt pain transmission at different levels resulting in additive or synergistic analgesia.

Though the level of satisfaction from the combined pentazocine and diclofenac analgesia and the pentazocine only analgesia were 87.1% and 77.1% respectively, there was no statistical significant difference between them. This is contrary to the findings by Olateju SO et al., in Ife and Adamou N et al., in Kano, where patients with multimodal analgesia were significantly more satisfied than the ones on unimodal analgesia [26,27]. The reason for no statistical significant difference between the two groups of participants on the level of satisfaction in this study may be because Igbo women cope satisfactorily with pain [30], and they constituted 97% of the parturients that participated in this study.

Though age, parity and educational status influence pain perception among obstetric women [30,31], these variables are similar in both groups of women in this study thereby removing any confounding influence of these variables. The faster onset of postoperative ambulation, bowel sound auscultation and onset of oral feeding on patients with multimodal analgesia when compared with those on unimodal analgesia in this study is similar to the findings by Adamou et al., in Kano [27]. This is clinically important as early ambulation and initiation of oral feeding in post caesarean section patients will improve their psychological and emotional well-being. It will also encourage breastfeeding, mother to child bonding as well as prevention of thrombo-embolism, uterine sub-involution and post-partum haemorrhage. Similar to the finding in Kano [27], the analgesic mode (unimodal versus multimodal) did not have any significant effect on the duration of hospitalization. This is because not only analgesia but other factors influence the decision on the discharge of patients. Such factors comprise the surgeon’s preference, choice and use of antibiotics, degree of wound healing, type of anterior abdominal wall incision (midline versus pfannenstiel incision) and maternal and neonatal clinical conditions. With the exception of maternal drowsiness experienced more by the patients on only pentazocine, the side effect profile was essentially similar in both groups. The reduced side effect profile in the pentazocine-diclofenac group compared to pentazocine only group may be because the cumulative effect of both drugs tends to reduce the side effects. Despite the advantages of multimodal analgesia over unimodal analgesia identified in this study, the high cost of combined use of pentazocine and diclofenac for post caesarean section analgesia in this study may prevent the patients from using it. This underscores the need for free obstetric services in this environment.

This study is weakened by pain being a subjective experience and therefore, the authors may not have been able to measure with certainty, how much pain each parturient felt. This was a single centre study which may not conclusively reflect the findings in other hospitals and therefore a multi-centre study is required.

The combined use of pentazocine and diclofenac in post caesarean section analgesia is more effective in achieving a satisfactory pain relief and has less side effects when compared with pentazocine only. This is very important especially in a resource-poor country like Nigeria where potent opioids are not readily available and affordable and yet there is need to achieve optimum pain control following caesarean section.