Postoperative Flank Bulge in Infants After Open CDH Repair: An Underreported Complication

Flank bulge (FB) is a rare postoperative complication, most commonly following surgery with retroperitoneal access through flank incision. It is characterized by relaxation of anterolateral wall muscles with abnormal protrusion of the abdominal wall. The assumed pathomechanism is iatrogenic injury of the intercostal nerves T11/T12. During congenital diaphragmatic hernia (CDH) repair, dissection and sutures are necessary at this thoracic level. We aimed to assess the risk of FB in a consecutive series of patients after CDH repair.We retrospectively analyzed charts of all patients after CDH repair (2007-2024) with a follow-up of ≥3 months. FB was diagnosed during clinical follow-up examinations and defined as protrusion of abdominal wall with no sonographic evidence for hernia. Surgical variables and their association with FB were evaluated. For statistical analysis, Pearson's and Student's t-test were used. Multivariate logistic regression was performed to identify independent risk factors associated with FB development after CDH repair.Among 67 infants undergoing CDH repair with follow-up, 76% underwent open surgery and 48% required patch repair. Postoperative FB occurred in 11% of patients, exclusively following open repair with patch, and was significantly associated with rib sutures and higher birth weight. One-third of FB cases resolved spontaneously, while the remainder persisted, though without functional impairment.FB may be an underestimated complication after open CDH repair. Routine assessment of abdominal wall tone is recommended during follow-up after CDH repair. Larger studies are needed to clarify the clinical impact, patient-perceived level of disability, and long-term sequelae.