The Anterior Pelvic Index (API) in the Classification of the Female Pelvis and Prediction of Fetopelvic Disproportion / El Índice Pelviano Anterior (API) en la Clasificación de la Pelvis Femenina y Predicción de la Desproporción Fetopélvica

SUMMARY: Measurements of the upper strait of the pelvis can be calculated using the Anterior Pelvic Index. The objective of the study was to determine the external validity and cut-off point of the API, to classify narrow pelvises from normal ones. We selected 214 women from 15 to 55 years old, 171 had vaginal delivery and 43 by caesarean section by feto-pelvic disproportion (FPD) of maternal origin, in whom the API was calculated, of which its mean difference was established with an alpha error of <0.05. Maximum values of sensitivity and specificity, ROC curve and Youden index were determined. The student's t gave a p-value =0.000 of the mean difference between the women who had vaginal delivery and those who had cesarean section by FPD of maternal origin; the value of the area under the ROC curve was 0.758 (CI 95% 0.695 - 0.814) with a p-value=0.0001. Maximum sensitivity was 74.42 % (CI 95%: 58.8 % to 86.5 %) and maximum specificity was 73.10 % (CI 95%: 65.8 % to 79.6 %), produced a Youden index of 0.475 (CI 95% 0.283 - 0.590) which is associated with the 15.44 (CI 95% 14.19 - 15.83) of the API scale. The API is a good tool for predicting women with suspected narrow pelvis and allows its classification into three types of pelvises: an API value of more than 15.83 would indicate pelvis suitable for vaginal delivery; an API value between 14.19 and 15.83 would be suspected of pelvic narrowness; an API value less than 14.19 would confirm a narrow pelvis.

Las medidas del estrecho superior de la pelvis pueden calcularse mediante el Índice Pelviano Anterior. El objetivo del estudio fue determinar la validez externa y el punto de corte del API, para clasificar pelvis estrechas de las normales. Seleccionamos 214 mujeres de 15 a 55 años, 171 tuvieron parto vaginal y 43 mediante cesárea por DFP de origen materno, en quienes se calculó el API, del cual se estableció su diferencia de medias con un error alfa de <0,05. Se determinaron valores máximos de sensibilidad y especificidad, curva ROC e índice de Youden. La t de Student dio un p-valor=0,000 de la diferencia de medias entre las mujeres de tuvieron parto vaginal y las que fueron sometidas a cesárea por DFP de origen materno; el valor del área bajo la curva ROC fue 0,758 (IC 95% 0,695 - 0,814) con un p- valor=0,0001. La máxima sensibilidad (74,42 %. IC 95%: 58,8 % a 86,5 %) y máxima especificidad (73,10 %. IC 95%: 65,8 % a 79,6 %), produjeron un índice de Youden de 0,475 (IC 95% 0,283 - 0,590) el cual está asociado al valor 15,44 (IC 95% 14,19 - 15,83) de la escala del API. El API es una buena herramienta de predicción de mujeres con sospecha de pelvis estrecha y permite su clasificación en tres tipos de pelvis: un valor de API de mas de 15,83 indicaría pelvis aptas para un parto vaginal; un valor de API entre 14,19 y 15,83 se sospecharía de estrechez pélvica; un valor de API menor a 14,19 confirmaría una pelvis estrecha.

The Pelvic Changes of Patients with Down Syndrome in Korea

PURPOSE: Since Caffey et al. first described the anomaly in pelvis among the Down patients, decreased iliac and pelvic indexes have been helpful in diagnosing the syndrome. For Korean cases, however, no definitive data are available as yet, prompting us to evaluate the pelvic changes in Korean Down's patients. METHODS: Subjected to this study were 68 children with Down's syndrome. As the control group served 126 patients with other diseases that do not affect the pelvis. The acetabular angle (AA) and the iliac angle (IA) were measured, and the iliac and pelvic indexes wer calculated from the following equations : Iliac index (Ii) = X + Y: pelvic index (Pi) = 0.3X + 0.42Y (where X is the mean of both acetabular angles, and Y is the mean of both iliac angles) RESULTS: 1) The sex ratio of the patients was 1.5 to 1, male prepondering. Their ages ranged from 1 day to 13 years, with the mean of 9.5 months, the majority (55.9%) falling under 1 month. The karyotype most frequently found in them was 21-trisomy (97%), followed by translocation (3%). 2) The AA of the Down patients was 18.49+/-4.92 (M+/-SD), significantly lower than that of the control group with 25.21+/-5.73; and the IA of the affected measured 43.53+/- 5.97, also signficantly (p<0.001) lower than the control (52.68+/-7.93). 3) The Ii and Pi of the Down groups were calculated as 62.01+/-9.04 and 23.83+/-3.38; both values were significantly lower than those of the control with 77.87+/-11.28 and 29.69+/-4.26, respectively. 4) The maximum likelihood estimate of Ii for Down syndrome was found to be 64, and at that level, the specificity 87.30%, and the sensitivity 66.18%. 5) In the Neonatal and infantile period, all parameters of Down syndrome were very significantly lower values when compared with those of the control of corresponding age In the childhood age, however, the AA of both groups did not significantly differ from each other, but the Down children had significantly lower values in the other parameters. The Ii decreased in relation to the increasing age in the control group, while no significant correlation was noted in the Down patients. 6) In the control group, a significant gender difference was found in the Ii, with females having higher values. In the Down patients, however, both sex did not significantly differ in the Ii. CONCLUSIONS: Decreased iliac and pelvic indexes manifested in Korean Down cases were quantitively evaluated in this study and it was found that an iliac index below 64 strongly supports the diagnosis of Down syndrome. For the Down cases, the Ii did not signficantly correlate with age, nor did both sexes differ in the Ii, in contrast to the control group which showed an age-related decrease and higher female values.