BACKGROUND: Abdominoplasty is one of the top five most commonly performed cosmetic procedures. Whereas widening of the linea alba is a well-accepted consequence of pregnancy, the changes to the rectus abdominis muscles are less well known and thus unappreciated and undertreated. METHODS: After institutional review board approval, the Northwestern Enterprise Data Warehouse identified nulliparous and multiparous women, aged 18 to 45 years, who underwent abdominal computed tomography between 2000 and the present. Measurements included the width and cross-sectional area of each rectus muscle, width of the linea alba, and circumference of the abdominal cavity at the level of the L3 vertebra. In addition, two case reports addressing these anatomical changes with muscle modification and mesh reinforcement are presented. RESULTS: Sixty women were identified that met our inclusion criteria: 15 nulliparous, 15 after one pregnancy (para 1), 15 after two pregnancies (para 2), and 15 after three or more pregnancies (para ≥ 3). The linea alba was significantly widened after one pregnancy from 1.14 cm to 2.29 cm, but did not significantly widen further with each subsequent pregnancy. The width of each rectus muscle was significantly widened from 6.00 ± 0.60 cm in nulliparous to 6.61 ± 0.58 cm in para 1, significantly widened again to 7.03 ± 0.46 cm in para 2, but not significantly widened after that (6.97 ± 1.00 cm in para 3). CONCLUSIONS: In addition to widening of the linea alba, pregnancy alters the shape of the rectus abdominis muscle. Correction of muscle width during abdominoplasty may be a necessary adjunct to achieve the proper tension in both primary and revision procedures. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.
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