Rectus diastasis: epidemiology and operative treatment

Background During pregnancy, the abdominal wall expands and linea alba stretches. Although the abdominal wall usually reverts after delivery, for some the recovery is only partial and rectus diastasis may persist. This thesis consists of studies addressing different aspects of post-pregnancy rectus diastasis (RD). The project was initiated to study the changes of the linea alba width after pregnancy and to determine what is normal inter rectus distance after pregnancy and what can be considered abnormal. In addition, we wanted to determine if there is a threshold level for linea alba width that is associated with increased RD-related symptoms. The aim was to find evidence for treatment indications in public health care. RD concerns the following two surgical specialties: general and hernia surgery and plastic and reconstructive surgery. The treatment algorithms in these specialties have not been the same. One aim of this thesis was to evaluate surgical outcomes together with health-related quality of life (HRQoL) following operative treatment. Two techniques are reported in this thesis. Midline hernia is relatively common in connection with diastasis. Umbilical hernia repair in general is one of the most common procedures performed. Treatment guidelines consider this patient group as one entity and tailored solutions based on etiology or patient characteristics are not considered. This thesis describes a subgroup of midline hernia patients that may benefit from a different approach than that suggested in widely accepted international hernia guidelines. Material, Methods, and Results In Study I, a minimally invasive, novel PSUM-mesh technique targeted to treat severe diastasis with and without a midline hernia is presented. Thirty-seven patients between June 2014 to May 2018 were operated. The mean inter-rectus distance (IRD) was 5.2 cm (range 4.0–9.0 cm). This is wider than in previous patient series in the abdominoplasty literature. Sixteen patients had an umbilical hernia and 3 an epigastric hernia. Patient-reported retrospective results were good; 80% had a reduction in back pain and 96% had a reduction in core instability. This study is a baseline work for an ongoing randomized controlled trial (RCT) where patients are randomized to PSUM and classical plication techniques (ClinicalTrials.gov NCT03509376). This RCT is presumed to be completed in 2024. In Study II, the width of the linea alba of 939 women was measured during early pregnancy screening ultrasound. Over 400 women answered the HRQoL and symptom questionnaires. In this large cohort, the average IRD in nulliparous women was 1.81±0.72 cm, which is considered normal. Already after one pregnancy, IRD was 2.36±0.83 cm, which is classified as mild diastasis. After two or more pregnancies, the rectus bellies are even farther from each other (mean IRD 2.55 ± 1.09 cm). HRQoL or back pain did not differ in groups under or over 3 cm IRD. Severe diastasis (IRD >5 cm) was rare. Only 1.5% had severe diastasis in study cohort. These results do not support 3 cm as one of the indications for surgery. In Study III, the same questionnaires as in Study II were repeated in the same cohort a year after index pregnancy. A minority of women reported increased back pain or core instability. In Study III, we recruited individuals from this symptomatic subgroup and controls who reported no change in their bodily experience after index pregnancy. IRD was measured with ultrasound in 14 cases and 41 controls. The study groups did not differ at baseline; mean IRDs were 2.41±1.01 cm in the symptomatic case group and 2.29±1.03 cm in the control group. A year later, symptomatic cases had significantly wider mean IRD (3.26±0.90 cm) than controls (2.47±0.79 cm). There was a significant difference in the sit-up test; in 30 seconds, symptomatic individuals performed 4.7±4.2 sit-ups and controls performed 8.2±3.9. As the abdominal wall expands during pregnancy, linea alba is not the only structure that elongates. Firmness of the abdominal wall also depends on lateral fascia structures, as these may be permanently saggy. In Study IV, we report in detail HELP abdominoplasty for treatment of RD with and without a midline hernia. This study reported the total plicated distance in a quantitative manner addressing lateral laxity. After HELP-abdominoplasty, rectus bellies were immediately side by side after 2 years of follow up. There were no hernia recurrences in the series even though mesh technique was not used. Total complication rate was