Biomedical Engineering Reference
In-Depth Information
pregnancy than does E
t
alone and provides additional
information on implantation and placental function.
Before the early 1960s, the only means of diagnosing
pregnancy in nonhuman primates was by palpation of the
uterus.
Hartman (1932)
was the first investigator to
describe in detail the method of bimanual rectal palpation
for accurately determining the stage of pregnancy by the
size of the uterus and size of the fetal head and for
following involution of the uterus postpartum. This
palpation procedure is still useful for diagnosing preg-
nancy in both indoor and outdoor breeding colonies as long
as it is performed by well-trained and experienced indi-
viduals. The examination is best done using ketamine
hydrochloride (Ketaset; 10 mg/kg) or similar anesthesia
with the animal lying on its side or placed in the supine
position (
Figure 8.2
). In larger species (i.e. M. mulatta,
M. nemestrina, Papio spp.), the examiner inserts the
middle finger of the right hand into the rectum as far as
possible, pressing toward the abdominal wall while
placing the left hand ventrally for counterpressure. In
smaller species (i.e. M. fascicularis), use of the little finger
may be more appropriate. For most Old World monkeys,
with the exception of large baboons, the entire length of
the uterus may be appreciated if the animal is not pregnant
or in the early stages of pregnancy; the ovaries may be
identified on either side of the uterine body. The cervix in
most macaques is readily distinguished by the sharp ridge
marking its cranial border. The vagina is difficult to
identify since it is collapsed against the symphysis pubis. If
the ovaries are palpated, their size can be described by
subjective terms such as “tiny (infantile), small, medium,
large, or very large.”
Wilson et al. (1970)
devised a set of
gauges covering the range of ovarian and uterine sizes;
however, he found that palpation of the ovaries did not
yield reliable information about
Hartman (1932)
and
Mahoney (1970, 1972, 1975)
appear
to be among the few who developed the skills required to
obtain useful information by ovarian palpation of M.
mulatta and M. fascicularis.
Diagnosing pregnancy by bimanual palpation is easier
from approximately GD 16 onward in macaques and
baboons because of the relatively rapid changes that occur
anatomically. Pregnancy is confirmed on the basis of size
and consistency of the uterus until the 11th or 12th week (in
macaques), at which time the head of the fetus can be
palpated directly. Uterine palpation can be used to accu-
rately diagnose pregnancy by GD 25 in M. mulatta and by
GD 20
e
21 in the baboon provided that the day(s) of mating
is known. Abdominal palpation can also be used to diag-
nose pregnancy in New World species. In the squirrel
monkey, this method is reliable by the 6th week of gesta-
tion, when a 4- to 5-mm mass is detectable initially in the
lower abdominal region cranial to the pelvis. The mass is
larger and spongier by about 10
e
12 weeks (
Kaplan, 1977
).
In the marmoset, estimates of uterine size based on external
palpation have allowed formulation of an equation that
permits prediction of parturition time (
Gengozian et al.,
1974; Phillips and Grist, 1975
).
One of the more recent techniques employed to detect
and monitor pregnancy in monkeys has been diagnostic
ultrasound. This method provides a reliable means for
evaluating and maintaining reproductive colonies in addi-
tion to its application for experimental purposes. For
macaques, animals may be hand held by experienced
animal handlers, placed in restraint chairs (if previously
trained), or immobilized with ketamine hydrochloride
(10 mg/kg) for examinations. To detect pregnancy, the
uterus is scanned transabdominally in both serial sagittal
and transverse planes (
Tarantal and Hendrickx, 1988a,d
).
Because of the characteristic thin abdominal wall in these
species (M. mulatta and M. fascicularis), the high-
frequency transducers (i.e. 7.5 or 10 MHz) provide optimal
resolution and image quality. The uterus will usually be
found midline, although anatomical variations and
abdominal/pelvic adhesions can result in alternate loca-
tions. In many cases, the uterine body may be highly
mobile and can be found flexed to the right, left, ventral
(anteflexed), or dorsal (retroflexed) in relation to the cervix.
This is frequently the case for females with an elongated
lower uterine segment. In roughly 90% of all cases evalu-
ated, a central linear echo is noted within the normal
nongravid uterus. This echo represents the uterine “cavity”/
interface between apposing layers of endometrium. The
uterine or endometrial cavity echo (ECE) is a useful land-
mark for (1) identifying the uterus, (2) detecting early
pregnancy, and (3) assessing uterine pathology.
Pregnancy can be identified in both the rhesus and long-
tailed macaques as early as GD 14
e
16 (
Tarantal and
Hendrickx, 1988a
). During this period of development, the
reproductive events.
FIGURE 8.2
Diagrammatic representation of bimanual palpation
for pregnancy detection. Adapted from
Wilson et al. (1970)
.(From
Teratology, 3. Copyright
1970, John Wiley & Sons, Inc. Reprinted with
permission of Wiley-Liss, Inc., a subsidiary of John Wiley & Sons, Inc.)
