ANORECTAL-MALFORMATIONS - EXPERIENCE FROM A PEDIATRIC-SURGERY UNIT INSAUDI-ARABIA

Objective: To investigate the association between spontaneous preterm birth and placental histology at high and low altitude. Design: Crosss ectional randomized prospective study. Setting: Mohayel (500 meters ab ove sea level) and Abha (3,100 meters above sea level), cities in sout hern Saudi Arabia. Subjects: Pregnant Saudi women living permanently a t the areas of study and placentae from spontaneous preterm birth with out an obvious cause, Methods: Paraffin sections of the placenta were stained by Periodic Acid Schiff, Hematoxyllin and Eosin for identifica tion of cytotrophoblastic cells and syncytial knots respectively by th e light microscopy. The volume fraction of the fetal capillary lumina and stromal tissue of the terminal villi was performed by the image an alyser. Results: The total percentage of preterm birth was 1.93% at lo w altitude compared to 4.41% at high altitude (p<0.01). The percentage of preterm births without an apparent cause was 1.3% at low altitude compared to 3.3% at high altitude (p<0.01). The histology of the termi nal villi of placentae, comparing high with low altitude, showed, resp ectively, syncytial knots in 45.4% and 13.1% (p<0,001) and cytotrophob lastic cells in 52.7% and 28.6% (p<0.001) of the villi. In addition, c omparing high to low altitude, there was a significant fail in the fra ctional volume of their stromal tissue (p<0.001) and an equivalent ris e in the fractional volume of their foetal capillary lumina ((p<0.005) . Conclusion: It is concluded that stimulation of syncytial knots form ation, persistence of villous cytotrophoblastic cells and hypercapilla risation are features of placental hypoxia. Since, it is known that pl acental hypoxia is associated with increased incidence of spontaneous preterm birth, it is suggested that high altitude may be involved in t he aetiology of spontaneous preterm birth.