Performance of a handheld point of care ultrasonography to assess IUD position compared to conventional transvaginal ultrasonography

Figures & data

Figure 1. Photography of the POCUS Butterfly-iQ device connected to the smartphone used in this study. OB 1/GYN was the chosen preset.

Figure 2. Illustration of the IUD-myometrium distance used in the current study (dashed line in blue).

Table 1. Baseline characteristics of subjects.

Characteristics	Total (n = 70)	Copper IUD  (n = 46)	Hormonal IUD (n = 24)	p value
Age (years)	-	29.2 ± 6.8	31.5 ± 13.0	0.94
BMI (Kg/m^2)  <30  ≥30	- 43 27	28.2 ± 6.7 29 (67.4) 17 (63)	27.8 ± 4.3 14 (32.6) 10 (37)	0.45
Previous surgery*  no  yes	46 24	32 (69.6) 14 (58.3)	14 (30.4) 10 (41.7)	0.50
Clinical features  asymptomatic  pelvic pain^†  AUB^†	47 12 14	31 (66) 8 (66.7) 8 (57.1)	16 (34) 4 (33.3) 6 (42.9)	0.59

Data are given as mean ± standard deviation or n (%).

BMI, body mass index; AUB, abnormal uterine bleeding.

*Only previous infra umbilical laparotomy were considered

^†Three patients had both symptoms: pain and abnormal uterine bleeding

Table 2. Detailed IUD position found by abdominal POCUS and conventional transvaginal US.

			Conventional US
	100% within the uterine cavity (n = 56)	<50% within the cervical canal (n = 6)	≥50% <100%  within the cervical canal (n = 3)	100% within the cervical canal (n = 4)	in the myometrium (n = 1)
POCUS
100%  within the uterine cavity  (n = 55)	54	1	–	–	–
<50% within the cervical canal  (n = 5)	1	4	–	–	–
≥50% <100% within the cervical canal  (n = 3)	–	–	3	–	–
100%  within the cervical canal  (n = 4)	–	–	–	4	–
in the myometrium*   (n = 3)	1	1	–	–	1

*IUDs embedded in the myometrium.

Table 3. Diagnostic performance of abdominal POCUS in predicting IUD malposition.

	Sens (%) (95%CI)	Spec (%) (95%CI)	PPV (%)	NPV (%)	Accuracy (%)
Malpositioned IUD	92.9 (66.1–99.8)	96.4  (87.7–99.6)	86.7	98.2	95.7

Sens, sensitivity; Spec, specificity; PPV, positive predictive value; NPV, negative predictive value; CI, confidential interval.

Table 4. Agreement between abdominal POCUS and conventional transvaginal US in detecting IUD position.

Type of comparison	Agreement (%)	Cohen's Kappa	p value
Copper IUD* (n = 46)	97.8	0.95	0
Hormonal IUD* (n = 24)	87.5	0.22^§	0.026
Overall IUDs*^† (n = 70)	95.7	0.87	<0.01
Detailed IUDs position evaluation^‡ (n = 70)	94.3	0.84	<0.01

*100% within the uterine cavity vs all malpositioned IUDs.

^†Copper and hormonal IUDs.

^‡Agreement between all the following IUD positions: 100% within the uterine cavity, <50% within the cervical canal, ≥ 50% <100% within the cervical canal, 100% within the cervical canal, and embedded in the myometrium.

^§The low prevalence of the condition in this group (only 2 malpositioned hormonal IUDs) might have affected the kappa statistic.

Figure 3. Ultrasonographic images. A - copper IUD entirely within the uterine cavity in a retroverted uterus by both POCUS (A1) and conventional US (A2); B - hormonal IUD entirely within the uterine cavity in an anteverted uterus by both POCUS (B1) and conventional US (B2). The top and the distal end of the IUDs are indicated by yellow arrows.

Figure 4. Ultrasonographic images. C - copper IUD entirely within the cervical canal by both POCUS (C1) and conventional US (C2); D - copper IUD embedded in the myometrium by both POCUS (D1) and conventional US (D2). The top and the distal end of the IUDs are indicated by yellow arrows. Asterisks indicate the fundal region of the endometrial cavity.

Figure 5. Ultrasonographic images. E - hormonal IUD identified as entirely within the uterine cavity by POCUS (E1) and the same IUD with a small portion within the cervical canal identified by conventional US (E2); F - a small part of a copper IUD apparently within the cervical canal found by POCUS (F1) and the same IUD entirely within the uterine cavity by conventional US (F2). The top and the distal end of the IUDs are indicated by yellow arrows. In the image F1, the proximal portion of the string was probably mistaken for the end of the IUD.

Figure 6. The concordance plot of IUD-myometrium distance between POCUS and conventional US.

Table 5. Case-by-case differences in IUD-myometrium distance and subjective impression for low-lying IUDs found by POCUS and/or conventional US.

	POCUS		Conventional	US
Low-lying IUDs	Distance* (mm)	Subjective impression	Distance* (mm)	Subjective  impression
Case 1	12	above internal os	12	above internal os
Case 2	16	above internal os	14	above internal os
Case 3	17	above internal os	–	<50% cervical canal
Case 4	12	above internal os	9.5	above internal os
Case 5	6.1	above internal os	13.9	above internal os
Case 6^†	–	myometrium	12	above internal os

*The distance from the top of the IUD to the myometrium including the endometrium tissue.

^†In case 6, conventional US did not confirm a portion of the IUD embedded in the myometrium.

Table 6. Clinical and ultrasound features that may affect the agreement between abdominal POCUS and conventional transvaginal US.

	Categories	Agree (%)	Do not agree (%)	p value
IUD type	copper (n = 46)	45 (97.8)	1 (2.2)	0.11
	hormonal (n = 24)	21 (87.5)	3 (12.5)
BMI	<30 (n = 43)	42 (97.7)	1(2.3)	0.29
	≥30 (n = 27)	24 (89.3)	3 (10.7)
Previous  laparotomy	0(n = 46)	43 (93.5)	3 (6.5)	1
	≥1(n = 24)	23 (95.8)	1 (4.2)
Uterine volume*	<110 (n = 51)	50 (98)	1 (2)	0.058
	≥110 (n = 19)	16 (84.2)	3 (15.8)
Endometrial thickness*	non-measurable (n = 9)	8(88.9)	1 (11.1)	0.39
	<7mm (n = 14)	13(92.9)	1 (7.1)
	>7mm (n = 47)	45 (95.7)	2 (4.3)
Uterine version	anteversion (n = 61)	57 (93.4)	4 (6.6)	0.73
	midline (n = 5)	5 (100)	0
	retroversion (n = 4)	4 (100)	0

Agreement between all the following IUD positions: 100% within the uterine cavity, <50% within the cervical canal, ≥ 50% <100% within the cervical canal, 100% within the cervical canal, and embedded in the myometrium.

BMI, body mass index.

*Considering the measurements evaluated by the POCUS.