Department of Obstetrics and Gynecology, Hammerfest Hospital, Hammerfest, Norway.
Ultrasound Obstet Gynecol. 2012 Jun;39(6):690-7. doi: 10.1002/uog.11104.
Normal anatomical and physiological development of the maternal anal canal during and after pregnancy has been documented scarcely. We aimed to study the position and volume of the anal canal, during and after pregnancy, in women without previous delivery.
This was a longitudinal study in which transvaginal three-dimensional ultrasound was used to measure anatomical structures in the anal canal during rest and squeeze in 23 nulliparous women. The total anal canal volume (ACV), anorectal curvature (ARC), anovaginal angle (AVA) and anal canal length were determined at 18, 28 and 36 weeks of pregnancy and at 3 months postpartum.
Total ACV at rest increased from a mean of 10.17 cm(3) at 18 weeks to 12.37 cm(3) and 12.21 cm(3) at 28 and 36 weeks, respectively (P = 0.001 and P = 0.010 vs. first measurement). For anal canal length, the corresponding mean measurements were 3.91 cm, 4.07 cm (P = 0.13) and 4.21 cm (P = 0.017). Postpartum, the mean total ACV was 10.86 cm(3) and length was 3.90 cm (P = 0.10 and P = 0.70 vs. first measurement). No significant changes were observed in ARC and AVA during or after pregnancy. Compared to at-rest status, the anal length significantly increased on voluntary squeeze (P = 0.007, 0.007, 0.022 and 0.004 at the four time points), while no differences in total ACV were observed. In mid-pregnancy AVA significantly increased during squeeze (P = 0.006 and 0.002 at weeks 18 and 28, respectively).
Anal canal length and total ACV increase during pregnancy in women without previous delivery. Voluntary squeezing elongates the anal canal and increases the angle formed with respect to the direction of the vagina. During postpartum involution, the characteristics of the anal canal revert to those observed at 18 weeks of pregnancy.
在怀孕期间和之后，母体肛门管的正常解剖和生理发育很少被记录下来。我们的目的是研究未经分娩的女性在怀孕期间和之后肛门管的位置和体积。
这是一项纵向研究，使用经阴道三维超声在 23 名未生育的女性中测量肛门管在休息和收缩时的解剖结构。在 18、28 和 36 周妊娠和产后 3 个月时，分别测量总肛门管容积（ACV）、肛门直肠曲度（ARC）、阴道肛角度（AVA）和肛门管长度。
休息时总 ACV 从 18 周的平均 10.17cm³增加到 12.37cm³和 12.21cm³，分别在 28 周和 36 周时（P = 0.001 和 P = 0.010 与第一次测量相比）。对于肛门管长度，相应的平均测量值分别为 3.91cm、4.07cm（P = 0.13）和 4.21cm（P = 0.017）。产后，平均总 ACV 为 10.86cm³，长度为 3.90cm（P = 0.10 和 P = 0.70 与第一次测量相比）。在怀孕期间和之后，ARC 和 AVA 没有观察到显著变化。与休息状态相比，肛门长度在自愿收缩时显著增加（在四个时间点 P = 0.007、0.007、0.022 和 0.004），而总 ACV 没有差异。在中期妊娠期间，在收缩时 AVA 显著增加（分别在 18 周和 28 周时 P = 0.006 和 0.002）。
在未经分娩的女性中，怀孕期间肛门管长度和总 ACV 增加。自愿收缩使肛门管伸长，并增加与阴道方向形成的角度。在产后萎缩期间，肛门管的特征恢复到妊娠 18 周时的特征。
