When in doubt of my diagnosis, I have access to the Aloka 7 or ProSound Alpha 7,
two very high performance non-portable ultrasound machines.
During mid gestation the foetus is usually visible trans abdominally in the inguinal
area and in between the mammary glands. Sometimes intestines are present
between the body wall and the foetus, which explains why it can be difficult to obtain
a nice diagnostic ultrasound images at that stage of the pregnancy.
As the pregnancy progresses, the foetus is detected more and more cranial. In a
foetus presented in anterior longitudinal presentation dorso pubic, the foetal
hindquarters are usually visualized in the mid abdomen at 5 to 6 months’ gestation;
mid to cranial up to 7 months and in the cranial third of the abdomen at 8 months of
gestation. To obtain a good quality diagnostic image of the foetus, the hair on the
ventral abdomen should be clipped from the mammary gland to the xyphoid
extending to the level of both stifles, followed by a thorough skin scrub, an
application of a good layer of ultrasound gel and finally alcohol to the skin. The
ventral abdomen should be scanned in a sagittal and a transverse lane. It is
recommended to examine all four quadrants of the placenta. (or as much as
possible). A good in depth trans abdominal U/S evaluation of the late term mare can
easily take up 2 hours.
The purpose of trans abdominal U/S ultrasound exam?
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To determine the number of foetuses and the position of the foetus, most
parts of the uterus should be scanned. In late gestation the head of the foetus
is positioned near the pelvic area where the orbital diameter can be measured
via trans rectal and trans abdominal ultrasound scanning.
To determine foetal orientation, the uterus should be scanned in a sagittal
section to find the thorax with the heart in the