Real-time ultrasonographic analysis of the normal postpartum uterus: technique, variability, and measurements.

Abstract

We evaluated normal uterine involution prospectively with real-time ultrasonography in 100 women after uncomplicated term vaginal delivery. Transducers easily distorted the spongy uterus during early postpartum scanning, an effect minimized with sector transducers that are superior to linear or convex probes for accurate early postpartum uterine measurement. Long-axis measurements correcting for uterine angulation were the most reproducible and accurate, irrespective of bladder distention. Uterine T o our knowledge, only three studies have addressed ultrasonographic measurement of normal postpartum uterine dimensions. 1-J Since only static scanners were utilized in these studies, the reported dimensions bear uncertain relevance to real~time ultrasonography owing to two factors: (1) The long axis of the postpartum uterus often is oriented obliquely rather than parallel to the sagittal plane of the body." Imaging in standard orthogonal planes may therefore underestimate the true sagittal uterine dimension. (2) Our initial real-time ultrasono--graphic observations indicated that the early postpar- contractions caused instability of particularly the transverse dimension. Increasing maternal parity was associated with slightly but significantly larger uterine dimensions up to 4 weeks post partum. The uterus reassumed nongravid dimensions by 6 to 8 postpartum weeks. Uterine involution was unrelated to infant birth weight or breast feeding. KEY WORDS: Uterus, ultrasonography; Uterus, size; Puerperium; Uterine involution; Obstetrics, ultrasonography; Pregnancy, ultrasonography. tum uterus is highly susceptible to distortion from trivial pressure applied via hand-held transducers as opposed to articulated-arm probes that glide across the abdominal skin surface without producing distortion.In each of the cited studies the sagittal dimension apparently was measured without correction for an~ gulation of the uterus as it arches over the sacral promontory in the early postpartum period. l -3 Moreover, uterine dimensions were markedly discrepant between studies, particularly the mean sagittal dimension, which varied from 17.3 to 21.2 cm in the early postpartum period.t. 2 In two studies the sagittal dimension was measured from the fundus to the internal cervical OS,2.3 apparently excluding the cervix, which was incorporated into the sagittal measurement in the other study. 1 Citing unspecified effects of bladder distention on uterine measurements, previous investigators scanned subjects at varying degrees of bladder fullness ranging from emptyJ to moderately distended' to full.

Attempt to quantify uterine involution using acoustic radiation force impulse before and after placental delivery

“…Sonography is frequently used during pregnancy to image shape. Wachsberg et al [6] sonographically evaluated normal uterine involution in 100 women after uncomplicated term vaginal delivery. They found that uterine involution was unrelated to the infant's birth weight and breast-feeding, although higher parity was associated with slightly larger uterine dimensions.…”

Sonographic Evaluation of the Puerperal Uterus: Correlation with Manual Examination

“…Wachsberg et al [3] sonographically evaluated normal uterine involution in 100 women after uncomplicated term vaginal delivery. They found that uterine involution was unrelated to the infant's birth weight and breast-feeding, although higher parity was associated with slightly larger uterine dimensions up to 4 weeks postpartum.…”

Ultrasound assessment of the effect of parity on postpartum uterine involution

“…Breastfeeding appears to be the most widely studied of these factors with regard to its effects on uterine involution (Bruce et al, 1991;Galli et al, 1993;Wachsberg et al, 1994;Cluett et al, 1997).…”

“…Several factors have been suggested as having an effect on the rate of uterine involution including breastfeeing (Galli et al, 1993;Wachsberg et al, 1994;Cluett et al, 1997), parity (Galli et al, 1993;Wachsberg et al, 1994), caesarean section (Galli et al, 1993) premature rupture of the membranes (Tsenov and Krusteva, 1995) and infant birth weight (Wachsberg et al, 1994). Breastfeeding appears to be the most widely studied of these factors with regard to its effects on uterine involution (Bruce et al, 1991;Galli et al, 1993;Wachsberg et al, 1994;Cluett et al, 1997).…”