Postpartum urinary retention

Postpartum urinary retention (PUR) is a common condition in obstetric units. It is also known as puerperal urinary retention (1) or insidious urinary retention after vaginal delivery (2). Despite its ubiquity, morbidity, and the distress brought on to postpartum women, PUR remains a poorly understood subject. Unlike urinary incontinence, female urinary retention in particular PUR, has not received much attention. Scientific publications on this subject are relatively sparse. In this review the scientific background, clinical significance, and management alternatives of PUR are discussed. There is currently no standardized definition of PUR. One common, symptom-based clinical definition of PUR is ‘the absence of spontaneous micturition within 6 h of vaginal delivery. In the case of a cesarean section, it is defined as ‘no spontaneous micturition within 6 h after the removal of an indwelling catheter (more than 24 h after delivery)’ (1, 3). On the other hand, if one views PUR as a form of acute urinary retention, the following definitions could also be used. Stanton (4) described acute urinary retention as the ‘sudden painful or painless inability to void over a 24-h period, requiring catheterization, which yields at least 50% of the cystometric capacity’ (4). This definition requires the diagnosis to be made retrospectively and with the aid of cystometry. Shah and Dasgupta (5) advocated a simpler definition in order to ensure all clinicians refer to the same condition. They defined acute urinary retention as ‘the sudden onset of the inability to void’. This may be either painful (where neurology is normal) or painless (where abnormal neurology is present). Another common clinical definition of urinary retention is significant post-void residual bladder volume (PVRBV), where PVRBV is defined as ‘the volume of fluid remaining in the bladder immediately following the completion of micturition’ (6). The presence of PVRBV implies that there is an imbalance between the forces of urine expulsion and the outflow resistance, or that there is failure or decrease in detrusor contractility (7). Accordingly, a significant PVRBV represents an abnormality of bladder function, and could be used as the definition of PUR. Various definitions for a significant PVRBV have been published by different authors and they include: 40 ml (8), 50 ml (5), 100 ml (9, 10), 150 ml (2, 11, 12), 200 ml (13-15), and 500 ml (16). However, these values appear arbitrary, as there was no reason offered. It seems that they are proposed mainly for the clinical management of urinary retention. The prevalence of PUR varies, reflecting the lack of a standardized definition (3). Using the symptom-based definition mentioned above, Kermans et al. (1) reported PUR in 17 (2.1%) out of 789 women with vaginal deliveries and in two (3.2%) out of 62 women delivered by a cesarean section (1). Burkhart et al. (17) studied 1000 postpartum women and performed bladder catheterization only when women complained of discomfort and the urge to void with inability to do so (17). Using these criteria, 4.9% of women in Burkhart et al.'s group had PUR (17). Recent publications on PUR continue to show a confusing picture (Table I). It shows that the prevalence of PUR ranges from 0.45% to 14.1%. A point of note is that all five studies used different diagnostic criteria for PUR. Without a standardized definition of PUR, it would be difficult to devise effective clinical management, and to compare results of similar studies. The pathophysiology of PUR is poorly understood and various mechanisms have been speculated in the past. Francis (20) reviewed obstetrics and midwifery textbooks of the first half of the twentieth century and found that PUR was variously attributed to the following conditions in the postpartum period: Nervousness, modesty and similar factors causing inhibition by the central nervous system. An unnatural posture. Lack of elasticity of the bladder. Injury, swelling and bruising of the vulva, urethra and bladder trigone. Reflex spasm of the external urethral sphincter from tears and incisions in the perineum. An unspecified temporary derangement of the neuromuscular mechanism of the bladder and urethra. Some of these speculations may be true but no evidence for them has been provided. However, recent advances in urodynamics and electrophysiology, and histochemical studies of detrusor muscle chemical receptors allow a greater understanding of the pathophysiology of PUR. There are two major areas of breakthrough that may help us to understand PUR: Hormones and contractile responses of the bladder. Injured bladder innervation. There are a number of animal studies examining the effects of estrogens and pregnancy on bladder contractile function. It is established that the bladder is a hormone-responsive organ, and its functions may be subjected to the fluctuations of hormones during pregnancy and in the postpartum period (21-26). In studies comparing age-matched virgin and pregnant rabbits there were no difference in maximal response of isolated bladder strips to field stimulation (26). However, the relative contributions of the cholinergic and purinergic components were altered substantially in the pregnant rabbits. The maximal response of the bladder to cholinergic stimulation was decreased by approximately 50%, and the maximal response to purinergic stimulation was increased by approximately 50%. Furthermore, the ability of isolated whole bladders from pregnant rabbits to empty in response to field stimulation, a function of cholinergic stimulation, was decreased significantly (22). The decreased response of the bladders from pregnant rabbits to cholinergic stimulation was associated with a significant decrease in muscarinic cholinergic receptor density (24). Another observation from these studies was that pregnancy resulted in a significant decrease in the response of isolated strips of bladder base and urethra to alpha-adrenergic stimulation (24). A decrease in the muscarinic responsiveness of the bladder body would be consistent with an increase in urine retention, which is associated clinically with pregnancy. Lesions in the nervous system produce specific types of bladder emptying problems according to the level of the damage. Urinary retention occurs when the neurological lesions occur below the spinal reflex arc, at or below the level of the outlet of the sacral nerves which render the bladder acontractile or hypotonic (5). A number of studies have shown that the pudendal nerve, with afferent nerve branches (S2–4) supplying the bladder, is damaged during pelvic surgery and vaginal delivery (27-32). Afferent nerves innervating the lower urinary tract are those passing in the pelvic nerve to the sacral spinal cord (S2–4). These afferent nerves are small-diameter fibres that are linked with tension receptors in the bladder wall. Afferent pathways from striated muscle sphincters and from the urethra, which transmit sensations of warm, cold pain, and passage of urine, travel in the pudendal nerve to the sacral spinal cord (S2–4) (33). Urinary retention after vaginal delivery may be the result of injury to the pelvic, hypogastric, and pudendal nerves. The typical pelvic plexus injury is usually thought to produce the classic picture of acontractile bladder (34). However, the nature of the neurological lesion and its consequences may be variable owing to the complex interaction of partial or complete injuries to the parasympathetic, sympathetic, and somatic nervous systems (35). Typically, parasympathetic nerve injury produces a hypocontractile or acontractile bladder with decreased sensation. Sympathetic nerve injury can result in a bladder with decreased compliance and high storage pressure due to beta-adrenergic denervation. With recent advances in electrophysiological investigations, the damaging effects of vaginal delivery to the pudendal nerve have been shown in a number of studies. Sultan et al. (30) recruited 128 women prospectively from 34 weeks' gestation until 6 to 8 weeks after vaginal delivery, and studied their pudendal nerve terminal motor latencies (PNTML) and the degree of perineum descent (30). They demonstrated that vaginal delivery, particularly in the first pregnancy, was associated with significant pelvic floor tissue stretching and pudendal nerve damage. Similar results were presented by Tetzschner et al. (31) who studied 17 nulliparous women who had had a normal vaginal delivery and were found to have PNTML increased significantly to a mean of 2.64 milliseconds in the first few days after delivery (31). The PNTML then slowly decreased over a 3-month period back to the normal mean value of 1.95 milliseconds. It was concluded from their study that the pudendal nerve was impaired immediately after a normal vaginal delivery, but recovers over a 3-month period. In a subsequent study, Tetzschner et al. (31) demonstrated that pudendal nerve damage was a result of the labor process and vaginal delivery, and was not related to any antepartum events (32). They studied the PNTML of 28 women at 14, 30, and 36 weeks of pregnancy. Their results showed that PNTML did not increase significantly during pregnancy but increased significantly after delivery. In a larger-scale study Lee and Park (28) studied the serial PNTML of 80 women (40 nulliparas and 40 multiparas) 3 months before vaginal delivery, 3 days after delivery, and 2 months after delivery (28). They found that there was no difference between nulliparas and multiparas before delivery. On the other hand, 3 days after delivery, regardless of parity, the PNTML was prolonged. Two months after delivery, the PNTML returned to pre-delivery levels. Similar to Tetzschner et al. (31, 32) they also concluded that pudendal nerve damage occurred during vaginal delivery but recovered several months after delivery. The results of this study suggest that the pudendal nerve damage sustained during vaginal delivery is a transient event and is unlikely to give rise to long-term pudendal dysfunction thus chronic urinary retention. In a study to evaluate the relationship between obstetric risk factors and PUR, Kermans et al. (1) studied 789 women who delivered by the vaginal route, and 62 women delivered by a cesarean section, they found that nulliparity and cesarean delivery for lack of progress in the first stage were significantly more frequent among women with PUR (1). However, the robustness of this study could be questioned as the diagnosis was based on an initial clinical screening by the nursing staff, and catheterization was performed if retention was suspected. Women with retention who were asymptomatic therefore might not be detected. Andolf et al. (2) studied 539 consecutive women using ultrasound to measure their PVRBV on post-vaginal delivery day three. Using a diagnostic criterion of PVRBV >150 ml for PUR, they found that forceps delivery and vacuum extraction were associated with a higher prevalence of urinary retention. They also found that parity was a risk factor, with more nulliparas than multiparas manifested PUR. However, no difference was seen in birth weight between women with and without retention. Yip et al. (12) did a similar ultrasound study on 691 women, using the diagnostic criterion of PVRBV ≥150 ml, and they demonstrated a significant relationship between urinary retention on post-vaginal delivery day one and the following obstetric risk factors: prolonged first and second stages of labor (12). Although it seems that vaginal delivery is the strongest risk factor for PUR, Kerr-Wilson et al. (36) held an opposite and did not that the management of labor women to bladder and PUR In a study of postpartum women nulliparas and using and to the effects of labor on the postpartum bladder, they found that the mean were within normal there was a significant in nulliparas between of labor and residual urine, and between of labor and detrusor pressure rise in bladder in They their results with that of and who found the bladder to be hypotonic and that management of labor with and more frequent of a cesarean section in obstetric the labor which in may to a in the risk of subsequent bladder the studies on the relationship between and PUR have shown demonstrated a relationship between the of and PUR. In a cystometric study on the of on the lower urinary tract in a group of nulliparous women with a vaginal delivery, et al. demonstrated that women who received had a higher prevalence of hypotonic bladders than women without Kermans et al. (1) showed that the of other obstetric was significantly more frequent among women with PUR. However, when was with other obstetric factors weight difficult vacuum and second stage of in a they showed no difference between those with and without PUR (1). Andolf et al. (2) also demonstrated in their ultrasound prevalence study the of during labor was more frequent in women with PUR. Recent studies on the relationship between and PUR showed a et al. studied women who had received during labor and delivery. These women had an ultrasound of their PVRBV at a mean of h after vaginal delivery, and of the women were as urinary retention. these women were with a group of there was no significant difference between the in the of et al. performed on women before and after and found no significant in the detrusor pressure at maximal cystometric in and in the mean Furthermore, of the women urinary retention after the The decrease in prevalence of PUR after may be due to a understanding of the effects of on the and central mechanisms the micturition which to a more of during The of a of may have also to the in prevalence of urinary retention in women an The of a cesarean section in PUR is difficult to a cesarean section, women have a indwelling catheter for the first 24 h and the effects of the and postpartum bladder in these pain, and lack of might to the risk of urinary retention The of in has been shown to give rise to urinary retention, which the the of was in a women with a cesarean section did not have an increased prevalence of urinary retention (1). It is not to a clinical diagnosis of PUR. is difficult to if the with asymptomatic PUR. PUR is a diagnosis can only be made after as catheterization or as ultrasound have been The diagnosis of urinary retention on an of the PVRBV to the PVRBV can be by the following or micturition These in of and and are either of or and the is not for clinical The clinically used to the PVRBV are catheterization, and for the bladder is the and least of all the diagnostic may a residual volume of 200 ml or of the lower may a bladder with ml or more (4). However, bladders than ml are not by therefore be as as a to PUR. can be used for diagnostic and catheterization is used to urinary retention of its catheterization is a common to the bladder and with it the PVRBV can be The of catheterization to PUR is not without which include: pain, and urinary tract is a major and common and showed that may to the urinary tract the catheter in catheter management, it remains an of of bladder volume have been used in prevalence studies of PUR they are and in obstetric (2, However, there is no on the volume that be used as diagnostic criterion for PUR. The puerperal may the of ultrasound of the it may the bladder ultrasound In a study by Yip et al. it has been shown that the bladder its and ultrasound of the PVRBV in the postpartum period is and it can be used as a to catheterization is It is a common in the to and first to urinary retention. In with urinary retention after and reported that of who in in the presence of an urge to void were to void after by nursing These the of the to and the a and the of the a of cold They risk to the postpartum women and to other management for urinary retention have been advocated but few have been shown to be of much In with as and were shown to detrusor function and used with in the of urinary retention However, studies could not similar results and these were in shown to be associated with an increase in the prevalence of urinary retention In a study, et al. studied used to urinary retention after vaginal and and found that all significantly increased the residual urine volume when with the and also found that the of in significantly increased the of urinary retention. are used for the of urinary retention. as and have been for the of urinary retention or PUR However, studies in which were used to urinary retention have to significant with a in a study and did not a significant in women with chronic urinary retention. were seen in residual residual mean and pressure at 100 ml volume and at maximal when the were with the group the for urinary retention alpha-adrenergic and are as and are effective for outlet reported and of urinary retention in who received a of with those who and Stanton et al. found as was for after for muscarinic receptors and can detrusor et al. studied the effects of in a study, and found that it bladder motor function and detrusor with no et al. also demonstrated in their study that urinary retention significantly after a vaginal However, results have been published which showed that increased the prevalence of urinary retention after vaginal surgery of the have been studied in postpartum women, and their in is of effects in the (3). However, of these may be for with urinary retention. of the bladder is the for urinary retention and urine from the bladder and the risk of acute failure or bladder Although PUR is defined as the absence of spontaneous micturition within 6 h of a vaginal delivery, this is not a criterion for The for catheterization is and on the and a postpartum the for urinary retention, of urinary or urge incontinence, or if a and of the areas a bladder then a indwelling catheter as the catheter is usually postpartum women, a or at catheter is usually used for catheterization may if PUR or failure to void after several to the catheter The of a more than catheterization, has been shown to nursing and urinary tract catheterization is the volume of urine may the for Burkhart et al. (17) found that of the postpartum with a urine volume of ml or catheterization, but it was for two out of with ml of residual urine and five out of with more than 1000 ml of residual Some authors that catheterization be h in who an initial postpartum catheterization until spontaneous occurs (3). There are to bladder catheterization is to the of an indwelling catheter in who are to void for more than 24 Some obstetric a management for the of PUR, catheterization of the bladder to the retention Some the of catheterization to bladder is not without risk to women are for than 24 h in the postpartum period, approximately The of urinary tract in women who or who have an indwelling catheter The of urinary tract can be substantially decreased by Although the who requires only one catheterization may not of urine and urine might be in these women to of (3). has shown in study on the of in PUR that at the of catheterization the prevalence of urinary tract any who to be at any in the postpartum period a of include: However, is in but and can be and they be the period of catheterization and for h after catheter removal (3). there are on the of PUR by is an system over as of the of and other It that the stimulation of specific areas on the the of of the the of the of is used as a and the may also be using a The value of has been shown in the management of female urinary as detrusor and In published the first on using to PUR women with urinary retention after vaginal delivery by to the and the women, had spontaneous after one after two five after and two after that all women were after an of Similar results were reported by in a study of with urinary retention. In this study a of with were with of and the were with one two with and with to et al. women with PUR by only one They the the point and of the women were reported to be and with only one who reported ‘no did not any effects of or Despite the in these scientific evidence on the of is The reported studies are The of the was not The effects of point to be and The effects of may the Furthermore, the of these studies was only the of and there was no of as the in the has been shown to be effective in specific types of female urinary retention but there is no of its in the of PUR. PUR is to be a to or neuromuscular of urethral as urethral and or with of the urethral and using an are not advocated (4). a form of using and at variable has been shown to be effective in the of chronic urinary retention requires the to the from the of to to the of the urinary the to within a then is to the for a period of at least 2 before However, this of has not been demonstrated in postpartum floor and are used to women with urinary but there is on using these for urinary retention. et al. reported the management of a case of urinary retention due to bladder, using a of and and Postpartum urinary retention is a particularly when the is There are few studies on the of PUR but published suggest that this condition to normal within a period after delivery, and specific is not by Andolf et al. Yip et al. and Lee et al. PUR is a and all their with PUR returned to normal within 2 to 6 days of diagnosis and no specific as catheterization or was et al. reported a of of PUR with women were nulliparas and had during labor Two forceps deliveries and all were to void after delivery. was to their when catheterization had to the PUR. The of retention before was 11, and 28 catheterization was performed at their and was for and and all returned to normal with removal of the et al. reported a similar of of PUR. Two indwelling catheterization and they returned to normal on postpartum days and Two catheterization and they returned to normal on postpartum days 28 and Although the relatively female urethra and urinary are risk factors for urinary tract in PUR of the five studies on the of PUR reported urinary tract as a of PUR (1, urinary tract was only reported to be associated with catheterization but not with PUR There are published on the long-term of PUR. and reported women with a of PUR. Two women had two 6 months after delivery and two had altered bladder they were There are two on the of women with a of PUR. Andolf et al. (2) out of the women who had been to have PUR in their ultrasound study (2). they reported the prevalence of was not higher than that in the and they concluded that not to have any in the normal However, the number of women on in Andolf et al.'s (2) study is therefore no could be for the relationship between postpartum retention and other urinary In a study by Yip et al. they a of women after their initial diagnosis of PUR They found that women with PUR did not have a higher prevalence of urinary and However, the presence of long-term was not in this There are to suggest PUR could to problems in and have out that the bladder could as much as one of urine in PUR, which the bladder and would result in detrusor damage and long-term recent studies using have shown that stretching of the bladder muscle could responses as increased bladder or increase of and of the for factor, an that has been linked to bladder these in abnormal can be to long-term bladder are Park et al. suggest these may in bladder muscle and a in bladder after urinary retention Postpartum urinary retention is a common which is associated with the labor but their have not been of obstetric risk urinary retention may be in at risk women, and or to the at