Ultrasound anatomy of the transversus abdominis plane region in pregnant women before and after cesarean delivery

Abstract

BackgroundAfter cesarean delivery, analgesia is often incomplete and a multimodal approach to analgesia is necessary. Transverse abdominal plane (TAP) block has been advocated in this setting, yet no systematic description of the ultrasound anatomy in pregnant women exists in the literature. Therefore, we aimed to describe the sonographical features of relevant structures in pregnant women before and after elective cesarean.MethodsSixty women at, or close to term scheduled for elective cesarean delivery underwent a standardized ultrasound examination before and after delivery. We assessed the visibility of the muscular layers and measured the distance from the skin to the layers of the abdominal wall muscles in the region for TAP block before and after cesarean section on both side.ResultsThe three muscular layers of the lateral abdominal wall (external oblique, internal oblique and transversus abdominis muscle) were visible in all examinations. Before cesarean section the median TAP distance was shorter: 2.9 cm (interquartile range 2.6–3.6) compared to 3.9 cm (3.1–4.5) after cesarean section (left side, p < 0.001). The external and internal oblique muscles were located closer to the skin surface before cesarean section. An increased body mass is associated with increased the TAP distance before and after birth (p < 0.001).ConclusionRelevant anatomical landmarks for a TAP block are sonographically well visible after cesarean delivery. Postoperatively, depth of the TAP as compared to before birth is increased significantly. Scanning the abdominal wall before CD will underestimate the target depth of the TAP after delivery. The obstetric anesthetist needs to be aware of these changes when planning a TAP block in the context of cesarean delivery.

Comparison of ultrasound‑guided iliohypogastric/ilioinguinal nerve block and transversus abdominis plane block for analgesia after cesarean section: A retrospective propensity match study

“…The clinical data of 368 maternal females who underwent cesarean section at Yueqing Third People's Hospital (Yueqing, China) between June 2016 and June 2017 were retrospectively collected. The inclusion criteria were as follows: i) Cesarean section under epidural analgesia; ii) peripheral nerve block, including TAPB or IHINB; iii) age of 18–40 years; iv) ASA grade I or II according to the American Society of Anesthesiologists (ASA) classification (10); v) complete data of pain evaluation, morphine request and consumption. A total of 242 patients met the above criteria, and after the propensity score match, 124 patients were finally included in the study, who were divided into the TAPB group and the IHINB group according to their post-operative analgesic treatment modality.…”

Evaluation of Ultrasonographic Anatomy of Transversus Abdominis Plane before and after Cesarean Section

“…In a prospective study performed by Kiefer et al . ( 2 ), when the TAP block anatomy before and after the 60 th gestational cesarean section was examined ultrasonographically, pre-cesarean measurements were found to be significantly lower than the TAP plane distance after cesarean section. In our study, there was no significant result regarding TAP distance when the external and internal muscle distance was significantly lower.…”

“…Kiefer et al . ( 2 ) found the pre-cesarean and post-cesarean TAP distance measurements to be increased in pregnancies with high BMI. The same result was found in our work.…”

“…The original technique was described by Rafi in the block technique; during passage through the external and internal oblique muscle fascia using the Petit’s triangle, local anesthetic is administered to the area. While this approach is known to be effective, some safety issues have arisen, and a new approach has been proposed instead of ultrasonography ( 2 ). The TAP block target are subcostal, ilioinguinal and iliohypogastric nerves ( 1 ).…”

An Evaluation of the Adding Magnesium Sulfate to Ropivacaine on Ultrasound-Guided Transverse Abdominis Plane Block After Abdominal Hysterectomy

“…By blocking the T6-L1 nerve roots, TAP block provides effective analgesia for the abdominal wall ( 21 ). The exact location of the needle for injection is the fascial layer between the internal oblique and the transverse abdominis muscles, which is the major pathway of the abdominal wall nerves ( 22 , 23 ).…”