Материал: Oxford American Handbook of Urology ( PDFDrive )

462 CHAPTER 10 Trauma to the urinary tract

Paraphimosis

Definition and presentation

Paraphimosis is when the uncircumcised foreskin is retracted under the glans penis and the foreskin becomes edematous, and cannot be pulled back over the glans into its normal anatomical position. It occurs most commonly in teenagers or young men and also in elderly men (who have had the foreskin retracted during catheterization, but where it has not been returned to its normal position).

Paraphimosis is usually painful. The foreskin is edematous and a small area of ulceration of the foreskin may have developed.

Treatment

The best initial maneuver for manually reducing paraphimosis is to forcefully squeeze the edematous prepuce for several minutes. Then the skin may be manipulated distally with the fingers of both hands as the glans is pressed down with the thumbs.

If this fails, the traditional surgical treatment is a dorsal slit under general anesthetic or ring block. A longitudinal incision is made in the tight band of constricting tissue and the foreskin pulled back over the glans. Close the incision transversely with chromic sutures to widen the circumference of the foreskin and prevent recurrences. Many patients subsequently require elective circumcision.

MALIGNANT URETERAL OBSTRUCTION 463

Malignant ureteral obstruction

Locally advanced prostate cancer, bladder or ureteral cancer may cause unilateral or bilateral ureteral obstruction. Locally advanced nonurological malignancies can also obstruct the ureters (e.g., cervical cancer, rectal cancer, lymphoma).

Unilateral obstruction

This is often asymptomatic and an incidental ultrasound finding that requires no specific treatment in the presence of a normal contralateral kidney in a patient with limited life expectancy.

Occasionally, flank pain and systemic symptoms may develop due to infection of the obstructed upper urinary tract. In this circumstance, drainage by nephrostomy or stenting is required.

Bilateral ureteric obstruction

This is a urological emergency. The patient either presents with symptoms and signs of renal failure or is anuric without a palpable bladder. A mass will probably be palpable on rectal examination.

Investigations

Renal ultrasound will demonstrate bilateral hydronephrosis and an empty bladder. Noncontrasted CT will confirm the presence of dilated ureters down to a mass at the bladder base.

Immediate treatment of bilateral ureteric obstruction

After treating any life-threatening hyperkalemia, options include bilateral percutaneous nephrostomy or ureteric stenting. Serum coagulation studies are required prior to nephrostomy insertion. Insertion of retrograde ureteric stents in this setting is usually unsuccessful because tumor involving the trigone obscures the location of the ureteric orifices.

More successful is antegrade ureteric stenting following nephrostomy insertion, both of which are performed under IV sedation. The double-J silicone or polyurethane ureteric stents require periodic (4–6 monthly) changes to prevent calcification or blockage.

In the case of prostate cancer, rapid reduction in testosterone through hormone therapy should be started if not previously used.

464 CHAPTER 10 Trauma to the urinary tract

Spinal cord and cauda equina compression

Spinal cord compression due to spinal metastases from urological cancers

This is a urological oncological emergency; failure to diagnose and treat promptly can lead to permanent paraplegia and autonomic dysfunction (failure of bladder and bowel emptying; inability to achieve an erection).

Due to epidural compression arising from vertebral body metastasis in the majority of cases, 95% of patients will complain of back pain and have a positive bone scan. Ten percent of cases do not exhibit these features because their disease is paravertebral.

Patients with back pain should be examined neurologically and evaluated radiologically. Pain usually precedes cord compression by about 4 months. Other clinical features include sensory changes and muscle weakness in the lower limbs and bladder and bowel dysfunction, and these can progress rapidly to become irreversible.

If cord compression is suspected, the investigation of choice is spinal MRI, which will reveal the deposits (multiple in 20% of cases).

Treatment

Initial treatment is with high-dose intravenous corticosteroids (e.g., dexamethasone 10 mg followed by 4 mg q6h for 2–3 weeks). If the patient has prostate cancer but has not had prior androgen deprivation therapy, ketoconazole should be started to lower circulating androgen levels.

Without delay, further treatment with direct spinal radiotherapy or, less frequently, neurosurgical decompression is carried out. Surgery should be considered preferable if there is a pathological fracture, unknown tissue diagnosis, or previous history of radiotherapy.

Cauda equina compression

The adult spinal cord tapers below L2 vertebral level into the conus medullaris. The cauda equina consists of nerve roots of spinal cord segments below L2, as they run in the subarachnoid space to their exit levels in the lower lumbar and sacral spines.

Pathophysiology

The cauda equina may be compressed by a central intervertebral disc prolapse, spinal stenosis, or a benign or malignant tumor within the lower lumbar or sacral vertebral canal.

Symptoms

The diagnosis should be considered in any female or young male presenting with difficulty voiding or in urinary retention. There may be back pain.

Signs

These include palpable bladder, loss of perianal (S2–4) and lateral foot sensation (S1–2), reduced anal tone, and priapism.

Treatment is intermittent self-catheterization.

Infertility

Male reproductive physiology 466

Etiology and evaluation of male infertility 470

Lab investigation of male infertility 472

Oligospermia and azoospermia 476

Varicocele 478

Treatment options for male factor infertility 480

466 CHAPTER 11 Infertility

Male reproductive physiology

Hypothalamic–pituitary–testicular axis

The hypothalamus secretes luteinizing hormone–releasing hormone (LHRH), also known as gonadotrophin-releasing hormone (GnRH). This causes pulsatile release of anterior pituitary gonadotrophins, called folli- cle-stimulating hormone (FSH) and luteinizing hormone (LH), which act on the testis.

FSH stimulates the seminiferous tubules to secrete inhibin and produce sperm; LH acts on Leydig cells to produce testosterone (Fig. 11.1).

Testosterone

Testosterone is secreted by the interstitial Leydig cells, which lie adjacent to the seminiferous tubules in the testis. It promotes development of the male reproductive system and secondary sexual characteristics.

Steroidogenesis is stimulated by a cAMP-protein kinase C mechanism, which converts cholesterol to pregnenolone. Further steps in the biosynthesis pathway produce intermediary substances (dehydroepiandrosterone and androstenedione) prior to producing testosterone.

In the blood, testosterone is attached to sex hormone–binding globulin (SHBG) and albumin. At androgen-responsive target tissues, testosterone is converted into a potent androgen, dihydrotestosterone (DHT), by intracellular 5A-reductase (see p. 64).

Spermatogenesis

Seminiferous tubules are lined with Sertoli cells, which surround developing germ cells (spermatogonia) providing nutrients and stimulating factors, as well as secreting androgen-binding factor and inhibin (Fig. 11.2).

Primordial germ cells (spermatogonia) divide via mitosis to form primary spermatocytes. These undergo a first meiotic division to create secondary spermatocytes (46 chromosomes), followed by a second meiotic division to form spermatids (23 chromosomes). Finally, these differentiate into spermatozoa.

Spermatogenesis takes 74 days. The nonmotile spermatozoa leave the seminiferous tubules and pass to the epididymis, where they undergo maturation (gain motility and the ability to fertilized). Ductal transit time takes another 2 weeks, so the total time from beginning of spermatogenesis to ejaculation is 3 months.

Motile sperm are stored in the globus minor of the epididymis until ejaculation. Spermatozoa that are not released are reabsorbed by phagocytosis.

Mature sperm

Mature sperm have a head, middle piece, and tail (Fig. 11.3). The head is composed of a nucleus covered by an acrosome cap, containing vesicles filled with lytic enzymes that break down the outer layer of the female ovum. The middle piece contains mitochondria and contractile filaments, which extend into the tail to aid motility.