Efficacy of Bilateral Transversus Abdominis Plane and Ilioinguinal-Iliohypogastric Nerve Blocks for Postcaesarean Delivery Pain Relief under Spinal Anesthesia

Background Caesarean delivery can be associated with considerable postoperative pain. While the benefits of transversus abdominis plane (TAP) and ilioinguinal-iliohypogastric (II-IH) nerve blocks on pain after caesarean delivery via Pfannenstiel incision have been demonstrated, no enough investigations on the comparison of these blocks on pain after caesarean delivery have been conducted in our setup. Method An institutional-based prospective observational cohort study was conducted to compare the analgesic efficacy of those blocks. We observed 102 postoperative parturients. The outcome measure was the severity of pain measured using a numeric rating scale. Result Twenty-four hours after surgery, the NRS score at rest was (0.90 ± 0.80) versus (0.67 ± 0.58) and at movement (1.2 ± 1.07) versus (0.88 ± 0.76) for the TAP and II-IH groups, respectively. Twenty-four hours after surgery, the mean tramadol consumption was (55.45 ± 30.51) versus (37.27 ± 27.09) mg in TAP and II-IH groups, respectively (p = 0.009). The mean first analgesic requirement time was also prolonged in the II-IH group. Conclusion and Recommendations There was no statically significant difference between TAP and II-IH blocks regarding postoperative pain score, but the II-IH block significantly reduced the total tramadol consumption and prolonged the time to first analgesic request than TAP. Thus, we recommend the II-IH nerve block.


Introduction
Pain management is crucially important in the postoperative period as it increases patient comfort and satisfaction [1]. Caesarean delivery (CD) has been one of the most frequently performed major surgical interventions and causes severe postoperative pain [2]. Caesarean delivery and subsequent manipulation performed through Pfannenstiel incision are associated commonly with a signi cant degree of pain in the postoperative period; 79% of women experience pain at the incision site that can last for up to 2 months [3].
Inadequate postoperative analgesia is one of the most common causes for poor patient satisfaction following caesarean delivery [3,4].
Childbirth is an emotion-lled event, and the mother wants to bond with her newborn as early as possible.
Inadequate postoperative pain relief after CD can negatively impact ambulation, breastfeeding, and even maternal bonding [2,5].
Poor pain control in the postoperative period can lead to chronic pain syndromes and poor quality of life [2,5]. e provision of e ective postoperative analgesia is a key to facilitate early mobilization of the mother, infant care, and prevention of postoperative morbidity. Improvement in postoperative analgesia may not only increase patient satisfaction but also diminish the duration of hospital stay and reduce the risk of complications [6,7]. e ideal form of postoperative analgesia is unknown, but many procedures are carried out under spinal anesthesia, and currently, opioids are commonly used for relief of postoperative pain after caesarean section, either by intrathecal administration prior to section or by postoperative parenteral administration as a component of multimodal analgesia during the postoperative period [6,8].
Even if opioids are available to be administered via the spinal or systemic route, they had adverse e ects such as nausea, vomiting, sedation, itching, and risk of delayed maternal respiratory depression, all of which reduce overall patient satisfaction [2,3,8].
Additionally, these opioid-related adverse e ects can produce other problems for new mothers such as delayed initiation of breastfeeding and impairment of mother/infant bonding [3].
An ideal method of pain relief after caesarean delivery should be cost-e ective, safe for the mother, require minimal monitoring, and use drugs that are not secreted into breast milk. Moreover, the mother should not be sedated by the drugs that prevent her from moving freely and caring for the newborn.
Minor side e ects, such as pruritus and shivering, may interfere with care of the newborn, leading to less maternal satisfaction. Drug availability, maternal health conditions, patient preferences, and availability of medical expertise and trained support sta also play a role in choice of the analgesic method.
Many scholars have been studying to nd the safest and e ective way of interventions for postoperative CD pain management, and they suggest methods like opioid or local anesthetic skin in ltration, epidural analgesia, intrathecal or intravenous opioids, and abdominal eld blocks like TAP and II-IH.
Among the above-listed ways of pain management, intravenous opioids and regional nerve blocks are the mainstay of treatment for postcaesarean pain here in the study area.
Epidural analgesia, which is the gold standard for control of labour pain and postoperative pain, is not commonly practiced in our setup due to lack of the epidural kit.
Abdominal eld blocks like TAP and II-IH are the mainstay of treatment for postcaesarean pain for both the midline and Pfannenstiel incision because of the opioid sparing e ect, prolonged pain relief, and technical simplicity, and also, it does not need repeated injection for optimal pain relief [3,9].
TAP and II-IH nerve blocks are well known and easy to perform, and currently, these blocks are done in the study area for post-CD pain management.
ere are no enough data concerning the e cacy of TAP versus II-IH nerve blocks in the management of postoperative pain in parturients undergoing caesarean section.
Most of the studies that have been done to determine the e cacy of those blocks in post-CD pain management are done in western countries, but there is no published literature in Ethiopia. e presence of racial, cultural, genetic, and sociodemographic di erences in the perception of pain has been well documented [10,11].
ere is also controversy regarding the e cacy of the two blocks [12,13], so comparing the e ectiveness of TAP blocks with that of II-IH nerve blocks will help us to have a best practice to the study area, and knowing the e cacy of these blocks will allow anesthetists to choose the most e ective one to manage postoperative CD pain. e aim of this study was to compare the e cacy of the TAP block and II-IH block in controlling postcaesarean section pain.

Methods
An institutional-based observational cohort study was conducted from April 1 to May 30, 2017, at Gondar University Teaching Hospital after we secured ethical approval from the University of Gondar Ethical Review Board. e minimum sample size calculated for this study was 102, and the sample size calculation was done based on the two population proportion principles: (1) (i) Hence, the incidence of moderate-to-severe pain after CD without intervention was 87%, and we got pain reduction after clients received bilateral TAP and II-IH blocks 40% and 70%, respectively. And we calculated p 1 by reducing 40% of 87% from 87% (p 1 � 0.87−0.348 � 0.522) and p 2 by reducing 70% of 87% from 87% (0.87−0.69 � 0.261) since we need only pain reduction after the block from the incidence of pain (87%) by taking _ f(α, β) � 7.85 with a power of 80% and 0.05 signi cance.
So per group, we have 51 participants. We included ASA I and ASA II patients. Finally, we selected every consecutive parturient for whom the abovementioned nerve blocks were done and who also volunteered to give consent to participate in the study till the required sample is achieved. Our primary outcome measure was the severity of pain which was measured using the numeric rating scale. e secondary outcomes were the total analgesic consumption and time for the rst analgesic request. As to the data collection procedure, two trained anesthetists collect all the required information based on the checklist prepared in English. e investigators had no power to decide which type of block would be given for the mother (only the responsible anesthesiologist had this right, i.e., he/she did the block as he/she wishes, either TAP or II-IH).
But the investigator stayed in the operating theater and saw the type of block that the responsible anesthesiologist had done and put the code on the chart. e type of block was not clearly recorded on the chart except the code so that data collectors are blinded to the type of block done for each mother.
e relative proportion of these blocks in our institution looks equal (1 : 1) because everybody is doing these blocks randomly as they wish for transverse incision, but for vertical incision, they do only TAP. e block was done by using the landmark technique for both types, and a total of 32 ml of 0.25% bupivacaine for II-IH block (8 ml in each side) and 40 ml of 0.25% bupivacaine for TAP block (20 ml in each side) were given.
Pain assessment was performed at 0 hr, 4 hr, 6 hr, 8 hr, 12 hr, and 24 hr in the ward by blinded data collectors who were unaware of the type of the nerve block done. And the total analgesic consumption within 24 hours was also recorded.
Data were coded, entered, cleaned, and cross-checked with SPSS version 20 statistical package. e data were tested for normality using the Shapiro-Wilk normality test. Normally distributed data were analyzed using Student's t-test.
All data other than categorical parameters were analyzed using Student's t-test.
e comparisons of categorical parameters were analyzed using the chi-square test or Fisher's exact test as required and expressed in % and numbers. Data were presented as mean ± SD. p value < 0.05 was considered statistically signi cant.

Results
A total of hundred and two clients were enrolled in the current study with a response rate of 100%. e age of participants was 26.98 with a standard deviation of 2.4 years. Assessment of the ASA physical status showed that 78% of the TAP and 76% of the II-IH groups were ASA I and 21.56% of the TAP and 23.5% of the II-IH groups were ASA II (Table 1).
Postoperative vital signs (postoperative pulse rate and mean arterial blood pressure) were comparable between the two groups (Tables 2 and 3).

Postoperative Pain Scores using Numerical Rating
Scale. With regard to the postoperative pain score, there was no di erence between the two groups. We assessed the pain score at rest, on coughing, and at movement. e result shows no statistically signi cant di erence between the two groups (Tables 4 and 5). e mean tramadol consumption for the TAP group was 52.45 with a standard deviation of 30.5, and for the II IH group, it was 37.25 ± 27.09 mg; the mean rst analgesic consumption time in this study was 10.71 ± 7.67 hr for the TAP group and 14.09 ± 8.20 hr for the II-IH group, with a p value of 0.03 (Table 6)

Discussion
We found that there was no statistically signi cant di erence between TAP and II-IH blocks in the numeric pain rating score both at rest and at movement for the rst postoperative 24 hours, but the II-IH nerve block signi cantly reduced total tramadol consumption and prolonged the time for the rst analgesic request. Studies comparing the two blocks are rare, so we compare our results separately for each block.   Our result was comparable with the randomized controlled study done in Russia which showed that there was no statistically signi cant VAS (visual analogue score) di erence between TAP and II-IH blocks after caesarean delivery via Pfannenstiel incision within 24 hours postoperatively [14].
A randomized comparative study done in New Zealand showed that the II-IH nerve block reduced the pain score signi cantly and postoperative total tramadol consumption (p � 0.03) than the TAP block after inguinal surgery [12].
is is consistent with our result regarding tramadol consumption.
A systematic review and meta-analysis done by Abdallah et al. in Canada demonstrated that the TAP block enhances analgesia after caesarean delivery with detectable analgesic e ects for the entire 24 hours [5].
Another review and meta-analysis done by Mishriky et al. concluded that the TAP block improved postoperative analgesia and reduced the pain score in women undergoing CD [4]. ese two are in agreement with our results.
A meta-analysis done by Champaneria et al. in 2016 showed that the TAP block provided e ective analgesia and reduced the postoperative pain score after caesarean section [15]. is is comparable to our result.
Our result is comparable with a randomized control trial study done in Saudi Arabia that showed the NRS score was signi cantly lower in the TAP group than the control up to 24 hr both at rest and at movement after caesarean delivery via Pfannenstiel incision [15].
On the other hand, a study done by Sakalli et al. showed that the II-IH nerve block decreased the mean VAS score both at rest and at movement within 24 hours after CD [2].
is is comparable with our nding. Similarly, a study done in Jordan showed a signi cant reduction in the mean VAS score after the II-IH nerve block when compared with the placebo group in parturients who underwent caesarean delivery under general anesthesia [16,17].
Our study demonstrated that II-IH reduced the NRS pain score which is consistent with a study done by Bunting and McConachie and Ganta and colleagues, who analyzed the mean VAS score, and they found it to be less with the II-IH block as compared with the placebo group in parturients who underwent caesarean delivery [18]. A study of Bell and colleagues also demonstrated that the VAS score was reduced with the II IH nerve block [3].
A study done in Turkey by Yucel and colleagues showed that the II-IH nerve block reduced the VAS score for the rst 24 hr postoperatively than the control group. is is comparable with the current study [19].
In this study, the mean time for the rst analgesic request was signi cantly prolonged in the II-IH group (p � 0.03).
is is consistent with the nding of the previous comparative study done in Russia which showed that the II-IH block prolonged the time to rst analgesic requirement in a statistically signi cant fashion than the TAP block following CD [14].
We found that the total amount of tramadol consumption over the rst 24-hour postoperative time was lower in the II-IH group than that in the TAP group. is result is comparable with the previous study [14]. One study done in New Zealand was also in line with this study [12].
Our nding was also comparable with the studies conducted by Yucel et al. and Naghshineh et al. where they have found that postoperative analgesic consumption was signi cantly lower in the parturients who received the II-IH block as compared with the control group [20].

Conclusion and Recommendation
ere was no statistically signi cant di erence between TAP and II-IH nerve blocks regarding the postoperative pain score in each time point both at rest and at movement, but the II-IH block signi cantly reduced total tramadol   consumption and prolonged the time to rst analgesic request than TAP. We recommend the II-IH nerve block for postcaesarean delivery pain management via Pfannenstiel incision.

Conflicts of Interest
e authors declare no con icts of interest.