Scrotum Anatomy and Technique PDF

ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 1 2 Scrotum & Groin textbook reference A.25 Scrotum & Groin Scrotum Anatomy & Technique Extra-testicular Pathology 1 Extra-testicular Pathology 2 Testicular Pathology 1 Testicular P...

ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 1 2 Scrotum & Groin textbook reference A.25 Scrotum & Groin Scrotum Anatomy & Technique Extra-testicular Pathology 1 Extra-testicular Pathology 2 Testicular Pathology 1 Testicular Pathology 2 Groin Hernia 3 Rumack 5th Edition • Chapter 13 (p. 470-488, 494-500) • Chapter 22 Curry 5th Edition • Chapter 28 4 Scrotum Anatomy & Technique Scrotum Anatomy & Technique • Physiology • Anatomy • Sonographic technique * * * * * * * * A.25 Scrotum & Groin https://youtu.be/9UAPhrL1OmM CT cine through male pelvis (on LEARN) 5 • Embryology scrotal wall testes coverings internal architecture vascular anatomy epididymis ductus deferens spermatic cord • Role of ultrasound 6 Key Points • Testes develop intra-abdominally from the urogenital ridge • Descend through inguinal canal into scrotum between 26-32 weeks GA * Guided by gubernaculum * Adjacent to a peritoneal diverticulum (processes vaginalis) Key Points • Know the layers of the scrotal wall & testis coverings * Skin * Dartos muscle * External spermatic fascia * Cremasteric fascia * Internal spermatic fascia from skin to testis * Parietal tunica vaginalis * Cavum vaginale (space) * Visceral tunica vaginalis 1 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 7 8 Key Points Key Points • Extensions of tunica albuginea enter the testis and divide the testis into lobules • Seminiferous tubules drain into rete testes, which drain into efferent ductules, which enter the epididymal head • Lobules contain seminiferous tubules • Rete testis enclosed in mediastinum testes • Seminiferous tubules contain: * Germ cells (precursors to spermatozoa) * Leydig cells (produce testosterone & estradiol) * Sertoli cells (nurse the developing germ cells, produce estradiol) 9 10 Key Points Key Points Vascular Anatomy Doppler • Testicular arteries arise from mid aorta • arteries supplying testis low resistance (centripetal arteries seen) * Branch to capsular artery, centripetal arteries, recurrent rami • arteries supplying extratesticular tissue higher resistance • Deferential and cremasteric arteries are not well seen • Transmediastinal artery is a common variant (50%) • Veins have low, slow flow • Pampiniform plexus drains testes to testicular veins * RT to IVC, LT to LRV (LT more likely to have a varicocele) 11 12 Key Points • Epididymis * Arises from efferent ductules and terminates in ductus deferens * Has a head, body, and tail adjacent to testis • Ductus deferens joins seminal vesicle at the ejaculatory duct, which enters the prostatic urethra Key Points • Spermatic cord contains ductus deferens, pampiniform plexus, deferential artery, lymphatics, & nerves * Inguinal canal is passageway in/out of pelvis * Internal inguinal ring in pelvis * External inguinal near scrotum Testicular physiology – heterocrine gland • Exocrine: produces spermatozoa • Endocrine: produces producing testosterone (and estradiol) 2 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 13 14 Key Points Key Points Sonographic appearance of testis • ovoid • ± prominent vessel(s) within septum • homogeneous • occasionally prominent • uniform echogenicity septa • mid-level echo intensity • hypoechoic radiating to • smooth contour mediastinum • always compare sides • transtesticular artery (50%) • Hyperechoic mediastinum • ± appendix testis (if hydrocele present) testis 15 Sonographic appearance of epididymis • Head normally seen superior to upper pole of testis * Isoechoic or slightly hyperechoic to testis * Comma shaped * 10 -12 mm • Body and tail variable in location * To find: scan in transverse * < 4 mm • ± appendix epididymis 16 The “Roots” “Joe, the plumber, had swelling in the left hemiscrotum. The differential included testicular cancer and orchitis.” Intro to Scrotum • Root from which testicular is derived is the Latin testis, which means witness terminology • Root from which orchitis is derived is the Greek orchis, which means orchid root words Why “witness” and “orchid” for testicles? 17 18 Testis and Orchis Testis Embryology • from Latin “testis” to “bear witness” or “swear under oath” Orchis • from Greek for testicle * Tuberous root of an orchid looks like testicles Orchis masculus! 3 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 19 20 Testicular Embryology Testicular Embryology • testes develop in the retroperitoneum high on embryo’s posterior abdominal wall Testicular migration (descent) • guided by gubernaculum through inguinal canal * urogenital ridge • external to a diverticulum of peritoneum, the processus vaginalis • start descent into the scrotum around 26 weeks (LNMP) • usually in scrotum by 32 weeks (LNMP) • 97% in scrotum at term 21 22 Urogenital ridge Development & Migration of Testes AKA gonadal ridge genital ridge If not down by 3 months post partum: cryptorchid • Two stage process: 1. Intra-abdominal 2. Inguino-scrotal 23 32 weeks GA 24 • Urogenital ridge Peritoneal cavity • Gubernaculum • “the rudder” • Processus vaginalis PV 10 weeks GA • outpouching of parietal peritoneum P.C. P.V. T. G. peritoneal cavity processus vaginalis testis gubernaculum 4 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 25 26 • Urogenital ridge • Gubernaculum • Processus vaginalis PV 18 weeks GA Term 27 28 Processus vaginalis closes In scrotum: • Parietal tunica vaginalis • Visceral tunica vaginalis • Cavum vaginale CV • Potential space between visceral and parietal tunica vaginalis • Normally only contains a couple of mL of serous fluid Testes descend through the inguinal canal Shortly after birth 29 30 Fetal scrotum Fetal scrotum 2 testes undescended testis 5 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 31 32 Scrotal Anatomy • • • • • • • • Scrotal Anatomy 33 Scrotal wall Testis (singular: testis) Coverings (tunics; tunicae) Internal architecture Vascular anatomy Epididymis (plural: epididymes) spelling hint: epi_didy_mis Ductus deferens (old term: vas deferens) Spermatic cord 34 Scrotal Wall • 2-8 mm thick Scrotal Wall • Multiple layers * * * * * * Skin Dartos muscle the “wrinkler” External spermatic fascia Cremasteric fascia Internal spermatic fascia Parietal tunica vaginalis Dartos helps regulate temperature 35 36 Scrotal Wall Compare Bilateral Scrotal Walls Ultrasound appearance • Thin • Echogenic COMPARE SIDES Gross difference in skin thickness in this case of trauma to left hemiscrotum 6 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 37 38 Interesting aside: Elephants are ascrotal and testicondal Outer Features • Their testes are intra-abdominal and never descend Scrotal raphe From Greek: “seam” 39 40 Testicular Anatomy • paired oval (elliptical) glands Testis • 4 - 5 cm long • 2.5 - 3 cm AP Anatomy 41 42 Testicular Coverings Testicular Coverings From parenchyma outwards: • Tunica albuginea • ‘Bare area’ • Visceral tunica vaginalis • Cavum vaginale * Potential space Cavum vaginale Bare area • Parietal tunica vaginalis 7 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 43 44 Tunica Albuginea Tunica Albuginea • Invaginates at mediastinum testis • Continuous with internal septa The strong white testicular capsule 45 46 Tunica Vaginalis • two layers of peritoneum which form a potential space (cavum vaginale) around each testis * visceral * parietal Tunica albuginea 47 48 Cavum Vaginale Bare Area • normally contains a small amount of fluid (1-2 mL) • Small region not covered by tunica vaginalis • is a potential space for accumulation of fluids, etc. • Adjacent to mediastinum testis * Hilus testis * hydrocele, pyocele, hematocele * herniation of bowel or omentum • Cavum vaginale is normally not continuous with peritoneal cavity in adult life 8 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 49 50 Internal Architecture testis 51 52 Internal Testicular Architecture Testicular Septa Rete: “net”, “network” • Each testis divided into 250 lobules by extensions of tunica albuginea called septa • 2 - 4 seminiferous tubules within each lobule • seminiferous tubules drain into rete testis at mediastinum • rete testis drains into efferent ductules and into epididymal head 53 • Not typically seen • Can be seen in some • Can be prominent with inflammatory disease 54 Wedge resection showing lobules with seminiferous tubules 9 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 55 56 Aside: Seminiferous Tubules Seminiferous Tubules • comprise 95% of testicular volume • each tubule is 30 - 70 cm long and 0.2 - 0.3 mm in diameter • ~ 500 - 1000 tubules per testis • 700 – 1400 meters of seminiferous tubules (both testes) That’s a lot of spermatozoa! 57 58 Seminiferous Tubules Seminiferous Tubules testosterone inner wall Leydig cell SPERMATOGENIC CELLS Spermatogonium (2n) (stem cell) Sertoli cell Primary spermatocyte (2n) “nurse” cell Germ cells Secondary spermatocyte (n) lumen Early spermatid (n) Late spermatid (n) Sperm cell or spermatozoon (n) lumen lumen Cross section of a seminiferous tubule 59 60 Germ Cells • Precursor cells to spermatozoon * Plural: spermatazoa • Most common source of testicular cancer * 95% of testicular tumours are germ cell tumours Leydig Cells Leydig cell Blood capillary Germ cells • Adjacent to seminiferous tubules Leydig cell Blood capillary SPERMATOGENIC CELLS Spermatogonium (2n) (stem cell) Sertoli cell Primary spermatocyte (2n) Secondary spermatocyte (n) Early spermatid (n) Spermatogonium (2n) (stem cell) • Endocrine cells * Secrete testosterone and estradiol Late spermatid (n) Sperm cell or spermatozoon (n) Sertoli cell Primary spermatocyte (2n) Secondary spermatocyte (n) Early spermatid (n) Late spermatid (n) • Rarely become malignant Sperm cell or spermatozoon (n) * Male children: precocious puberty due to ↑testosterone * Young adult males: gynecomastia due to ↑estradiol 10 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 61 62 Leydig Cells Produce Testosterone Sertoli cells Leydig cell • “Nurse” cells in seminferous tubules Blood capillary SPERMATOGENIC CELLS Spermatogonium (2n) (stem cell) Sertoli cell Leydig cell Blood capillary SPERMATOGENIC CELLS Spermatogonium (2n) (stem cell) Primary spermatocyte (2n) • Nurture spermatozoa during development Secondary spermatocyte (n) Early spermatid (n) Sertoli cell • Rarely become malignant Late spermatid (n) Sperm cell or spermatozoon (n) Primary spermatocyte (2n) Secondary spermatocyte (n) Early spermatid (n) Late spermatid (n) Sperm cell or spermatozoon (n) * young males: gynecomastia due to ↑estradiol “You need Leydig cells to dig deep holes” 63 64 Seminiferous tubule Germ cells Leydig cell 65 66 Seminiferous Tubules 3 types of cells 1. Germ cells Mediastinum Testis * Precursor cells to spermatozoa 2. Leydig cells * Testosterone and estradiol 3. Sertoli cells * Nurse cells and estradiol 11 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 67 68 Mediastinum Testis The mediastinum testis is at the periphery of the testis • A network of fibrous tissue along the length of the testis It is not in the centre of the testis * Attached to the septa * Enclosing the rete testis * Adjacent to hilum/bare area 69 70 Mediastinum Testis Gross specimen Cross-section of the human testis Drawing of a microscope slide ×2.5 magnification • An echogenic fibrous structure Transverse mediastinum testis 71 • The point of confluence of the efferent ductules and the septa • Note its triangular echogenic appearance on the ultrasound (M) and how well it correlates with the dense white fibrous stroma on the specimen (M) 72 Mediastinum Testis • In longitudinal it can be seen as a bright white line Transverse mediastinum testis (arrow) 12 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 73 74 transverse Mediastinum testis Mediastinum testis 75 76 Rete Testis • A network of tubules draining the seminiferous tubules and leading to the efferent ductules Rete testis • within mediastinum testis • Drains seminiferous tubules • Leads to efferent ductules * located within the mediastinum testis * not normally seen * can be seen when ectatic • “tubular ectasia of the rete testis” 77 78 Vascular Anatomy Testicular arteries Vascular Anatomy • Arise from _______________ Blood Vessels 13 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 79 80 Vascular Anatomy Vascular Anatomy Testicular artery branches Other arteries • capsular artery • deferential • centripetal arteries • cremasteric • recurrent rami Not typically well seen Cremasteric muscle elevates scrotum rapidly for temperature regulation 81 “Cremasteric reflex” on LEARN 82 Capsular and centripetal arteries 83 84 Transmediastinal Artery Transtesticular Artery Normal transmediastinal (transtesticular) artery seen in ~ 50% of normals common variant 14 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 85 86 Potential pitfall: May be mistaken for an intratesticular lesion in any one frame Normal transmediastinal (transtesticular) artery Watch it as you sweep through the testis! seen in ~ 50% of normals 87 88 Intratesticular artery appearing as a focal hypoechoic region Potential pitfall: may be mistaken for an intratesticular lesion Turn on it! Colour and spectral Doppler proving that this is an intratesticular artery Be a scanner, not a picture taker 89 90 Refractive shadowing from intratesticular artery 15 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 91 92 Vascular Anatomy Vascular Anatomy Testicular veins AKA spermatic veins, gonadal veins Testicular veins • pampiniform plexus * Function ______________ • Right drains into _______________ • Left drains into _______________ NB: Lymphatic system parallels vessels * Testicular malignancies metastasize to abdominal nodes (not inguinal nodes) 93 94 Normal pampiniform plexus Pampiniform plexus aids regulation of scrotal temperature 95 96 Left Testicular Vein Varicoceles are much more common on the LEFT Significance of draining into LRV: ______________________________________________ Varicoceles are much more common on the left 16 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 97 98 Testicular Veins Vascular Doppler • Normally, intrascrotal veins are not well seen Arteries supplying testis • low resistance (RI < 0.62) • Prominent intrascrotal veins with diameters >2-3 mm should make you think of a varicocele * flow in centripetal arteries should be seen Arteries supplying extratesticular tissue • higher resistance Veins • low, slow flow * ensure settings are sensitive 99 100 high resistance low resistance Normal intratesticular waveform Spermatic cord: deferential artery…high resistance Normal extratesticular waveform 101 102 Epididymis epi: above Normal vascularity didymis: the twins ALWAYS!! Compare the two testes 17 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 103 104 Epididymis Epididymis • tightly packed, coiled tube • comma-shaped structure * head (globus major) * body * tail (globus minor) H • located immediately adjacent to testis B T * head at upper pole * tail at caudal end 105 106 Where is the body of the epididymis? (Ductus Deferens) testis Tail of the Epididymis Hemiscrotum 107 108 Ductus Deferens vas deferens 18 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 109 110 Ductus (Vas) Deferens • arises from the tail region of the epididymis • ascends along the posterior border of the testis and travels into the pelvis in the spermatic cord • not usually seen 111 112 Spermatic Cord AKA funiculus spermaticus • a supporting structure which contains: Spermatic Cord * * * * ductus deferens arteries, veins (pampiniform plexus) lymph vessels but not nodes! nerves • extends from the testis into the pelvis by way of the inguinal canal 113 114 Spermatic Cord External (superficial) inguinal ring Spermatic cord 19 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 115 116 (external) (external) Inguinal Canal • passageway for the spermatic cord in the anterior abdominal wall * lateral to the symphysis pubis * superior to the inguinal ligament • frequent site of inguinal hernia 117 118 Inguinal Canal Internal (deep) inguinal ring Testicular Physiology External (superficial) inguinal ring testes are glands 4 cm long 119 120 Testicular Physiology heterocrine gland exocrine gland • spermatozoa develop in seminiferous tubules from germ cells • mature in epididymis endocrine gland • interstitial Leydig cells secrete testosterone Spermatozoa mature in the epididymis Leydig & Sertoli cells also produce estradiol 20 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 121 122 Are these structures normally visible with grey scale ultrasound? • • • • • • • • • • • pampiniform plexus rete testis efferent ductules mediastinum testis epididymis transtesticular artery testicular artery seminiferous tubules testicular septa ductus deferens spermatic cord Yes (should be small) No No Yes (hyperechoic) Yes Yes No No Occasionally No Yes Sonographic Technique Scrotum 123 124 Scrotal Technique Scrotal Technique • high frequency linear array (7 - 13 MHz) ...or higher • patient consent • patient supine • scanning in sagittal, transverse and oblique planes • scrotum supported by a towel and/or patient’s legs • special attention to the area of pain or palpable lesion or cradled in the examiner’s gloved hand? • careful palpation of scrotal contents and good history taking * has the patient had a vasectomy? • ALWAYS COMPARE SIDES!! Find a technique with which you are comfortable! 125 126 Testis Sonographic appearance • ovoid • homogeneous E Testis • uniform echogenicity • mid-level echo intensity • smooth contour Normal ovoid homogeneous testis 21 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 127 128 17 MHZ ! Transverse mediastinum testis Septae radiating to mediastinum 129 Always COMPARE! 130 Always COMPARE! This case: right was larger and hypoechoic compared to left normal, homogeneous RT testis heterogeneous LT testis 131 132 Left testis was soft, hypoechoic and tender consistent with left orchitis Compare echogenicity Pitfall: right testis ‘appears’ more echogenic due to enhancement through hydrocele 22 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 133 134 Testis Mediastinum testis Normal intratesticular structures • brightly echogenic, linear structure • mediastinum testis • invagination of tunica albuginea • ± prominent vessel(s) within septum • location of rete testis • occasionally prominent septa • usually medial * hypoechoic radiating to mediastinum * variable • transtesticular artery (50%) Do not mistake for pathology Scan in two planes 135 136 Short axis Long axis Long testis mediastinum testis Normal mediastinum testis 137 138 mediastinum Post-orchiopexy orchiopexy (orchidopexy): Fixation of the testis in the scrotum Hyperechoic, shadowing sutures NOT the mediastinum testis! 23 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 139 140 Appendix Testis • Müllerian vestigial remnant • small, polypoid soft tissue mass • arises from upper pole of testis * common (75% of adults in one autopsy series) • usually only seen sonographically in presence of a hydrocele • can torque (torsion of the appendix testis) Long: appendix testis Vestige: bodily part or organ that is small and degenerate or imperfectly developed 141 142 The appendices know these two: Appendix epididymis Appendix epididymis Appendix testis Appendix testis 143 144 Long: appendix testis 24 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 145 146 A small testicular appendage with a cyst 147 148 epi_didy_mis Sonography of the Epididymis Head AKA globus major; caput epididymis Sonography of the Epididymis Body and tail H AKA corpus and globus minor • normally seen superior to upper pole • To find: scan in transverse • isoechoic or slightly hyperechoic to testis • Diameter: < 4 mm B T • comma shaped • Diameter: 10 -12 mm 149 150 transverse Scanning and finding the epididymis Scan and locate the epididymis 25 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 151 152 Now you can take the longitudinal image Normal head of epididymis Normal head of epididymis 153 154 Body Epididymis Head Efferent ductules? 155 156 Appendix Epididymis • Wolffian remnant • small, soft tissue mass arising from the head of the epididymis • less common than appendix testis * (25% of adults in one autopsy series) • usually only seen in the presence of a hydrocele prominent body of epididymis 26 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 157 158 Head of epididymis Appendix epididymis Appendix epididymis 159 160 Appendix testis Role of Ultrasound Appendix epididymis Scrotum Transverse: appendix testis and appendix epididymis 161 162 Role of Ultrasound Role of Ultrasound (continued) Evaluation of: Evaluation of: • scrotal enlargement or palpable lesion • testicular size • follow-up of patients with prior testicular neoplasm, leukemia or lymphoma • scrotal pain • follow-up of infections • scrotal trauma • search for undescended testes • occult testicular neoplasm • metastatic nodal involvement from testicular neoplasm 27 ULTR-3016 Superficial Structures and Vascular Sonography Module A.25: Scrotum& Groin 1 Scrotum Anatomy & Technique 163 The End 28