88 CHAPTER 3 Bladder outlet obstruction

TURP and open prostatectomy

TURP

TURP involves removal of the obstructing tissue of BPH or obstructing prostate cancer from within the prostatic urethra, leaving the compressed outer zone intact (the “surgical capsule”).

An electrically heated wire loop is used, through a resectoscope, to cut the tissue and diathermy bleeding vessels. The cut chips of prostate are pushed back into the bladder by the flow of irrigating fluid, and at the end of resection are evacuated using specially designed evacuators—a plastic or glass chamber attached to a rubber bulb that allows fluid to be flushed in and out of the bladder.

Indications for TURP

•Bothersome lower urinary tract symptoms that fail to respond to changes in life style or medical therapy

•Recurrent acute urinary retention

•Renal impairment due to BOO (high-pressure chronic urinary retention)

•Recurrent hematuria due to benign prostatic enlargement

•Bladder stones due to prostatic obstruction

Open prostatectomy

Indications

•Large prostate (>100 g)

•TURP not technically possible (e.g., limited hip abduction)

•Failed TURP (e.g., because of bleeding)

•Urethra too long for the resectoscope to gain access to the prostate

•Presence of bladder stones that are too large for endoscopic cystolitholapaxy, combined with marked enlargement of the prostate

Contraindications

•Small fibrous prostate

•Prior prostatectomy in which most of the gland has been resected or removed; this obliterates the tissue planes

•Carcinoma of the prostate

Techniques

Suprapubic (transvesical)

This is the preferred operation if enlargement of the prostate involves mainly the middle lobe. The bladder is opened, the mucosa around the protruding adenoma is incised, and the plane between the adenoma and capsule is developed to enucleate the adenoma. A 22 Fr urethral and a suprapubic catheter are left, together with a retropubic drain.

Remove the urethral catheter in 3 days and clamp the suprapubic Fr. at 6 days, removing it 24 hours later. The drain can be removed 24 hours after this (day 8).

Simple retropubic

Compared with the suprapubic (transvesical) approach, this procedure allows more precise anatomic exposure of the prostate. It allows better

TURP AND OPEN PROSTATECTOMY 89

visualization of the prostatic cavity and more accurate removal of the adenoma. Better control of bleeding points and more accurate division of the urethra can be accomplished, reducing the risk of incontinence.

As well as the contraindications noted above, the retropubic approach should not be employed when the middle lobe is very large because it is difficult to get behind the middle lobe and to incise the mucosa (safely) distal to the ureters.

The prostate is exposed by a Pfannenstiel or lower midline incision. Hemostasis is achieved before enucleating the prostate, by ligating the dorsal vein complex with sutures placed deeply through the prostate.

The prostatic capsule and adenoma are incised transversely with the cautery just distal to the bladder neck. The plane between the capsule and adenoma is found with scissors and developed with a finger. Sutures are used for hemostasis. A wedge of bladder neck is resected.

A catheter is inserted and left for 5 days and the transverse capsular incision is closed. A large tube drain (30 Fr. Robinson’s) is left for 1–2 days.

Complications

These include hemorrhage, urinary infection, and rectal perforation (close and cover with a colostomy).

90 CHAPTER 3 Bladder outlet obstruction

Acute urinary retention: definition, pathophysiology, and causes

Definition

Acute urinary retention is the painful inability to void, with relief of pain following drainage of the bladder by catheterization.

The combination of reduced or absent urine output with lower abdominal pain is not in itself enough to make a diagnosis of acute retention. Many acute surgical conditions cause abdominal pain and fluid depletion, the latter leading to reduced urine output, and this reduced urine output can give the erroneous impression that the patient is in retention when, in fact, they are not.

Thus, central to the diagnosis is the presence of a large volume of urine, which when drained by catheterization leads to resolution of the pain. What represents “large” has not been strictly defined, but volumes of 500–800 mL are typical. Volumes <500 mL should lead one to question the diagnosis. Volumes >800 mL may be defined as acute or chronic retention.

Pathophysiology

Normal micturition requires the following:

•Afferent input to the brainstem and cerebral cortex

•Coordinated relaxation of the external sphincter

•Sustained detrusor contraction

•The absence of an anatomic obstruction in the outlet of the bladder

Four broad mechanisms can lead to urinary retention:

•Increased urethral resistance (i.e., BOO)

•Low bladder pressure (i.e., impaired bladder contractility)

•Interruption of sensory or motor innervation of bladder

•Central failure of coordination of bladder contraction with external sphincter relaxation

Causes in men

Causes include benign prostatic enlargement, malignant enlargement of the prostate, urethral stricture, and prostatic abscess (see also Box 3.2).

Urinary retention in men is either spontaneous or precipitated by an event. Precipitated retention is less likely to recur once the event causing it has been removed. Spontaneous retention is more likely to recur after a trial of catheter removal and more likely to require definitive treatment (e.g., TURP).

Precipitated retention can be caused by events such as anesthetic and other drugs (anticholinergics, sympathomimetic agents such as ephedrine in nasal decongestants), nonprostatic abdominal or perineal surgery, and immobility following surgical procedures.

ACUTE URINARY RETENTION 91

Box 3.2 Causes of acute urinary retention in either sex

•Hematuria leading to clot retention

•Drugs (e.g., anticholinergics, sympathomimetic agents)

•Pain (adrenergic stimulation of the bladder neck)

•Postoperative retention (see below)

•Sacral cord (S2–4) injury

•Sacral (S2–4) nerve or compression or damage, resulting in detrusor areflexia—cauda equina compression (due to prolapsed L2–L3 disc or L3–L4 intervertebral disc pressing on sacral nerve roots of the cauda equina, trauma to vertebrae, or tumors [benign or metastatic])

•Suprasacral spinal cord injury (results in loss of coordination of external sphincter relaxation with detrusor contraction—detrusor- sphincter dyssynergia (DSD)—so external sphincter contracts when bladder contracts)

•Radical pelvic surgery damaging pelvic parasympathetic plexus (radical hysterectomy, abdominoperineal resection): unilateral injury to pelvic plexus (preganglionic parasympathetic and postganglionic sympathetic neurons) denervates motor innervation of detrusor muscle

•Pelvic fracture rupturing urethra (more likely in men than in women)

•Neurotropic viruses involving sensory dorsal root ganglia of S2–4 (herpes simplex or zoster)

•Multiple sclerosis (can affect any part of the CNS—Fig. 3.2); retention caused by detrusor areflexia or DSD

•Transverse myelitis

•Diabetic cystopathy (causes sensory and motor dysfunction)

•Damage to dorsal columns of spinal cord causing loss of bladder sensation (tabes dorsalis, pernicious anemia)

Causes in women

These include pelvic prolapse (cystocele, rectocele, uterine); urethral stricture; urethral diverticulum; post-surgery for stress incontinence; pelvic masses (e.g., ovarian masses); and Fowler syndrome.

Fowler syndrome

Increased electromyographic activity can be recorded in the external urethral sphincters of these women (which on ultrasound are of increased volume) and is hypothesized to cause impaired relaxation of the external sphincter.

Fowler syndrome occurs in premenopausal women, often in association with polycystic ovaries.

Risk factors for postoperative retention

Risk factors include instrumentation of the lower urinary tract; surgery to the perineum or anorectum; gynecological surgery; bladder overdistension; reduced sensation of bladder fullness; pre-existing prostatic obstruction; and epidural anesthesia. Postpartum retention is not uncommon, particularly with epidural anesthesia and instrumental delivery.

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94 CHAPTER 3 Bladder outlet obstruction

Acute urinary retention: initial and definitive management

Initial management

Urethral catheterization is used to relieve pain (suprapubic catheterization if urethral route not possible). Record the volume drained—this confirms the diagnosis, determines subsequent management, and provides prognostic information on outcome from this treatment.

Definitive management in men

Discuss trial without catheter (TWOC) with the patient. Precipitated retention often does not recur; spontaneous retention often does. Half of patients with spontaneous retention will experience a second episode of retention within the next week or so, and 70% within the next year.

A maximum flow rate (Qmax) <5 mL/s and low voiding detrusor pressure predicts subsequent retention. Thus, while most patients will require definitive treatment (e.g., TURP), a substantial minority will not need surgery.

Options to avoid TURP

•Prostate-shrinking drugs followed by a voiding trial several months later (5A-reductase inhibitors in those with benign-feeling prostates, LHRH agonists in those with malignant-feeling prostates on DRE, confirmed by TRUS-guided prostate biopsy)

•Prostatic stents

•Long-term urethral or suprapubic catheter

•Clean, intermittent self-catheterization (CISC) is not a realistic option for most men, but some will be able and happy to do this.

Definitive management in women

Use CISC either until normal voiding function recovers or permanently if it does not. For Fowler syndrome use sacral neuromodulation (e.g., Medtronic InterStim).

Risks and outcomes of TURP for retention

Relative risks of TURP for retention vs. TURP for lower urinary tract symptoms (LUTS) are as follows: postoperative complications 26:1; blood transfusion 2.5:1; in-hospital death 3:1.1

High retention volume, greater age, and low maximum detrusor pressure are predictive for failure to void after TURP; 10% of those with acute retention of urine and 40% of those with chronic retention fail to void after initial post-turp. Overall, 1% of men will fail to void after subsequent voiding trial and will require long-term catheterization.2

1 Pickard R, Emberton M, Neal D (1998). The management of men with acute urinary retention. Br J Urol 81:712–720.

2 Reynard JM (1999). Failure to void after transurethral resection of the prostate and mode of presentation. Urology 53:336–339.

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