Diastasis of rectus abdominis muscles: patterns of anatomical variation as demonstrated by ultrasound

The aim of our study was to categorise the anatomical variations of rectus abdominis muscle diastasis (diastasis recti) by using ultrasound (US).

In a one-year period 92 women were evaluated with US because of suspected diastasis of rectus muscles. Patients were examined in a supine position, with head extended, upper limbs aligned to the trunk, and knees flexed. US was performed with high-frequency, broad-band transducers. Trapezoid field-of-view and extended field-of-view were employed to measure diastasis exceeding 5 cm. Diastasis was defined as a margin-to-margin distance > 20 mm at rest and classified according to the following anatomical patterns: open only above the navel, open only below the navel, open at the navel level, open completely but wider above the navel, and open completely but wider below the navel.

Diastasis was found in 82 patients (30-61 years old, mean age 35 years). The width was 21-97 mm, mean 39 mm. The prevalence and severity of the anatomical patterns was as follows: open only above the navel in 48 patients (21-88 mm, mean 40 mm), open only below the navel in one patient (33 mm), open at the navel level in seven patients (23-39 mm, mean 34 mm), open completely but wider above the navel in 24 patients (21-97 mm, mean 41 mm), open completely but wider below the navel in two patients (21-29 mm, mean 25 mm).

The above-navel patterns of recti muscle diastasis are the most common. Even when open completely, diastasis is usually wider above the navel. Knowledge of the anatomical type of rectus muscle diastasis could be of value to the patient (exercises to do and to avoid) and to the surgeon (abdominoplasty planning).