The inguinal testis; how accurate is the volume measurement

A recent study by the Alkmaar research group showed that in three out of four
boys with acquired undescended testis, the testis spontaneous descents at the
beginning of puberty.
Testisvolume is an important markter for the development of the testis and for
the different puberty stages.
For inguinal testis the follow-up of the testisvolume is complicated by its
location.
It is unclear whether the volume measured while the testis is located in the
groin region is a valid measure.
To our knowledge it has not been investigated how the measured volume of the
inguinal testis compared with the same testis in scrotal position is
correlated.

The purpose of this study is to evaluate the accuracy of the measurement of
testisvolume located in the groin area.

We hypothesize that the inguinal testis has a smaller volume compared to the
normal value for the same age at a scrotal position.
However, it is unclear whether the inguinal testisvolume is substantially
behind or that the volumes measured are affected by the testis location during
measurement.

All boys, aged 2-12 years, who will undergo an orchidopexy at our hospital
will be asked to participate in this study.
Just before the start of the operation a volumemeasurement will be made **by
means of ultrasonography and orchidometer of the undescended testis located in
the groin area.During the orchidopexy a volume measurement using the slide
caliper will be performed.

We will determine the length, breadth and depth of the testis with ultrasound
and with the slide caliper. The testicular volume will be calculated using the
formula; D1 (length) x D2 (width) x D3 (depth) x pi / 6.
The participating boys will be seen two-times postoperative at the outpatient
clinic, after 6 weaks and 6 months respectively. This is in line with the
current protocol for boys who undergo orchidopexy. For those boys that
participate in this study an additional volume measurement will be performed.
The volume measurement with orchidometer and ultrasound will be repeated using
the same method. Considering that the testis will have a scrotal position at
that time.

The primary outcome parameter is the testicular volume, pre- operatively,
during orchidopexy and post-operatively.

Statistical analysis will take place using SPSS, anonymous.The agreement
between the measurement methods will be tested using the Bland-Altman plot and
intraclass correlation coefficient (ICC).
The volume will be correlated with the normal values **for testicular volume as
recently defined by the study group of Alkmaar. (Goede et al)

The burden and risk associated with participation are negligible
There are no additional follow up moments. The subject receives only two
additional ultrasounds during regular follow-up at the outdoor patient clinic.
This is a non- invasive procedure without risks. During the orchidopexy a slide
caliber will be used to measure the volume, this is indeed an invasive
procedure. The risks of this invasive procedure are negligible, in particular
when it is used by an experienced surgeon or urologist.