Use of laproscopy and Ultrasonography for Diagostics in Mammals

Abstract
The use of laparoscopy for ovulation detection in Small Ruminants ( sheep, goats) has revealed that ovulation occurs earlier (12-24 hrs) in ewes than in goats (24-42 hrs) after onset of heat. It has been used to study development of conceptus in ewes and was used to predict ovarian response in super ovulated ewes and used to predict ovarian response in superovulated ewes and ewe-lambs with 73-95% accuracy.

Use of both A-mode and B-mode ultrasonography in small ruminants has been reviewed. The present day, real time ultrasonic imaging has made it possible to detect pregnancy in sheep and goats as early as day 20. The accuracy of B-mode (linear array and sector scanner systems) is higher than A-mode equipments. (doppler or amplitude modes). The B-mode realtime imaging systems allow non-invasive visualization of the internal reproductive organs and their conceptus. Its present and future use in the study of maternal recognition of pregnancy , transuterine migration, Foeto-maternal interaction, Preimplantation embryo signals, early embryonic mortality and diagnosis of reproductive disorders and failures is reviewed and discussed.

Laparoscopy:

Since the adoption of laparoscopy in sheep and goats (Phillipo et al 1971, Wani, 1982), a number of investigations have been carried in these species through laparoscopy. We shall present a review of our studies here under following headings.

1. Ovulation Detection in Muzaffarnagri Sheep:

The appearance of corpus luteum (CL) was observed at laparoscopy after every 6 hourly intervals from the beginning till the end of heat (0-48 hrs). The laparoscopy was thereafter conducted at 3 days interval from 3rd to 28th day post mating. The ovulation was observed to occur between 12024 hrs after the onset of heat. The corpus lateum started regressing around day 9th and regresses between 12-15 day of the cycle. (Wani and Sahni, 1988).

2. Ovulation detection in Jamunapari goats:

Similar procedures as in sheep were adopted in goats. About 87% examined in this study ovulated within 24-36 hrs after the onset of heat. All ovulated between 24-42hrs. The ovulation rate was 1.55 CL. (Corpus luteum) started regressing around the day 12th in goats and regressed between 15th-18th day of the cycle (Wani, 1989).

3. Development of Conceptus in Corriedale ewes:

The uterine distention (development of conceptus) was examined through laparoscopy. First group was laparoscopied between 28-35 days post mating. Group 2 ewes were examined around 58± 0.6 days post-mating and Group 3 ewes were examined on 93 ± 0.8 days post-mating. The laparoscopic observations are shown in Tab-1. For confirmation of these observations laparotomy was conducted immediately after laparoscopy (Wani and Bachoo, 1990).

Table-1 Development of Conceptus in Sheep.

Group -I Laparoscopy Laparotomy

Uterine horns, thin fluid filled Uterine horns distended
Transparent appearance. Asymmetry of gravid horns.
Uniform distention, uterine
Blood vessels hypertrophied

Group-II. Pregnant uterine horn distended Gravid horn distended like
Like a balloon. Fallopian tubes a ballon. Looked as if few
Enlarged . Gravid horn thick. Ballons are joined together
Small marks as budding Distended uterine horn
Cotyledons. Difficult to bring out of
Incision.

Group-III Pregnant horn like a big ballon, Pregnant uterine horns very
Foetus recognized,cotyledons much distended whole gravid
Identified as small rounded dark horn unable to be examined.
Buds. Full foetus felt.

….Ref. Wani and Bachoo, 1990

4. Prediction of Ovarian Response in Superovulated ewes:

Eleven superovulated corridale ewes were laparoscopied on 5th or 6th day post-mating. The number of corpora lutea and ovulated follicles were counted. Accuracy % was calculated by comparing observations at laparscopy with those actually observed at laparotomy. The overall accuracy in predicting ovulating rate and unovulated was 73.7% and 80.4% respectively. (Wani and Bachoo, 1990).

(ii) In Superovulated ewe lambs:

Twenty two crossbred ewe lambs were superovulated as per Wani et al (1989). Those in heat were laparoscopied 5-6 day post –mating . The number of corpora lutea and un-ovulated follicles were counted at laparoscopy and compared with actual observations at laparotomy. The overall occuracy % of predicting unovulated follicles and ovulations varied from 75-95% respectively (Wani et al, 1990).

The use of laparoscopy in future may include aspiration of follicular fluid, estimation of foetal numbers, flushing of superovulated donors, diagnosis of reproductive disorders intrauterine insemination, laparoscopic embryo transfer and study of foeto-maternal relationship.

Ultrasonography:

Ultrasonography consists of two system: The A-mode ultrasounds: consists of amplitufe mode, sonar or echo systems. For two decades now, these systems have been in use of pregnancy diagnosis in small ruminants. (Wani, 1981, Wani and Sahni, 1981, Watt et al, 1984).Now real-time B-mode ultrasonography is available. If used correctly, it can help not only to detect pregnancy as early as 20-25 days post-mating, but real time imaging systems can help in the diagnosis of reproductive disorders both in male and female small ruminants. It can also help, in the monitoring of embryo development, transfer implantation, foeto-maternal relationship and foetal growth and placentation. Let us review the use of ultrasonography under following three heads.

a. Past use of ultrasounds
b. Present use of ultrasonography and
c. Future prospects of ultrasonography.

( a) Past use of ultrasounds:

The ultrasound equipments mostly used in the past were A-mode equipments. They were mostly of two types:-

a) Doppler system

The doppler equipments worked on the principle of altered ultrasound frequency. It mainly employed detection of foetal pulse, movements and uterine artery circulation as a means of detecting pregnancy (Wani, 1981, Wani and Sahni, 1980, Wani and Sahni, 1981). The accuracy of pregnancy detection after 50 days post-mating ranged between 75-90% in ewes and she-goats. The equipment was used to predict foetal age too. This was done by counting foetal heart heats.

b) Amplitude mode

Another type of early ultrasonic equipments were based on the detection of the difference in a coustic impedance between the contents in the gravid uteres and the abdominal viscera. These equipments were Amplitude depthscope, or amplitude-depth ultrasonic analyzer. They were mostly used by Australian workers with 90-95% accuracy after 2 months of pregnancy (Lindhi, 1966, 1969).

II. Present use of Ultrasonography:

With the availability of real-time ultrasound systems, the past A mode systems are almost replaced. These B Mode real-time systems allow non-invasive visualization of the internal anatomy of the reproductive organs and their conceptus (Buck-rell, 1988). These systems have been described as most advanced technology of reproductive research after RIA (Ginther, 1986). The advantages/non-pregnancy tests in small ruminants, can provide informations on foetal numbers, foetal viability and diagnosis of reproductive tract diseases.

Equipment

The equipments marketed for use in animals have been mostly modeled for Mare. Two systems are in use for veterinary purposes.

(i) Linear array system
(ii) Sector Scanner

However, now some systems have the capability to provide both linear and sector scanning systems. Sector systems have some advantage over linear array, system, such as,

i. They require less skin surface contact which reduces the scan time required per ewe.
ii. They have superior resolution power especially in its electronic model

The cost of these systems vary between 10,000 to 15,000 US dollars. Sectors scanners are constlier than linear array models. Image quality comparison are suggested before purchase (Buckrell. 1988).

Transducers

Transducers are available both for abdominal and rectal use. The head frequency of a transducer is important for getting better images. Higher the transducer head frequency, the better will be the resolution power. With higher and better resolution, image quality shall improve. With higher and better resolution, image quality shall improve. At present three frequency transducers are available 7,5,5 and 3 MHz. For rectal use the 7.5 MHz transducer gives better results, for visceral use 5 MHz transducers may be used. For deeper penetration (e.g.flank) the lower frequency transducers 3 MHz are used.

Advantages and limitations:

The major benefit of using present day real-time systems is that we get image copy on a polarid film, slides, video or papers. This record serves as teaching aid or for self learning. The image can be frozen and tissues can be identified, measured before recording the image.

The another advantage of real-time systems is that the image can be freezed or we can have a hard copy of the image the chances of error in making diagnosis is minimized. The accuracy in diagnosis using real-time systems may be as high as 90% even during early gestation; however it depends on the choice of region and position while scanning i.e. rectal, flank standing, inguinal, clipped unclipped belleys etc.(Logue et al, 1987). As the accuracy and efficiency of using real-time ultrasound may be influenced by many factors. It is advisable to provide following information while publishing date on these systems:-

a) System used- "Linear or Sector"
b) Transducer frequency.
c) Stage of gestation
d) Region of scanning
e) Duration of scan
f) Fasting
g) Breed and parity of the ewe or she-goat
h) Operator
i) Early embryonic death.

False positive diagnosis may result from an early diagnosis of pregnancy in ewes between day 20-25 post-mating. This may be the result of subsequent embryonic death or abortion (Fowler and Wilkins, 1984).

III. Future prospects of ultrasonography:

The efficiency of the real-time systems is expected to be increased, both in terms of resolution and real-time elaborative imaging system. It is hoped that use of ultrasonography shall help in increasing our understanding, on feeto-placental, foeto-maternal, embryo- endometrial interactions, besides monitoring embryo-foetal development. Some of its present days used could be improved, such as:-

a. Maternal recognition of pregnancy:

The study of pre-implantation embryos, estimations of endometrial secretions and real-time imaging of the events involved in implantation may help us to understand the factors involved in the maternal recognition of pregnancy. Some studies using ultrasonography have suggested that maternal recognition of pregnancy takes place around 14-17 days in ewe and does, respectively (Riera, 1984). Ultrasonography along with assays for detection of antiproges terone antibodies in the uterine epithelium could help us to understand the signals responsible for sustained progesterone secretion (C.L. growth) during early pregnancy. The understand shall increase on the embryoendometril interactions. This can be possible by biopsy studies on morphological charges in endometruim, modulated and monitored by use of ultrasonography.

b) Trans uterine migration:

trans uterine migration of embryos has been found to occur in 8% ewes with single ovulation, in 87.%% ewes with multiple ovulations. The assessment of blastocyst effects on the endothelium, especially to assess the role of embryonic stages involved in transition of maternal to embryonic control may be possible by combined use of ultrasonography with histochemistry and recent methods of reverse transcription of RNA into DNA (Schultz,1990).

c) Foetal-maternal interaction:

Ultrasonography has been used to understand the mechanism of epithelial-chorial placentation in ewes. In ewes 60-80 concave carundes were differentiated . In doe this number was more 160-180. Evidence of caruncular development could be undertaken in future, using real-time , freezed mode imaging systems. The study of fluid dynamics in relation to expanding vehicle may help cur understanding of the foeto-maternal relationship in future.

d) Detection of early pregnancy and embryonic motility:

Using a 5 MHz rectal probe pregnancy was detected as early as day 20 post mating. On screen such pregnancies produce an image resembling small pockets of fluid ventral and anterior to bladder. Embryonic death in an ewe too was captured on avideo attached to ultrasonography (Buckreli, 1980). Between 40-50 days post mating accuracy % has been near 100% with these B-mode systems.

References:

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