Post Caesarean-Section Pain Control Regimens: Oral Regimen With and Without Transversus Abdominis Plane Block

Patients at Mbarara Regional Referral Hospital (MRRH) in Uganda who present for routine caesarean sections often go without a set post-operative pain control regimen. Due to lack of established protocols and supplies of essential pain control medications are not reliable, upwards of 90% of women receive no postoperative pain control. There are regional techniques that are effective, easy to perform, low risk, and inexpensive. One of these techniques is a tranversus abdominis plane (TAP) block.

A TAP block is a regional anesthesia technique that provides analgesia to the parietal peritoneum as well as the skin and muscles of the anterior abdominal wall [1, 3-7]. First described just over a decade ago, it has undergone modifications in technique, and has been shown to be useful in providing 12-24 hours of significant post-operative pain relief for a wide array of surgical procedures [2]. It is best used as the cornerstone of a multi-modal approach to pain control and combines well with oral and intravenous opioid and non-opioid medications.

This is a technically straightforward procedure that involves injection of local anesthetic within the fascial plane located between the two deepest muscle layers (transversus abdominis and internal oblique muscles) of the lower abdominal wall. Given the simplicity of the TAP block and its long-lasting diminution in post-operative pain after many abdominal and pelvic surgeries, the incorporation of TAP blocks into post- caesarean section pain management should be considered as an achievable and simple remedy to the lack of reliable pain mediations after surgical delivery at MRRH.

This is a study that examines the efficacy of tranversus abdominis plane (TAP) blocks in providing post-operative analgesia after caesarean section under spinal anesthesia at Mbarara Regional Referral Hospital (MRRH) in Uganda, Africa. We will look at the value of TAP blocks in supplementing a routinely used (when available) post-operative non-opioid oral analgesic regimen.

Primary Hypothesis:

The administration of a TAP block on completion of caesarean section will decrease the level of pain as measured by a visual Numerical Rating Score (NRS) at 8, 16 and 24 hours, both at rest and with movement.

Secondary Hypotheses:

1. The administration of a TAP block on completion of caesarean section will increase the satisfaction score at 8, 16, and 24 hours; and
2. The administration of a TAP block will decrease or prevent the need for postoperative nurse- administered pethidine (meperidine) as a "rescue" medication.

This is a prospective, randomized, double-blind, sham controlled, single-center trial. A total of 240 patients will be enrolled in the study.

Following completion of the caesarean section, all patient will be screened for enrollment into the study. Enrollees will be randomly assigned to an arm via a predetermined undisclosed random number generator that will not be known by the staff at the MRRH. The anesthesiologist performing the TAP or sham block will be given a sealed envelope with the study arm which the patient has been randomized.

The study procedure is a TAP block and it will be placed on 50% of the enrollees.

TAP BLOCK:

Physicians who have been fully trained on the performance and potential risks of the technique will place TAP blocks under ultrasound-guidance. Briefly, under sterile conditions, ultrasound will be used to identify the targeted abdominal fascial plane. Once located, a predetermined amount of local anesthetic will be injected. This will be performed, bilaterally. The patient will be monitored during the block and for 30 minutes to follow.

SHAM BLOCK:

Sham blocks will consist of a non-invasive ultrasound scan over the abdomen. To mimic the injection of medicine, a dull/blunt object will be gently pressed on either side of the abdomen. The patient will be monitored during the sham block and for 30 minutes to follow.