FIGURE 131.15 Longitudinal view of uterus through the bladder Arrows designate the potential space of pouch of Douglas posterior to uterus An endocavitary probe should be used for the transvaginal approach Although the transvaginal transducer is of higher frequency and produces sharper images, the field of view is more limited The bladder should be emptied prior to performing the scan After the probe is cleaned and covered, it is inserted into the vaginal canal with the marker facing anteriorly It often helps to have the anxious patient insert the probe into the vaginal canal herself A standard transvaginal longitudinal view is obtained (Fig 131.16 ) Once the longitudinal view is obtained, the probe should be rotated such that the marker is to the patient’s right to obtain a transverse view With each planar view, it is important to fan the probe along the scanning plane axes to visualize the entire body of the uterus More experienced sonographers may also be able to visualize the fallopian tubes and ovaries, but it is important to emphasize that the purpose of the examination is primarily to determine the presence or absence of an IUP FIGURE 131.16 Standard transvaginal view of uterus In normal pregnancy, the earliest sonographic finding of an IUP is the gestational sac, which appears as a round fluid collection within the uterus ( Video 131.15 ) In transabdominal scanning, the gestational sac can be seen as early as to weeks’ gestational age Transvaginal scanning can reliably detect this finding about to 10 days earlier The yolk sac can be seen inside the gestational sac at approximately to weeks’ gestational age (5 to weeks by transvaginal scanning) and most authors consider this as definitive evidence of IUP A normal embryo will appear at the margin of the yolk sac at about 6.5 to 7.5 weeks’ gestational age and cardiac activity can be detected shortly thereafter ( Video 131.16 ) In the pregnant female, the standard for confirming an IUP on an emergency physician performed bedside ultrasound requires visualization of an intrauterine yolk sac, fetal pole, or intrauterine fetal heartbeat Visualizing only the gestational sac is not adequate as this can be the result of hormonal stimulation from an ectopic pregnancy When a fetal heartbeat can be seen, it should be documented with M-mode In an ectopic pregnancy, an adnexal mass or free fluid in the pelvis can sometimes be seen However, visualization of the ectopic pregnancy should not be the goal of the emergency physician Several protocols have been developed addressing the use of bedside pelvic sonography in the pregnant female In general, if an IUP is not seen in a patient with a positive urine B-HCG, gynecology consultation should be arranged A low-serum HCG level, implying an early IUP, may allow outpatient follow-up with precautions for possible ectopic pregnancy Pitfalls A pregnancy less than weeks’ gestational age (3 weeks post conception) may not be visible The gestational sac should be located off-center and should have a circular appearance; elliptically shaped, centrally located sacs are concerning for an abnormal sac that may not be representative of an IUP Kidney Ultrasound Kidney ultrasound provides important diagnostic information in patients presenting with hematuria and/or abdominal pain Nephrolithiasis is an increasingly recognized cause of pediatric abdominal pain and bedside ultrasound offers the ability to quickly determine a diagnosis in the patient presenting with obstructive nephropathy Early obstruction may initially only result in hydroureter but as the obstruction persists, hydronephrosis will develop Identification of hydronephrosis in a patient with undifferentiated abdominal pain can help to focus further treatments for presumed nephrolithiasis and often precludes the need for additional diagnostic tests While nephrolithiasis is the most common cause of acute obstructive nephropathy, the possibility of extrinsic compression should also be considered Ultrasound has become the first-line imaging modality in cases of suspected renal colic The pediatric literature is limited to case reports regarding the use of bedside ultrasound for evaluation of renal pathology In contrast, adult literature has shown that bedside ultrasound is sensitive and specific for identification of hydronephrosis secondary to obstructive uropathy in patients with renal colic Anatomy Bilateral kidneys are located in the retroperitoneum, with the left kidney located slightly more cephalad than the right The kidneys are obliquely oriented with the upper pole oriented medially and posteriorly The kidney, along with the adrenal gland, is surrounded by Gerota fascia, a hyperechoic linear structure The outer layer of the kidney comprises the renal cortex, a hypoechoic homogeneous tissue with anechoic-appearing medullary pyramids interspersed In the central kidney the calyces, which appear hyperechoic due to the fat in the area, converge to form the renal pelvis In the inferior central kidney, the central hilum houses the entry site of the ureter, renal vein, and renal artery (Fig 131.17 ) FIGURE 131.17 Normal kidney Note that on the right side, the liver may be used as an acoustic window Technique The same approach used to perform the FAST should be used to perform a focused image of the kidney A low-frequency abdominal probe will allow for best imaging and, in pediatric patients, a probe with a small footprint is often preferable given the position of the kidneys within the thoracic ribcage The patient can be in the supine or decubitus position The probe marker should be positioned toward the head for the long-axis image and then rotated 90 degrees to perform the short-axis image Obstructive ureteronephrolithiasis may initially cause dilation of the ureter, which can be noted at the level of the central hilum With worsening obstruction and progression to hydronephrosis, the calyces and renal pelvis will dilate and the central region of the kidney will become anechoic ( Video 131.17 ) Identification of an obstructive stone is often difficult but, when noted, may appear hyperechoic and cause shadowing (Fig 131.18 ) ... shortly thereafter ( Video 131.16 ) In the pregnant female, the standard for confirming an IUP on an emergency physician performed bedside ultrasound requires visualization of an intrauterine yolk... sometimes be seen However, visualization of the ectopic pregnancy should not be the goal of the emergency physician Several protocols have been developed addressing the use of bedside pelvic sonography... presenting with hematuria and/or abdominal pain Nephrolithiasis is an increasingly recognized cause of pediatric abdominal pain and bedside ultrasound offers the ability to quickly determine a diagnosis