Ultrasound of the Reproductive System Stacy Fielding

Technique 7.5-10mHz transducers Dorsal recumbency is routine 5 mHz in mid to late term pregnancy, pyometra, ovarian tumors Dorsal recumbency is routine Larger animals standing Full bladder enhances visualization of uterus Acoustic window

Ovaries Near caudal pole of kidney 1.5cm x 0.7cm x 0.5cm Homogenous parenchyma Cortex and medulla Hard to differentiate Cortex contains follicles

Ovaries-cont’d Anestrus/early proestrus Diestrus Small, oval to bean shaped Homogenous echogenicity (like renal cortex) Follicles anechoic, become larger as ovulation approaches Diestrus CL/CH has multifocal anechoic to hyperechoic areas

Ovarian Structures

Ovaries Cystic Ovaries Ovarian Neoplasia Anechoic Thin walls Acoustic enhancement Solitary/multiple Unilateral/bilateral May see associated pyometra or hydrometra Ovarian Neoplasia Several kinds Mostly unilateral Smooth or irregular margins Variable appearance MET CHECK!

Normal Uterus Location: between urinary bladder and descending colon Various sizes Uterine horns: 10-14cm x 0.5-1.0cm Uterine body: 1.4-3cm x 3cm Cervix: 1.5-2cm x 0.8cm Solid, homogenous, relatively hypoechoic May have thin hyperechoic border Cannot differentiate layers

Normal Uterus-cont’d Uterine horns not easily identified Cervix Lost in mesenteric fat and small bowel echoes Cervix Hyperechoic, linear

Pyometra U/S is modality of choice for Dx Enlarged uterus & uterine horns Luminal contents Homogenous, anechoic Echogenic, “swirling” May see varying wall thickness Endometrium may contain anechoic foci Ddx: hydrometra, mucometra Monitor response to therapy

Uterine Neoplasia Adenomas Leiomyomas Leiomyosarcomas Isoechoic to surrounding tissue, may project into the lumen

Pregnancy Diagnosis 21-35 days after breeding Remember conception can occur several days afterward May be difficult to count fetuses Radiography recommended late in gestation, following mineralization Earliest change = enlarging uterus Non-specific Gestational sac (blastocyst) First confirmatory sign Anechoic, several mm diameter Thin, hyperechoic wall 17-20 d

18 day pregnancy

Pregnancy-cont’d Embryo: 23-25 d Yolk sac: 25-28 d Oblong, echogenic, several mm Yolk sac: 25-28 d U-shaped echogenic structure Extends across gestational sac Zonary placenta: 27-30d Thin hyperechoic layer surrounding gestational sac

Fetal Viability Cardiac activity Fetal movement Fetal resorption Day 23-25 post LH surge Fluttering echoes Fetal movement Day 35 Fetal resorption before day 25 Embryonic fluid becomes hypoechoic Echogenic particles Abortion After day 35 Sonographic appearance disappears

Organogenesis (From Nyland & Mattoon) Fetal Structure Days Post LH Surge Fetal orientation 28 Limb buds 35 Skeleton 33-39 Stomach, bladder 35-39 Lungs 38-42 Kidneys, eyes 39-47 Cardiac chambers 40 Intestines 57-63

Prostate Caudal to bladder, at level of trigone Ventral to rectum Normal appearance varies Age Neuter status Young to middle age intact male: homogenous, moderate echogenicity Smooth margins, hyperechoic rim Prostatic urethra Hypoechoic to anechoic round structure on midline

Prostate Diseases Benign Prostatic Hyperplasia Prostatitis Older intact dogs Symmetrical enlargement May be up to 4 times normal Variable echogenicity and texture Prostatitis Acute or chronic Symmetrical or asymmetrical Heterogenous appearance May see hypoechoic areas (cyst or abscess) Mineralization, fibrosis

Prostate Diseases Neoplasia Cysts Paraprostatic Cysts Older neutered dogs Enlarged Irregular shape Texture varies Hyperechoic foci with acoustic shadowing = mineralization May see cyst-like lesions Examine surrounding structures! Cysts Developmental or congenital Anechoic contents Thin hyperechoic wall Vary in size and # Paraprostatic Cysts Muellerian duct remnant or extension of lobe Anechoic, fluid filled May see swirlies Variable wall thickness May see compartments

Prostatic Cyst www.merckvetmanual.com

Testes Homogenous texture Parietal and visceral tunics: hyperechoic Mediastinum testis: Echogenic linear structure on midline Tail of the epididymis Nearly anechoic Coarse echotexture

Testicular Neoplasia Interstitial, Sertoli cell, seminoma May all appear the same Mixed appearance on U/S Hemorrhage Necrosis May obliterate mediastinum testis +/- epididymis

Testes-cont’d Retained testes Orchitis Small size Caudal to kidneys to inguinal canal Difficult to see on U/S Orchitis Patchy, hypoechoic parenchyma Hyperechoic if chronic Epididymal enlargement Abscesses Irregular shaped Hypoechoic contents May look like neoplasia!