Transverse Abdominis Plane Block Reduces Post-Operative Pain
Intensity and Analgesic Consumption in Elective Cesarean Delivery
under General Anesthesia
1. Laleh Eslamian, Associate Professor of Obstetrics & Gynecology, Dr Ali Shariati
Hospital, Tehran University of Medical Sciences.
2. Zorvan Jalili, obstetrician and gynecologist
3. Ashraf Jamal, Associate Professor of Obstetrics & Gynecology, Dr Ali Shariati
Hospital, Tehran University of Medical Sciences.
4. Vajiheh Marsoosi, Associate Professor of Obstetrics & Gynecology, Dr Ali Shariati
Hospital, Tehran University of Medical Sciences.
5. Ali Movafegh, Associate Professor of Anesthesiology, Dr Ali Shariati Hospital,
Tehran University of Medical Sciences.
*Corresponding Author: Ali Movafegh M.D., Department of anesthesiology and critical care,
Dr Ali Shariati Hospital, Jalal-Al Ahmad Street,
Tehran 1411713135, Iran
Tel : +98-912-3021389, Fax : +98-21-88220032
E-mail Address: firstname.lastname@example.org
Short title: TAP block significantly reduced analgesic use following cesarean delivery
Word Count of the main text=2184
Word count of the abstract=214
The number of tables: 2
The number of figures: 2
Purpose: It is reported that following abdominal surgeries, Transversus Abdominis Plane (TAP)
Block can reduce postoperative pain. The primary outcome of this study was
evaluation of the efficacy of TAP block on pain intensity following cesarean delivery with
Methods: Fifty pregnant women were randomized blindly either to receive TAP block with 15
ml 0.25% bupivacaine in both sides (group T, n=25) or no blockade ( group C,n=25) at the end
of the surgery, which was performed with Pfannenstiel incision under general anesthesia. The
pain intensity of patients was assessed by a blind investigator at the time of discharge from
recovery and at 6, 12 and 24 hours post-operatively with visual analogue scale (VAS) for pain.
Results: The women in TAP block group had significantly less VAS pain scores at rest and
during coughing and consumed significantly less tramadol (50mg(0-150) vs 250mg(0-400), P =
0.001). There was a significantly longer time to the first request of analgesic in the TAP block
group (210min (0-300) vs 30min(10-180) in C group, P=0.0001).
Conclusion: Two sides TAP block with 0.25% bupivacaine in parturients who undergo cesarean
section with Pfannenstiel incision under general anesthesia can decrease post-operative pain and
analgesic consumption. The time for the first analgesic rescue is longer in parturients who
received TAP block.
Key words: Analgesia-Cesarean delivery – Pain intensity- TAP block.
The pain and discomfort following cesarean delivery is mostly due to abdominal wall incision and
dissection of muscles; it delays early ambulation and breast feeding. This can lead to the post-
operative complications such as thromboembolic disorders (1). So, providing an effective and safe
post-operative analgesic method seems to be mandatory. Opioid analgesia remains the most effective
means of relieving pain in wide variety of conditions (2); however, it may cause adverse effects such
as nausea, vomiting, pruritus, urinary retention and respiratory depression (3-5). As the analgesia
and the side effects of opioids are dose-dependent, a multimodal approach may enhance analgesia
which in turn leads to decrease the side effects (3).
Mc Donnell and colleagues reported that transversus abdominis plane (TAP) block can decrease the
post- operative pain following abdominal surgery (6). The landmarks of this block were first
described in 2001 by Rafi (7). The TAP block has been performed in patients undergoing radical
prostatectomy, hysterectomy, cesarean delivery under spinal anesthesia and laparoscopic surgery for
post-operative analgesic control (8,10– 12 -13-15).
To our knowledge, the use of the TAP block in cesarean delivery parturients under general
anesthesia has not been surveyed in any studies so far. So, we designed this study to evaluate the
analgesic effect of the TAP block as part of a multimodal analgesic regimen. The primary outcome
of this study was the effect of TAP block on post-operative pain intensity. Post-operative analgesic
consumption and the time for the first analgesic request were considered as a secondary outcome.
After getting the approval of the Institutional Ethics Committee and having the informed consent
signed, 50 ASA physical status I-II term primiparous single tone pregnant women aged 20–40 years
were scheduled for elective cesarean section with Pfannenstiel incision under general anesthesia
enrolled in the study.
Patients with a history of addiction (including opioids, benzodiazepines),sensitivity to prescribed
analgesics, psychological disorders and coagulopathy, any patients with surgical complications
during cesarean section, infection of block injection site, and those receiving any drugs within 48
hours of surgery( except of study protocol) were excluded from this study.
In a controlled, randomized double-blind design, patients were allocated into 2 groups using a
computer generated randomization list to receive either 30ml of bupivacaine 0.25% (15 mL in each
side) as TAP block(T group, n=25), or nothing (C group, n=25) at the end of surgical procedure.
At the time of pre-operative visit, a trained investigator explained the study plan and the scale
(visual analogue scale for pain) used in the study for the patients. Drug solutions were prepared and
blocks were done by an anesthesiologist who was not involved in the data collection, and patients
received their block when they were under anesthesia, thus, both the investigators and the patients
were blinded to the group assignment.
The severity of post-operative pain was measured and recorded using a 10-cm visual analog scale
(VAS), where 0=no pain and 10=the worst possible pain. Patients were asked to score the pain after
the operation at different times, both at rest and during coughing, including the time of discharge
from recovery and 6, 12, 24 hours later.
In the operating room, an infusion of 7 mL/kg lactated ringer’s solution was commenced. All
patients were monitored with an electrocardiogram (ECG), non-invasive blood pressure and pulse
oximetry. All patients received rapid sequence induction of anesthesia. Anesthesia was induced with
sufentanil 5 μg and thiopental sodium 5 mg/kg , the trachea was intubated after administration of
succinylcholine 1.5 mg/kg . After tracheal intubation, anesthesia was maintained with isoflurane
0.8%, N20 50% and 0.4 mg/kg atracurium. After delivery of neonate, 0.1mg/kg morphine and 15 μg
sufentanil was administrated. Ventilation was adjusted to maintain normocapnia(end-tidal carbon
dioxide partial pressure 4.7-5.3 kPa).Patients were actively warmed to keep core temperature
At the end of surgical procedure and wound dressing, the patients in the T group received the TAP
block. The TAP block was performed bilaterally as described by Mc Donnell et al (6). The triangle
of Petit was identified and a blunt regional anesthesia 22 G needle of 50 mm lenght was inserted at a
right angle and advanced till second “pop sensation” indicated correct needle position in the
transversus abdominis fascial plane. Fifteen ml of bupivacaine 0.25% was injected in each side. No
injection was done in the control group. Subsequently, anesthetics administration was stopped and
neuromuscular blockade was antagonized by IV administration of 2.5 mg of neostigmine along with
1.0 mg atropine. Patients were considered awake when they opened their eyes on command or after
gentle tactile stimulation, they were extubated soon thereafter.
Patients in both groups were advised that they could ask for rescue analgesia at any time following
the surgery. Intravenous 50mg tramadol was given as a rescue analgesic at minimum 4-h intervals
and all patients received 100mg diclofenac suppository daily.
It was estimated that a minimum of 22 patients in each group would be required to have a 95%
power of detecting 3 scores in the VAS for pain, considering SD= 2.7 at a significance level of
0.05. This number was raised to 25 in each group to allow a predicted drop-out of almost 10%.
Bonferroni correction was applied for multiple comparisons and in these cases P value adjusted at
Statistical analysis was performed using SPSS package (SPSS Inc., Chicago, IL, USA) version 13.5.
The distribution of data was checked by the Kolmogorov-Smirnov test. Age, weight, height and
duration of surgery followed a normal distribution, so they were compared between two groups by
independent t student’s test. The VAS for pain, the time to first analgesic rescue and post-operative
tramadol requirement didn’t follow normal distribution, so they were compared in groups by Mann-
Whitney test. Two tailed P<0.05 were taken as significant.
We randomized 50 patients, 2 patients (one in each group) were excluded from the study because of
the surgical complication.
Demographic characteristics, ASA physical status class, intraoperative opioid administration and the
duration of surgery were similar in the two groups (table 1).
The VAS pain scores during coughing were measured in recovery, 6, 12 and 24 hours following the
surgery, they were as: 7(1-10), 8(5-10), 5(3-8),4(0-6) in the C group and 0(0-5), 4(1-6), 3(0-6) and
0(0-5)* in the T group. At the same mentioned times, the VAS pain scores at rest were 4(0-8), 6(3-9),
3(1-5), 0(0-3) in the C group and 0(0-2), 1(0-4), 1(0-3), 0(0-1) in the T group. Apart from the pain
at rest, 24 hours following discharge of recovery, there was a significant difference in the VAS for
pain both at rest and during coughing, measured over time between the two groups (Mann-Whitney
U test, Between-Subjects effects, P <0.001) (Graphs 1,2). The changes in VAS for pain over the time
was significant in each group (Friedman test, tests of Within-Subjects Effects, with significant
interaction between VAS pain score and group, P <0.001) (Graphs 1,2).
In the patients who received the TAP blockade, the time of first request for analgesic was
significantly longer [210min (0-300min)* in T group vs 30min (10-180min) * in C group, P =
0.0001)] (Table 2).
The total tramadol consumption was significantly less in the T group than C group [(50mg (0-
150mg) * in T group vs 250mg (0-400mg)* in C group, P = 0.001)] (Table 2).
* Data are presented as median (range)
The current study demonstrates that in elective cesarean delivery with Pfannenstiel incision
under general anesthesia, bilateral TAP blockade with 30 mL 0.25% bupivacaine (15 mL in
each side) could decrease 24 hours post-operative pain intensity and analgesic consumption.
The first analgesic rescue was longer in parturients who received the TAP block. In both
groups, the maximum pain intensity was at the 6th hour, following the surgery, and it
decreased after this time. Yet, the pain intensity in each measured time was less in mothers
who received the TAP block. Exceptionally, the pain score at rest 24 hours following the
discharge from recovery were the same in both groups.
The pain and discomfort after cesarean delivery delays early ambulation and breast feeding
which can result in post-operative complications and mother discomfort (1). So, providing an
effective and safe post-operative analgesia can prevent these morbidities. These goals were
likely achieved through a multimodal approach. The opioids are often used for post-operative
pain control. However, there are some concerns about opioids administration to the breast
feeding women. Intravenous opioids can appear in the milk, so it can potentially induce some
side-effects in the neonate (9).
Some studies have showed the efficacy of the TAP block in reduction of post-operative pain
intensity and analgesic requirement in patients who undergo radical prostatectomy,
hysterectomy, cesarean delivery and laparoscopic surgery (8, 10– 14). In one study the
blockade by 1.5 mg/kg ropivacaine bilaterally in the cesarean delivery parturients,
successfully decreased post-operative patient-control IV morphine requirement. They found
that the TAP block was effective for 36 hours. The fact that TAP region is relatively
vascularised poorly was considered as a reason for this prolong blockade (10). In our center,
under normal conditions mothers stay in hospital for 24 hours, so post-operative pain
intensity and analgesic requirement were assessed in our study in this duration.
Recently, two studies haven’t been able to show any differences between pain intensity or post-
operative analgesic requirement when the TAP block was used as a multimodal analgesic
regimen in cesarean delivery parturients under spinal anesthesia (16-17). However, both studies
were performed on parturients who underwent spinal anesthesia, and in one of them, intrathecal
morphine was used. It seems that the design of these studies mainly differed from ours. Probably
it can elucidate the reason of discrepancy in our findings. However, in another study on cesarean
delivery parturients under spinal anesthesia, the TAP block reduced post-operative morphine
In the TAP block, the T7-T12 intercostal nerve, ilioinguinal nerve, iliohypogastric nerve, and
the lateral cutaneous branches of dorsal rami of the L1-L3 at the neurofascial plane between
internal oblique muscle and transverse abdominis muscle are blocked by local anesthetic. It has
been illustrated that TAP block can provide excellent analgesia for somatic (skin and
musculature) pain of abdominal wall (10,11). In our study, TAP block led to the less pain
intensity during coughing in the 24 hours after cesarean delivery. This observation shows that
TAP block successfully reduced the somatic pain on our cases. In the first 12 hours following the
surgery, the pain intensity at rest in TAP group was lower than control group. However, the pain
score at the 24th hour was alike in the groups. Probably, the low pain intensity at rest in this time
can explain this observation.
There are some concerns about local anesthetic systemic toxicity, especially bupivacaine
systemic toxicity in pregnant women. In a study, it was showed that 3 mg. kg-1of ropivacaine in
the TAP block in adult female results in potentially toxic plasma concentrations. Relatively high
dose of ropivacaine was used in that study and the volume of local anesthetics that injected in
each site was 20 mL (19). In our study, we used low volume and concentration of bupivacaine
successfully; the total dose of the injected bupivacaine was 75 mg. It seems that the risk of
systemic toxicity with this dose is probably low, and we achieved a prolonged analgesia with this
relatively small dose. However, the risk of local anesthetic toxicity in this method should
consider and careful observation of patients seems to be mandatory.
The absence of major vascular or neurologic structures in the block area is an important
advantage of the TAP block. However, there are a few hypotheses about potential side-effects of
this block. In one report, the TAP block led to hepatic trauma (20). Colon puncture or hematoma
formation in the injection site is another theoretical side-effect of this block (21).
The high ratio of elective cesarean section under general anesthesia may raise some concerns. In
our country, and especially in our patients, there is a great fear of spinal anesthesia and needle
insertion in the back or into the spine. So, most of our parturients refuse the spinal or epidural
anesthesia. As patient refusal is one of the spinal anesthesia contraindication, the rate of cesarean
section under general anesthesia in our country is relatively high.
There are some limitations to this study. Firstly, because of our hospital policy, morphine is not
available for post-cesarean delivery pain control; therefore, we have been using tramadol for this
purpose. Besides, patient-control analgesia pumps are not routinely used in our Center for post-
cesarean delivery pain control, so we couldn’t use this device to more precise evaluation of the
analgesic rescue of our parturients. Secondly, because of ethical consideration and our University
Review Board suggestion, we didn’t inject placebo (for example saline) in the control group.
Furthermore, the post-operative side-effects such as nausea and vomiting were not our surveyed
outcome, so we did not evaluated them.
In conclusion, bilateral TAP block with 0.25% bupivacaine in elective cesarean delivery
parturients with Pfannenstiel incision under general anesthesia can decrease post-operative pain
and analgesic consumption up to the 24h hour. The time of first analgesic rescue is longer in
mothers who received the TAP block.
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Table 1. Demographic data and duration of surgery
162.8 ± 3.34
Duration of surgery (min)a
ASA physical status class(I/II)15/9
There were not significant differences between groups.
a Values are expressed as mean ± SD.
Table 2. Post-operative analgesic consumption and time to first opioid request
Time to 1st opioid request (min)a
a Values are expressed as mean ± SD.
Graph 1. Post-operative VAS pain scores at rest
Graph 2. Post-operative VAS pain scores during coughing