Significance of ultrasound pelviometry in the diagnostics of anatomical and clinical narrow pelvis

Rational management of labor with a narrow pelvis is one of the most difficult sections of practical obstetrics, because narrow pelvis is the main cause of birth trauma and childhood disability.

The aim of the study was to determine significance of ultrasound pelviometry in the diagnostics of anatomical and clinical narrow pelvis. On the basis of maternity hospitals of Trans-Baikal Region in the years 2013-2017 was held retrospective and prospective analysis of 150 labor histories, which were divided into 3 equal groups: group 1 – pregnant women with normal sizes of the large pelvis, group 2 – pregnant women with macrosomia, group 3 – pregnant women with a reduced sizes of the large pelvis. Ultrasonic pelvimetry included measurement of direct and transverse sizes of the planes of the pelvic cavity and the angle of the pubic arc through the integrated use of abdominal, transvaginal and translabial sensors of ultrasound machine Toshiba Aplio 500. In the group of pregnant women with normal sizes of the large pelvis frequency of diagnosis of anatomical narrow pelvis used by ultrasound pelvimetry is 32%. In the group of pregnant women with macrosomia is dominated the normal size of the pelvic cavity (62%) and “wide pelvis” (18%). In 20 % of cases the diagnosis of anatomical narrow pelvis in group 3 was not confirmed by the data of ultrasonic pelvimetry. The most common forms of the narrow pelvis were the transversal pelvis (46%), the simple flat pelvis (14%), the uniformly narrow pelvis (10%). On the basis of mathematical modeling defined pattern, which is expressed by the formula:

where AE – angle extension of the head, PC – angle of the pubic arc, TD1 – transverse size of the plane of the entrance, TD2 – transverse size of the plane of the output, FD1 – direct size of the plane of the entrance, FD2 – direct size of the narrowest part of the pelvic cavity, GA – gestational age, BPD – biparietal size, OFD – fronto-occipital size of the fetus’s head. When the value of the coefficient less than 1 is projected clinically narrow pelvis (r2 = 0,92). Thus, ultrasonic pelvimetry allows to determine not only the size of the pelvic cavity, but also to predict clinically narrow pelvis.