Surgical Approach to the Rectus Diastasis

The abdominal wall is composed of four paired muscle groups: rectus abdominus, external oblique, internal oblique, and transversalis ( Fig. 19.1 ). The rectus muscles are separated by the linea alba, which is a fascia extending from the xyphoid process to the pubic symphysis. It is formed by aponeuroses of the transverse abdominal, external oblique, and internal oblique muscles. It functions to maintain the abdominal muscles, particularly the rectus muscles, at a certain proximity to each other. The paired semilunar lines mark the lateral border of the rectus abdominus muscles and are formed by the same aponeuroses.

Rectus diastasis is the widening of the linea alba along its length, with separation of the paired rectus muscles from the midline. The amount of diastasis can be measured as the inter-recti distance. However, there is controversy regarding the definition of normal distance and when it can be classified as pathologic. According to the literature, the width of the linea alba has a broad range of values, varying mostly from 2 to 5 cm, indicating that beyond that range it might be limited in its ability to stretch. It is usually widest at the umbilicus.

Clinically the condition is associated with protrusion of the abdomen as a result of laxity of the myoaponeurotic system. Rectus diastasis is not the sole reason for protrusion and stretching of the abdominal wall, but stretching of the entire musculofascial structures is evident in such patients.

Rectus diastasis by itself is not a true hernia, but it could manifest with epigastric and umbilical hernias. Large ventral hernias can also coexist with rectus diastasis, occurring after incisions made through the linea alba.

Female pattern diastasis (mostly caused by pregnancy and multiparity) is centered at the level of the umbilicus, whereas male pattern diastasis (usually seen in the fifth to sixth decades of life as a result of increased intra-abdominal fat) is primarily supraumbilical. Other predisposing factors for diastasis include cesarean section, lack of physical activity, obesity, and aging.

Patients occasionally may present with congenital lateral insertion of the paired recti at the costal margins. This condition necessitates advancement of rectus muscles toward the midline, as opposed to a simple plication.

In Fig. 19.2 , the four types of female pattern diastasis are depicted. Patients with type A present with classic rectus diastasis with separation in the midline. Patients with type B present with laxity of the musculoaponeurotic layer after the correction of rectus diastasis. Patients with type C present with congenital rectus diastasis, in which the insertion of the recti muscles is lateral in the costal margins. Patients with type D present with a poorly defined waistline.

Repair of rectus diastasis is commonly indicated in patients who are undergoing an abdominoplasty procedure. It is mostly done for cosmetic reasons but could also be indicated during repair of ventral hernias.

There is not necessarily coherence between the anatomic location, severity of the diastasis, and protrusion of the abdomen. Patients with a diastasis and without significant protrusion have been observed. Furthermore, there is no consensus on the definition of when a myoaponeurotic laxity requires repair. Thus, evaluation of the abdominal protrusion, rather than the diastasis itself, should primarily influence the decision of surgical repair.

Patients should be evaluated preoperatively in supine and upright positions. When the patient is lying supine with legs flexed, he or she is asked to lift the head and shoulders (scapulae) off the table with arms extended, reaching forward in a half sit-up position. The surgeon then palpates the medial border of rectus muscle and assesses the diastasis. In the upright position, patients are asked to relax and then contract their abdominal muscles. The abdominal shape (location of most prominent protrusion) and muscle tone are evaluated from the frontal and lateral views. Ultrasound and computed tomography scan additionally can be used to help diagnose diastasis; however, they are time consuming, costly, and not always practical in the clinical setting. Imaging is indicated if there is clinical concern for a coexisting ventral hernia. Computed tomography is the recommended modality to rule out a hernia, the existence of which might change the operative plan necessitating mesh repair.

Surgical repair of rectus diastasis is done via either an open or an endoscopic approach. The most common method of repair involves repositioning the rectus muscles by plication of the anterior sheath of the fascia and by invagination of the linea alba. In cases of isolated rectus diastasis (patients who have minimal excess skin and good skin elasticity), an endoscopic repair can be undertaken, minimizing abdominal scars.

Fig. 19.3 depicts the different closure techniques, including midline plication, T-shaped epigastric plication, oblique plication, and L-shaped plication on the external oblique.

Upper transverse plication, oblique plication, and L-shaped external oblique plication have been proposed in patients continuing to have laxity in the flank and hypogastric area despite midline plication. These extra maneuvers aim to improve overall tension of the musculoaponeurotic layer, to increase tension around the umbilicus, which cannot be plicated during midline plication, and to decrease vertical length of the abdomen to prevent relative prominence that is observed after midline plication.

In patients with marked musculoaponeurotic laxity or an existing hernia, an overlay/underlay mesh to reinforce the repair should be considered.

There are many variations in plication technique and in materials that are used such as type of suture (absorbable, nonabsorbable, barbed) and mesh, if used. Regardless of technique, it is questionable whether the repair will last over time, as repeated contraction forces, intra-abdominal pressure, and tissue elasticity might drive the muscles back to their original, more lateral position.