GUINEA PIG FETUS DOES NOT CHANGE ITS PRESENTATION DURING SECOND HALF OF GESTATION

Abstract

Objectives: The aims of this paper are: 1. To investigate spontaneous changes in fetal presentation during the second half of gestation in guinea pig fetus, 2. to observe provoked changes of fetal presentation, by passive positioning fetus into an upside-down position and “sitting” position. Eight fetuses from singleton pregnancies were included. Experimental design: Ultrasound examinations (Toshiba Nemio SSA-550A apparatus) were started on the 26th day of gestation (GD). Each fetus was examined 2-3 times in each 5-day interval until the end of gestation. First the spontaneous orientation of fetus was determined by tracking along the longitudinal and transversal axes of the fetus with the ultrasound probe. Then the fetus was brought into a head-down position relative to gravity for 5 minutes. The examination was repeated with the fetus in the head-up position. Results: In the period from the 26th – 30th GD in 7 of 21 observations spontaneous changes of presentation were observed. From the 31st GD all 133 observations were negative regarding spontaneous changes of presentation and situs. The chi-squared test showed that difference in spontaneous changes of presentation and situs before versus after 30th day of gestation had a statistical significance (χ² = 25.16 p 0.05). Fetuses were brought into a head-down and head-up 154 times. In none of these attempts did a fetus change presentation during the five minutes of observation. Conclusion: Guinea pig fetuses do not spontaneously or at provocation change presentation after 30th GD. Key words: fetal presentation; gestation; guinea pig; ultrasound PLODOVI MORSKIH PRAŠIČKOV NE SPREMENIJO LEGE V DRUGI POLOVICI BREJOSTI Namen prispevka je: 1. raziskati spontane spremembe v legi plodu v drugi polovici brejosti pri plodovih morskih prašičkov; 2. opazovati vzpodbujene spremembe lege plodov v položaj od zgoraj-navzdol in v »položaju sedenja«.V raziskavo je bilo vključenih osem plodov iz ene brejosti. Z ultrazvočnimi pregledi (aparat Toshiba Nemio SSA-550A) smo pričeli 26. dan brejosti. Vsak plod je bil pregledan 2-3-krat v 5-dnevnih razmikih do konca brejosti. Najprej je bila ugotovljena spontana orientacija plodu z določanjem njegove vzdolžne in prečne osi z ultrazvočno sondo. Potem je bil plod za 5 minut obrnjen v položaj z glavo navzdol, sorazmerno s težo. Pregled plodu je bil ponovljen v položaju z glavo navzgor. V obdobju od 26. do 30. dneva brejosti smo v 7 od 21 opazovanj opazili spontane spremembe lege plodu. Od 31. dneva brejosti dalje pri vseh 133 opazovanjih ni bilo opaziti spontanih sprememb lege plodu. Analiza Hi-kvadrat je pokazala, da je razlika v spontanih spremembah lege plodu pred in po 30. dnevu brejosti statistično značilna (χ² = 25,16 16 p <0,05). Pogostnost ultrazvočnih preiskav pred in po 30. dnevu brejosti ni bila statistično značilna (Fisherjev natančni Hi-kvadrat test p = 0,46). Plodovi so bili postavljeni v položaj z glavo navzdol in navzgor 154- krat. V nobenem od teh poskusov ni prišlo do spontane spremembe lege plodu med petminutnim opazovanjem. Ti rezultati torej kažejo, da plodovi morskih prašičkov ne spremenijo lege spontano ali po provokaciji po 30. dnevu brejosti. Ključne besede: sprememba lege plodu; brejost; morski prašiček; ultrazvok