Diagnosis of femoral shaft fracture in pregnancy by ultrasound.

A 29 year old woman, known to be eight weeks pregnant, presented to the accident and emergency department having twisted and fallen onto her left leg while playing netball. The limb was painful and she was unable to weight bear. On examination there was no deformity or swelling but the entire leg was painful and the patient was unable to locate an area ofmaximal tenderness. There was no neurovascular deficit or systemic disturbance. Initially, because of the relatively trivial nature of the trauma, soft tissue injury was suspected. The patient's symptoms, however, were disproportionately severe and a pelvic radiograph was requested to rule out bony injury of the hip. The radiographer was reluctant to irradiate an early pregnancy particularly as the index of suspicion of serious injury was low. A portable ultrasound scan was requested with the intention of excluding soft tissue haematoma or an effusion at the hip joint. Ultrasound examination of the hip joint was normal. However, on wider examination of the leg, an area of focal tenderness over the anterior aspect of the mid-thigh (not apparent from the patient's presenting symptoms or evident on initial examination) was found. The femoral shaft was visualised and a discrete discontinuity in the cortex was seen (fig 1). Slight displacement of the femoral shaft below this was also noted. There was no evidence of significant haematoma overlying the upper femoral shaft, in keeping with the lack of soft tissue swelling clinically. The diagnosis of femoral shaft fracture with distal angulation was made on the basis of the ultrasound examination. A limited radiography examination, with appropriate pelvic shielding, confirmed the diagnosis (fig 2) and excluded associated injury at the hip. There was no evidence of underlying bony pathology at the fracture site, which radiographically appeared normal. There was no history to suggest a stress fracture. The fracture was treated initially on a Thomas splint and was subsequently fixed surgically with an intramedullary nail. During surgery there was full shielding of the fetus and a minimum of fluoroscopic screening was used. The fracture subsequently united uneventfully and the patient went on to deliver a healthy baby at full term. Ultrasound is a useful investigation in cases of trauma but its use is usually limited to abdominal injury. Our case illustrates the Figure 1 Ultrasound image: longitudinal view of the left mid-femoral shaft showing the fracture (normal cortex, solid arrowheads; cortical discontinuity offracture, open arrowhead).