ABSTRACT
To evaluate the strength of uterine scar in pregnancy following primary cesarean section [CS] and its effect on the mode of delivery, and subsequently to define the safe interval of pregnancy spacing after primary CS. Ninety cases were recruited from the outpatient clinic of Sohag University Hospital [SUH] during the period from Feb. 2005 to Jan. 2006. All had singleton pregnancy in the third trimester and previous one uncomplicated CS for a relative indication done in the emergency sector of SUH with no other risk factors in the current pregnancy. The patients were allocated into 3 groups, G I [13 patients] who got pregnant within 6 months after CS, GII [27 patients] who got pregnant 6 months to one year after CS, and G III [50 patients] who got pregnant after more than one year of CS. During every antenatal visit, in addition to the routine evaluation, ultrasonographic measurement of the lower uterine segment [LUS] was done and a thickness < 3 mm was considered to be abnormal according to Tanik et al [1996]. Elective CS was done for those with thin LUS [<3mm] or for those who developed other complications of pregnancy. Otherwise, patients were allocated for the trial of vaginal delivery. The patients characteristics showed that most of the patients were primiparous, noneducated and from rural areas with a mean age of 28 +/- 3.7. The LUS thickness at 36 weeks was found to have a thickness of <3mm in 9 cases [69%] of GI, 7 cases [26%] of GII and 5 cases [10%] of GIII. A LUS of >/= 3mm was detected in 4 cases [30%] of GI, 20 cases [74%] of GII and 45 cases [90%] of GIII; the differences were statistically significant. With regard to the mode of delivery, 92% of patients in GI were delivered by CS [elective+emergency] compared to 20% in GIII where 80% of patients were delivered vaginally, and the difference was statistically significant. This study can conclude that the interval of 6 months or more after CS can be considered safe for pregnancy to be allowed and the safety increases with more than one year interval. An interval of less than 6 months does not seem to be safe; the LUS is frequently too thin to stand for trial of vaginal birth. Sonographic measurement of the thickness of the LUS is considered a reliable method for determining the strength of the scar and the mode of delivery