Urethrography: Recognition of Cowper's glands and ducts

oinical RadiologY (1982) 33, 71-73 © 1982Royal Collegeof Radiologists

0009-9260/82/01560073 $02.00

Urethrography: Recognition of Cowper's Glands and Ducts JAMES J. FLANAGAN

Department of Radiodiagnosis, Addenbrooke's Hospital, Hills Road, Cambridge The urethrograms of four patients are reported in order to discuss the radiographic anatomy and pathology of Cowper's ducts and glands. Normal urethrographic landmarks like the urethral conus are of particular help in interpretation.

A Cowper's duct is only occasionally seen on adult urethrograms and probably more frequently in children (Currarino and Fuqua, 1972). Opacification of the gland as well as the duct of Cowper is a rare event in urethrography (McCallum, personal communication). This may be anticipated when spasm, a stricture and/or infection is present in the proximal urethra. Four illustrative cases are presented-two of which show gland and duct together. Contrast medium in the duct should not be mistaken for a fistulous tract or fortuitous extravasation. Furthermore, the importance of a normal urethral conus is stressed: this is a useful sign for differentiating a pathological stricture from spasm.

PATIENTS In the following four patients, ascending urethrograms were carried out in standard fashion under fluoroscopy, using water-soluble contrast media. CASE REPORTS Case 1. A 22-year-old army recruit presented with difficulty in micturition and had a past history of uretliritis, At urethrography contrast medium could not be passed beyond the external sphincter but there was filling of a Cowper's duct

Prostate ANATOMY The paired glands of Cowper are situated between the layers of the urogenital membrane (Fig. 1). Their 3-4 cm ducts run through the inferior part of the urogenital membrane to enter the bulbous urethra. They enter the ventral aspect of the penile urethra having traversed the submucosa for 2 - 2 . 5 c m (Currarino and Fuqua, 1972; McCallum, 1979). The membranous segment is an important feature in the radiographic anatomy of the urethra as is the urethral eonus. This latter term refers to the even, symmetrical tapering of the urethra just (distal) below the point at which it pierces the urogenital membrane. Any alteration in this conical shape makes an abnormality of the posterior urethra very likely. Sometimes there will be gross irregularity of this urethral segment so that the presence of an abnormality is quite obvious. However, occasionally the first and only sign of a urethral lesion may be an alteration in the normal Urethral conus.

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Fig. 1 - Diagram of oblique and frontal projection anatomy.

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CLINICAL RADIOLOGY

Fig. 2 - Contrast medium has entered a gland of Cowper-the duct is also well seen (on the posterior aspect of the urethra). Note that the urethra is quite distended because of the injection pressure applied, and that no contrast medium passes through what might be considered a stricture (in the membranous urethra). The symmetrical tapering of the urethra just below the urogenital membrane should be noted. This is a normal conus and the 'stricture' is therefore due to spasm.

Fig. 3 - Contrast medium has entered the distal part of a Cowper's duct as it enters a urethral diverticulum. A Cowper's gland is opacified and its radiographic similarity to Case 1 (Fig. 2) is apparent. (Courtesy of Dr C. D. R. Flower.)

can be distinguished from other spaces such as a fistulous tract or prostatic and ejaculatory ducts ,and gland (Fig. 2). The urethral conus just distal to the (Case 4). Recognition is of course particularly easy if narrow external sphincter (membranous urethra) is normal a Cowper's gland as well as the duct, i~ opacified. The and therefore this narrowing is due to spasm (McCallum, frond.like appearance of the normal gland is charac1979). Case 2. This 15-year-old boy had a past history of urethral teristic (Figs 2, 3). It is unlikely to be mistaken for trauma caused by the cross bar of his bicycle. He presented 3 extravasation, a fistula or other structures. In addition years later with a slow stream. A urethral diverticulum was to this appearance a knowledge of the (low) anatorn. found at urethrography (Fig. 3). This had occurred at the site ical site in the pelvis of Cowper's glands is a useful of insertion of Cowper's duct. Case 3. A 42-year-old laboratory assistant with a recurrent discriminating feature. Strictures or other urethral abnormalities were external meatal stricture was admitted to hospital for further dilatation of this lesion. A urethrogram (his first) was per- present in all four patients who showed Cowper's formed and a bulbar urethral stricture shows (Fig. 4), together duct opacification. This is in agreement with other with a Cowper's duct. Case 4. This 56-year-old man was admitted with acute reports and teaching on this subject. Cowper's ducts bladder outflow obstruction. He had a 12 months' history of are unlikely to be Filled by the normal injection frequency and dysuria, and a palpable perineal abscess was pressures applied to a normal urethra during ascending found. Several attempts to catheterise the bladder were studies in the adult. The glands themselves may unsuccessful and for this reason a urethrogram was requested occasionally be the site of disease, usually infection (Fig. 5). This showed reflux into ducts other than Cowper's, with possible abscess formation (Brodney and Robins, and serves as a useful differential diagnostic picture. 1940; McCallum and Colapinto, 1976). Such distorted glands may then be difficult to recognise if they are DISCUSSION opacified during urethrography and a good knowledg~ It is helpful to recognise Cowper's glands and of the normal duct and gland anatomy becomes ducts as u n c o m m o n l y demonstrated structures. They helpful.

URETHROGRAPHY: COWPER'S GLANDS AND DUCTS

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Fig. 4 - The meatal stricture is not included. Note the bulbar stticutre with opacification of a Cowper's duct. An asymmetricalurethra is demonstrated and therefore the urett~ral conus sign is absent, indicating that a true stricture is present (as opposed to spasm). (Courtesy of Professor T. Sherwood.)

Fig. 5 - An obvious perineal fistula is present. Reflux into prostatic ducts has occurred, It is clear that these features will not be mistaken for a Cowper's duct, The high (proximal) pocket of contrast (arrow) does not bear the radiographic architecture of a Cowper gland, moreover it lies too high in the pelvis above the membranous urethra or urogenital membrane. It is a seminal vesicle.

The urethral conus is seen on ascending urethrograms as a pointer to a normal urethral segment just below the urogenital diaphragm. This finding has helped interpretation of the patients presented in this paper. To make good use of this sign it is worth while remembering that radiographs should be exposed during injection of the contrast medium ('dynamic urethrography') as advocated by McCallum (1979).

Acknowledgements. I am grateful to Professor T. Sherwood for his encouragement and advice. My thanks to Dr R. W. McCallum, Dr C. D. R. Flower, MrP. W. Sergeant and Dr M. J. Brindle. I would also like to thank Miss Anita Wright for typing the manuscript.

CONCLUSION Cowper's ducts and glands are not often seen but radiologists can have a considerable advantage in urethrogram interpretation because of acquaintance with the simple radiographic anatomy of this area.

REFERENCES

Brodney, M. L. & Robins, S. A. (1940); Urethrography in bulbo-urethral adenitis. Journal o f Urology, 43, 844-850. Currarino, G. & Fuqua, F. (1972). Cowper's glands in the urethrogram. American Journal o f Roentgenology, 116, 838-842. McCallum, R. W. & Colapinto, V. (1976). UrologicalRadiology of the Adult Male Lower Urinary Tract, p. 41. C. C. Thomas, USA. McCallum, R. W. (1979). The adult male urethra. Radiological Clinics o f North America, XVII, 11,227-244.