Discussion
Congenital unilateral absence of the vas deferens (CUAVD) is mostly
diagnosed incidentally since it is rarely symptomatic nor a cause of
infertility.7 Based on vasectomy data, the incidence
in the general population is estimated to be 0.5% - 1.0%.2 CUAVD is
found on the left side in 66%.7 The incidental
finding of CUAVD during inguinal hernia repair is clinically relevant
for the operating surgeon, firstly because it is associated with renal
abnormalities. Ipsilateral renal agenesis is found in 74% - 79% of men
with CUAVD and in one third of these men abnormalities of the
contralateral solitary kidney are also present.7,8Secondly, when absence of the vas deferens is found during unilateral
surgical exploration of the inguinal canal, the contralateral vas
deferens could be absent as well as a part of congenital bilateral
absence of the vasa deferentia (CBAVD).
CBAVD naturally leads to azoospermia and is therefore mostly diagnosed
during infertility examination. It is estimated to be the cause of
azoospermia in 1% - 6% of infertile men.7 Renal
anomalies occur with CBAVD but are found less often (10-21%) than in
men with CUAVD.9,10 CBAVD is genetically linked with
cystic fibrosis (CF) and is almost invariably present in male CF
patients.11–14 Male CF patients rarely have renal
anomalies.5,9,15 Men with CBAVD without renal
anomalies or clinical signs of CF are considered to have a mild, genital
form of CF since CF transmembrane conductance regulator (CFTR) gene
mutations have been found in 64% - 75% of these
men.7,10,11,16–18 CTFR gene mutations have rarely
been described in men with CBAVD and renal anomalies and have never been
described in fertile men with CUAVD and renal anomalies but have been
described in men with CUAVD and associated infertility due to
non-patency of the solitary vas deferens.19–21
The co-occurrence of CUAVD and CBAVD with renal anomalies originates
from the close association of the reproductive and urinary tracts during
embryogenesis. Between the fourth and sixth week of gestation, the
mesonephric (Wolffian) ducts connect the mesonephros to the urogenital
sinus and form ureteric buds, which later differentiate into the ureter,
renal pelvis and metanephric kidneys. After seven weeks of gestation,
the mesonephric ducts separate from the differentiating ureteric buds.
The proximal parts of the mesonephric ducts remain fixed to the
urogenital sinus to form the ejaculatory ducts, seminal vesicles and
juxta-urethral vasa deferentia whilst the upper parts form the corpus
and cauda epididymis and the scrotal and inguinal vasa
deferentia.2,8,22 Because of this separation of the
primitive reproductive and urinary tracts after 7 weeks of gestation,
CUAVD or CBAVD with renal anomalies is caused by a genetic or toxic
disturbance in the development of the mesonephric ductal system before
the seventh week of gestation, whilst CUAVD or CBAVD without renal
anomalies is caused by a later developmental disturbance. The caput
epididymis, vasa efferentia and testes develop separately from the
mesonephros and are therefore never affected.2,8,22 It
remains unclear how renal agenesis occurs unilaterally in CBAVD, and why
unilateral renal agenesis does not occur in CBAVD in CF patients. The
exact pathophysiology of CBAVD and CUAVD, with or without renal
anomalies, thus remains poorly understood.
The reported patient had children of his own and never experienced
symptoms suggestive of CUAVD. His medical history stated epididymitis 5
months before the operation, but this was right-sided and was therefore
considered coincidental. Palpation of the vasa deferentia was omitted in
the pre-operative physical examination. In retrospect, this could have
revealed CUAVD and associated ipsilateral renal agenesis
pre-operatively. Even though the reported patient was asymptomatic and
had a normal renal function, pre-operative knowledge of CUAVD and
potential unilateral renal agenesis is important to prevent problems in
patients with a decreased renal function and to urge the surgeon to take
even more care to prevent iatrogenic damage to the contralateral
solitary vas deferens. Some studies suggest that a congenital solitary
kidney increases the risks of hypertension, proteinuria and mild renal
insufficiency23 and therefore we advised the patient
long-term annual surveillance of blood pressure, urinary protein and
serum creatinine. Fortunately, patient survival has never been found to
be less in patients with a congenital solitary
kidney.23 The reported patient had no history or
clinical signs of CF. His family history revealed no CF, infertility or
abnormalities of the urinary or reproductive tracts. No genetic
investigations regarding CFTR gene mutations were required in the
reported patient since laparoscopic evaluation of the contralateral
inguinal canal revealed an anatomically normal vas deferens, ruling out
CBAVD, with normal fertility and ipsilateral renal agenesis.
Based on the literature and our experiences in the reported case we
state recommendations for surgeons who encounter CUAVD or CBAVD
incidentally during inguinal hernia repairs. Firstly, we advise thorough
pre-operative physical examination before inguinal hernia repair in male
patients, including palpation of the vasa deferentia to assess CUAVD or
CBAVD. Vasa deferentia are easily palpable in adult patients and
therefore CUAVD or CBAVD can be diagnosed by physical examination
without imaging or surgical exploration.8 Therefore,
when absence of the vas deferens is found during unilateral inguinal
hernia repair and pre-operative bilateral palpation of the vasa
deferentia has been omitted, we recommend palpation of the contralateral
vas deferens to assess for CBAVD. In our opinion, surgical exploration
for assessment of the contralateral vas deferens is not indicated when
CUAVD is found in adult patients, since this could increase morbidity
and the risk of infertility due to iatrogenic damage. For pediatric
patients, however, some authors advise concomitant laparoscopic
evaluation of the contralateral vas deferens when unilateral absence of
the vas deferens is found.[5] Naturally, adequate palpation of the
vasa deferentia is more difficult in pediatric patients whilst accurate
diagnosis of CBAVD is important because of the resulting infertility and
potential presence of CF.5 We therefore agree with
recommending surgical exploration of the contralateral inguinal canal to
assess CBAVD in pediatric patients, preferably by laparoscopy in the
same general anaesthetic. Naturally, the surgeon should explain the
possibility of required contralateral exploration of the inguinal canal
to the parents and pediatric patient pre-operatively. When this has been
omitted, one could offer contralateral exploration of the inguinal canal
either intra-operatively to the parents by telephone or postoperatively
to be planned as a second laparoscopy. Secondly, we recommend
postoperative renal ultrasonography in all men with CUAVD or CBAVD to
assess unilateral renal agenesis, renal abnormalities or renal ectopia.
When renal anomalies are found we advise to consult a nephrologist for
management or long-term surveillance of blood pressure, urinary protein
and serum creatinine. Thirdly, we recommend genetic evaluation of CFTR
gene mutations in when CBAVD is found in either pediatric or adult
patients, or when CUAVD is found in infertile men. Finally, we advise
adequate counselling when CBAVD is found in pediatric patients regarding
infertility and further genetic evaluation with potentially
disconcerting outcomes for relatives.
In conclusion, we report the first incidental finding of CUAVD with
ipsilateral renal agenesis during laparoscopic TEP repair of bilateral
inguinal hernias in an adult patient. The finding of unilateral absence
of the vas deferens is clinically relevant because it could either
indicate CUAVD, in which associated renal anomalies are found in a
majority of men, or CBAVD, in which associated renal anomalies are found
in a minority of men but which leads to azoospermia and often has a
genetic link to CF. Adequate physical examination is important to assess
for CUAVD or CBAVD preoperatively. When absence of the vas deferens is
found during unilateral laparoscopic inguinal hernia repair in an adult
patient we advise palpation of the contralateral vas deferens to assess
the contralateral vas deferens and to rule out CBAVD. When absence of
the vas deferens is found during unilateral laparoscopic inguinal hernia
repair in pediatric patients, concomitant laparoscopic evaluation of the
contralateral inguinal canal is advisable. We advise renal
ultrasonography in all patients with CUAVD or CBAVD and to consult a
nephrologist when renal anomalies are present. Genetic evaluation of
CFTR gene mutations is advisable in all children or men with CBAVD or in
men with CUAVD who are infertile.