Functional obstructed voiding in the neurologically normal patient

External urethral sphincter electromyography in asymptomatic women and the influence of the menstrual cycle

OBJECTIVE

To investigate by electromyography (EMG), the presence of complex repetitive discharges (CRDs) and decelerating bursts (DBs) in the striated external urethral sphincter during the menstrual cycle in female volunteers with no urinary symptoms and complete bladder emptying.

SUBJECTS AND METHODS

Healthy female volunteers aged 20-40 years, with regular menstrual cycles and no urinary symptoms were recruited. Volunteers completed a menstruation chart, urinary symptom questionnaires, pregnancy test, urine dipstick, urinary free flow and post-void ultrasound bladder scan. Exclusion criteria included current pregnancy, use of hormonal medication or contraception, body mass index of >35 kg/m(2) , incomplete voiding and a history of pelvic surgery. Eligible participants underwent an external urethral sphincter EMG, using a needle electrode in the early follicular phase and the mid-luteal phase of their menstrual cycles. Serum oestradiol and progesterone were measured at each EMG test.

RESULTS

In all, 119 women enquired about the research and following screening, 18 were eligible to enter the study phase. Complete results were obtained in 15 women. In all, 30 EMG tests were undertaken in the 15 asymptomatic women. Sphincter EMG was positive for CRDs and DBs at one or both phases of the menstrual cycle in eight (53%) of the women. Three had CRDs and DBs in both early follicular and mid-luteal phases. Five had normal EMG activity in the early follicular phase and CRDs and DBs in the mid-luteal phase. No woman had abnormal EMG activity in the early follicular phase and normal activity in the luteal phase. There was no relationship between EMG activity and age, parity or serum levels of oestradiol and progesterone.

CONCLUSIONS

CRDs and DB activity in the external striated urethral sphincter is present in a high proportion of asymptomatic young women. This abnormal EMG activity has been shown for the first time to change during the menstrual cycle in individual women. CRDs and DBs are more commonly found in the luteal phase of the menstrual cycle. The importance of CRDs and DBs in the aetiology of urinary retention in young women remains uncertain. The distribution and or quantity of abnormal EMG activity in the external urethral sphincter may be important. In a woman with urinary retention the finding of CRDs and DBs by needle EMG does not automatically establish Fowler's syndrome as the explanation for the bladder dysfunction. Urethral pressure profilometry may be helpful in establishing a diagnosis. Opiate use and psychological stress should be considered in young women with urinary retention.

Urinary retention

Urinary retention, defined as the inability to void, is a common medical problem. If unidentified and/or untreated, it may become a serious condition that can lead to kidney damage or urosepsis, compromising the patient's life.
Acute urinary retention (AUR) is usually easy to identify and to treat as patients usually complain of hypogastric pain and anuria. Proper bladder drainage with urethral or suprapubic catheter is the first line of treatment, with posterior studies to determine the cause of retention.
Chronic urinary retention (CUR) is often much more difficult to identify. It is invariably linked to increased post-void residual urine (PVR), but its asymptomatic nature makes it often a hidden condition.
There is a wide range of intrinsic and extrinsic, obstructive and non-obstructive causes affecting the lower urinary tract, which can lead to urinary retention. Due to the differences in urinary physiology and in order to simplify diagnosis and management, these are usually studied separately in men and in women. Management consists of a variety of options depending on the cause of retention, including conservative treatment, drug therapy and several forms of surgery. 
In this review, we make an overview of the main causes of acute and chronic urinary retention in men and women, focusing on the main aspects of diagnosis and management.