Obstructing urethral membrane in a girl: a rare cause of female bladder outlet obstruction

Abstract

Bladder outlet obstruction is known to produce back pressure changes on the urinary tract with devastating sequelae more often than not. Among the causes, posterior urethral valve, which is the most common, is documented to occur exclusively in males. Female posterior urethral valves have been reported in the past in less than 25 cases in existing literature. We discuss the case of a female toddler who presented with symptoms of straining to void and recurrent urinary tract infections. On evaluation, she was found to have an obstructing urethral membrane causing bladder outlet obstruction, which was endoscopically ablated with success.

Background

The female urethra is usually overlooked in discussions of conditions causing congenital urethral obstructions. Several anomalies in males including hypospadias, epispadias, diaphragms/valves, strictures, duplication and absence of urethral portions have been described in literature,¹ with stricture and hypospadias being the most common. However, when a girl presents with recurrent urinary infections, vesicoureteral reflux (VUR) or a neurogenic bladder is thought to be the causative factor. Obstructive pathologies with the potential to cause back pressure changes and renal dysfunction are often missed unless a history is elicited carefully. Additionaly, many times, parents do not pay attention to lower urinary tract symptoms as a child wears diapers and is not yet toilet trained.

Case presentation

A female toddler was brought by her parents to the paediatric surgical outpatient department with passage of foul-smelling urine and straining to void since the age of 3 months. On further probing, a history of poor urinary stream and occasional dribbling was elicited. She had been treated at her hometown for febrile urinary tract infections on several occasions with temporary resolution of the fever but no change in the other symptoms. Her blood pressure was normal and she had a sensate bladder with no bowel or neurological abnormalities. The local and systemic examinations were unremarkable.

Investigations

Her serum creatinine was normal (0.29 mg/dL) and theurine culture was positive for an infection with Escherichia coli. An abdominal ultrasonogram revealed only mild splitting of the left pelvicalyceal system. The bladder wall thickness and post-void residue could not be assessed as the child was unable to maintain a full bladder. A voiding cystourethrogram (VCU), cystoscopy and examination were performed under anaesthesia. The VCU demonstrated three refluxing moieties, one on the right (grade 3) and two on the left (grade 3 and grade 1), confirming a complete duplication of the latter (figure 1). In the micturating phase, an outpouching was noted, arising from the region of the bladder neck, causing dilatation of the proximal urethra and almost resembling a spinning top (figure 1). Cystoscopy revealed mild trabaculations of the bladder mucosa, with two near-normally placed ureteric orifices and a third ureteric opening in the midline, very close to bladder neck (likely the ectopic left upper moiety ureter). There was a thick whitish membrane, arising from the region of the bladder neck, which extended diagonally into the urethra and was causing significant luminal obstruction via a flap valve mechanism (figure 2). A radionuclide renal cortical scan revealed a scarred and smaller-sized left kidney with reduced uptake (37.5%).

Figure 1.

Voiding cystourethrogram film demonstrating the third refluxing moiety (blue solid arrow), the dilated proximal urethra (dotted arrow) and the scale used to compress the bladder (red solid arrow).

Figure 2.

Cystoscopic images. (A) Cystoscopic image of the thick white membrane (dotted arrow) arising from near the bladder neck (solid arrow) and extending distally into the urethra causing outflow obstruction. (B) Cystoscopic image of the fulguration of the membrane (dotted arrow) using the hook of the resectoscope (solid arrow) in the first sitting. (C) Cystoscopic image of the fulguration (solid arrow) of the flimsy residual membrane (dotted arrow) in the second sitting 1 month later (solid arrow pointing to the resectoscope). (D) Follow-up cystoscopy demonstrating a patent roomy urethra with a small residual tongue of tissue (dotted arrow) that was not causing any obstruction (solid arrow corresponding to the bladder neck).

Differential diagnosis

The history of recurrent infections clubbed with symptoms of lower urinary tract obstruction (LUTO) in a female child prompted us to consider a differential diagnosis of VUR with a neurogenic bladder or a meatal stenosis. Prior to the cystoscopy, the diagnosis of a urethral membrane was not considered.

Treatment

Transurethral fulguration of the membrane was performed with a resectoscope, in two sittings, 1 month apart from each other, and the patient was discharged on antibiotic prophylaxis for her VUR.

Outcome and follow-up

A month following the ablation, she had significant improvement in her voiding symptoms and no further infections. A cystoscopy was done during which time a flimsy residual valve was easily ablated. Six months later, a check-up cystoscopy revealed a small tongue of tissue protruding from the bladder neck which was not causing any obstruction. A repeat sonography demonstrated a decrease in the hydronephrosis. A uroflowmetry was done to document the improved urinary flow, but the child was unable to hold a full bladder. A follow-up VCU and renal cortical scan are due at 1 year, with a plan to continue conservative management with uroprophylaxis if there is no increase in the VUR or no new renal scars.

Discussion

The proposed theories for posterior urethral valve (PUV) in males include malformations of the inferior urethral crest and fins,² and failure of the Wolffian ducts to properly integrate into the urethra, resulting in a membrane.³ The incidence of obstructing urethral membranes (OUMs) in females has been mentioned by a few authors only in the past.^{2 4 5} The lower incidence in females could be due to the absence of an analogous structure in the female urethra. The membrane in our patient seemed to be similar to a type II PUV, as described by Young’s criteria.³

Stevens, in a 1936 publication, attributed persistent malformation of the cloacal membrane to be the cause of female urethral obstructions.¹ Nearly all of his patients had OUMs located at the external meatus with varying degrees of obstruction, the complete variety often being fatal. He proposed that more proximal obstructions are mostly acquired rather than congenital.¹ According to Hendren, urethral valves in females are of three types: (1) true valves, (2) postoperative remnants of ectopic ureteroceles and (3) valves arising from a rudimentary verumontanum in girls, with adrenogenital syndrome and masculinisation of the lower urinary tract.⁴ Accordingly, several anatomical variations have been described including transverse bands and longitudinal urethral folds, some of which may be delivered into the urethra.^{2 4} Complete obstructions are confused with urethral atresia and result in mortality unless they drain into a patent urachus, empty into the vagina, uterus or colon,^{1 6} or antenatal interventions have been done.⁷

Symptoms associated with most incomplete obstructions include frequency, dysuria, urgency, dribbling, infection and retention.¹ Less frequent presentations, including straining and enuresis, should prompt a thorough investigation to rule out LUTO. Patients with complete urethral obstruction may present with an umbilical fistula or bladder diverticulae, both of which act as pop-off mechanisms, as in PUV.¹ Varying degrees of hydroureteronephrosis and VUR can result, secondary to the back pressure or obstructed ureteric orifices from bladder wall thickening.¹ Unlike in PUV, where about one-third of patients develop bladder failure and subsequently renal failure, there is no documented evidence of its incidence or prevalence in females. This is likely due to the rarity of the condition in females and thereby, a lack of a consensus. When present, associated hypospadias or a urogenital sinus could be suggestive that some degree of masculinisation is responsible for this condition.⁸ As there was no clinical or sonological evidence of masculinisation in our patient, we did not proceed with biochemical hormonal testing.

VCU is helpful to identify VUR, abnormalities of bladder contour and emptying, urethral dilatation and vaginal voiding, thereby guiding further evaluation. Voiding in a small child is difficult to elicit, especially when performed under anaesthesia. Cystoscopy is therefore essential to corroborate the VCU findings as well as concurrently manage any obstructive pathologies. In our patient, the VCU picked up the third refluxing moiety likely to be the non/poorly functioning upper moiety on the left side, and the cystoscopy helped identify the ectopic ureteric opening and the OUM. In patients with congenital stenosis or stricture of the urethra, the obstruction is fixed and catheterisation or passage of the scope may be difficult.² In our patient, the ease of catheterisation indicates that the obstruction was secondary to a flap valve mechanism.²

Unlike in males, the female urethra is shorter and more distensible, thereby more easily accessible to treatment.¹ Olive tip bougies, skenoscopes and cystourethroscopes have been employed to hook the membrane and section it under vision (transurethral excision).^{2 4 6} This works well for distally placed membranes, while those that are thicker or closer to the bladder neck require endoscopic management. When accompanied by meatal stenosis, dilatation is first required to create an adequate working channel with or without meatotomy.

No procedure is without its complications. As documented by Everett,⁹ excessive use of a resectoscope or diathermy at the proximal urethra and bladder neck can result in incontinence and vesicourethrovaginal fistulas that pose a great challenge to manage. We therefore ensure that when a PUV or membrane is thick, a second-look cystoscopy is always done a month later to fulgurate any residual tissue. This is done to prevent damaging the delicate paediatric urethra from the disastrous consequences of excessive thermal energy.

Secondary problems including elevated bladder pressures and VUR are well managed with anticholinergics⁶ and uroprophylaxis until resolution is documented. Aggressive and prompt management of these is warranted to prevent deterioration of renal function by means of regular follow-ups and check-up VCUs/cystoscopies. Independent problems like renal duplication and primary VUR, however, have to be addressed individually on follow-up after the effects of the obstruction have been given adequate time to resolve.

Patient’s perspective.

My daughter was used to strain a lot to pass urine and she was frequently sick from urinary infections. She is now able to void easily and has been free from infections. She still has further treatment pending but we are relieved that she is now symptom free.

Learning points.

• Obstructing urethral membranes in females are extremely rare, behave akin to posterior urethral valves in males and must be treated with equal priority.

• During evaluation of a female child with recurrent urinary tract infections, it is crucial to include a voiding cystourethrogram and a cystoscopic examination.

• Prompt management should take priority with long-term follow-up aiming at preservation of renal function.

Ethics statements

Patient consent for publication

Consent obtained from parent(s)/guardian(s).