Postpartum Sacral Stress Fracture in a Primiparous Woman: A Case Report

Sacral stress fractures are rare in young adults and are an uncommon cause of postpartum lumbosacral pain. Due to nonspecific symptoms and frequently normal initial radiographs, diagnosis is often delayed. Increased mechanical loading and pregnancy-related biomechanical changes are thought to contribute to their development. We report the case of a 32-year-old primiparous woman who presented with progressive low back and unilateral buttock pain beginning 18 days after an uncomplicated vaginal delivery. Physical examination revealed focal sacral tenderness and pain with provocative sacroiliac maneuvers. Laboratory investigations were unremarkable except for vitamin D insufficiency. Plain radiographs were normal. Magnetic resonance imaging (MRI) demonstrated a unilateral stress fracture of the left sacral ala with associated bone marrow edema. Bone mineral density assessment showed normal values, supporting a fatigue-type fracture. The patient was treated conservatively with activity modification, analgesia, and calcium-vitamin D supplementation. Complete symptom resolution was achieved within 10 weeks. Postpartum sacral stress fractures should be considered in women presenting with focal sacral pain that worsens with weight-bearing, even in the absence of metabolic bone disease. Early MRI facilitates prompt diagnosis and prevents unnecessary diagnostic delays. Conservative management is usually effective and results in excellent clinical outcomes.