Nonobstructive right circumcaval ureter associated with double inferior vena cava

Nonobstructive right circumcaval ureter associated with double inferior vena cava

NONOBSTRUCTIVE RIGHT CIRCUMCAVAL URETER ASSOCIATED WITH DOUBLE INFERIOR VENA CAVA R. NURI SENER, M.D, From the Department of Radiology, Private Hosp...

2MB Sizes 0 Downloads 5 Views

NONOBSTRUCTIVE RIGHT CIRCUMCAVAL URETER ASSOCIATED WITH DOUBLE INFERIOR VENA CAVA R. NURI SENER,

M.D,

From the Department of Radiology, Private Hospital of Isparta, Isparta, Turkey ABSTRACT-Computerized tomography (CT), intravenous pyelography @VP), and ultrasound characteristics of nonobstructive right circumcaval ureter associated with double inferior vena cava in an adult is presented. The CT appearance of the retrocaval segment of the circumcaval ureter which was detected as a “thin, long line” suggests it might be a useful sign in the incidental diagnosis of the anomaly even on noncontrast-enhanced abdominal CT examination. Because of the unique 1VP appearance of circumcaval ureter in this case, a new classification is presented.

Retrocaval ureter is a developmental defect of the inferior vena cava (IVC) rather than a ureteral anomaly.’ True retrocaval ureter in which the ureter length runs behind the IVC and some variants of it which may be associated with various vascular anomalies are rare.1-3 One of these rare entities is the association with double vena cava which has mainly been diagnosed at autopsy or at an operation.2,4*5 The so-called circumcaval ureter in which the proximal right ureter courses medially behind and then anteriorly around the inferior vena cava to partially encircle it, is the common form of the anomaly. 2~6This has further been classified into two distinctive types by intravenous and retrograde pyelography. The vast majority are those with

obstruction and only a few without obstruction.2,7J Up to the present time there are a few reports of computerized tomography (CT) demonstrating circumcaval ureters, usually the obstructive types.s.eJo

FIGURE1. IVP at fijteen minutes shows bilateral normal pelvocaliceal systems without obstruction and kink at right ureteropelvic junction. From this point right ureter follows abnormal course (almost horizontally) toward LZ-L3 interspace (created by circumcaval route of right ureter [see Fig. 4B, type 21). Distal right ureter cannot be seen as was also the case with prone and lateral positions on x-ray films and CT. On left side, proximal ureter shows arc-like appearance of middle third running near lateral margin of psoas muscle toward medial sacroiliac joint. This lateral displacement due to persistent left zvc.

UROLOGY

I

APRIL 1993 / VOLUME

41, NUMBER4

FIGURE 2.

US at level of third lumbar vertebra (transverse scan): Left side IVC shown closer to aorta and right shown as more oval vascular structure. They formed single vessel anterior to aorta at level of upper pole of right kidney and then drained into right atrium with normal caliber (A0 = aorta; LIVC = left injerior vena cava; RZVC = right inferior vena cava.)

The case presented herein-apart from its association with double WC and lateral displacement of the left ureter because of the left IVCshows a kink at the ureteropelvic junction of the nonobstructed right ureter on IVP which is in contrast to previous reports,2 thus expanding the previous classifications. Also, the CT appearance of the ureteral segment behind the right IVC, shown as a thin, long line that does not seem to retain intravenous contrast medium,2.6 suggests that even on noncontrastenhanced CT scans, this can be used to make an incidental diagnosis of nonobstructive circumcaval ureter in symptomless patients. Case Report A thirty-six-year-old normotensive man without any significant clinical findings had a history of being successfully treated for mild urinary tract infection six years before. He had never experienced flank pain, renal colic, or hematuria. Results of blood studies and urine analysis were normal. On intravenous pyelogram (IVP) (following intravenous injection of 40 cc meglumine diatrizoate and sodium diatrizoate, ratio 66: 10 %) the proximal right ureter showed a kink at the ureteropelvic junction and coursed almost horizontally toward the L2-L3 intervertebral space, and the left ureter ran at the lateral margin of the psoas muscle creating an arc medially toward the sacroiliac joint. The

UROLOGY

/

APRIL

1993

/

VOLUME

41, NUMBER 4

pelvocaliceal systems of both kidneys were normal (Fig. 1). On ultrasound (US) examination the kidneys were normal. There were two great vessels besides the aorta-the left one running closer to it-which represented the right and left IVC (Fig. 2). The left renal vein could be identified draining into the left IVC. Both great veins were joined to form a single vessel at the level of the upper pole of the right kidney and drained into the heart (vessel was 1.7 mm wide at this level). On CT examination both IVC were easily seen, and the azygos vein (as wide as 8 mm) could be detected, but the hemiazygos vein was not apparent (Fig. 3). The left renal vein joined the left IVC (Fig. 3A), and the left ureter ran lateral to the left IVC (Fig. 3B, C). The nonobstrutted right ureter coursed behind the right IVC. The proximal part of the retrocaval portion of the right ureter (5 mm in width, tapering gradually) contained contrast medium and some compression of the right IVC was evident (Fig. 3A, B). The more distal part (1 mm in width) was seen without contrast medium inside and was as long as 2 cm (posterolateral to anteromedial) within a scan slice of 9.0 mm thickness (Fig. 3C). Several more scans obtained up to the first hour of injection of the contrast medium did not show any enhancement of this “thin and long” segment as well as the distal right ureter. Since both IVC were easily seen on CT scans, contrast medium injections into pedal veins to enhance them was thought unnecessary. Also, retrograde pyelography or inferior venacavography was thought to be unnecessary, and no treatment was required because of absence of obstruction. Follow-up by laboratory evaluation for urinary tract infection as well as follow-up sonogram of the right kidney, and, if required, IVP were recommended. Comment Circumcaval ureter results from anomalous development of the IVC in which the fetal posterior cardinal vein fails to regress, becoming a major portion of the infrarenal inferior vena cava which subsequently produces medial displacement of the ureter following lateral migration of the kidney, 1 The anomaly develops almost exclusively on the right side, but 1 case of bilateral involvement and 1 case of left-side retrocaval ureter associated with situs inversus have also been reported.2,3 By persistence of

357

3. Consequent transverse CT scans beginning below pedicles of L2 (with g-mm slice thickness within region of 18.6 mm thickness). Right and left IVC clearly identijied (A, B, C). Left renal vein drains into left ZVC(A). Left ureter runs lateral to left ZVC(B, C), and both of them were detected more laterally placed on lower scans. Somewhat dilated axygos vein can be seen while hemiazygos vein cannot (A, B, C). This may suggest an additional anomaly such as absence of hemiazygos vein although x-ray film of lungs was normal without prominence of azygos vein. Proximal right ureter (about 5 mm in width) tapers gradually (A) and some compression of right ZVC shown (B). More distal segment (retrocaval port,ion) shown 2 cm long and 1 mm wide. (C) Anterior end of retrocaval portion of ureter shown at level of anterior border of right ZVC, confirming circumcaval nature of anomaly. Neither this segment nor distal right ureter could be detected with contrast medium on several scans obtained up to one hour. FIGURE

fetal right and left supracardinal veins, the anomaly of “double inferior vena cava” occurs and is classified as type BC by Chuang, Mena, and Hoskins.” They also have termed the persistence of fetal right posterior cardinal vein as type A.” According to this classification the present case can be identified as type A and type BC. Also, because a somewhat dilated azygos vein can be seen but not the hemiazygos vein, an additional anomaly such as the absence of the hemiazygos vein may be present, although the chest x-ray film was normal without prominence of the azygos vein. The frequency of circumcaval ureter has been reported to be about 1 in 1,000 persons.e*s~e The vast majority are associated with urinary tract obstruction. A review of the literature shows the frequency of nonobstructive circumcaval ureter seems to be at least ten times less.2 To emphasize the IVP and CT properties of the nonobstructive circumcaval ureter of the present case apart from the associated venous

358

anomaly, the classifications given previously are reviewed. Newer classifications were reported by Kenawi and Williams2 and others.‘T8 These included a common form of type 1 circumcaval ureter (low loop) with reversed J appearance on IVP and S-shaped obstruction shown on retrograde pyelogram, and a rare type 2 circumcaval ureter (high loop) with IVP showing right upper ureter lying almost horizontally and inverted J appearance without ureteral kinking and obstruction shown on retrograde pyelogram.2 Because obstruction is absent in type 2 cases, they suggested that kinks along with compression by IVC are important factors in producing obstruction2 However, the IVP appearance of the present case is contrary to this because there is a kink at the right ureteropelvic junction and no obstruction (Figs. 1 and 4B). IVP appearance of the aforementioned types are regarded as new classifications, obstructive type 1 and nonobstructive type 2 (Figs. 4 and 5).

UROLOGY

I

APRIL

1993

I

VOLUME

41, NUMBER 4

Obstructive FIGURE 4. circumcaval ureter (type 1): (A) Low loop, most common form, with kink between dilated descending segment and narrower ascending part, and (B) rarer type, with obstruction less marked. In both types level of retrocaval segment is most frequently at third lumbar vertebra, usually medial to pedicle of L3 or L4, but sometimes overlying it or reaching midline. Retrocaval segment and distal ureter frequently not opacified. (Blackfilled lines = retrocaval part; broken lines = distal ureter, both usually cannot be seen on IVI?)

FIGURE 5. Nonobstructive circumcaval ureter (type 2): (A) High loop, nonobstructive circumcaval ureter, renal pelvis and upper ureter lie almost horizontally so that retrocaval segment of ureter is on same level as renal pelvis with no kinking and no obstruction. (B) In present case right side is similar to (A) except for kink at ureteropelvic junction which does not cause obstruction. On the left, middle third of ureter displaced laterally due to the presence of left IVC. On right retrocaval segment and distal ureter could not be seen on IVP and CT. (C) Intermediate type of nonobstructive circumcaval ureter shows medial deviation of middle third of ureter at level of L3 or L4 pedicles. Distal ureter usually can be seen on IVP (Black-filled lines = retrocaval part, and broken lines = distal ureter, both usually cannot be seen on IVI?)

UROLOGY

i

APRIL

1993

/ VOLUME

41, NUMBER 4

359

On CT the present case demonstrated a difference in width of the right proximal ureter (5 mm) and the retrocaval segment (1 mm) (Fig. 3). Also IVC compression of the ureter was also evident to some extent (Fig. 3B). Despite these findings and the ureteropelvic kink, there was no obstruction. Since there is no obstruction of the right ureter in spite of kinking, compression by IVC, and narrowing of the retrocaval segment, it is suggested that the presence of longstanding ureteritis may contribute much to the possible cause of obstruction developing in nonobstructive type 2 cases (Fig. 5). In obstructive type 1 cases, the possible causes of obstruction have included compression by the IVC, kinking between the descending and ascending limbs of the ureter (Fig. 4A), crossing of gonadal or lumbar veins, encasement by a localized fibrotic reaction, and a periureteral venous ring.2~3~s~g Ultrasound can demonstrate hydronephrosis and ureteral dilatation in obstructive circumcaval ureter9 and in venous anomalies such as the present case (Fig. 2) and can be used to follow the kidneys in the nonobstructive cases. CT is the imaging procedure of choice to (1) confirm the diagnosis of all types of circumcaval ureter, (2) show associated venous anomalies, and (3) exclude other causes of ureteral displacement. Furthermore, on noncontrastenhanced abdominal CT examinations the incidental diagnosis of nonobstructive circumcaval ureter can be made by demonstrating the “thin

360

and long” retrocaval segment of the anomaly and then to confirm the diagnosis by injecting intravenous contrast medium, Division of Radiology University of Texas Health Science Center 7703 Floyd Curl Drive San Antonio, Texas 78284-7800 (DR. SENER) References 1. Persky L, Kursh ED, Feldman S, and Resnick MI: Retrocaval ureter. in Walsh PC. Gittes RF Perlmutter AD. Stamev TA (Eds): Campbell’s Urology, ed 5, Philadelphia, W.B. Saunders, vol 1, chap 10, 1986, p 584. 2. Kenawi MM, and Williams I: Circumcaval ureter: a report of 4 cases in children with a review of the literature and a new classification, Br J Urol 48: 183 (1976). 3. Carrion H, et al: Retrocaval ureter: report of 8 cases and the surgical management, J Urol 121: 514 (1979). 4. Arikuni T, et al: Double inferior vena cava with right retrocaval ureter: a case report, Kaibogaku Zasshi 59: 701 (1984). 5. Shown TE, and Moore CA: Retrocaval ureter: 4 cases, J Urol 105: 497 (1971). 6. Gefter WB, et al: Computed tomography of circumcaval ureter, AJR 131: 1086 (1978). 7. Bat&on EM, and Atkfnson D: Circumcaval ureter: a new classification. Clin Radio1 20: 173 (1969). 8. Crosse JEW, Soderdahl DW,‘ lbphck SK, and Clark RE: Nonobstructive circumcaval (retrocaval) ureter, Radiology 116: 69 (1975). 9. Murphy BJ, Casillas J, and Becerra JL: Retrocaval ureter: computed tomography and ultrasound appearance, J Comput ‘lbmogr 11: 89 (1987). 10. Lautin EM, et al: CT diagnosis of circumcaval ureter, AJR 150: 591 (1988). 11, Chuang VP, Mena CE, and Hoskins PA: Congenital anomalies of the inferior vena cava, review of embryogenesis and presentation of a simplified classification, Br J Radio1 47: 206 (1974).

UROLOGY

I

APRIL 1993

I VOLUME 41, NUMBER4