AZOOSPERMIA II: EXCURRENT DUCT OBSTRUCTION
Excurrent ductal obstruction results in azoospermia from blockage of the ductal system after sperm exit the testicle. The posttesticular reproductive tract includes the epididymis, vas deferens, seminal vesicles, and associated ejaculatory apparatus (see Plate 3-3). Ductal obstruction can be due to congenital or acquired causes. In cases of idiopathic obstruction, 65% of blockages will be found in the epididymis, 30% in the vas deferens, and 5% at the level of the ejaculatory duct. Rarely, intratesticular obstruction of testis efferent ductules (see Plate 3-3) may occur.
The most common congenital cause of obstruction is cystic fibrosis (CF) or
its variant, congenital absence of the vas deferens (CAVD, see Plate 4-22). CF
is the most common autosomal recessive genetic disorder in the United States
and is fatal. Men with CF are missing parts of the mesonephric ducts that may
include the epididymis, vas deferens, seminal vesicles, or ejaculatory ducts.
CAVD, a “form fruste” of CF, may simply present as infertility and accounts for
1% to 2% of such cases. On examination, no palpable vas deferens is observed on
one or both sides. As many as 80% of CAVD patients will harbor a detectable CF
mutation. In addition, 15% will have renal malformations, most commonly
unilateral agenesis. The diagnosis is made on physical examination and confirmed
by transrectal ultrasound (TRUS, see Plate 4-12) showing seminal vesicle,
ampullary vas deferens, or ejaculatory duct agenesis or hypotrophy. Most cases
are not microsurgically reconstructable, and sperm retrieval (see Plate 5-7) is
required with assisted reproduction to conceive.
Idiopathic epididymal obstruction is a relatively uncommon condition
found in otherwise healthy men. It may be linked to prior occult infection, but
has also been shown to be related to CF in that one-third of affected men
harbor CF gene mutations. It is often amenable to microsurgical reconstruction.
Young syndrome presents with a triad of chronic sinusitis,
bronchiectasis, and obstructive azoospermia. The pathophysiology of the
condition is unclear but may involve abnormal ciliary function or abnormal
mucus quality, resulting in fluid concretion and block- age in the fine
epididymal ducts. Spermatogenesis is usually normal, and microsurgical
procedures can be performed to reestablish reproductive tract continuity. Adult
polycystic kidney disease is an autosomal dominant disorder associated with
numerous cysts of the kidney, liver, spleen, pancreas, epididymis, seminal
vesicle, and testis. Disease onset usually occurs in the twenties or thirties
with symptoms of abdominal pain, hypertension, and renal failure. Infertility
is usually secondary to obstructing cysts in the epididymis or seminal vesicle, which may be amenable to microsurgery.
Ejaculatory duct obstruction involves blockage of the ejaculatory
ducts—the delicate, paired, collagenous tubes that connect the vas deferens and
seminal vesicles to the urethra. It is the cause of infertility in 5% of
azoospermic men. It can be congenital, resulting from müllerian duct
(utricular) cysts, wolffian duct (diverticular) cysts, or congenital atresia or
acquired from seminal vesicle calculi or postsurgical or inflammatory scar
tissue. It presents as hematospermia, painful ejaculation, or infertility. The
diagnosis is confirmed by finding a low-volume ejaculate, and TRUS reveals dilated
seminal vesicles or dilated ejaculatory ducts. Treatment with endoscopic
unroofing of the ejaculatory ducts can restore fertility
and reduce symptoms (see Plate 5-9). A substantial proportion of idiopathic
cases are associated with CF mutations.
The most common cause of acquired ductal obstruction is due to vasectomy.
Vasectomies are performed on 1 to 3 million U.S. men annually for
contraception, and approximately 5% of men desire to have the vasectomy
reversed, most commonly because of remarriage. Groin and hernia surgery can
result in inguinal vas deferens obstruction, especially in cases in which the
Marlex mesh is used in repair. This is thought to be due to perivasal inflammation causing vasal obstruction. Bacterial infections
such as tuberculosis, Escherichia coli (in men age 35), or Chlamydia
trachomatis may involve the epididymis or vas deferens, with scarring and
obstruction that may or may not be amenable to microsurgical repair. Commonly,
a testis biopsy (see Plate 5-6) is needed to distinguish between a failure of
sperm production and obstruction in azoospermic men. If normal, obstruction is
confirmed, and formal surgical investigation of the reproductive tract begins
with a vasogram followed by
microsurgical reconstruction.
