To describe prospectively the normal abdominal and pelvic ultrasound features within 24 h following uneventful Cesarean section. Transabdominal ultrasound examination was performed between 1 and 3 h, and again at 24 h, following lower-segment Cesarean section (LSCS). The myometrium, endometrium, and amount and distribution of free peritoneal fluid were studied in 30 women with singleton pregnancies who underwent LSCS delivery. Examinations were performed easily in all cases except one who was morbidly obese (body mass index > 40 kg/m(2)). At 1-3 h after delivery, mean +/- SD endometrial thickness was 13 +/- 2 mm. Mean uterine length, from the fundus to the cervical external os, was 160 +/- 15 mm. Measurement of uterine length in the mid-sagittal plane of the pelvis was impossible in eight cases (27%) owing to pain. No abnormal intrauterine findings were observed. Mean uterine width was 110 +/- 10 mm. Mean distance between the sacral promontory and uterine fundus was 104 +/- 11 mm. Mean thicknesses of the anterior and posterior walls of the uterus were 40 +/- 5 mm and 39 +/- 7 mm, respectively. No fluid was seen in Morrison's or Douglas' pouches. There was a consistent and significant reduction between the measurements performed at 1-3 h and those at 24 h after LSCS, except for the distance between the fundus and external os. Ultrasound examination is feasible after Cesarean section. Images are obtained easily, even when scanning through the scar. In normal pregnancies, there is no fluid in the abdomen or pelvis. These results could help clinicians in the decision-making process in cases of early postpartum hemorrhage or hemodynamic instability following LSCS.