During a teaching round on wound complications, a surgical resident is asked to identify the most common site of wound dehiscence in patients who develop burst abdomen in the immediate postoperative period. Which anatomical site is most frequently affected?

Explanation

## Most Common Site of Wound Dehiscence: Midline Vertical Incision ### Incision Types and Dehiscence Risk **Key Point:** The midline vertical incision carries the highest risk of dehiscence and burst abdomen, accounting for 60–70% of all abdominal wall dehiscence cases. ### Comparative Analysis of Incision Types | Incision Type | Orientation | Blood Supply | Nerve Supply | Dehiscence Risk | Strength at 1 Week | |---|---|---|---|---|---| | Midline vertical | Longitudinal (linea alba) | Poor (avascular plane) | Minimal | **Highest** | ~10% of final | | Paramedian | Longitudinal (lateral to linea alba) | Good (rectus sheath) | Preserved | Low | ~40% of final | | Transverse | Horizontal (across muscle fibers) | Excellent (segmental) | Segmental | Very low | ~60% of final | | Pfannenstiel | Transverse suprapubic | Excellent | Preserved | Very low | ~60% of final | ### Why Midline Incisions Are Prone to Dehiscence 1. **Avascular plane:** The linea alba is a relatively avascular plane between the rectus abdominis muscles; healing depends on collagen deposition without robust blood supply. 2. **Tension concentration:** All abdominal wall tension is borne by the incision line itself; there is no muscular support lateral to the incision. 3. **Healing timeline:** At postoperative day 5–7, tensile strength is only ~10% of final strength; any stress (coughing, straining, increased intra-abdominal pressure) can cause failure. 4. **Suture mechanics:** Sutures placed in linea alba tissue have less holding power than those placed in muscle or fascia with better vascularity. **High-Yield:** Burst abdomen typically occurs between postoperative days 5–14 and is preceded by serosanguineous discharge from the wound; it is a surgical emergency requiring immediate re-exploration and closure. ### Clinical Pearl Risk factors for dehiscence include: - Increased intra-abdominal pressure (coughing, straining, ascites, obesity) - Malnutrition and hypoproteinemia - Infection (SSI) - Inadequate suture technique (too few sutures, too wide spacing, poor knot security) - Corticosteroid use and immunosuppression ### Mnemonic: VITAL **V**ascular supply (poor in linea alba) — **I**ncision type (midline worst) — **T**ension (all borne by incision) — **A**ge of wound (weakest at day 5–7) — **L**ack of muscular support.