Nigerian Postgraduate Medical Journal

ORIGINAL ARTICLE
Year
: 2018  |  Volume : 25  |  Issue : 4  |  Page : 220--224

Ultrasonographic characterisation of obstructive uropathy in Nigerian women with uterine fibroids


Bukunmi Michael Idowu1, Bolanle Olubunmi Ibitoye2, Victor Olufemi Oyedepo1, Stephen Olaoluwa Onigbinde1, Tolulope Adebayo Okedere1,  
1 Department of Radiology, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Osun State, Nigeria
2 Department of Radiology, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria

Correspondence Address:
Dr. Bukunmi Michael Idowu
Department of Radiology, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Osun State
Nigeria

Abstract

Objectives: The objective of this study was to determine the prevalence of upper renal tract obstructive changes in women with uterine fibroids using ultrasonography (USG). Methods: We enrolled 140 women with uterine fibroids and performed USG of the uterus and upper renal tract with full and empty urinary bladders, respectively. The number of fibroid nodules and the uterine volume were determined. The presence of hydronephrosis was graded and documented. Uterine volumes >200 cm3 were denoted as large and vice versa. Statistical analysis was done using Chi-square and non-parametric tests. Results: The median uterine volume was 556 cm3. Application of a 200 cm3 cut-off value yielded 126 (90%) large uterine volumes and 14 (10%) small uterine volumes. Of the 140 women enrolled, 52 (37.1%) had renal backpressure changes. Of these 52 patients, 51 (98.1%) had uterine volumes >200 cm3. Both kidneys were affected in the vast majority (36 out of 52 = 69.2%) of those with renal backpressure changes, and 23 (44.2%) of the 52 women with renal backpressure changes had mild (Grade 1) hydronephrosis, while 25 (48.1%) had moderate (Grade 2) hydronephrosis. When unilateral, however, backpressure changes were significantly more common on the right side. Conclusion: Approximately one in three women with fibroids had renal backpressure changes in this study. Large uterine volume is a key predisposing factor. Routine sonographic assessment of fibroids should include a focused/targeted evaluation of the kidneys.



How to cite this article:
Idowu BM, Ibitoye BO, Oyedepo VO, Onigbinde SO, Okedere TA. Ultrasonographic characterisation of obstructive uropathy in Nigerian women with uterine fibroids.Niger Postgrad Med J 2018;25:220-224


How to cite this URL:
Idowu BM, Ibitoye BO, Oyedepo VO, Onigbinde SO, Okedere TA. Ultrasonographic characterisation of obstructive uropathy in Nigerian women with uterine fibroids. Niger Postgrad Med J [serial online] 2018 [cited 2019 Aug 22 ];25:220-224
Available from: http://www.npmj.org/text.asp?2018/25/4/220/248215


Full Text

 Introduction



Uterine leiomyomas/uterine fibroids are three to nine times more common and tend to be larger in women of African descent than women of other racial groups.[1] It is often asymptomatic but may present with debilitating genitourinary signs including acute urinary retention, obstructive uropathy and haematuria.[2]

'Obstructive uropathy refers to structural impedance to the flow of urine anywhere along the urinary tract leading to pelvicalyceal dilatation/hydronephrosis',[3] which may progress to obstructive nephropathy if neglected.[4] Hydronephrosis, which is a symptom of obstructive uropathy, refers to dilatation of the urinary collecting system (calyces, infundibula and pelvis) of the kidney.[5] However, obstructive uropathy and hydronephrosis are not synonymous since pelvicalyceal dilatation can also occur in the absence of urinary obstruction.[3] Obstructive uropathy could be congenital or acquired, acute or chronic, unilateral or bilateral, symptomatic or asymptomatic, episodic/intermittent or permanent. The upper urinary tract dilatation associated with uterine leiomyoma is usually chronic in nature.[6] In a previous study of sixty patients with obstructive uropathy, twenty (33%) of them were secondary to uterine leiomyomas.[7] Similarly, Soyebi and Awosanya[8] reported that uterine fibroids (23 cases = 11.4%) were the most common cause of obstructive uropathy in their study of 202 patients.

Although numerous researchers have reported on the epidemiology and management of uterine fibroids, very few have studied specifically the usually asymptomatic and sinister complication of obstructive nephropathy. Our aim was to evaluate the obstructive effect(s) of uterine fibroids on the upper urinary tract in our locality using ultrasonography (USG).

 Methods



This prospective descriptive cross-sectional study was done in the Department of Radiology of Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Osun State, Nigeria, from November 2013 to November 2014. The Ethics Committee of the hospital approved the study (Protocol Number: ERC/2013/09/13; Approval Date: 5th September, 2013). Documented informed consent was obtained from all the participants.

One hundred and forty women who were sonographically diagnosed with uterine fibroids were enrolled consecutively. Exclusion criteria were congenital uterine anomalies, coexisting ovarian and pelvic mass(es), pregnancy, polyuria, history of renal pathology or renal replacement therapy and renal masses/space-occupying lesion discovered on sonography.

Model DC-7 Mindray® ultrasound machine (Shenzhen Mindray Bio-Medical Electronics, Nanshan, Shenzhen, China) with a 3.8–5.0 MHz transducer was utilised for the sonographic examinations which were performed by the first author. Each patient was positioned supine on the examination couch. Following adequate urinary bladder distension, the uterus was scanned in orthogonal planes.

The uterine volume was determined using the prolate ellipse formula as follows: length (cm) × anteroposterior (cm) × transverse (cm) × 0.523. The length of the uterus was measured on midline sagittal image from the fundus to the external cervical os; its anteroposterior diameter was measured perpendicular to the length, while the transverse diameter was taken as the intercornual distance on a transverse image. Each measurement was taken three times to limit intraobserver error, and the average value was recorded.

The uterine volumes were classified as large or small if they were greater or lesser than 200 cm3, respectively.[9] The following were also documented: position/location of the fibroids within the uterus (fundus, anterior, posterior or lateral corpus, lower uterine segment and cervix), number of fibroid nodules and fibroid type (intramural, subserosal, submucosal, pedunculated or multiple sites). Submucosal fibroid was identified as ‘any leiomyoma in contact with or distorting the uterine cavity without identifiable myometrium between the leiomyoma and the endometrium’;[10] subserosal fibroid as ‘a nodule distorting the external contour of the uterus with >50% of its volume protruding out of the uterine surface’;[10] intramural fibroid as ‘a nodule that is completely within the myometrium, distorting neither contour nor cavity’[10] and a pedunculated fibroid as ‘a nodule that is attached to the uterus with an identifiable stalk’.[10]

The participants were instructed to empty their urinary bladder and then placed in the prone position to assess the kidneys. This was done for optimal visualisation of the kidneys and to prevent false-positive distension of the calyces. The kidneys were examined for sonographic evidence of backpressure changes/hydronephrosis. If backpressure changes were noted, they were graded using the sonographic grading for hydronephrosis as reported by Ellenbogen et al:[11] ‘Grade 0 = central collecting system echo is compact (closely apposed) and homogeneous; Grade 1 = slight separation of the renal collecting system echoes with a central ovoid or fusiform sonolucency; Grade 2 = further separation of the collecting system echoes with a rounded sonolucency seen centrally; Grade 3 = renal pelvis is dilated and there are fluid-filled calyces throughout the kidneys/major portion of the kidney is replaced by a sonolucent sac and Grade 4 is the same as Grade 3, but the renal parenchyma over the calyces is thinned’[11] [Figure 1]a, [Figure 1]b, [Figure 1]c, [Figure 1]d. The right and left ureters were looked for and, when visualised, the diameter of each was taken and graded as below: Grade 0: non-visualised or ureter calibre ≤3 mm; Grade 1: ureter calibre between 4 and 6 mm; Grade 2: ureter calibre between 7 and 9 mm and Grade 3: ureter calibre >10 mm. The uterine volume data of the 140 patients have been re-used with permission.[12],[13] Sample size was calculated using a leiomyoma prevalence of 9.3%[14] in the Fisher formula.[15]{Figure 1}

The Statistical Package for the Social Sciences (SPSS) software version 20 for Windows (SPSS Inc., Chicago, IL, USA) was used for data analysis. Mann–Whitney U-test, Kruskal–Wallis test, Chi-square test and Spearman's rank correlational analysis were used as appropriate. Statistical significance was set at P ≤ 0.05.

 Results



The mean age of the participants was 37.9 ± 7.4 years (range = 23–57 years). The 30–39 years' age range had the highest occurrence of uterine leiomyoma, while the ≥50 years' age range had the least. The mean parity was 1.67 ± 1.14.

The median uterine volume was 556 cm3 (range = 37–9384 cm3; mean = 1032 ± 1259 cm3). The cut-off value of 200 cm3 yielded 126 (90%) large uterine volumes and 14 (10%) small uterine volumes.

The dominant leiomyoma nodule had a median volume of 133 cm3 (range = 1.5–2575 cm3; mean = 354 cm3 ± 491 cm3). The dominant leiomyoma nodule volume was ≤200.0 cm3 in 83 (59.3%) women but >200.0 cm3 in 57 (40.7%) women.

The mean number of leiomyoma nodules per woman was 5.1 ± 3.3 (range = 1–14). Twenty-five women (17.9%) had solitary leiomyoma nodule, while 115 (82.1%) had multiple (two or more) leiomyoma nodules. Further subgrouping of the number of leiomyoma nodules is illustrated in [Table 1]. The total number of leiomyoma nodules in all the women was 715. Uterine volume showed a weak positive correlation with the number of leiomyoma nodules (Spearman's rho = 0.4; P < 0.0001).{Table 1}

The locations of the fibroid nodules are shown in [Table 1], while the distribution of renal backpressure changes is shown in [Table 2].{Table 2}

Of the total study population of 140 women, 52 (37.1%) had renal backpressure changes – all were asymptomatic. Of these 52 patients, 51 (98.1%) had uterine volumes >200 cm3. Both kidneys were affected in most (36 of 52 = 69.2%) of those with renal backpressure changes. Twenty-three (44.2%) of the 52 women with renal backpressure changes had mild (Grade 1) hydronephrosis, while 25 (48.1%) had moderate (Grade 2) hydronephrosis [Table 2].

Of the 126 participants with uterine volume >200 cm3, 51 (40.5%) had renal backpressure changes, while only one woman (7.1%) with uterine volume ≤200.0 cm3 had renal backpressure changes; P = 0.01 [Table 3].{Table 3}

Of the 82 women with ≤5 fibroid nodules, renal backpressure changes were seen in only 23 (28%) compared to the occurrence of renal backpressure changes in 29 (50%) out of 58 women with ≥5 fibroid nodules; P = 0.01.

No relationship/association was demonstrated between fibroid location and presence/absence of renal backpressure changes.

[Table 4] juxtaposes our findings with those of previous studies.{Table 4}

 Discussion



Leiomyomas have a profound impact on the reproductive history of women.[10],[20] Indeed, their presence in a woman is predictive of future major uterine surgical procedures.[20] There is a large body of literature on leiomyoma epidemiology, symptomatology, investigation and treatment,[12],[13],[21] but studies on the effects of fibroids on the urinary tract are fewer.[2]

The prevalence of obstructive uropathy in this study was 37.1% (approximately one in every three patients with uterine fibroids) which is higher than the prevalence (3.7%–14.4%) reported by other researchers.[16],[17],[18],[19] This disparity is likely due to differences in uterine volume and/or dominant leiomyoma volume of the various studies. For example, the mean volume of the dominant fibroid in this study (354 cm3) is much higher than 233 cm3 reported by Alyeshmerni et al.[17] The study results as reported by the other researchers precluded meaningful direct comparison (some reported mean diameter but not the volume of the dominant fibroid nodule and/or expressed uterine size as clinical weeks rather than volume).[16],[18],[19] However, the overall pattern of findings in all these studies (including ours) is similar; patients with hydronephrosis had significantly larger uterine volumes than those without.[17],[18] In addition, we observed that renal backpressure changes were more likely with increasing number of fibroid nodules, which tends to increase the uterine volume. The vast majority of patients (62.9% of the total sample size) in this study group did not have obstructive uropathy. Among those with obstructive uropathy (37.1% of the total sample size), Grade 2 obstruction was the most common pattern (48.1%) followed by Grade 1 (44.2%) and Grade 3 obstruction (7.7%). In agreement with previous reports,[17],[18],[22] unilateral right hydronephrosis (9.3%) was more common than unilateral left hydronephrosis (2.1%). This observation is said to be due to the protective effect of the sigmoid colon on the left ureter.[22]

The renal obstruction complicating uterine leiomyomata is often due to a large fibroid(s) compressing the ureter at the ureterovesical junction/pelvic brim[22] or elsewhere within the pelvis. It bears reemphasis that fibroid-related ureteral compression can progress to acute or chronic renal impairment with renovascular hypertension, which is not always completely reversed following treatment.[17],[23]

Leiomyomata-related urinary tract obstruction is usually insidious and painless, with no derangement of renal function test indices in the vast majority of affected patients.[18],[24] This has been attributed to the fact that most cases are often mild and/or unilateral[25] (we obtained similar findings), coupled with the fact that there is no significant renal derangement of biochemical indices of renal function until about 60% of renal function has been impaired.[25] The findings of Fletcher et al.[18] corroborated this as over 61% of women with hydronephrosis in their study had normal creatinine clearance. The reason for this ‘preserved’ renal function despite obstruction is that even though glomerular filtration rate (GFR) is decreased by half when there is total unilateral renal loss, the compensatory glomerular hypertrophy in the other kidney increases GFR over the course of 2 weeks to a level that is 80% of previous function, which could be maintained for up to 30 years in the absence of any other renal insult.[26],[27]

Imaging is crucial in the evaluation of suspected fibroid-associated urinary tract obstruction.[8],[28] The gynaecologist and urologist may be interested in getting answers to the following questions: ‘What is causing the obstruction? What is the size of the obstructing “something”? At what level is the obstruction? What is the diameter, the position and the tortuosity of the ureter above and below the obstruction? Is there any clue for how long the obstruction has been present, for example, from the degree of dilatation of the upper urinary tract? and given the information derived from the imaging, how best should the patient be managed’?[29] In patients with uterine fibroids, some of these questions could be answered reasonably with USG: cause of obstruction, size of the obstructing lesion, and visualising that there had been dilatation for a while (based on the degree of calyceal dilatation, renal cortical thinning and ureteral dilatation).

In this environment, USG and intravenous urography (IVU) are the readily available investigative methods for answering these questions in patients with uterine fibroids. USG and IVU have their strengths and weaknesses,[29],[30] but USG should be the first choice and complementary IVU should be reserved for carefully selected cases of large fibroid tumours.[31] The combination of both USG and IVU routinely is not supported by available evidence,[31],[32],[33],[34],[35],[36],[37],[38] is definitely not cost-effective and exposes the patient to unnecessary risks of radiation and intravenous contrast media reactions. An informal enquiry in private radiodiagnostic centres and government hospitals across the country puts the cost of IVU between 10,000 naira ($28) and 40,000 naira ($111); this is in a country where about 70% of citizens live in poverty and health insurance covers <5% of the population.[39] Furthermore, the accuracy of USG in detecting urinary tract obstruction is improved significantly with the addition of renal artery Doppler and renal vein Doppler, which further obviates the need for routine IVU.[7],[30],[40]

 Conclusion



Urinary tract obstruction by uterine leiomyomata is not uncommon though most cases appear to be mild or moderate in severity. Women with large fibroid masses and large uterine volumes are at a higher risk. Patients with fibroids should have routine ultrasound scan of their kidneys/ureters to detect this condition promptly since it is often asymptomatic. USG should be the first line of investigation, rather than subjecting all patients with uterine fibroids to IVU, for identifying urinary tract involvement.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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