Ovarian Tumor Index of Twickler et al for Predicting the Risk of Malignancy

Description

The Ovarian Tumor Index can be used to estimate the risk of malignancy in small ovarian tumors.

Parameters:

(1) age of the patient

(2) ovarian volume

(3) morphology score from Sassone scale

(4) Doppler pulsatility index

(5) location of blood vessels

(6) intensity of echoes

Parameter	Finding	Points
patient age	age in years	age in years
ovarian volume	volume in mL	volume in mL
morphology scale of Sassone et al	4 - 15	4 - 15
Doppler pulsatility index (PI)		(-10 * (PI))
vessel location	peripheral	-10
	central or septal	+10
intense echoes	absent	0
	present	-10

where:

• The ovarian volume for tumors studied ranged from a few mL to about 70 mL (the volume data is only given as mean +/- SD). The volume of larger tumors would dominate the index. Some benign ovarian tumors can be quite large, so false positive diagnoses of tumor could be returned based on volume if not upper limit set.

• The volume of an ellipsoid = (x axis) * (y axis) * (z axis) * π / 6, where each axial measurement is the entire length along the axis (as opposed to the semiaxis).

• The morphology scale of Sassone et al (Table I) is reported as having values from 1 to 15, but minimum score is 4.

• Scoring of vessel location is a little unclear to me. Option 1 is that either one or the other value used (option implemented) while option 2 is that both could occur giving a value of 10 - 10 = 0.

ovarian tumor index =

= (points for age) + (points for volume in mL) + (points for morphology scale of Sassone et al) + (points for pulsatility index) + (points for vessel location) + (points for echoes)

Interpretation:

• The higher the index, the greater the risk for malignancy.

Ovarian Tumor Index	Percent Malignant
19	2%
28	4%
34	6%
39	8%
42	10%
45	12%
47	14%
50	16%
52	19%
53	20%
55	22%
57	25%
58	26%
59	27%
61	30%
62	32%
63	33%
65	37%
66	38%
67	40%
68	42%
69	44%
70	45%
71	47%
73	51%
74	53%
75	54%
76	56%
77	58%
78	60%
79	61%
81	65%
82	66%
83	68%
84	69%
86	72%
87	74%
89	77%
90	78%
92	80%
94	82%
96	84%
98	86%
100	88%
103	90%
107	92%
111	94%

When plotted out this data gives a cumulative distribution curve.

probability for scores less than or equal to 50 =

= (0.0001899 * ((index)^3)) - (0.007252 * ((index)^2)) + (0.23435 * (index)) - 1.11436

probability for scores 50 to 61 =

= (1.23529 * (index)) - 45.588

probability for scores 61 to 70 =

= (1.6958 * (index)) - 73.4708

probability for scores 70 to 81 =

= (1.79348* (index)) - 80.228

probability for scores 81 to 90 =

= (1.49338 * (index)) - 56.185

probability for scores greater than or equal to 90 =

= (-0.000275 * ((index)^3)) + (0.0630469 * ((index)^2)) - (3.5418 * (index)) + 86.559

To read more or access our algorithms and calculators, please log in or register.

Description

Specialty

ICD-10

Ovarian Tumor Index	Percent Malignant
19	2%
28	4%
34	6%
39	8%
42	10%
45	12%
47	14%
50	16%
52	19%
53	20%
55	22%
57	25%
58	26%
59	27%
61	30%
62	32%
63	33%
65	37%
66	38%
67	40%
68	42%
69	44%
70	45%
71	47%
73	51%
74	53%
75	54%
76	56%
77	58%
78	60%
79	61%
81	65%
82	66%
83	68%
84	69%
86	72%
87	74%
89	77%
90	78%
92	80%
94	82%
96	84%
98	86%
100	88%
103	90%
107	92%
111	94%

Ovarian Tumor Index	Percent Malignant
19	2%
28	4%
34	6%
39	8%
42	10%
45	12%
47	14%
50	16%
52	19%
53	20%
55	22%
57	25%
58	26%
59	27%
61	30%
62	32%
63	33%
65	37%
66	38%
67	40%
68	42%
69	44%
70	45%
71	47%
73	51%
74	53%
75	54%
76	56%
77	58%
78	60%
79	61%
81	65%
82	66%
83	68%
84	69%
86	72%
87	74%
89	77%
90	78%
92	80%
94	82%
96	84%
98	86%
100	88%
103	90%
107	92%
111	94%

Ovarian Tumor Index	Percent Malignant
19	2%
28	4%
34	6%
39	8%
42	10%
45	12%
47	14%
50	16%
52	19%
53	20%
55	22%
57	25%
58	26%
59	27%
61	30%
62	32%
63	33%
65	37%
66	38%
67	40%
68	42%
69	44%
70	45%
71	47%
73	51%
74	53%
75	54%
76	56%
77	58%
78	60%
79	61%
81	65%
82	66%
83	68%
84	69%
86	72%
87	74%
89	77%
90	78%
92	80%
94	82%
96	84%
98	86%
100	88%
103	90%
107	92%
111	94%