Hip Acute onset of limp and refusal to bear weight are common presenting complaints to the pediatric ED In some patients, it can be difficult to localize the site of pain and the differential diagnosis is broad Point-of-care hip ultrasound is primarily used to detect joint effusions and can be useful in the evaluation of pediatric patients who present with limp or refusal to bear weight Ultrasound is more sensitive than radiographs for the detection of hip effusions in children and is therefore suggested as the imaging modality of choice for the initial evaluation of patients presenting with irritable hip Anatomy With the patient lying supine, the femoral head can easily be identified and appears as a round, hyperechoic structure with posterior shadowing In growing children, a notch can be seen in the femoral head, which represents the physis The femoral neck is the curvilinear hyperechoic structure extending distally from the femoral head Superficial to the femoral neck, the muscle fibers of the iliopsoas muscle can be seen running directly above the joint capsule (Fig 131.13 A ) An effusion is identified by the presence of fluid deep to the iliopsoas muscle (Fig 131.13 B ) Technique The patient should be positioned supine with the legs extended and the hips in neutral position to allow for pooling of any joint fluid A linear, high-frequency probe is positioned parallel to the femoral neck in the sagittal plane The probe marker should be pointing to the patient’s umbilicus (Fig 131.14 ) An effusion is identified by the presence of an anechoic fluid collection deep to the iliopsoas muscle in the synovial space, bordered by the synovial capsule (Fig 131.13 ) Once the capsule is identified, the distance between the anterior surface of the femoral neck and the posterior surface of the iliopsoas muscle is measured for each hip A measurement of greater than or equal to mm or a difference of greater than mm from the contralateral hip is considered positive for an effusion FIGURE 131.13 A: Normal hip B: Hip effusion (arrow ) Pitfalls It is important to obtain images of both hips because comparison views of the unaffected side can be helpful in identifying true pathology versus an anatomical variant As with all musculoskeletal ultrasound, it is important that the probe be held perpendicular to the skin and as parallel to the femoral neck as possible; a slightly oblique angle may cause the synovial space to appear falsely hypoechoic (an artifact known as anisotropy) Finally, these authors have found that the accepted criteria for the diagnosis of hip effusion may be misleading in some patients A patient with small bilateral effusions (less than mm) may not meet official criteria by measurements, but if the joint space appears convex with anechoic fluid within it, an effusion is likely present FIGURE 131.14 Probe position for hip ultrasound GENITOURINARY ULTRASOUND First Trimester Ultrasound Abdominal pain in the pregnant adolescent female is a common presenting complaint The differential diagnosis is broad, ranging from benign self-limited conditions to a spectrum of life-threatening and organ-threatening conditions Ectopic pregnancy must be identified and treated rapidly It is the leading cause of maternal mortality in the United States and has a reported prevalence as high as 8% for a pregnant patient presenting to the ED Multiple studies have demonstrated the value of emergency bedside ultrasound to evaluate first trimester pregnant patients with vaginal bleeding or abdominal pain, specifically in ruling in those patients with a normal intrauterine pregnancy (IUP) and thus, ruling out ectopic pregnancy A pregnancy of only to weeks’ gestation can usually be seen Not only is there excellent sensitivity and specificity for identifying an IUP by bedside ultrasound, there is also reduction in the time to definitive therapy in patients with an ectopic pregnancy, as well as reduction in the length of stay in patients with IUPs The basic question that needs to be answered in first trimester ultrasound is: “Is there an intrauterine pregnancy?” By virtue of visualizing an IUP, an ectopic pregnancy is ruled out by exclusion, except in rare cases of multiple gestation pregnancies with concomitant ectopic pregnancies and IUPs In patients with increased risk of heterotopic pregnancies, confirming an IUP does not obviate the need to search for an ectopic pregnancy when there is clinical suspicion This subset of pregnant patients should always have a formal comprehensive ultrasound done by the radiology or gynecology service Anatomy The bladder lies anterior to the uterus This relationship allows a full bladder to be used as an acoustic window to visualize the uterus An empty bladder renders the transabdominal approach much more difficult When the bladder is empty, the uterus will often lie more anterior and superior and the transvaginal approach is preferred to maximize visualization of the uterus Technique Either a transabdominal or transvaginal technique can be used to assess for IUP A low-frequency curvilinear or phased array probe should be used for the transabdominal approach As detailed above, transabdominal sonography should be performed through a distended urinary bladder This may not be practical in a busy ED The probe should be positioned longitudinally just above the pubic symphysis and directed through the bladder to visualize a longitudinal view of the uterus, cervix, and pouch of Douglas with cephalad structures on the left side of the monitor (Fig 131.15 ) In the nonpregnant female, the endometrial stripe may be visualized without any uterine contents The ovaries can often be visualized by sliding the probe laterally and directing the beam toward the opposite side; compression of the abdominal wall externally may also aid with visualization Transverse images should also be obtained and may allow for visualization of the uterus and adjacent adnexa in the same image ... 8% for a pregnant patient presenting to the ED Multiple studies have demonstrated the value of emergency bedside ultrasound to evaluate first trimester pregnant patients with vaginal bleeding