PEDIATRIC EMERGENCY ULTRASONOGRAPHY: TRICKS OF THE TRADE

KL Moreng MD, RM VanHulle MD, DA Bloom MD, MR Aquino MD, DP Gibson MD, Section of Pediatric Imaging,Beaumont Children’s Hospital , Beaumont Health Systems, Oakland University William Beaumont School of Medicine, Royal Oak, MI

TORSION OF THE APPENDIX TESTIS

HYPERTROPHIC PYLORIC STENOSIS

OVARIAN TORSION

REFERENCES1. Aso C, Enríquez G, Fité M, et al. Gray-scale and color Doppler sonography of scrotal disorders in children: an update. RadioGraphics 2005; 25: 1197–1214.2. Hernanz-Schulman M. Infantile Hypertrophic Pyloric Stenosis. Radiology 2003; 227:319-331.3. Puylaert JBCM. Acute Appendicitis: US Evaluation Using Graded Compression. Radiology 1986;158:355-360. 4. Servas S, Zurakowski D, Laufer MR, et al. Sonographic findings of ovarian torsion in children. Pediatric Radiology 2007 May; 37 (5):446-451.5. Siegel MJ, ed. Pediatric sonography. 3rd ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2002.

TESTICULAR TORSION

Xiphoid process. The gastric antrum is identified by air and fluid. If the stomach is distended with gas, repositioning the patient to left anterior oblique or right side down decubitus allows the antrum to fill with fluid to better evaluate the pylorus. A useful technique is to feed the infant Pedialyte or formula/breast milk before repositioning the patient into right decubitus for clearer visualization of the pylorus. If the stomach is distended, the pylorus is sometimes found by scanning through the flank/liver.

spermatic cord and inguinal canals. Extratesticular and testicular vascularity should be evaluated using color Doppler set to detect low flow velocities for the asymptomatic testis and then compared. Power Doppler may be used but has higher sensitivity to low flow and is more susceptible to movement.

Technique:A transabdominal approach is undertaken. Transvaginal imaging can be done if the patient is sexually active or has had a prior pelvic exam. The urinary bladder is filled by oral hydration, intravenous hydration or Foley catheter. Use of a curvilinear or sector transducer is typical. It should be remembered that the ovary may be cephalad to the uterus or behind the bladder. Color Doppler is useful to compare ovarian blood flow, but its presence does not exclude ovarian torsion.

Technique: Same as for Testicular Torsion.

Findings: 1-3 hours: Normal testicular architecture. 4-6 hours: Enlargement and heterogeneous echogenicity of the affected testis. The twisted spermatic cord (torsion knot) is seen as a redundant twisted structure above the testicle. Presence of Doppler flow in the normal testis and absent or decreased flow in the affected testis. >24 hours: Heterogeneous echotexture, significant testicular enlargement, marked hyperemia of the scrotal wall and paratesticular soft tissues and absent testicular flow, all evidence of testicular infarction and necrosis (missed torsion).

Findings:Small hyperechoic or hypoechoic mass adjacent to superior aspect of testis or epididymal head.Associated finding include an enlarged and hypoechoic testicle and/or epididymis, reactive hydrocele and skin thickening. An infarcted appendix may calcify and detach, becoming a scrotolith. Color Doppler demonstrates epididymal/testicular hyperemia and the avascular torsed appendix testis.

Findings:Enlarged ovary, free fluid in the cul-de-sac and a dilated fallopian tube. The most specific finding in adolescents is a solid ovary with multiple, small 8-12 mm peripheral cysts - the “string of pearls” sign. Cysts and solid masses may be found in association and as the cause of the ovarian torsion.

Findings: The pylorus is typically uniformly hypoechoic. The abnormal pyloric muscle should be ≥ 3-4 mm and the pyloric channel ≥ 14-20 mm. Ancillary signs include the antral mucosal nipple sign- prolapsed pyloric channel mucosa into the gastric antrum, double-track sign- presence of linear sonolucent stripes of fluid in the crevices of the pyloric mucosa, minimal gastric emptying,

Fig 4. a. Left ovary normal in echotexture with small follicles. b. Enlarged and heterogenous right ovary with peripheral follicles and through-transmission. c. and d. Flow along periphery of right ovary anteriorly by color and spectral Doppler.

Fig 2: a. Enlarged pyloric muscle measuring 4 mm in thickness b. Pyloric channel length of 14 mm.

a b

Technique: A high frequency linear arraytransducer is chosen depending on infant size and pylorus depth. The patient is scanned in the supine position and the probe in the transverse plane immediately below the

Tricks:Use Pedialyte to outline the pylorus and move air to the fundus. Scan in left anterior oblique or right side down decubitus position. Use the liver as an acoustic window if the stomach is already overdistended. Scanning through the back can help in certain cases (Image 1) . Identify the abnormal pylorus by its resemblance to the uterus (another thickened muscle). Avoid sector or curvilinear transducers. gastric dilatation with fluid and exaggerated peristaltic waves in the gastric antrum (pyloric teet).

INTESTINAL INTUSSUSCEPTION

Findings: The intussusception presents as a mass with a hypoechoic rim and echogenic center or multiple concentric rings of alternating echogenicity (the target sign). In the longitudinal plane there are hypoechoic layers on each side of an echogenic center giving a pseudo-kidney appearance or sandwich sign. Other findings can include free peritoneal fluid and trapped fluid in the intussusception. Lead points can be found which include Meckel’s diverticulum, duplication cysts and lymphoma (especially Burkitt lymphoma).

Fig 1. a. Transverse target appearance at splenic flexure. b. Longitudinal – sandwich sign. c. Blood flow demonstrated to all portions of the intussusception.

a b c

Technique:With the patient in supine position, the entire abdomen and pelvis should be scanned in longitudinal and transverse planes using a high frequency linear transducer. The colon should be traced from right to left. Most idiopathic intussusceptions are ileocolic.

Tricks:Look for the target sign. Trace the entire course of the intussusception. Look for signs of small bowel obstruction on ultrasound. Look for potential lead points. Try and distinguish ileocolic intussusception from small bowel-small bowel intussusception (size).

Tricks:Look for the “sting of pearls” sign. Look for uterine deviation towards the side of torsion. Have a high index of suspicion when there is ovarian enlargement even with the presence of some Doppler flow.

Technique: The patient is in supine position with the scrotum gently elevated by supporting towels between the thighs. Abundant warm gel should be applied to reduce friction and pain. Both testes should be scanned in longitudinal and transverse planes using high frequency, linear array transducers . It is essential to evaluate the upper scrotal sac,

Tricks: Use transverse imaging of both testes to compare, including color Doppler flow. Set your color and spectral gains to the asymptomatic side and without changing settings, compare to the symptomatic testis. Look for the torsion knot. Always scan the inguinal canal.

a b

c d

Fig 5. a. and b. Twisted spermatic cord above right testicle. c. Presence of flow within the left testicle but no significant flow within the right testicle.

a b c

Fig 6. a. Homogeneous right testicle. b. Complex fluid collection surrounding the left testicle, scrotal wall and skin thickening. c. Marked hyperemia within the left epididymis and left testicle. d. Heterogenous echogenic 9 mm x 5 mm left testicular appendage (arrow) without flow, consistent with torsion of the testicular appendix.

a b c d

Tricks:Most prepubertal boys will have a torsed appendix testis as the cause of reactive “epididymo-orchitis”, as compared to infection in older boys who are sexually active. Follow up ultrasound to make sure this resolves is useful.

superimposed gas-filled bowel loops. Patient cooperation maximizes the efficiency of the exam by localizing the site of pain for the ultrasonographer. Visualization of the psoas and iliac vessels indicate adequate penetration of the abdomen.

ACUTE APPENDICITIS

Findings:A normal appendix should be tubular, ≤ 6 mm in diameter, compressible and blind-ending.An inflamed appendix is typically fluid-filled, non-compressible, and > 6mm in diameter. If transverse to the appendix, a target appearance is seen. An appendicolith is an echogenic focus with acoustic shadowing. .

Technique:Evaluation of the appendix is best done with a high frequency linear-array transducer and in supine position. Utilization of graded compression technique is recommended. The transducer applies gentle compression which is gradually increased during expiration, allowing for a shorter distance between the transducer and the appendix, and displacing

Tricks:Have the patient point to the region of maximal tenderness and start there. Use color and power Doppler to localize the inflamed appendix. Coronal scanning along the flank can find the occasional retrocecal appendix (Image 2). Use your other hand from behind to increase graded compression.

Fig 3: a. Noncompressible, fluid and debris filled 10 mm appendix. b. 8 mm appendicolith with shadowing c. Hyperemia of the dilated distal appendix.

a b c

Image 1

Image 2