A 27-year-old woman, gravida 1 para 0, with gestational diabetes mellitus comes to the hospital at 38 weeks gestation for evaluation of abdominal pain. The patient is scheduled for an elective cesarean section at 39 weeks as a recent ultrasound revealed that the estimated fetal weight is 5200 g (11 lb 4 oz). Examination reveals that the patient is in active labor and the fetus is in breech presentation; an urgent cesarean section is performed. During the surgery, the rectus abdominus muscle is split vertically, but space appears to be limited. In anticipation of a large-for-gestational-age baby, a decision is made to transect the rectus abdominis muscle. If the rectus abdominis muscle is incised laterally, which of the following structures is at greatest risk of injury?

Question

A 27-year-old woman, gravida 1 para 0, with gestational diabetes mellitus comes to the hospital at 38 weeks gestation for evaluation of abdominal pain.  The patient is scheduled for an elective cesarean section at 39 weeks as a recent ultrasound revealed that the estimated fetal weight is 5200 g (11 lb 4 oz).  Examination reveals that the patient is in active labor and the fetus is in breech presentation; an urgent cesarean section is performed.  During the surgery, the rectus abdominus muscle is split vertically, but space appears to be limited.  In anticipation of a large-for-gestational-age baby, a decision is made to transect the rectus abdominis muscle.  If the rectus abdominis muscle is incised laterally, which of the following structures is at greatest risk of injury?

Quizplus · Accepted Answer

11ec160b_3579_5d2d_9249_29217a90f037_MD0001_00 The rectus abdominis is a pair of vertically aligned muscles that connect the xiphoid process to the pubic symphysis. The arcuate line is a horizontal line located below the umbilicus that demarcates the lower limit of the posterior rectus sheath. Above the arcuate line, the rectus abdominis is surrounded by anterior and posterior sheaths; below, the muscle is covered only by the anterior sheath. The superior (Choice F) and inferior epigastric arteries supply the superior and inferior portions of the rectus abdominis muscle, respectively. The epigastric artery ascends the posterior surface of the rectus abdominis muscle and enters the lateral aspect of this muscle at the arcuate line. Because there is no supporting posterior sheath, trauma to the inferior epigastric artery below the arcuate line can result in significant hemorrhage. Regardless of the direction of skin incision, a cesarean delivery typically involves midline vertical separation of the rectus abdominis muscle. Horizontal transection of the rectus abdominis muscle may be considered when additional space is necessary (eg, due to fetal weight or position). If the rectus abdominis is transected horizontally, the inferior epigastric arteries must be identified and ligated bilaterally to prevent bleeding complications (eg, hematoma). (Choice A) The deep circumflex iliac artery supplies blood to the anterior iliac crest and arises from the lateral aspect of the external iliac artery. It is located significantly laterally and inferiorly to the rectus abdominis muscle. (Choice B) The inguinal canal contains structures (eg, ilioinguinal nerve, round ligament [women], spermatic cord [men]) between the abdomen and external genitalia. Men are more susceptible to inguinal hernias compared to women due to their relatively larger deep inguinal ring. (Choice C) The femoral sheath is located in the inguinofemoral region and contains the femoral artery, femoral vein, and femoral canal. (Choice E) The lateral femoral cutaneous nerve travels under the inguinal ligament. It provides sensory innervation to the anterolateral thigh. Entrapment (meralgia paresthetica) most commonly occurs in obese or pregnant persons or in those who wear garments that are tight around the hip. Educational objective: Horizontal transection of the rectus abdominis muscle must be performed with great caution as the inferior epigastric arteries enter this muscle at the level of the arcuate line. The inferior epigastric arteries below the arcuate line are susceptible to injury (eg, hematoma) due to lack of a supporting posterior rectus sheath. __________ References: Reviewing the vascular supply of the anterior abdominal wall: redefining anatomy for increasingly refined surgery. (http://www.ncbi.nlm.nih.gov/pubmed/18189276) Rectus sheath hematoma: a review of the literature. (http://www.ncbi.nlm.nih.gov/pubmed/25529279)

A 27-Year-Old Woman, Gravida 1 Para 0, with Gestational Diabetes